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Oral Presentations Friday O1±O74 O1 Multislice spiral CT and secondary reconstruction of the paranasal sinuses M. G. Mack, J. O. Balzer, M. Baghi, Scharhram Schafti, C. Herzog, T. J. Vogl Dept. of Radiology, University Hospital Frankfurt, Germany Purpose: To evaluate the diagnostic potential of multislice CT and secondary reconstructions for the work-up of pathologies of the paranasal sinuses. Materials and Methods: 179 patients were examined using a multislice CT (SOMATOM Plus 4, Siemens, Erlangen). Scans were performed exclusively in axial slice orientation. Multiplanar reconstructions (MPR) were performed in coronal, sagittal and interactive oblique orientations using the standard MPR software of the scanner. The visualization of the course of the nasolacrimal duct, the internal carotid artery, the optic nerve and all connections between the nasal cavity and the paranasal sinuses were evaluated. Results: Axial scanning and secondary reconstructions were sufficient for diagnosis and surgical planning in all patients. The most helpful reconstruction for planning surgery was the coronal reconstruction. 3 mm reconstructions were sufficient for detection of normal structures in most of the patients. To detect all normal structures and to follow and evaluate the course of the nerves, ducts, and arteries, interactive evaluation using standard and oblique MRPs was found to give the most precise diagnostic results. Conclusions: Axial multislice CT and secondary MPR were found to be an optimal imaging modality for the evaluation of the paranasal sinuses. O2 Navigation-CT for image-guided paranasal sinus surgery N. Husain, 2D. Holzmann, 1A. Valavanis, 1B. Schuknecht 1 Institute of Neuroradiology, University Hospital of Zurich, Switzerland 2 Dept. of Otorhinolaryngology, Head and Neck Surgery, University Hospital of Zurich, Switzerland 1

Purpose: To analyse the value of high resolution navigation CT for image-guided paranasal sinus surgery Patients and Methods: 15 patients were investigated by multi-slice spiral CT prior to paranasal sinus surgery. The acquired volume data set (4 ” 1 mm) was reconstructed with a high resolution bone algorithm of 1 mm slices at 0.5 mm increment. The data set was transferred to a workstation in the operation theatre. Using a laser pointer (ªz-touch, BrainLAB, Germany) the anatomy of the patient's midface and forehead was scanned and matched with the surface anatomy of the CT-data set. For navigation a handheld probe was linked to a marker sensor consisting of two infraredemitting cameras. Results: A high degree of accuracy was achieved between the position of the navigation probe and the corresponding orthogonal images in the axial, coronal and sagittal plane provided by the navigation system. The initial step of thorough scanning of the patient's surface anatomy by the z-touch laser proved crucial in the determination of subsequent anatomical accuracy. The immediate availability of three orthogonal image planes at any chosen point within the nasal cavity and paranasal sinuses during surgery facili-

tated orientation with respect to anatomical landmarks and thus increased the safety of the surgical procedure. Interactive delineation of the osseous anatomy at any point of surgery allowed safe progress in surgical resection along the frontal recess, ethmoid roof and orbital apex. Conclusions: The system facilitates topographical/anatomical orientation at any point during paranasal sinus surgery and thus aids in the prevention of potential complications. O3 Assessment of a CT/MR-based surgical navigation system in FESS of paranasal sinuses L. Palvarini, D. Farina, M. Trimarchi1, D. Lombardi1, R. Maroldi Dept. of Radiology and Otolaryngology1 ± University of Brescia, Italy Purpose: To assess the reliability of a real-time surgical navigation system (LandmarX) based on CT and MR images in FESS of paranasal sinuses. Materials and Methods: 10 patients who were candidates for FESS of the paranasal sinuses underwent a specific imaging protocol fitting the navigation system requirements. CT or MR (SET1 sequence) was performed on the axial plane, acquiring contiguous scans with 1±3 mm slice thickness. In each case, CT or MR images were reformatted by the software, reconstructing a 3D model of the patient's head. At least four landmarks (tragus bilaterally, tip of nose, glabella frontalis) were fixed on the cutaneous surface both in vivo and on CT/MR images, in order to obtain a correspondance between radiological and endoscopic anatomy. Accuracy checkpoints (medial wall of the bulla ethmoidalis, uncinate process, ground lamella of middle turbinate, cribriform plate) were chosen to match the position of the endoscopy in vivo and on CT/MR images, as referred by the navigation system. Results: In 36/40 examined checkpoints a precise correspondance was found; a mismatch of 2±3 mm occured in three cases (2/3 cribriform plate, 1/3 ground lamella) probably due to the onset of oedema during the surgical procedure. Conclusions: The LandmarX navigation system appears to be a reliable tool to guide FESS procedures, in particular through critical anatomical areas (sphenoid sinus, frontal recess) and may reduce the risk of iatrogenic complications. O4 CT characterization of inflammatory paranasal sinus disease in cystic fibrosis patients H. B. Eggesbù1, S. Sùvik2, S. Dùlvik3, F. Kolmannskog4 1 Department of Radiology, Aker Hospital, University of Oslo, 2Institute of Physiology, Department Group of Basic Medical Sciences, University of Oslo, 3Department of Otorhinolaryngology, 4Sentrum Rùntgeninstitutt, Oslo, Norway Purpose: In patients with cystic fibrosis (CF), paranasal sinus affection approaches 100 %. We hypothesized that the hyperviscous mucus that reduces mucociliary clearance in CF could give different sinonasal inflammatory patterns in CF patients than in non-CF patients. Hence we designed a prospective study to compare the extent and overall distribution of paranasal sinus disease and the inflammatory patterns in these two groups of patients. Patients and Methods: 108 CF patients (3±54 years of age) and 79 controls (7±51 years of age) with paranasal sinus disease confirmed upon coronal CT were compared. The extent of the disease was noted for each sinus and summed for all sinuses. Inflammatory patterns were identified and classified into 1) routine surgery group (sporadic, infundibular and ostiomeatal complex (OMC) patterns)

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and 2) complex surgery group (sinonasal polyposis and sphenoethmoid recess (SER) patterns). Results: CF patients had more widespread sinonasal inflammatory changes (p < 0.0001) and more advanced disease for each sinus (p < 0.01) than did controls. CF patients most often displayed sinonasal polyposis and SER patterns, while controls most often displayed sporadic, infundibular or OMC patterns. As a result, 67 % of CF patients were classified in the complex surgery group, compared to only 19 % of controls (p < 0.0001). Conclusions: CF patients have sinonasal inflammatory patterns that more often require extensive surgery, which implies a higher risk of CSF leakage and bleeding (sinonasal polyposis), or is located in areas that are more difficult to reach with the endoscope (SER pattern). O5 Chronic invasive paranasal sinus aspergillosis 1 N. Husain, 2D. Holzmann, 3D. Simmen, 1A. Valavanis, 1B. Schuknecht 1 Institute of Neuroradiology University Hospital of Zurich, Zurich, Switzerland 2 Dept of ENT Surgery University Hospital of Zurich, Zurich, Switzerland 3 ENT Center, Klinik Hirslanden Zurich, Zurich, Switzerland Purpose: To analyse and characterise the radiological appearance of chronic invasive paranasal sinus aspergillosis Patients and Methods: The imaging findings for 6 non-immunocompromised patients with an invasive type of paranasal sinus aspergillus infection were reviewed. Coronal/axial high-resolution contrast-enhanced CT scans were available for each of the patients, while MRI had been performed in 4 patients. Results: The imaging appearance of invasive aspergillus infection was entirely different from the imaging findings in aspergillus mycetoma and allergic aspergillus sinusitis. Invasive aspergillus infection was recognized as a focal infiltrative lesion originating within the sphenoid sinus in 4 patients and within the maxillary sinus in 2 patients. Infiltration affected the cavernous sinus in the former location, with concomitant involvement of the orbital apex and the pterygopalatine fossa in one patient each. In the two patients with maxillary sinus origin, infiltration affected the orbit and the pterygopalatine fossa respectively. MRI demonstrated the extent of infiltration to better advantage than CT. In all patients high resolution CT demonstrated the presence of both osteolysis and sclerosis at the point of penetration of the sinus wall. Conclusions: Invasive aspergillus infection may mimick a paranasal sinus neoplasm. MR and CT are thus required to provide radiologic clues.

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O6 The contribution of virtual laryngoscopy in the diagnosis of laryngeal cancer A. Fotinos, A. Michaelides, V. Maniatis, A. Papadopoulos, S. Kavadias, E. Kamarioti, C. Samara, G. Zois, K. Stringaris, Athens General Hospital ªG. Gennimatasº, Athens, Greece

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of the tumour. The results of helical CT and virtual laryngoscopy were compared, as was conventional endoscopy vs. virtual laryngoscopy. Results: In 13/13 patients, helical CT and virtual laryngoscopy demonstrated the presence of a laryngeal tumor. The histological diagnosis was laryngeal cancer in all patients. In 10/13 patients virtual laryngoscopy was superior to conventional endoscopy in estimating the tumour's intraluminal extent, while in 3/13 patients the results of the two methods were equivalent. In 13/13 patients helical CT provided information analogous to that provided by virtual laryngoscopy, while also giving important additional information (infiltration of cartilage, adjacent soft tissues and lymph nodes). Conclusions: Virtual laryngoscopy represents a simple non-invasive method for the diagnosis of laryngeal cancer. Additionally, helical CT provides complementary information on the extent of extraluminal tumours.

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O7 CT findings of laryngeal tuberculosis: a report on three cases and a review of the literature L. Vannucchi, L. Carmignani, *G. Borri, F. Niccolai, D. Gadda, A. Neri, *P. Calamandrei, P. Pacini U.O. Radiologia, * U. O. Otorinolaringoiatria Ospedale del Ceppo, Pistoia, Italy Purpose: To describe CT findings of laryngeal tuberculosis. Materials and Methods: During the last six months, three male patients (47±62) with dysphonia underwent neck CT examinations to define possible laryngeal neoplastic involvement. In all cases there was no evidence of lesions in chest radiographs. Laryngoscopy demonstrated swelling of the aryepiglottic folds (n = 3) and of the epiglottis (n = 2), and impairment of vocal cord mobility (n = 3). All patients underwent multislice CT examinations before and after i. v. administration of iodinated contrast medium. Results: CT revealed thickening of the aryepiglottic folds (n = 3) and of the free margin of the epiglottis (n = 2), and an irregular profile of the left vocal cord (n = 1). In one patient significant contrast enhancement of the left vocal cord and of the aryepiglottic folds was detected. No focal masses were demonstrated. Neither infiltration of the preepiglottic and paralaryngeal fat spaces nor cartilage destruction was seen. All patients presented bilateral cervical necrotic lymph nodes. Definitive diagnosis was made bacteriologically and histologically in all patients. Conclusions: The imaging and clinical features of laryngeal tuberculosis are varied and non-specific and frequently mistaken for those of carcinomas. Early diagnosis and therapy are required to avoid permanent loss of function or surgery. O8 Local intra-arterial chemotherapy in squamous cell carcinomas of the oral cavity 1 B. Turowski2, A. Kovµcs1F. E. Zanella 1 Institute of Neuroradiology University of Frankfurt, 2Department of Reconstructive maxillo-facial Surgery University of Frankfurt Frankfurt, Germany Purpose: Adjuvant local high-dose intra-arterial chemotherapy with cisplatin in a multi-modality regimen for the treatment of oral cancer is presented. Sodium thiosulfate (Na2S2O3) can inactivate cisplatin and was used as systemic neutralising agent. Materials and Methods: Between November 1997 and May 2000, 123 patients were treated consecutively for squamous cell carcinomas of the oral cavity (tumor stages I±IV) with intra-arterial chemotherapy, surgery and chemoradiation. A subgroup of 73 opera-

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ble, previously untreated patients was also studied. Kaplan-Meier analysis of recurrence-free survival was compared to the expected rate calculated with the therapy-dependent prognosis factor (TPI). Results: Remission was assessed clinically and with CT three weeks after chemotherapy. There were 9.6 complete remissions, 24.7 % partial remissions and no local tumor progression. Systemic sodium-thiosulfate protection was found to limit or even eliminate side-effects such as nausea and renal or bone marrow toxicity, thus resulting in an increased quality of life. The rate of recurrence-free survival for this multimodality therapy was 85 % after 30 months, as compared to an expected survival rate of 64 %. Conclusions: The efficacy of intra-arterial chemotherapy as an adjuvant therapeutic strategy for the treatment of oral squamous cell carcinomas was demonstrated. Moreover, due to a reduction in untoward side effects, this strategy allowed the preservation of quality of life when used as part of a multimodality treatment concept. O9 Effectiveness of MR in detecting subclinical recurrence in the followup of 30 treated oral cavity squamous cell carcinomas A. Marconi, L. Palvarini, F. Simeone, D. Farina, G. Battaglia, R. Maroldi Department of Radiology, University of Brescia, Brescia, Italy Purpose: To assess the accuracy of MR in detecting subclinical recurrences in patients treated by radical surgery and/or RT for malignant oral cavity neoplasms. Materials and Methods: Thirty patients were considered, all of whom had been previously treated either with radical surgery (6) or RT (10) alone, or with a combination of surgery and RT (14); all of the patients were affected with oral cavity squamous cell carcinomas (5T1, 12T2, 8T3, 5T4; 13N0, 6N1, 10N2, 1N3). The patients had clinical and radiological follow-up longer than 12 months (avg. = 25). Overall, 93 MR examinations were performed. Suspected relapses were confirmed by biopsy, FNAC or follow-up. Results: Twenty-one out of 93 MR exams were positive, 19/21 were confirmed by FNAC or surgery. In both false-positive cases, enhancing tissue (suspected as relapse) was not confirmed by pathology (granulation tissue). Among the seventy-two negative exams there were 3 false-negative studies: two were superficial lesions, while one was a recurrent tumor growing as a diffuse lesion rather than as a mass. The most relevant MR finding was the presence of a mass (SE 86.3 %). Bone destruction was detected in 5/22 (22.7 %). The sensitivity of MR was superior to the clinical evaluation (86.3 % vs. 68.1 %). The NPV of MR is significant (95.8 %). Imaging yielded a higher rate of FP (2.1 % vs. 1.1 %). Although the accuracy of MR was found to be superior to that of clinical examinations (94.6 % vs. 88.2 %), this difference was not statistically significant (chi square test , p > 0.11). Conclusions: During the follow-up of 30 patients treated for oral cavity squamous cell carcinoma, the overall prevalence of relapsing disease was very high (73.3 %), MR demonstrated 4 subclinical recurrences. O10 SPIO enhanced MRI for surgical planning M. G. Mack, J. O. Balzer, M. Baghi, R. Knecht, T. Vogl University Hospital Frankfurt, Frankfurt, Germany Purpose: To compare findings on SPIO enhanced MRI of the head and neck with resected lymph node (LN) specimens and to determine the effect of such imaging on surgical planning in patients with histopathologically proven squamous cell carcinoma of the head and neck.

Materials and Methods: Thirty patients were examined with noncontrast and intravenous Sinerem-enhanced MRI with T1 and T2 SE sequences and T2-weighted GE sequences to detect possible LN metastasis. Signal intensity decrease was evaluated by ROI measurements. Visual analysis was performed by 2 radiologists by consensus. Initial planning of surgery was based on clinical examination and ultrasound evaluation and was modified, if necessary, on the basis of the MRI findings. Resected LN were analyzed by a pathologist and the results obtained were compared with MR findings. Results: A total of 1029 LN were histopathologically evaluated. Of these, 69 were determined to be metastatic. MRI revealed 59 of the 69 LN metastases. The MR diagnosis was correct in 26 of the 27 patients who underwent surgery: only one LN metastasis was localized in level II by MRI, while histopathology placed it at level III. In 7 of 27 patients, the extension of surgery was changed after Sinerem-enhanced MRI. The best sequence for differentation between benign and malignant LN was the T2-weighted GE sequence. Conclusions: Sinerem-enhanced MRI can make a significant contribution to planning the extension of surgery. O11 Wait-and-see policy for the N0 neck in early-stage oral and oropharyngeal SCC using ultrasound-guided fine-needled aspiration cytology (USgFNAC). E. J. C. Nieuwenhuis, C. R. Leemans, vd Brekel, G. B. Snow, J. Castelijns Medical Center Vrije Universiteit, Amsterdam, The Netherlands Purpose: We describe the clinical outcome of patients with small oral or oropharyngeal carcinomas who underwent transoral tumor excision only and a wait-and-see policy for the neck including USgFNAC. Patients and Methods: The study group consisted of 161 patients with T1-T2 N0 HNSCC in the oral cavity or oropharynx. All patients had initial negative USgFNAC findings, and were therefore treated with transoral tumor excision only and an observation policy for the neck. Follow-up visits were performed every 6 weeks, including USgFNAC every 12 weeks. Results: Of the 161 patients, 34 (21 %) patients developed lymph node metastases in the neck within the 1 st (30) or 2 nd (4) year after transoral excision. All 34 patients were treated with therapeutic neck dissection, and 31 of these patients received postoperative radiotherapy based on histopathological findings. Twenty-seven out of 34 (79 %) patients were salvaged (follow-up 5±75 months), whereas 7 patients died of the disease. The regional control rate was 88 %. The number of tumor-containing lymph nodes and the presence of extranodal spreading in the 7 patients who died of the disease differed significantly from those in the 27 patients who were salvaged. Conclusion: USgFNAC at initial staging can considerably reduce the risk of occult metastases for T1-T2 SCC of the oral cavity or oropharynx. This finding justifies local excision of the tumor and a wait-and-see policy for the neck. The use of USgFNAC for followup enabled early detection of a significant percentage of neck failures and a high salvage rate upon therapeutic neck dissection. O12 MR Findings of inverted papillomas: does the ªcolumnar patternº depend on size? L. Palvarini, D. Farina, G. Battaglia, P. Maculotti, R. Piazza, R. Maroldi Departament of Radiology, University of Brescia, Brescia, Italy Purpose: To evaluate whether the demonstration by MR of the columnar pattern of inverted papillomas (IPs) depends on size of lesions.

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Materials and Methods: MR examinations of 15 patients affected by IPs (13 primary, 2 recurrent) were evaluated. All IPs arose from the lateral nasal wall apart from one arising from the septum. The size (maximum diameter) of the lesions was evaluated. Signal intensities on SET2 and SET1 were compared to muscles, enhancement to the nasal septum mucosa. Results: The size of the lesions ranged from 15 to 60 mm (avg. 34, median 30). All lesions were hyperintense on SET2 and isointense on SET1. In 14/15 IPs there was a strong enhancement, 1/15 showed lesser enhancement. In all IPs the enhancement was not homogeneous: a pattern of alternate hyper and less intense parallel striate framework was detected in all cases, regardless of size. The columnar pattern was demonstrated on SET2 in all lesions (10/15) with a maximum diameter greater than 2 cm (Pearson 0.67). Conclusions: The ªcolumnar patternº shown by IPs on both SET2 and enhanced SET1 reflects its histological framework, which is characterized by the repetition of a single basic pattern: stroma plus investing mucosa. Enhanced SET1 was found to be the most sensitive sequence in detecting this pattern. Conversely, the identification on SET2 appears related to the size of the IP. O13 Comparison of an iodinated contrast agent with a comparably radiopaque but more viscous barium suspension in the detection of pharyngeal perforation: how important is the viscosity? M. Keberle, G .Wittenberg, A. Trusen, W. Baumgartner, D. Hahn Institut für Röntgendiagnostik der Universität Würzburg, Würzburg, Germany Purpose: In contrast to esophageal perforations, more radiopaque barium-suspensions are not as important as iodinated aqueous contrast agents for the detection of pharyngeal perforations. This study was performed to find out whether the highly different viscosities of the agents used are a reason for this. Materials and Methods: Viscosity, subjective difference in contrast, and CT-density of an iodinated aqueous (Telebrix) and a 50 % (wt/ vol) barium-containing contrast agent (Micropaque) were determined. Moreover, to exclude postoperative perforation, 104 patients were prospectively examined by pharyngography using both contrast media. Pharyngographies of patients with perforation were later compared by two independent readers. All patients with perforation were followed up clinically to exclude complications due to barium application. Results: In vitro comparison showed comparable radiopacity but the 50 % (wt/vol) barium suspension was much more viscous than the iodinated contrast agent (12.7 vs. 6.6 mPas at ambient temperature). During pharyngography, 14 perforations were clearly delineated with the iodinated aqueous contrast agent. However, two of them were not detected with the barium suspension. All the other perforations were detected equally well with the two agents. Conclusions: Given a sufficient radiopacity, a low viscosity appears to be essential for a contrast agent, especially in the detection of pharyngeal perforation. Thus, we recommend the sole use of an iodinated contrast agent for this purpose in cases involving suspicion of aspiration as isoosmolar variant. O14 Meningiomas with extension to the infratemporal fossa D. Haba 1, F. Veillon 2, S. Riehm 2, C. Aldescu 1, J. Tongio 2 1 University of Medicine and Pharmacy ªGr.T.Popaº, Iasi, Romania 2 Hopital de Hautepierre, Strasbourg, France Purpose: The aim of this study was to describe the CT and MRI findings in meningiomas of the middle cranial fossa with an extension to the infratemporal fossa.

Materials and Methods: We report six cases (all women) with meningiomas of the cranial fossa studied with CT (n = 5) and MRI (n = 4). The different pathways for meningioma development in the infratemporal fossa, i. e. the foramen ovale and foramen rotundum, were analyzed. Results: In all cases, the meningioma originated in the middle cranial fossa and presented an extension into the infratemporal fossa through the foramen ovale. Mucosal invasion was observed in three cases. An extension to the middle ear was observed in five cases. In four cases an important reduction in the diameter of the internal carotid artery was found. Conclusions: Understanding the different pathways of extension of meningiomas of the middle cranial fossa with involvement of the infratemporal fossa, of the parapharingeal space and the middle ear is essential to medical and surgical treatment. MRI allowed a better delineation of the perineural and mucosal invasion better than did CT. O15 CT and MRI evaluation of pterygopalatine and infratemporal fossa pathologies 1 D. Haba, 2F. Veillon, 2S. Riehm, 2J. Tongio 1 University of Medicine and Pharmacy, Iasi, Romania 2 Hopital de Hautepierre, Strasbourg, France Purpose: The aim of this study was to classify the CT and MRI features of lesions of the pterygopalatine (PPF) and infratemporal fossa (ITF) and thus contribute to the detection and diagnosis of these lesions. Patients and Methods: 95 patients with lesions of the PPF and ITF were studied with CT and MRI. Lesion origins were classified in three groups: A) origin in one or both fossae; B) origin in other oral and maxillofacial regions but involving the PPF and ITF; C) multicentric origins. Results: In group A (n = 4) delineation was found to be confined with both CT and MRI and involvement of the adjacent structures was shown on MRI in all patients. In group B (n = 88), CT and MRI revealed 8 lesions in the PPF, 44 lesions in the ITF and 38 lesions involving both fossae through different routes. Group C (n = 3) had lesions affecting one PPF and 2 patients had lesions involving both fossae. Conclusions: The lesions in group A involved the adjacent structures in every direction. Those in group B had different pathways of involvement in the PPF or ITF. Both CT and MRI is very useful in the detection and diagnosis of these lesions; however, perineural infiltration and intracranial extension are more clearly visible with MRI. 016 MRI evaluation and 1-year follow-up of optic pathway gliomas J. Tsitouridis, M. Emmanouilidou, S. Chondromatidou, Ch. Papastergiou, A. Morichovitou, V. Souftas Radiology Dept, Papageorgiou General Hospital, Thessaloniki, Greece Purpose: The purpose of our study is to present our experience in the MRI evaluation of 27 patients with gliomas of the optic pathway. Materials and Methods: All the examinations were performed using a 1 Tesla, Siemens Expert Plus Scanner. Oblique axial, coronal and sagittal pre- and post-contrast T1-weighted images, with and without fat supression, and T2-weighted images at the same planes, were obtained. Results: The location of the gliomas was: 7 in one optic nerve, 2 bilateral in the optic nerve, optic tract and chiasm, 11 in the optic tract and chiasm and the rest 5 in the optic chiasm. Enlargement of the involved area was the main finding in all 27 lesions. Some of

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them (9/27) revealed focal enhancement after intravenous administration of 20 ml Gd-DTPA. After 1 year, we examined again the patients and found that in 10 patients the lesion was the same without or with treatment, in 7 patients there was an increase in size and in the enhancement and in 10 patients there was only increased enhancement. Conclusions: In conclution, we believe that MRI is the method of choice not only in detecting the lesion, but also for lesion management and follow-up. O17 Diffusion-weighted imaging (DWI): a routine sequence in cerebral MRI? A.M.S. Low, M . Omar, S. E. S. Ng, J. W. M. Hoe, R. K. Kwok MRI Center, Mount Elizabeth Hospital, Singapore Purpose: While DWI plays an integral role in stroke imaging, recent reports allude to an extended use in imaging neoplastic and infectious conditions. This paper seeks to define the role of DWI in evaluating cases in a clinical practice. Materials and Methods: Over 6 weeks, 184 consecutive brain MRIs were performed on 182 patients. Conventional sequences were applied in all cases. All cases also had a supplementary DWI sequence performed axially. This generated 28 images in 40 seconds. The images were then reviewed by 2 radiologists who determined if DWI (A) influenced the report, (B) aided in the diagnosis and (C) changed the management of each case. The number of hyperintense lesions seen only on, or best seen on, DWI was also recorded. A correlation was also made between the symptoms presented and the DWI findings. Results: DWI was deemed to (A) influence the report, (B) aid in the diagnosis and (C) change the management in 115 (63 %), 58 (32 %) and 39 (21 %) cases, respectively. 75 lesions (in 45 cases) were best visualized on DWI. 11 lesions (in 8 cases) were seen only on the DWI. DWI was most useful when the presenting symptoms were non-specific (e. g. headache, vertigo, ataxia). It had a limited utility under certain well-defined settings (e. g. in ruling out brain tumors or temporal lobe epilepsy). Conclusions: DWI is an effective sequence in neuroimaging in most clinical situations. It can be easily integrated into the routine brain protocol with minimal, if any, alteration to the total imaging time. O18 Quantification of tissue damage in Alzheimer's disease using diffusion tensor and magnetization transfer MRI *S. Pontesilli, *A. Falini, *M. Bozzali, **M. Franceschi, *M. Filippi, G. Scotti *Neuroradiology, IRCCS San Raffaele, Milano, Italy **HSR Castellanza (VA), Italy Purpose: To measure the mean diffusivity (D) and magnetization transfer ratio (MTR) of cerebral gray matter (GM) and white matter (WM) from patients with Alzheimer's disease (AD). Materials and Methods: Dual-echo turbo spin-echo, T1-weighted spin-echo, MT and diffusion-weighted MR scan of the brain were obtained from 18 patients with AD and 16 sex-and-age matched healthy controls. Brain volumes were measured from T1-weighted images. After image co-registration, GM and WM were segmented from 10 supratentorial slices using diffusion anisotropy thresholds. Histograms of the average MTR and D were created. Results: Brain volume was lower in patients with AD than in controls (p < 0.001). The peak height of brain tissue D (p < 0.001) and MTR (p < 0.001) histograms were lower and average brain D (p < 0.001) higher in AD patients than in controls. The same MR quantities taken from cortical GM histograms differed between

patients and controls (p < 0.001). Average D (p < 0.007) and peak height of the D histograms (p = 0.01) of the WM were different between the two groups. An MR score based on brain volume and GM MTR peak height was strongly correlated with patient cognitive impairment (r = 0.65, p = 0.003). Conclusions: This preliminary study presents a novel approach with which to quantify AD-related tissue damage, which has the potential to improve our ability to monitor AD evolution. O19 Identification of the pre- and post-central gyrus by diffusionweighted imaging (DWI) *C. Fitzek, **S. Fitzek, ***M. Rusch, *H.J. Mentzel, * J. R. Reichenbach, * W. A. Kaiser, ***P. Stoeter *University of Jena, IDIR, MRI / Neuroradiology, Jena, Germany **Neurology, Jena, Germany ***Neuroradiology, Mainz, Germany Purpose: Imaging of the motor cortex is still a challenge. There are different ways to identify the central sulcus with a limited reliability (20 % to 90 %) and the analysis of multiple thin slices is necessary. Anisotropy of EPI ± DWI can directly show white matter tracts. Materials and Methods: 20 healthy volunteers underwent MRI after informed consent: EPI-DWI (TR/TE = 4000 / 103 ms, b = 1164 s/mm3,128 matrix, 20 slices, thickness 5 mm, 8 measuremts) and Flash-3D sequences (1 mm isovoxel). The sulcus centralis and the motor cortex were identified by two investigators on the basis of five typical signs in the 3D dataset. These signs were compared with the bright anisotropy signal of the EPI-DWI. In addition, 10 patients with lesions near the central sulcus were imaged. Results: In all 20 volunteers the central sulcus was seen in the 3D dataset with the standard signs on both sides. In all 20 volunteers, the white matter tracts leading to the motor cortex and the primary sensory cortex showed anisotropy, leading to exact identification of these regions in different slices. In all of the patients the motor cortex of the non-diseased hemisphere was identified using this approach. The differentiation of the central region in the diseased hemisphere was more dependent on the perifocal edema than on the mass effect of the lesion. Conclusions: With EPI-DWI it is possible to identify the motor cortex and the primary sensory cortex on the basis of the anisotropy of the white matter tracts. O20 Differentiation of tumor recurrence from treatment-induced necrosis using quantitative diffusion MRI X.J. Zhou, N.E. Leeds, A. J. Kumar, J. Chong, V. A. Levin M.D. Anderson Cancer Center, Houston, Texas, U. S. A. Purpose: Using conventional MRI techniques it has been difficult to unambiguously differentiate between treatment-induced nonneoplastic effects and tumor recurrence. In this study, we employed a quantitative diffusion MRI technique to address this deficiency. Materials and Methods: In additional to conventional MR studies, a diffusion-weighted scan was performed using a single-shot EPI pulse sequence (GE 1.5T Signa NV/i scanner, Milwaukee, WI) in eighteen patients that developed new brain lesions 3±30 months following surgical resection and radiation treatment of the original tumor. The resultant diffusion-weighted image was computed as the geometric average of the three images. The total acquisition time for the diffusion study was 30 seconds. Quantitative ADC values were calculated in the region of the lesions using customdesigned software. Selection of the region of interest (ROI) was guided by FLAIR and contrast-enhanced T1-weighted images.

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Results: Clinical findings based upon biopsies, surgery and followup MRI of the patient group revealed 10 necrotic lesions and 8 recurrent malignant gliomas. Among the 10 patients with necrotic lesions, the mean ADCs were found to be in the range of 1.2±1.5 ” 10 ±3 mm2/s, whereas the 8 patients with recurrent tumors showed mean ADCs ranging from 0.5 to 0.9 ” 10 ±3 mm2/s. Conclusions: It is well known that ADC is sensitive to cell volume fraction and cellularity in biological tissues. According to van Zijl, et al. (1990), the intracellular diffusion coefficient is approximately 10 times smaller than that of the extracellular compartment. In necrotic tissues, the extracellular volume fraction is augmented due to the breakdown of the cell membrane. The ADC for necrotic tissues is expected to be higher, as we observed in this study. On the other hand, solid tumors, such as recurrent gliomas, may have more densely packed cells than necrotic tissues, resulting in a lower ADC. This is consistent with our experimental results. O21 Whole brain diffusion histograms: a new tool for evaluation of leukoaraiosis M. Moretti, C. Tessa, R. Della Nave, S. Martini, V. Boddi, G. Pellicanò, D. Inzitari, M. Mascalchi Radiodiagnostics, University of Florence, Florence, Italy Purpose: The aim of this study was to test whole brain ADC histogram analysis for assessment of leukoaraiosis (LA). Materials and Methods: T2-weighted fluid-attenuated inversion recovery and diffusion-weighted images were obtained in fifteen elderly patients. LA extension was assessed on T2-weighted images, assigning a visual score. Apparent diffusion coefficient (ADC) maps of the entire brain were generated and, after exclusion of skull pixels with manual tracing and of the cerebrospinal fluid (CSF) by application of a threshold D value of 289  25 mm2/s, whole brain ADC histograms were obtained. Moreover, a brain atrophy index (BAI) was calculated on ADC maps as (intracranial volume ± CSF volume) /intracranial volume. Results: The kappa inter-observer agreement for LA visual scoring was 0.69. Manual segmentation of the skull showed a mean interoperator coefficient of variation below 3 %. The median value of whole brain ADC histogram correlated (p = 0.013) with the visual score of LA extension. Moreover, a significant correlation (p = 0.002) was found between whole brain ADC median value and loss of bulk of the brain as expressed by the BAI. Conclusions: Whole brain ADC histograms are a reproducible alternative tool for assessing LA extension and severity and are likely to be more sensitive than visual scores for monitoring LA progression. O22 The role of conventional MRI, diffusion-weighted imaging and magnetization transfer imaging in the diagnosis of amyotrophic lateral sclerosis (ALS) A. Gambini, A. Falini, M. Corbo, E. Munerati , M. Bozzali, M. Cercignani, M. Filippi, G. Scotti Department of Neurosciences, IRCCS H. San Raffaele, Milan, Italy Purpose: To determine the diagnostic sensitivity of conventional MRI, diffusion-weighted imaging (DWI) and magnetization transfer imaging (MTI) in patients with ALS. Materials and Methods: 30 patients with ALS (8 suspected, 4 possible, 13 probable, 5 definite) and 20 healthy age-matched volunteers were studied with the following techniques: ± Conventional MRI: double spin-echo; double-fast spin-echo; FLAIR;

± DWI: spin-echo Planar with diffusion gradients applied in three orthogonal directions, mean b value 867 sec/mm2; ± MTI: 2D gradient echo with and without saturation pulse. The evaluated data were: a) cranio-caudal extension of corticospinal tract hyperintensity; b) hypointensity of the motor cortex; c) selective or diffuse atrophy of the precentral gyrus; d) apparent diffusion coefficient (ADC) and MT ratio (MTR) values in 6 points along the corticospinal tract. Results: Conventional imaging was highly significant for suspected ALS, while it did not allow discrimination between possible ALS and controls. T2-Spin-echo and FLAIR demonstrated high sensitivity in patients with definite ALS, while proton density-spin echo demonstrated high sensitivity in probable ALS. Hypointensity of the motor cortex correlated with disease duration and selective atrophy of the precentral gyrus was more evident in primary lateral sclerosis patients. ADC was significantly higher in patients, while MTR was normal. Conclusions: The study confirms the utility of conventional MR techniques in diagnosing ALS. Among the advanced techniques, DWI increases diagnostic sensitivity. O23 The value of diffusion-weighted imaging and ADC maps in the differential diagnosis of intracranial tumors N. Sadeghi, D. BalØriaux, P. David, T. Metens ULB-Erasme, Brussels, Belgium Purpose: To assess the value of diffusion-weighted imaging (DWI) and apparent diffusion-coefficient (ADC) maps in the diagnostic imaging work-up of intracranial tumors. Materials and Methods: 34 patients had conventional SE T1-(with and without gadolinium) and T2 images. ADC values were measured in different tumoral compartments within each type of tumor and in contralateral normal cerebral tissue. The tumor was a highgrade glioma in 11 cases, a low-grade glioma in 9 cases, a metastasis in 7 cases, a meningioma in 6 cases and a cerebral abscess in 1 case. Results: In 4 cases, high-grade gliomas presented hemorrhagic regions with a very low ADC value. No statistically significant difference was found between the ADCs of non-enhancing and enhancing compartments of the tumor, either in high-grade or in lowgrade gliomas (p > 0.01). Low-grade gliomas presented a statistically significantly higher rADC than that of high grade gliomas (p < 0.01). No statistically significant difference was found between metastases and either high- or low-grade gliomas (p > 0.01). Conclusions: ADC does not relate to blood brain barrier integrity and is independent of tumor enhancement. Necrotic tumors with large areas of hemorrhage may present very low ADCs and must be differentiated from cerebral abscesses. ADC measurement may be useful in differential diagnosis between high- and low-grade tumors. O24 Diffusion-weighted imaging of acute intracerebral hematoma D. Ducreux, C. Oppenheim, J. F. Meder, J. L. Mas, D. Fredy Service de Neuroradiologie, C. H. U. de Bic†tre, le Kremlin-Bic†tre, and C. H. U. PitiØ SalpØtri›re, Paris, France Purpose: Little is known about diffusion-weighted imaging (DWI) of acute intracerebral hematomas (AICH). The purpose of this study was to describe the apparent diffusion coefficient (ADC) variations of AICH. Materials and Methods: We studied 11 patients with hematomas using conventional T1-, T2- and DWI-weighted-sequences obtained within 8 days after an intracerebral hematoma (post-trau-

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matic = 1, post-ischemic = 7, aneurysm = 1, cavernoma = 2). The ADC in abnormal brain was compared with that of contralateral normal brain regions using z-score analysis, and correlated with imaging findings on conventional sequences. Results: Normal (ADC = 0.92  0.23 SD 10±3 mm2/s, z-score = 0.084  1.10 SD), increased (ADC = 1.65  0.23 SD 10±3 mm2/s, z-score = 3.55  1.08 SD) or decreased (ADC = 0.32  0.17 SD 10±3 mm2/s, z-score = ±2.75  0.8 SD) average ADC values were found within hematomas, surrounded by oedematous areas of normal (ADC = 1  0.28 SD 10±3 mm2/s, z-score = ±0.55  1.31 SD) or decreased (ADC = 0.45  0.024 SD 10±3 mm2/s, z-score = ±2.15  0.11 DS) ADC values. Normal or decreased ADC values were found in areas consistent with the presence of deoxyhemoglobin and increased ADC values in areas containing intra- or extra-cellular methemoglobin. Conclusions: There is no set ADC pattern in acute brain hematoma. Increased ADC values may exist in post-ischemic hematomas. O25 Diffusion-weighted imaging patterns of brain damage in cerebral venous thrombosis D. Ducreux, C. Oppenheim, X. Vandamme, D. Dormont, Y. Samson, G. Rancurel, G. Cosnard, C. Marsault Service de Neuroradiologie, C. H. U. de Bic†tre, le Kremlin-Bic†tre, and C. H. U. PitiØ SalpØtri›re, Paris, France Purpose: Apart from case studies, little is known about diffusionweighted imaging (DWI) of brain lesions in human cerebral venous thrombosis (CVT). Our aim was to describe the initial DWI patterns observed in brain areas with MR signal changes associated with CVT and compare them with follow-up imaging. Materials and Methods: Nine patients with brain lesions associated with CVT, imaged with CT scan and DWI 3 hours to 4 days after sudden neurological onset, were retrospectively reviewed. The ADC in abnormal brain was compared with that of contralateral normal regions using z-score analysis. MR follow-up performed after three to six months was available for seven patients. Results: All patients had non-hemorrhagic T2-hyperintense brain regions, which in 4 patients were associated with partially hemorrhagic areas on CT scan. In non-hemorrhagic edematous areas, ADC was heterogeneous (coexistence of increased, normal, or decreased ADC) in five patients and homogeneous in four. In the latter four, ADC values were within the normal range in three patients, while a large homogeneous hyperintensity with decreased ADC values (0.3±0.4 10±3 mm2/s, < -3 z-scores) was observed in one patient. When available, imaging follow-up always showed hemorrhagic sequelae in initially hemorrhagic areas. Non-hemorrhagic edematous areas with initially increased ADC values returned to normal. Initially normal or decreased ADC values were predictive of reversibility, although imaging sequelae were rarely observed. Conclusions: The DWI/ADC pattern of venous stroke is more heterogeneous than previously thought. Large brain regions of reduced ADC values can be observed that are not predictive of ultimate infarction in case of CVT. O26 Diffusion-weighted MRI of brain metastases: their potential to mimic focal ischemic lesions B. Geijer, S. Holtås Department of Radiology, University Hospital, Lund, Sweden Purpose: Focal small ischemic stroke lesions are considered easy to identify in the acute stage and to differentiate from older lesions using diffusion-weighted imaging (DWI) in combination with con-

ventional T2-weighted magnetic resonance imaging (MRI). Brain metastases also have a considerable incidence and the aim of this study was to evaluate the risk for diagnostic overlap with ischemic lesions in a standard MR protocol for clinical stroke. Materials and Methods: Twelve of 26 patients examined with MRI for clinical reasons for an optimal evaluation of brain metastases were found to have metastatic brain lesions. There were representatives for most tumors, with a high incidence of brain metastases. A 1.5 T MR scanner was used. The applied DWI sequences were the standard echo-planar sequences provided by the manufacturer. Also T2-weighted and T1-weighted images without and with triple-dose contrast medium were obtained. Results and Conclusions: We found metastases, primarily from lung tumors, with the potential to mimic small focal infarcts of all ages in DWI and in T2-weighted images. O27 Perfusion MR Imaging in cerebral infiltrating gliomas: a correlative study with mr-guided stereotactic brain biopsy N. Yunten1, C. Calli1, O. Kitis1, S. Islekel2, E. Demirtas3 Ege University Medical Faculty, Departments of Radiology1, Neurosurgery2, and Pathology3, Bornova, Izmir, Turkey Purpose: To assess guidance in MR-guided stereotactic biopsy of infiltrating cerebral gliomas by displaying dynamic susceptibility MR perfusion-weighted imaging (PWI) abnormalities for an optimal approach. Materials and Methods: 20 patients showing cerebral infiltrating cerebral glioma criteria on standard MRI (T1W, T2W, postcontrast images) were included in the study. The ages of the patients ranged from 27 to 63 years-old. All patients were studied by EPI-SE PWI (TR:2000 msec, TE:63.86 msec, FA:90 , No acq:40, slice thickness: 5 mm, matrix:64 ” 128) prior to MR-guided stereotactic biopsy in a 1.5T MR unit (Magnetom Vision Siemens Erlangen, Germany). For PWI, 0.3 mmol/kg of paramagnetic contrast agent were injected intravenously via an automatic injector at a flow rate of 4 ml/sec. Stereotactic biopsy was directed according to the perfusion abnormalities in the tumor. Results: 12 patients displayed PWI abnormalities inside the tumor, suggesting high-grade areas which were confirmed by biopsy and pathological examination; thus, these patients underwent surgery. 8 patients with low-grade glioma criteria on all examinations were placed under follow-up. Conclusions: PWI is an effective and practical method for the guidance of stereotactic biopsy procedures, as well as for further therapeutic management of these patients. O28 Clinical usefulness of dynamic ct brain perfusion imaging using iodinated contrast agents in patients with carotid stenosis J. Sikorska *, J. Walecki, D. Gawlikowska**, W. Staszkiewicz** Evaluation of tumoral necrosis in glioblastomas with perfusion mri * Dept. of Radiology and Diagnostic Imaging, ** Dept. of Vascular Surgery, Center of Postgraduate Education, Warsaw, Poland Purpose: To assess the usefulness of parameters such as cerebral blood flow (rCBF), cerebral blood volume (rCBV), mean transit time (MTT), time of arrival (T0) and time to peak (TTP) in the evaluation of regional and generalized hemodynamic conditions in cerebral circulation. Materials and Methods: 36 patients with clinically confirmed transient or reversible neurological deficits (24 pts) or complete ischaemic strokes (12 pts), all with carotid stenosis (unilateral stenosis- 15 pts, bilateral stenosis- 21 pts) demonstrated by Duplex Ultrasonography, were examined with a CT spiral scanner (GE,

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HiSpeed). Standard CT images for initial evaluation of the brain and perfusion images using a first pass of the contrast agent ( bolus 50 ml, strength 300 mg/ml, rate 5 ml/s, delay 5 s, scan time 50 s) were obtained. Parametric maps of rCBV, rCBF, MTT, T0, TTP and relative contrast attenuation curves were performed. Results: Our results show high agreement between detected regions of hypoperfusion and clinical /morphological findings on standard CT. T0, TTP and MTT were found to be important parameters that strongly correlate with degree of carotid stenosis. Indicators such as CBV and CBF in relation to MTT exactly reflected the efficiency of cerebral autoregulation mechanisms. Conclusions: Dynamic CT permits quantitative analysis of cerebral perfusion with the assessment of autoregulation and extra- / intracranial vascular conditions. O29 Evaluation of tumoral necrosis in glioblastomas with perfusion MRI *M. Principi, **M. Italiani, *I. Aprile, * M. Muti, * P. Ottaviano *U. O. Neuroradiologia, Azienda Ospedaliera S.Maria, Terni, Italy **Servizio Fisica Sanitaria Az. Osp. S. Maria, Terni, Italy Purpose: The aim of this study was to evaluate ªangiogenesisº and tumoral necrosis in glioblastomas and to find possible reciprocal correlations. In particular, total tumoral volume (sum of solid and necrotic portions) was correlated with the regional cerebral blood volume (rCBV), on the basis of the hypothesis that perfusion-MRI, which is particularly suitable to evaluate capillary circulation, could demonstrate an inadequate vascular network, a phenomenon that biologically conditions intratumoral necrosis. Materials and Methods: The study involved 10 patients with glioblastomas, who underwent MRI examination (1.5 T) by standard sequences and perfusion sequence (GRE-EPI T2*). Post ± processing provided perfusion maps ªpixel by pixelº of rCBV. The total tumoral volume and the necrotic one were calculated as the product of the three longer axes divided by two. Results: It was found that an inverse relationship exists between average rCBV and tumoral volume. This correlation confirms in vivo the pathological knowledge about tumoral necrosis: an inadequate vascular network of the tumor, even in the solid portions of the tumor, e. g. those portions that did not show macroscopic necrosis. Conclusions: With due caution relative to the limited number of cases, it can be affirmed that perfusion-MRI is an effective tool with which to study tumoral necrosis in glioblastomas in vivo, and in particular to demonstrate the inadequate vascular network of these tumors. O30 Creutzfeldt-Jakob disease: the role of MRI H. Urbach1, S. Paus2, H. J. Tschampa1,E. Keller1, H. H. Schild1 Depts. of Radiology/Neuroradiology1, and Neurology2, University of Bonn, Bonn, Germany Purpose: To define the role of MRI in the diagnosis of CreutzfeldtJakob disease (CJD). Materials and Methods: Eighteen patients with suspected CJD were studied over 4 years. MRI findings were correlated to WHOestablished diagnostic criteria (clinical findings, EEG, CSF with 14±3-3 protein assay). Results: 15 patients were found to have CJD. Of the three other patients, one patient suffered from Hashimoto's encephalitis, one from Lewy body dementia, and one from ALS dementia complex. Twelve of the 15 CJD patients had increased signal intensity of the striate (n = 11), pulvinar thalami (n = 6) and/or cerebellar and ce-

rebral cortex (n = 3), respectively. Signal intensity was most pronounced on FLAIR sequences; 9 CJD patients studied with diffusion-weighted MRI showed impaired diffusion in these areas. All patients without CJD did not show the above-mentioned signal changes (sensitivity 80 %, specificity and positive predictive value 100 %, respectively). Conclusions: If patients with suspected CJD are studied with FLAIR and diffusion-weighted sequences, this disorder can reliably be proven or ruled out. Typical MRI findings narrow the differential diagnosis and should be included in WHO diagnostic criteria. O31 Depressive symptoms and changes in MRI in patients with multiple sclerosis *M. Ukmar, **M. Zorzon, **R. Zivadinov, **D. Nasuelli, **A. Bratina, *C. Furlan, **G. Cazzato, *R. Pozzi-Mucelli *Department of Radiology, Ospedale Cattinara, Trieste, Italy **Department of Clinical Medicine and Neurology, Trieste, Italy Purpose: Recent MRI studies provided evidence of a correlation between depression and structural lesions in the frontal, temporal and parietal lobes of patients with multiple sclerosis (MS). This evidence suggests that MS lesions in specific neuroanatomic pathways contribute to the development of depression. The purpose of the present study was to further examine the relationship between MRI changes and symptoms of depression in MS. Materials and Methods: 90 patients (58 women and 32 men, mean age 42.3) with definite MS were studied. Disability, independence, cognitive performance, as well as symptoms of depression and anxiety were assessed at baseline and 2 years later. All patients underwent a 1.5 Tesla MR examination of the brain including T1and T2-weighted images. Calculations of the regional and total lesion loads were performed using a semiautomatic technique; regional and total brain volumes were calculated using a fully automatic, highly reproducible interactive computer program. Results: Measurement of regional and total lesion load did not show any significant differences between depressed and non-depressed patients. Brain atrophy was significantly more evident in the left frontal lobe (p = 0.039) and in both frontal lobes (p = 0.046) and showed a trend of difference in the right frontal lobe (p = 0.056), right temporal lobe (p = 0.057) and in both temporal lobes (p = 0.072). Disability, indipendence and cognitive performance were similar in depressed and non-depressed patients (p = NS). Spearman correlation analysis and multiple regression analysis demonstrated an association of symptoms of depression score with both disability and right temporal volume. Conclusions: Destructive lesions in the frontal and temporal lobes can contribute to cause depression in patients with MS, but the influence of disability should not be disregarded. O32 Brain T2-weighted signal abnormalities in liver cirrhosis and their time-course normalisation after liver transplantation A. Rovira-Caæellas, J. Córdoba, J. Alonso, E. GrivØ, E. Sµnchez, A. Rovira-Gols Unitat de Ressonància Magn›tica, Servei de Medicina InternaHepatología, Hospital Universitario Vall d'Hebron, Barcelona, Spain Purpose: Hepatic encephalopathy may be the clinical manifestation of low-grade cerebral edema. However, abnormal signal intensities in patients with chronic liver failure, supporting the presence of brain edema, have not been previously described on T2weighted images. We investigated such abnormalities and their se-

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rial changes after normalization of liver function in a group of patients with chronic liver failure. Materials and Methods: MR studies (MTR and T2-weighted images) from 24 patients with non-alcoholic liver cirrhosis were obtained before, and in a subgroup of patients after, liver transplantation. Baseline scans were compared with those of twelve healthy controls. The presence of T2-weighted abnormalities on the baseline scans and their time-course changes were analysed and compared with serial MTR changes. Results: Baseline studies showed a moderate or substantial bilateral, symmetrical increased signal intensity along the corticospinal tract in half of the patients (sensitivity 50 %; specificity 75 %). After liver transplantation (1 month, 1 year) the signal abnormalities progressively normalised in all patients. This progressive signal normalisation followed the time-course normalisation of MTR values. Conclusions: Reversible signal abnormalities along the corticospinal tract demonstrated on T2-weighted MR imaging may be a common finding in cirrhotic patients. This abnormality may reflect the presence of low-grade cerebral edema. O33 T2* shortening in the motor cortex: correlation between hypointensities and clinical features in amyotrophic lateral sclerosis M. Caulo, R. De Amicis, M. Di Pietro, P. Pagano, C. Masciocchi, M. Gallucci Dept of Radiology, University of L'Aquila, L'Aquila, Italy Purpose: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder involving both first and second motor neurons and the MRI finding of T2 decrease in the motor cortex has been well described. Nevertheless, some authors have expressed criticisms, suggesting that the finding is not constant, nor is it specific. This study aims to determine the sensitivity of EPI-T2*-weighted sequences versus GRE T2* ones, and the correlation between signal changes within the motor cortex and clinical presentation. Materials and Methods: 13 patients (7 males and 6 females) with clinical and electrophysiological diagnosis of ALS were submitted to highfield (1.5T) MR examination using, among others, EPI-T2* sequences. MR images were analyzed in a double-blind protocol by physicians unaware of the patients' clinical history. Results: Decreased signal intensity in the motor cortex was always observed. In 5 patients with predominant low-intensity in the right motor cortex the symptoms were mostly observed in the left emisoma; on the contrary in 4 patients with more evident T2 decrease in the left motor cortex, symptoms predominated in the right hemisoma. In 4 patients a bilateral and homogeneous distribution of low-intensity areas in both motor cortexes corresponded with no side prevalence of neurological symptoms. Conclusions: The diagnosis of ALS was clinical and electrophysiological. The finding was constant and lateralized in strict correlation with the clinical presentation. EPI-T2* sequences were found to be highly sensitive and may help by supporting clinically uncertain diagnoses. O34 MR Imaging features of primary T-cell lymphoma of the brain differing from B-cell lymphoma E.C. Chung, J.W. Ryoo, D. G. Na, H. S. Byun Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea Purpose: Primary T-cell lymphoma (PTCL) of the brain is an extremely rare disease. The purpose of this study was to determine if certain MR features of primary cerebral T-cell lymphomas are

sufficiently characteristic to distinguish them from B-cell type lymphomas. Materials and Methods: Seven immunocompetent patients with proved primary T-cell lymphomas in the brain were analyzed. All diagnoses were confirmed with immunochemistry including CD3 (pan T-cell Ab) and L26 (pan B-cell Ab). MR imaging features including location, signal characteristics and enhancement patterns were also compared to those of B-cell lymphomas. Results: A total of 12 lesions were present in the 7 patients. The locations of the PTCL were in supratentorial subcortical or deep white matter, with the temporal lobe being the most common site (5/7). Only 1 lesion was in the deep gray matter. All lesions showed dishomogeneous enhancement following contrast injection, and four lesions showed thin or thick rim-enhancement. The primary manifestation in one patient was intracerebral hemorrhage with extensive peripheral edema. Conclusions: The most common MR imaging pattern of PTCL in our series was profuse perilesional edema, dishomogeneous or rim-like enhancement, and temporal location. The MR imaging features of PTCL were more aggressive than were those of B-cell lymphoma.

O35 Congenital left heart disease: Presurgical and postsurgical brain MRI evaluation F. Tavani, W. Mahle, R. A. Zimmerman The Children's Hospital of Philadelphia, Philadelphia, USA Purpose: To describe MRI pre- and post-surgical treatment and in particular to study if diffusion technique is able to detect new ischemic lesions in postsurgical follow up and if the presence of lactate on spectroscopy is predictive of an ischemic brain injury. Material and Methods: 24 full term babies with congenital left heart disease had brain MRI examination prior to any surgical procedure to detect the existence of ischemic lesions. An MRI follow up after surgery was done for all the patients except one. Results: Presurgical MRI examination showed 4 patients with ischemic change in the brain and 1 with a small hemorrhage. The other 19 had normal MRI examination. The follow up after surgery detected 10 children with new brain lesions and with worsening in three patients with presurgical brain involvement. 9 children had new choroid plexus hemorrhages and small posterior fossa extra-axial bleeding that were not seen on the prior examinations. 8 children had a normal MRI. Conclusion: The surgical treatment for congenital left heart disease increases the risk of ischemic lesions in infants. Diffusion was unable to detect PVL 5±12 days post-operatively, but was positive in larger ischemic lesions and in one hemorrhagic infarct. The presence of small amounts of lactate on MRS was not predictive of ischemic changes in the brain.

O36 Computer support for training, differential diagnosis and research in neuroradiology using interactive overview displays G.H. du Boulay 1,2, B. A. Teather2, D. Teather2, N.P. Jeffery2, F. A. de Garcia2, B. du Boulay3, M. Sharples4, L. Hinkley5 1 Institute of Neurology, London, UK 2 Medical Systems Research Unit, De Montfort University, Leicester, UK 3 School of Computing and Cognitive Science, University of Sussex, UK 4 School of Electronic and Electrical Engineering, University of Birmingham, UK 5 Department of Psychology, Oxford Brookes University, UK

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Purpose: The aim of this presentation is to report and discuss the use of computer support for training, differential diagnosis and research in neuroradiology using interactive overview displays. Materials and Methods: A long-term multidisciplinary project has led to the development of a detailed structured image description language (IDL) for MRI of the brain, an image archive of 895 cases with confirmed diagnoses, associated image descriptions based on the IDL, novel overview plots which provide visualisations of the overlap between diseases and a prototype computer system providing access to the data and images. The overview plots are constructed utilising the statistical technique of multiple correspondence analysis (MCA), applied to disease clusters which represent clinically significant diagnostic problems at MRI. The approach mirrors the ªsmall worldsº view of diagnostic reasoning identified in cognitive science studies of diagnosis. Results: Twenty-one ªsmall worldsº were identified from questionnaires sent to 24 experienced neuroradiologists. We describe the results of applying MCAs to a set of detailed descriptions, recorded blind to diagnosis, of the appearance of both PD and T2weighted images of 37 cases from the database of confirmed diagnoses for the ªsmall worldº of glioma, meningioma and infarct. Conclusions: Preliminary findings will be presented which suggest that clusters of cases observed in the overview spaces may indicate interesting relationships between lesion appearance and pathology, particularly in relation to malignancy and type of glioma, which are worthy of further investigation.

weighted mean ADC (rwmADC)º to obtain a better estimate of the infarcted tissue and the penumbra. Materials and Methods: Ten cases of acute ischemic stroke were studied. We used a standard stroke protocol including diffusionand perfusion-weighted images (DWI and PWI). A region-of-interest (ROI) was drawn around the bright area on the DWIs and the ªdiffusion-lesion volumeº (DLV) was calculated. Another ROI was placed in the same anatomical location in the normal cerebral hemisphere. The weighted mean ADC (wmADC) was calculated. The ratio between the wmADC in the ischemic region and on the normal side constituted the rwmADC. With the help of rwmADC, those pixels within the ADC defect which have false high or low values were eliminated. A ªcorrected ADC-lesion volumeº (CALV) was obtained. Results: The mean ADC in the CALV was 514.28 ” 10 ±3 mm2/s (55 % relative to the ADCs of the normal side), while they reached 646.37 ” 10 ±3 mm2/s (69 % relative to the ADCs of the normal side) in the DLV. The correction factor of our technique (DLV / CALV) had a mean of 2.42 + /- 0.19. The CALV correlated well with the CBF-lesion volume (correlation factor: 0.79). The CBF reduction in the CBF lesion was about 54 %, which is considered to be significant ischemia. Conclusions: Weighting the mean ADC within the infarct and the reference side can give a more correct estimate of the diffusion defect and the volume of the severely ischemic brain parenchyma, thus helping to define the ischemic penumbra.

O37 Differential diagnosis of acute ischemic stroke with modern and fast imaging methods *R. Bartunek, *C. Fitzek, *T. Azhari, **S. Fitzek, *H.J. Mentzel, *D. Sauner, * W. A. Kaiser *IDIR University of Jena, Jena, Germany **Neurology, Jena, Germany

O39 Diffusion-weighted imaging (DWI), T2*-weighted gradient echo imaging (T2*wGRE) and MRA in acute posterior circulation stroke H.R. Jäger, V. Beric, N. Losseff, M. Brown Lysholm Radiology Dept., NHNN, London, UK

Purpose: The list of differential diagnosis in an acute stroke is multifarious, in that this condition can be caused by ischemic territorial infarction, lacunar stroke, TIA, brainstem infarction, basilary thrombosis, venous thrombosis, tumors, encephalitis, seizures and bleeding. Furthermore, hemiplegia can be also caused by hemiplegic migraines or neurotic disturbances. The aim of this presentation is to describe ten different patterns of these differential diagnoses in CT (with CT and CT-perfusion) and in MRI (with DWI, MRA, and MR-perfusion). Patients and Methods: 54 patients with ischemic and non-ischemic strokes were retrospectively analyzed ( CT: GE LightSpeed QXI; MR: Siemens Vision Plus, 1.5 T). Imaging findings of early infarction were compared to clinical data and stroke outcome. Results: The different patterns and the pros and cons for discrimination of differential diagnosis with acute CT and MRI are shown. Conclusions: Modern imaging methods with standardised CT and MRI stroke schemes can be used in differential diagnosis of acute ischemic stroke.

O38 Weighted ADC mapping improves the evaluation of the ischemic penumbra in acute stroke M. El-Koussy, C. Kiefer, K.-O. Lövblad, M. Bischof, T. Wels, M. Arnold, L. Remonda, H.-P. Mattle, G. Schroth Inselspital, University of Bern, Bern, Switzerland Purpose: Accurate MRI assessment of acute stroke patients requires a thorough analysis of the apparent diffusion coefficient (ADC) in the ischemic area. We developed the concept of ªrelative

Purpose: DWI and T2*-weighted GRE are useful in acute stroke of the anterior cerebral circulation but can be hampered by susceptibility artefacts from the skull base in the posterior fossa. We examined their usefulness in the diagnosis of posterior circulation strokes. Materials and Methods: 72 consecutive patients with acute stroke underwent MR imaging using 3D TOF MRA, T2 wFSE, T1 wSPGR, FLAIR, T2*w GRE, and DWI EPI sequences. Angulated axial slices were used for DWI and T2*GRE to minimise susceptibility artefacts. 17 patients had posterior circulation infarcts with lesions in the occipital lobe (7), the pons (6), the cerebellum (8) midbrain (1) and medulla oblongata (2) and had MRI at day 0±5 (median 36 hrs). The conspicuousness of ischaemic lesions and haemorrhage was rated on a five-point scale. Results: DWI was superior in demonstrating all acute ischaemic posterior circulation lesions (followed by T2 wFSE and FLAIR) and exclusively demonstrated lesions in 2 cases. T2*wGRE was best in detecting primary haemorrhages (2) and haemorrghagic transformations (2). MRA showed vertebral or basilar artery occlusion in 7 cases. Conclusions: DWI and T2*wGRE are extremely useful in posterior circulation stroke. Susceptibility artefacts can be minimised with appropriate techniques. MRA demonstrated the level of vascular compromise in less than 50 % of cases.

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O40 Detection of haemorrhage and haemorrhagic transformation in acute stroke with T2*wGRE and its influence on the analysis of diffusionweighted images (DWI) H R Jäger, V Beric, N Losseff, M Brown Lysholm Radiology Department, NHNN, London, United Kingdom Purpose: T2*-weighted gradient echo imaging (T2*wGRE) is inherently sensitive to the presence of paramagnetic blood products. We compared T2*wGRE to other MR sequences in the detection of haemorrhage in acute stroke and assessed the influence of blood products on the interpretation of DWI. Materials and Methods: 72 consecutive stroke patients underwent MRI using 3D TOF MRA, T2 wFSE, T1 wSPGR, FLAIR, T2*w GRE and DWI EPI sequences. MRI was performed at day 0±7 (median 48 hrs) of the stroke. The probability of presence of blood products was rated on a five-point scale for each sequence, distinguishing between primary cerebral haemorrhage (PCH), haemorrhagic transformation (HT) and microhaemorrhage in small vessel disease (MH). Results: PCH was found in 2 patients, HT in 9 and MH in 3. T2*w GRE was most sensitive in detecting all three forms of haemorrhage, followed by the FLAIR sequence. T2*wGRE was the only sequence to detect haemorrhage in 5 cases. The presence of HT causes loss of signal on diffusion trace images and may lead to an underestimation of the infarct size. Conclusions: T2*wGRE is most sensitive sequence in detecting haemorrhage and is essential for stroke imaging. DWI images should be interpreted in conjunction with T2 wGRE images. O41 Cerebral CT angiography in acute ischemic stroke management *T. Azhari, *C. Fitzek, *M. Herzau, *R. Bartunek, *H.J. Mentzel, **S. Fitzek, **U. Sliwka, * W. A. Kaiser *Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany **Department of Neurology, University Hospital Jena, Germany Purpose: Acute stroke management has changed in favour of penumbra / mis-match identification. The purpose of this study was to evaluate the impact of the additional information provided by cerebral CT-angiography and 3D-reconstruction in comparison to native and perfusion CT. Materials and Methods: Native CCT, perfusion CCT and cerebral CTA were performed in 44 patients with clinical symptoms of acute ischemic hemispheral stroke, using a multislice CT scanner (Light Speed Qxi, General Electric). The examinations were analysed by 2 neuroradiologically experienced radiologists in a blinded retrospective study. Results: In 16 cases cerebral CT angiography showed pathologic findings of the intracerebral arteries according to the infarct area, while in 26 patients intracerebral arteries were found to be correct. An exact analysis of the arterial vessels was feasible for the ACI, MRA (M1/M2), ACA (A1/A2), PCA (P1/P2), vertebral and basilar arteries. Variations such as a carotid origin of PCA or a hypoplastic AI were identified easily. In 6 cases mild side effects occurred. 2 examinations were aborted due to technical problems. Conclusions: Cerebral CT angiography, in addition to the native CCT and perfusion CT, is a secure, useful and fast technique in acute stroke evaluation which provides relevant information for further treatment.

O42 Radiological investigation of vertebrobasilar insufficiency and quantification of the vertebrobasilar flow with magnetic resonance imaging *M. Gulsun, *I. Saatci, *D. Akata, *M. NasyÂh Ozmen, ** L. Sennaroglu, ** T. Yucel * Department of Radiology, ** Department of Ear Nose Throat, Hacettepe University Faculty of Medicine, Ankara, Turkey Purpose: To evaluate the contribution of cervical spine radiograms, Doppler US, cervical and cranial MRI, MRA and two-dimensional quantification flow in the diagnosis of vertebrobasilar insufficiency. Materials and Methods: We prospectively examined 25 patients having signs of vertebrobasilar insufficiency, as well as 25 controls of the same age and sex, with MRI, Doppler US and cervical radiograms. Cervical spine radiograms were evaluated for the presence of degenerative changes, osteophytes and loss of height. By using two-dimensional quantification flow, via region of interest drawn on transverse sections and corresponding time-velocity graphics, the flow velocities in basilar artery and vertebral arteries were measured. On brain MR images, posterior circulation infarcts and slow flow in vertebrobasilar system arteries and on cervical MR images, the presence of cervical osteophytes, spinal cord compression and the effect of the presence of degenerative changes on vertebral arteries were investigated. Results: The pathologic findings on MRA, the presence of ªunidentified bright objectsº on brain MR images, osteophytes on cervical MR images, loss of height and the presence of osteophytes on radiograms significantly affected the velocities measured by MRI in patients, as compared to the control group. In both groups, the measurements of velocity of vertebral arteries by Doppler US did not correlate with the measurements by two-dimensional quantification flow. Conclusions: MRA was the most specific technique in the diagnosis of patients with vertebrobasilar insufficiency. O43 Utility of contrast MRA in the evaluation of acute stroke patients *S. Pedraza, *J. Teruel, **Y. Silva, *J. Vera, **A. Dµvalos, *L. Inaraja *Hospital Josep Trueta de Girona, Unidad de RM. Servicio de Radiologia, C/ de França, Girona, Spain **Neurology Service, Hospital Josep Trueta,Girona, Spain Purpose: The occlusion of the internal carotid artery (ICA) without middle cerebral artery (MCA) patency has been considered an exclusion criteria for thrombolysis in acute ischemic stroke. The purpose of the present study was to determine the usefulness of magnetic resonance angiography (MRA) with contrast (CMRA) in the study of vessel patency in patients with acute stroke. Materials and Methods: 7 patients with an acute hemispheric stroke underwent MR studies on admission (1±12 h after onset) and at 72 h. The study protocol included a pre-contrast MRA and other CMRA. (thrombolysis in myocardial infarction) TIMI classification was used to assess the permeability of vessels. Results: In 4 patients the MRA showed an ICA occlusion, in all cases associated with an absence of MCA flow. In two patients CMRA disclosed a better vascular flow than did MRA. The first patient showed a better flow (from TIMI 1 to TIMI 2) in the MCA. In the second patient, CMRA showed flow in the distal ICA and proximal MCA (from TIMI 1 to TIMI 2) with a distal embolic occlusion. Conclusions: This study suggests that CMRA should be used to assess vessel patency in patients eligible for thrombolytic treatment.

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O44 Prognostic value of diffusion-perfusion MRI in acute stroke patients *S. Pedraza, **M. Castellanos, *J. Teruel, *J. Vera, **A. Dµvalos, *L. Inaraja *Unidad de RM, Servicio de Radiologia, Hospital Josep Trueta, Girona, Spain **Servicio de Neurología, Hospital Josep Trueta, Girona, Spain Purpose: To study whether the hemodynamic changes established throughout diffusion (DWI)- and perfusion (PWI)-magnetic resonance imaging (MRI) are related to early clinical outcome. Materials and Methods: Study Design: Prospective, non-random, monocentric clinical study. 10 patients with acute cerebral stroke underwent MR studies on admission (1±12 h after onset) and at 72 h from onset. The volume of the lesion in DWI and PWI was measured in each exploration. Clinical outcome was evaluated using the NIH stroke scale. The clinical evolution during the first days was classified as stable, improvement and worsening. Results: In 8 patients there was a mismatch between DWI-PWI and in 2 patients the exploration was normal. The 4 patients with stable clinical outcome showed a mean increase of 376 % in DWI volume. In 3 patients with clinical improvement there was a mean increase of 12 % increase in DWI volume. In 1 patient with neurological worsening the mean increase in DWI volume was 5000 %. In all patients DWI lesions increased within the hypoperfused area. Conclusions: This study suggests that early clinical outcome might be related to an increase in the cerebral infarct evaluated by DWI. O45 Multi-slice CT Angiography in the Evaluation of Patients With Acute Cerebrovascular Disease R. Klingebiel*, M. Busch**, F. Masuhr*** *Neuroradiology Section, Dept. of Radiology, CharitØ CM, Berlin **Dept. of Neurology CharitØ, Georg Bohner, Neuroradiology Section, CharitØ, CM, Berlin ***Dept. of Neurology CharitØ, CM, Berlin Germany Purpose: Evaluation of multi-slice CT angiography (MS-CTA) in patients with acute symptoms of arterial or venous occlusive disease. Material and Methods: 46 patients, clinically suspected of an acute cerebrovascular (CV) insufficiency, underwent MS-CTA in a multi-slice CT scanner. A single bolus, monophasic helical scan technique was applied subsequent to i. v. administration of 120 ml iodinated contrast medium with a flow of 4 ml/s. All scans were evaluated for depiction of the vertebral arteries, basilar artery, extra- and intracranial segments of the internal carotid artery, first to third segments of major cerebral arteries, dural sinus, great vein of Galen and internal cerebral veins. The patient's records were reviewed for the results of other CV imaging techniques and for the clinical outcome. Results: In all patients, in whom imaging and clinical follow-up proved major CV occlusion (n = 24), MS-CTA detected the underlying vascular pathology. In 2 patients, SVT was confirmed by CTA, visualizing thrombuses in various dural sinuses. Only by MSCTA comprehensive imaging of the arteriovenous CV system was achieved non-invasively including the cervical carotid bifurcation. Conclusion: Multi-slice CT angiography is an important new diagnostic tool for the rapid and comprehensive assessment of the CVS in patients with clinical signs of cerebrovascular insufficiency.

O46 Radiation-induced cavernous hemangiomas of the brain: a late effect predominantly in children *S. Heckl, **A. Aschoff, * S. Kunze *Department of Oncological Diagnostics and Therapy, German Cancer Research Center, Heidelberg, Germany **.Neurosurgical Department, University of Heidelberg, Germany Purpose: The induction of cavernomas as a consequence of brain radiation was first suspected in 1994 and has been controversial since then. Methods: 5 of our patients (5±29 years old) developed cavernomas after radiation. The age distribution of these cases, together with 33 from the literature, was compared with that of naturally occurring cavernomas operated in our hospital (132 cases) as well as with the total collective of brain-radiated patients (3902 cases). The relationship between radiation dose and the interval between radiation and diagnosis of cavernoma was examined. Results: At the time the cavernomas were diagnosed, 47 % of all patients were aged between 11 and 20. Most of those were radiated in the first decade of life (63 %). In children up to age 10, a dose higher than 30 Gy was followed by a shorter latency (p = 0.0035). In patients older than 10, post-radiation cavernomas rarely occurred when the dose was less than 30 Gy. In children younger than 15 years, radiation was followed by cavernoma in 20 % (3 out of 15) of patients whereas in cases older than 15 years, cavernomas developed in only 1.1 % of patients (2 out of 179 ) (p = 0.0034). Conclusions: These results indicate a strong correlation between radiation and cavernoma, especially in children under ten years of age. In adults, cavernomas rarely result and then only after high dosages (more than 30 Gy).

O47 Early diagnosis of hypoxic-ischemic fetal brain damage: prenatal MRI in the survivor of a monochorionic co-twin A. Righini, U. Nicolini*, E. Bianchini, P. Gementi*, C. Bonifacio, F. Triulzi Unità Operativa di Radiodiagnostica e Neuroradiologia, Ospedale dei Bambini V. Buzzi, Milan, Italy. *Unità Operativa di Ostetricia e Ginecologia, Ospedale dei Bambini V. Buzzi, Milan, Italy Purpose: Prenatal ultrasounds are routinely used to detect the atrophic sequelae of fetal brain hypoxia-ischemia. However, the sensitivity of ultrasound to damage in the earlier phases is poor. Although prenatal MRI is now used to add information to ultrasounds, MRI data on the evolution of hypoxic-ischemic fetal damage are scarce. We present prenatal MRI findings of fetal hypoxicischemic brain lesions in the survivor of a twin pregnancy. Materials and Methods: A monochorionic twin pregnancy was complicated at 23 weeks by the death of one fetus and by consequent severe acute anemia and hypovolemia in the survivor, due to twin-to-twin transfusion. The survivor brain was studied in the uterus by single-shot fast spin-echo T2 -weighted MRI. Results: None of the follow-up ultrasound exams showed brain abnormalities in the survivor. A 12-days prenatal MRI revealed a large leukomalacic area in the right hemisphere with initial lateral ventricle enlargement, compatible with recent hypoxic-ischemic damage. A 17-days prenatal MRI showed severe hemisphere volume loss. Based also on MRI findings, the pregnancy was terminated. Conclusions: MRI detection of fetal brain damage can influence clinical decisions and contribute to investigating hypoxic-ischemic brain pathophysiology.

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O48 Neoplasm-simulating CNS lesions in neurofibromatosis type 1: MRI and clinical follow-up of five lesions *R. Raininko, ** L. Thelin, ** O. Eeg-Olofsson *Department of Radiology, University Hospital, Uppsala, Sweden **Section of Pediatrics, Department of Women's and Children's Health, Uppsala University, Sweden Purpose: High T2 signal lesions are common on brain MRI in children and adolescents having neurofibromatosis type 1 (NF1). Typical non-neoplastic lesions do not show contrast enhancement or mass effect. We describe five expansive lesions without evidence of a neoplasm. Materials and Methods: All four patients satisfied the criteria for NF1. Three patients had one expansive non-neoplastic lesion, the fourth had two. Three lesions were situated in the brain stem, one in the cerebellum and one in the cerebrum. One of the brain stem lesions extended into the spinal cord. The lesions were followed up with MRI and clinical examinations for 2, 3, 6 and 9 years. Results: All expansive lesions were hyperintense to the gray matter on T2-weighted images. One showed enhancement after intravenous contrast medium. Four lesions showed normalizing of the signal intensity but the expansiveness was more constant. The contrast-enhancing lesion practically disappeared. One lesion did not change in signal intensity and increased minimally in size during the 3-year follow-up. None of the patients showed clinical symptoms or signs related to these lesions. Three patients were untreated but one received chemotherapy for optic glioma. Conclusions: The radiological diagnostic criteria between neoplastic and non-neoplastic lesions in NF 1 are not clear. O49 Diffusion imaging of primary white matter hypoxic injury in children R. A. Zimmerman, L.T. Bilaniuk, E. M. Simon, J. V. Hunter Children's Hospital of Philadelphia, Philadelphia, PA, USA Purpose: To demonstrate that hypoxic injury to the brain in children can affect primarily the white matter as opposed to the concept that grey matter is the principal site of injury. Materials and Methods: Six children with hypoxic injury, ages 2±14, were examined by MRI (Siemens 1.5 tesla MR scanners) utilizing routine sequences and diffusion imaging with B values of 0, 500 & 1000 and x, y, z gradient directions. ADC (apparent diffusion coefficients) values were measured. Results: All 6 patients showed some overall abnormality of increased signal on T2 and FLAIR in the supratentorial brain. However, all showed on diffusion imaging that the abnormal diffusion bright signal with low ADC values was restricted to the supratentorial white matter. Subsequent studies in survivors showed the development of significant supratentorial atrophy. Conclusions: Hypoxic injury to the supratentorial brain in children can be associated with cytotoxic cell swelling that affects primarily the oligodendroglia and astrocytes and is manifest as abnormal white matter diffusion. O50 Clinical and neuroradiological findings in 29 cases of pediatric demyelinating disorders. *M. Caulo, *G. Cerone, *A. Splendiani, *R. De Amicis, *M. Polito, *C. Masciocchi, *M. Gallucci, ** M. Conti, ** A. Achene *Dept of Radiology, University of L'Aquila, L'Aquila, Italy **University of Sassari, Sassari, Italy Purpose: The aim of this study was to retrospectively review 29 cases of demyelinating diseases beginning during childhood, to record the main clinical and neuroradiological evidence and to es-

tablish whether significant differential criteria between multiple sclerosis (MS), Schilder's disease (SD) and neuromyelitis optica (NMO) are available. Materials and Methods: 29 pediatric patients affected with demyelinating disease were enrolled: 24 were diagnosed as typical remitting-relapsing MS, 3 as SD and 2 as NMO. Clinical presentation at onset, CSF analysis, size, number and morphology of plaques were evaluated using MRI. Results: In 6 of 24 cases of MS, an atypical clinical presentation was reported: seizures were the clinical onset in 2 cases, lethargy in 1 case and signs of intracranial hypertension had been detected in 3 cases. Oligoclonal bands were absent in SD patients and also in 6 cases of MS. MRI revealed giant plaques in SD cases and in 14/24 MS cases. Conclusions: In light of our data, we postulate that pediatric MS represents a wide category of disease with clinical, laboratory and MRI findings different from typical adult presentations. The absence of statistically significant differences between MS and SD and SD and NMO in our groups led us to not consider SD and NMO as specific entities or MS variants. We postulate that SD and NMO represent the occasional combination of clinical and radiological findings mostly occurring during pediatric MS.

O51 Early neuroradiological findings in 14 cases of Rasmussen encephalitis (RE) L. Chiapparini, L. Farina, T. Granata, F. Ragona, *L. Fusco, G. Gobbi, #G. Capovilla, §L. Tassi, + L. Giordano, R. Spreafico, M. Savoiardo Istituto Nazionale Neurologico ªC. Bestaº, Milan; *Ospedale Pediatrico Bambino Gesu', Rome; Ospedale Maggiore Pizzardi, Bologna; #Ospedale Poma, Mantova; §Ospedale Niguarda Ca' Granda, Milan; + Ospedale Civile, Brescia, Italy Purpose: To review the neuroradiological findings in 14 cases of RE in order to detect the changes that may contribute to an early diagnosis. Materials and Methods: Data were collected on 14 patients (9M, 5F) aged 4.7±26 years, with onset of symptoms at age 14 months11 years, in whom RE had been diagnosed because of drug-resistant focal epilepsy, progressive neurological deficits, and progressive hemispheric atrophy involving only one side. Twelve patients underwent hemispherectomy and diagnoses was neuropathologically confirmed. CT and MRI were performed in all the patients (totals: 19 and 69, respectively), PET in 3 patients, SPECT in 2, MRS in 1. Results: The earliest MRI abnormalities, observed in the examinations performed from 1 day to 4 months after the first seizure (available in 12 cases), included: focal areas of hyperintensity on T2-w.i. in the gray and white matter (9 cases), enlargement of the sulci and lateral ventricle in one hemisphere, usually involving the fronto-insular region (8), atrophy of the head of the caudate nucleus (6), only enlargement of the lateral ventricle (1). Findings observed during the follow-up were: progression of the hemispheric atrophy, always prevalent in the region primarily involved (14 cases), progression of the atrophy of the head of the caudate nucleus (9), spreading of signal abnormalities (13) with late neardisappearance in 3 cases, cerebellar contralateral atrophy (5). PET revealed hypometabolism, SPECT decreased perfusion and MRS marked reduction of metabolites in the affected hemisphere. Conclusions: MRI can be used to demonstrate the progression of RE, and can aid in diagnosis in the early stages of the disease, before appearance of neurological deficits. Functional studies did not provide specific findings.

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O52 Imaging of cerebral Serratia abscesses in preterm infants D. Prayer, *A. Messerschmidt, *R. Birnbacher, **W. Dietrich, *A. Pollak, E. Schindler Department of Neuroradiology, University of Vienna, Vienna, Austria *Department of Neonatology, Congenital Disturbances, and Intensive Care, University of Vienna, Vienna, Austria **Department of Neurosurgery, University of Vienna, Vienna, Austria Purpose: To demonstrate the imaging presentation of cerebral Serratia abscesses in preterm infants. Patients and Methods: 3 preterm infants, born in the 25 th, 28 th, and 31 st week of pregnacy, underwent ultrasound, CT and MR examinations after presenting apnoea and bradycardia on the 9 th, 23 rd and 24 th days of life. 4 MR studies were performed (1.5 T superconducting unit, T2-weighted TSE, T1-weighted GRE, T2*weighted GRE, contrast-enhanced T1-weighted sequences, and diffusion-weighted sequences). Results: Ultrasound and CT-studies showed unspecific areas of pathological attenuation/density. MR studies revealed giant lesions with incomplete membrane formation in the first infant, several lesions of around 10 mm in diameter with complete membrane in the second, and smaller lesions with incomplete membrane in the third. One infant became clinically normal, while in the other two seizures and neurological signs persisted. Conclusions: The morphological presentation of Serratia abscesses in premature infants is non-specific on ultrasound and CT. MR shows inconsistant findings, which may be due to the different stages of maturity of the immune system and to the temporal onset of specific therapy. Because the clinical outcome depends on the timing of antibiotic therapy, the neuroradiologist has to be aware of the fact that any lesion in a previously normal preterm infant brain that cannot be clearly interpreted as vascular might correspond to early cerebritis.

053 Focal cortical dysplasia of Taylor's balloon cell type: MRI, neuropathological and clinical findings H. Urbach1, B. Scheffler2, T. Heinrichsmeier1, J. von Oertzen3, T. Kral T, J. Schramm4, I. Blümcke2 Depts. of Radiology/Neuroradiology1, Neuropathol.2, Epileptol.3, and Neurosurg.4 University of Bonn, Bonn, Germany Purpose: To characterize the topography of focal cortical dysplasias of Taylor's balloon-cell type (FCD-TS) and to analyze clinical outcome following surgery. Materials and Methods: From an epilepsy data bank with 547 histological specimens, 17 FCD-TS for which high resolution MRI was available were re-evaluated. Histopathological (H&E, H&ELFB, Nissl, Bodian) and immunhistochemical features (GFAP, NFP, Vimentin Synaptophysin, NSE, MIB 1, CD 34) as well as outcome following lesionectomy were analyzed. Results: All FCD-TS were located outside the temporal lobe and slightly hyperintense on FLAIR images. All but two FCD-TS had a distinctly hyperintense nodular, triangular or dumbbell-like zone which was located at the inner border of the disarrayed cortex and adjacent subcortical white matter and tapered towards the lateral ventricle. Histopathologically, dysplastic neurons were located within the disarrayed cortex and subcortical white matter, whereas the distinctly hyperintense zones mainly contained radially oriented balloon cells. All patients with complete lesionectomies (n = 16) became seizure-free.

Conclusions: Focal cortical dysplasias of FCD-TS have characteristic MRI and histopathological findings. On FLAIR images, distinctly hyperintense subcortical zone tapering towards the lateral ventricle is the radiological hallmark of this disease. MRI recognition is important, since outcome following resective surgery is favorable. O54 MRI of the spine in children suspected of Guillain-BarrØ syndrome *P. Skejö, **M. Dahlin, *O. Flodmark *Department of Neuroradiology, Karolinska Hospital, Stockholm, Sweden **Department of Pediatric Neurology, Astrid Lindgren Hosptal for Children, Stockholm, Sweden Purpose: To account for the changes and evaluate the usefulness of magnetic resonance imaging (MRI) of the spinal canal in children suspected of Guillain-BarrØ syndrome (GBS). Material and methods: Retrospective study of children with clinical diagnosis of GBS. MRI of the head and spinal canal preferably before and after intravenous administration of contrast media was performed in 4 children 1±12 years of age. The indication for investigation was suspicion of expansive process, demyelinating process, ADEM or other forms of myelitis. Results: All patients had a normal MRI of the brain. None had visible changes in the medulla. Two children had MRI of the spine before contrast injection and in one of them thickened nerve roots were visible in the cauda equina. The other investigation had a normal appearance before injection of contrast. All children exhibited enhancement of both anterior and posterior nerve roots of the conus medullaris and cauda equina. All but one demonstrated marked enhancement, the last one had moderate enhancement, and mostly of anterior roots. No follow up investigations where performed. Conclusion: Enhancement of intrathecal spinal nerve roots has been described in several other diseases and are therefore non specific to GBS. Never the less the enhancement may help both in bringing the suspicion of GBS into mind and increasing the likelihood of the diagnosis. Another imperative comment to make is the importance of giving contrast to a patient with a seemingly normal non-contrast enhanced investigation when the neurological examination is abnormal. O55 Neuroradiological evaluation of hydrocephalus: pre- and post-operative studies in relation to endoscopic surgical techniques L. Simonetti, U. Godano*, A. Bacci, R. Agati U.O. di Neuroradiologia, Ospedale Bellaria, Bologna, Italy *U.O. di Neurochirurgia, Ospedale Bellaria, Bologna, Italy Purpose: The neuroradiological study of hydrocephalus during endoscopic surgery raises new questions and yields new findings. The aim of this research was to review pre- and post-operative studies in relation to endoscopic surgical techniques. Materials and Methods: We report our experience in 25 cases. Results and Discussion: Although CT remains the method of choice in the initial diagnosis of hydrocephalus and in the study of early complications, it is no longer useful in medium and long-term post surgical follow-up. MR is the gold standard for surgical planning, due to its capability to demonstrate the anatomy of the third ventricle. This is also true in the post surgical follow-up of third ventriculocisternostomies, in that the functional information obtained on the patency of the stomy is more significant than the morphological information on the ventricular dimensions. Quantitative studies performed with specific flow sequences and cine-

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MR are accurate, but of little value in clinical practice: a higher sensitivity over the quantitative information (flow vs. no flow) obtained with FSE and TSE T2 w sequences has not yet been demonstrated. O56 MR myelography in the diagnosis of lumbar spinal synovial cysts J. T. Wilmink Radiology Department, University Hospital Maastricht, The Netherlands Purpose: To assess the value of heavily T2-weighted MR myelographic sequences in the detection of intraspinal synovial cysts, and in the evaluation of nerve root compression. Materials and Methods: The MRI studies of six patients were retrospectively studied. In 4 cases the intraspinal synovial cyst was located at L4±5 and in 2 cases at L5-S1. In all cases there was associated facet joint effusion. Nerve root compression by the cyst was present in 4 cases, while in 2 cases the dural sac was compressed by degenerative spinal narrowing. MRI was performed in a .5T system, using standard sagittal and axial images. Additionally, two oblique coronal heavily T2-W MR myelographic images were acquired. In 3 cases an additional axial T2-W MR myelogram was acquired using a 3D multi-chunk volume acquisition producing an image resembling a CT myelogram which was less heavily T2weighted. Results and Conclusions: (a) T1-W images produced absent to poor visualization of synovial cysts, which were iso-intense to flaval ligaments and dural sac. Nerve root compression, present in 4 cases, could not be well assessed. Joint space effusion could be recognized with some difficulty. (b) T2-W sagittal images allowed adequate detection of synovial cysts but poor localization. Nerve root compression could not be assessed. Joint space effusion could be identified. (c) Heavily T2-W oblique coronal MR myelographic sequences provided excellent depiction of even small synovial cysts, as well as nerve root and joint space effusions. Axial 3D volume myelograms with less heavy T2-weighting imaged synovial cysts almost as well and provided better anatomic references. O57 High-contrast axial myelographic sequences for lumbar spinal MRI: a comparative study. S.A.A. Verhaegen, J.T. Wilmink Radiology Department, University Hospital Maastricht, The Netherlands Purpose: This study deals with two pulse sequences which produce a bright CSF signal (myelographic effect), in a rapid acquisition: DRIVE and balanced FFE (BFFE). Materials and Methods: In 15 patients a standard MR imaging protocol was performed along with two coronal oblique MR myelographic sequences. For the comparative study two extra sequences were acquired using 3D DRIVE and 3D BFFE. All examinations were performed on a 1.5 T Philips Intera system. The axial T1-SE, DRIVE and BFFE images were graded for anatomic and pathologic features. Results: For structures bordered by fat (extradural nerve root, spinal canal, neuroforamina) T1TSE images were generally superior. When contrast was provided by CSF, however, (intradural nerve root, dural sac and root sleeve), DRIVE and BFFE provided better images. Facets and flaval ligaments were usually better distinguished with the T1TSE sequence. The visualization of disk herniation and spinal narrowing was almost equivalent on T1TSE and DRIVE images, as was that of nerve root compression, especially of the extradural root segment.

Conclusions: T1TSE axial images provide a good anatomical view of normal and pathologic spinal anatomy, but suffer the drawback of inadequately imaging the intradural nerve root and root sleeve. The DRIVE sequence provides contrast by a bright intradural CSF signal O58 Postmyelographic CT: value of spiral versus incremental techniques in multi-slice CT A. Hohmann, MD; H.-R. Mahlo, MD; F. B. Lacey, E. Januschek, MD; N. Rilinger, MD Klinikum Offenbach, Offenbach / Main, Germany Purpose: Comparison of postmyelographic helical with incremental scans of the spine for evaluation of important diagnoses, detail recognition and duration of examinations and postprocessing. Materials and Methods: 100 consecutive patients were randomized into two groups of 50 pts. each for helical or incremental spinal CT examinations (Mx8000 or Mx8000D, Marconi Medical Systems). Scan parameters were comparable in both groups. Diagnostic categories (disk herniation, degenerative changes, nerve root compression and listhesis) were assessed independently by 3 experienced radiologists and a neurosurgeon. Detail recognition (bony degeneration, spinal ganglions, root sheaths, nerve fibers) was graded in consensus on a scale of 1 ± 5. Time was measured for planning and execution of scans and for multiplanar reconstructions (spiral: Transversal, curved sagittal and coronal; incremental: Sagittal and coronal). Results: Detail recognition for spiral CT was equal or superior to the incremental technique. Sagittal and coronal projections often provided additional information. Overall agreement on diagnostic categories was ~85 %. The spiral technique was of significantly shorter duration in planning and scanning phases, but not for reconstructions. Conclusions: Spiral scanning in postmyelographic CT is superior to the incremental technique with regard to duration of examination, detail recognition and clarity of reconstructions. O59 Spinal stroke demonstrated by echo-planar DWI K.-O. Lövblad, T.Loher, M. El-Koussy, F. Stepper, C. Bassetti, G. Schroth Neuroradiology NRAD DRNN, Inselspital Freiburgstrasse, Bern, Switzerland Purpose: Diffusion-weighted MR (DWI) is becoming an established method for the investigation of cerebral ischemia. Its value in spinal ischemia has yet to be demonstrated. Methods and Patients: MR Imaging was performed on a commercial 1.5 T magnet (Siemens Magnetom Vision, Erlangen, Germany) capable of echo-planar imaging. The standard head isotropic EPI single-shot spin-echo DWI sequence was used with b values of 50, 500 and 1000 s/mm2. T2-weighted images in the axial and sagittal planes were also obtained. 5 patients with signs of spinal cord ischemia were submitted to our neurology department which referred them for acute investigation with MR. Results: DWI showed strong susceptibility artifacts; however, in the area corresponding to the spinal cord, hyperintense lesions could be noted on the DW image at a high b value. The lesions correlated well with the suspected anatomical level and were found to have decreased ADC values and to correspond to high intensity changes on follow-up T2-weighted imaging. Conclusions: We have reported a few cases presenting typical signs suggestive of spinal ischemia. DWI demonstrated an ischemic region in the spinal cord which tended to partially regress

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on follow-up imaging. The presence of bone and various tissue interfaces causes severe image artifacts induced by important susceptibility disturbances. However, by using a standard EPI sequence and a spinal coil, we could demonstrate areas of hyperintensity on DWI corresponding to a decrease in the local ADC (75 % of normal values) when compared to non-affected spine. The values reported in the spine seem to correspond to those reported in previous animal literature and the time course of the changes in the ADC values corresponds to what has been reported for the brain. These changes were in the same region as T2weighted hyperintensities present in the central spinal cord on follow-up imaging. Further investigation of spinal stroke with less susceptibility-related sequence techniques could be helpful in increasing image quality.

O60 Tuberculous spinal meningitis: MRI evaluation J. Tsitouridis, D. Melidis, Ch. Papastergiou, S. Chondromatidou, M. Emmanouilidou, A. Morichovitou, V. Souftas. Radiology Dept, Papageorgiou General Hospital, Thessaloniki, Greece Purpose: The purpose of our study is to present our experience gained in the examination of 29 patients with tuberculous meningitis, and the follow-up of the patients after one year. Materials and Methods: The patients were 15 women and 14 men, with ages ranging from 12 to 60 years. The majority of the patients were immigrants form Albania and the former Soviet Union who were working in Greece. MRI examinations were performed using a 1T Siemens Expert plus scanner. Sagittal T2±weighted images (TR 4000 msec, TE 110 msec) and axial, sagittal and coronal preand post-contrast T1±weighted images (TR 500 msec, TE 17 msec) were obtained. Results: Spinal meningitis was an isolated finding in only 19 patients, 5 of whom had associated Tbc abscesses. Spinal meningitis and cerebral meningitis were found in 6 patients and in the remaining 4 patients there was also vertebral involvement. CSF cultures were positive in only 13 cases and negative in the other 11 cases. Tuberculous meningitis of the lungs was found in only 12 patients. Conclusions: We believe that MRI is the method of choice in the evaluation and follow-up of patients with tuberculous meningitis. The most valuable images obtained were the post±contrast T1±weighted images.

Results: Axial Loaded Computed Tomography disclosed variously associated changes in 38 patients. The analysis of the static and dynamic images allowed an accurate evaluation of lumbar spinal instability. Conclusions: Axial Loaded Computed Tomography allows a virtual evaluation of spine dynamics, and thus is useful in studying patients with a clinical suspicion of vertebral instability. O62 Axial loaded MR of the lumbar spine: preliminary observations G. Trasimeni,E. Ramundo*, A. Raco*, L. M. Fantozzi *Ist. di Neurochirurgia, Ospedale Sant' Andrea Università di Roma ªLa Sapienzaº, Rome, Italy Purpose: To evaluate the effect of compressive axial loading MR imaging of the lumbar spine in patients with sciatica or lower back pain. Materials and Methods: A total of 75 non-selected consecutive patients with sciatica or lbp were examined with MR in neutral standard position -psoas relaxed-. Then, the examination was repeated during supine axial compression (65 % of the patient's weight) in slight extension with an appropriate new device (Mikai manufactoring) using axial and sagittal TT2 wi. Results: The most frequent observations after load were in this order: firstly, increased spinal stenosis; secondly, increased dimension of herniated disk or protrusion; thirdly, increased lystesis after load. An interesting observation in 6 cases was the re-distribution of pathological interarticular fluid after load, which reflects an increased vertebral motion. In two cases the load produced a small ªfunctionalº synovial cyst. In one patient who had already been operated on twice for a herniated disk, but without benefit, axial loaded MR radically changed treatment by sending the patient to surgery again because of the appearance of a clear and voluminous disk herniation after load.; in this case, the surgeon positioned a cage in the intervertebral space. Conclusions: Our preliminary data show interesting modifications after load, not only in increased spinal stenosis. We recommend this examination in patients with lower back pain during the load. Another important group is patients with lumbar spinal stenosis, for whom this examination may help to decide between simple laminectomy or laminectomy and fixation. It will be important to perform a study on a selected patient group to define the exact diagnostic gain.

O61 Functional study of the lumbar spine with axial loaded computed tomography R. Agati, L. Simonetti, M. Messia, M. Leonardi U.O. di Neuroradiologia, Ospedale Bellaria, Bologna, Italy

O63 Cervical lateral disc herniations: Imaging with a 3D TSE t2-weighted sequence C. Calli1, N. Yunten1, O. Kitis1, M. Zileli2, E. Emin Ustun1 Ege University Medical Faculty, Departments of Radiology1 and Neurosurgery2, Bornova, Izmir, Turkey

Purpose: This presentation will describe a personal experience in spine kinetics evaluation of the lumbar spine using the Axial Loader device, which allows a functional evaluation of the lumbar spine developing a variable and reproducible axial load in patients during computed tomography study. Materials and Methods: In the period from August 1999 to January 2001, we studied 62 patients with a clinical suspicion of lumbar spine instability. We applied an axial load equal to 65 % of body weight to all patients. Two CT studies were acquired, usually from pedicles of L3 to S1; the first one without load, the second one during axial load. The CT images were reconstructed on a Workstation (VoxelQ, Marconi), on the same planes and perspectives. These images were organised in cine sequences, producing the impression of virtual motion.

Purpose: To determine the efficacy and contribution of a 3D TSE T2 sequence in the MRI evaluation of cervical lateral and foraminal disc herniations. Materials and Methods: 39 patients who had radicular pain and for whom a cervical lateral disc herniation had been disclosed on standard MRI were included in the study. On standard MRI, sagital T1W, turbo spin-echo (TSE) T2W and multi-echo data image combination (MEDIC) sequences were obtained, including axial MEDIC and T1W sequences. The 3D TSE T2W images were taken from the laterally herniated disc space and the data obtained from the 3D images were postprocessed using a multiplanar reformatting (MPR) technique. The imaging parameters of the 3D TSE T2W sequence were TR/TE/FA:2000/120/140, slab thickness:16±20 mm, and slice thickness:1.5±1.75 mm.

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Results: In 39 patients, 43 lateral-foraminal cervical disc herniations were detected on the 3D TSE T2W sequence; 28 in the C5±6, 15 at the C6±7 level. 4 patients had double-level lateral disc herniations. Though the herniations were seen or suspected on standard MRI sequences, the relationship with the neural foramina and degree of the disc herniation could not be established as well as with the 3D TSE T2W sequence. The 3D TSE T2W images clearly showed the degree of herniation and its relation with the neural foramena, as well as the nerve root, because it allowed thin slices to be obtained with high resolution and the use of the MPR technique. Moreover, the disc extrusion was identified correctly on MPR images. Conclusions: The degree of cervical lateral disc herniations, suspected both on clinical and standard MRI examinations, can be shown with high accuracy using a 3D TSE T2W sequence, which can thus affect the therapeutic management of the patient. O64 Diffusion-weighted MR Imaging in spondylodiscitis and vertebral malignancies: a comparative study C. Calli1, N. Yunten1, O. Kitis1, M. Zileli2 Ege University Medical Faculty, Departments of Radiology1 and Neurosurgery2, Bornova, Izmir, Turkey Purpose: To investigate the diffusion-weighted imaging (DWI) findings in spondylodiscitis and malignancies of the spine. Materials and Methods: 17 patients with spondylodiscitis diagnosed on standard MRI were included in the study. The ages of the patients ranged from 21 to 60 years-old. DWI were performed in all patients using a PSIF (reverse FISP) sequence on a 1.5T MR unit (Magnetom Vision Siemens, Erlangen, Germany). For comparison, 15 patients with malignant lesions of the vertebrae were also included in the study and the DWI findings of these two entities were confronted. Results: On postcontrast MRI all the infectious lesions showed enhancement in the intervertebral discs, affected vertebrae and the paravertebral mass, consistent with spondylodiscitis. In 12 of 17 patients DWI revealed hyperintensity in the infected vertebrae and paravertebral-epidural abscesses, a finding which was also detected in the malignant lesions in 15 patients of the comparative group. However, in 5 patients with long-standing spondylodiscitis, DWI showed iso-hypointensity in the vertebrae, whereas the accompanying paravertebral-epidural abscess disclosed hyperintensity. Conclusions: Acute spondylodiscitis and malignant vertebral lesions show similar DWI features, whereas DWI seems to be effective in the differentiation of long-standing infectious disease. O65 Evolution of intervertebral lumbar disk herniation: predictive value of contrast-enhanced MRI. A. Splendiani, S. Delli Colli, G. Cerone, M. Caulo, F. D'Emidio, C. Masciocchi, M. Gallucci Dept of Radiology, University of L'Aquila, L'Aquila, Italy Purpose: Disk herniation demonstrates a natural tendency toward anatomical and clinical regression in up to 70 % of cases. The aim of our study was to search for eventual predictive signs of disk herniation natural history offered by MRI with the use of i. v. contrast medium. Materials and Methods: 50 patients affected by acute intervertebral lumbar disk herniation were enrolled in this prospective study. MRI examinations were performed on 1.5 T magnet, using SE T1 w sequences on sagittal and axial planes before and after contrast-medium i. v. administration, and FSE T2 w on the same

planes. The following parameters were considered: age, sex, level and size of disk herniation, its relationship with the spinal canal, clinical onset interval, type of disk herniation (focal buldge, extrusion, free fragment), herniated material signal intensity on T2 w sequences and its pattern of contrast enhancement. All the patients were conservatively treated and underwent clinical and MRI follow-up after 6 months: disk herniation size and contrast-enhancement variations were evaluated. Results: At the 6-months MRI follow-up, a spontaneous regression of disk herniation was observed in 32 cases The better clinical-anatomical results (spontaneous regression in 100 % of cases) were obtained for free fragments; extruded disks with high signal intensity on T2 w sequences and peripheral contrast-enhancement showed regression in 83 % of cases. Rest in bed for at least 15 days was found to be a significant factor for a favourable evolution of acute disk herniation. Disk herniation evolution did not show any relationship with its side, size and level. Conclusions: Our study demonstrates the usefulness of contrast medium MRI in predicting disk herniation evolution, thus helping in its prognostic assessment. O66 Idiopathic transdural thoracic spinal cord herniation: neuroradiological features, follow-up and differential diagnosis C. Colosimo, *A. Cerase, **G.M. Di Lella, ***C. Anile, ***G. Maira Neuroradiology Section, Institute of Advanced Biomedical Technologies, Dept of Clinical Sciences and Bioimaging, Ud'a., Chieti, Italy *Neuroradiology Unit, Policlinico, Siena, Italy **Dept. Of Radiology. U. C. S. C. ± Rome ± Italy ***Inst. of Neurosurgery, U. C. S. C., Rome, Italy. Purpose: To indicate MRI features that allow a definite diagnosis of idiopathic transdural thoracic spinal cord herniation (ITTSCH), to describe imaging and clinical follow-up findings after surgery, to consider diseases that may mimic ITTSCH and to identify criteria for differential diagnosis. Materials and Methods: 6 female patients (age range 33±56) with a definite diagnosis of ITTSCH were studied; 5/6 were operated on (follow-up 11±96 months). All patients were pre- and post-operatively examined by MRI; CT-myelography (CTM) was pre-operatively obtained in 3/6 patients. Results: Typical features of ITTSCH were found to be: focal thinning and tethering of the upper/middle thoracic spinal cord to the anterior epidural space, lack of anterior pre-medullary subarachnoid space and enlargement of the posterior one. Adjacent disk herniations were found in 4/6 cases. All 5 operated patients improved after surgery; 1/5 developed post-operative extradural CSF-containing collection. Conclusions: Many different intraspinal diseases can mimic ITTSCH: intradural and extradural arachnoid cysts, dural ectasia, chronic adhesive arachnoiditis, tumors with CSF loculations and localized atrophy of the thoracic cord. The key for differential diagnosis is the recognition of the abnormal ventral extradural location of the thoracic cord; the above-indicated MRI features are typical of extradural herniation, thus allowing correct differential diagnosis and making CTM unnecessary.

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O67 To be or not to be . . . a spinal dural arteriovenous fistula D. BalØriaux, G. Rodesch, C. Neugroschl, Ph. David,Th. Metens Hopital Erasme, UniversitØ Libre de Bruxelles, Belgium Purpose: The diagnosis of a spinal dural arteriovenous fistula (AVF) may be difficult and is often made with great delay compared to the time of initial symptoms. MR imaging including MR myelography and MR angiography are the procedures of choice for detecting AVF, although conventional angiography must still be performed in order to confirm this difficult diagnosis. Thanks to recent technical improvements in MRI, spinal millimeter-sized vessels may actually be seen. However, the differential diagnosis of normal versus abnormal medullary vessels may sometimes appear difficult. Materials and Methods : We reviewed 11 patients with surgically confirmed AVF and several patients with suspected AVF on standard MR examination. All spine MR examinations were performed on a 1.5 T MR unit and included T1-weighted (without and with gadolinium) as well as T2-weighted sequences. All the patients had also undergone an MR myelography as well. Moreover, 2 patients had undergone MR angiography using 3D TOF, 3DPC and T1 bolus angiography. All patients underwent conventional angiographic studies of the spinal cord. Results: On T1-weighted images, the spinal cord was usually normal. For all surgically proven AVF, increased (although sometimes only slightly) signal intensity of the cord was seen on T2-weighted sequences. After contrast injection, 9/11 patients had moderate to intense cord enhancement with enlarged vascular structures. In the cases of suspicion of an AVF, an anatomic variation with abundant and hypertrophic but normal veins was found at conventional angiography. Conclusions: The diagnosis of spinal dural arteriovenous fistula is an underestimated cause of myelopathy. Normal vessels and anatomic variations can now be better shown thanks to recent MR improvements. The likelihood of finding a spinal AVF in a patient without increased signal on T2±weighted images in the cord is low. O68 Nomenclature and Classification of Lumbar Disc Pathology B. Appel, Department of Neuroradiology-CT-MRI AZ Middelheim, Antwerp-Belgium The so common pathology of lumbar discs has been described since many years and in many different ways. In some papers of the literature, the disc lesions were even described as herniated disc, herniated nucleus pulposus, ruptured disc and prolaps disc for the same lesion by the same author. Since many years also some consensus was looked for to have a better communication, not only between radiologist and referring neurologist, neurosurgeon, or orthopedic surgeon, but also between the radiologists themselves. For this reason, a new attempt to simplify the nomenclature was made by a new group of seven radiologists, four European, all members of the ESNR and three radiologists from the USA under Chairmanship of dr. Pierre C. Milette from Canada. The results of more than two years work were finalized in December 2000. This proposed nomenclature only devoted to lumbar disc pathology will be presented with theoretical approach, schematical drawings and clinical illustrations. The document defines a nomenclature based only on the morphology of the disc and not upon symptoms, etiology, specific test or upon treatment. Normal disc, anular tear and disc herniation will be described. Standardized terminology is essential to ensure the uniformity and reliability of data. This terminology is established by way of con-

vention and consensus and does not mean unanimity: some degree of compromise is expected from all who are involved. The hope of all of us, who have worked on this project, is that it will ultimately improve the care of patients with spinal disorder.

O69 Magnetic resonance angiography of intracranial aneurysms: evaluation with contrast-enhanced double-stack technique C. Neugroschl, D. BalØriaux, T. Roger, P.David, F. Rio, N. Sadeghi, G. Rodesch, T. Metens Department of Neuroradiology , Erasme Hospital, UniversitØ Libre de Bruxelles, Brussels, Belgium Purpose: The purpose of this study was to assess the clinical utility and accuracy of a gadolinium-enhanced double-stack 3D T1weighted MR angiography procedure in the evaluation of intracranial aneurysms. Materials and Methods: In 23 patients with 27 aneurysms, a fast gadolinium-enhanced acquisition of two consecutive 3D stacks (coronal and transversal, duration 42 sec), followed by a 3D inflow acquisition, was performed. The location, size, shape and orientation of all aneurysms were determined separately on each volume and the aneurysmal neck was measured. The complementarity of the two stacks was assessed. The double-stack technique was compared to 3D inflow and to DSA. Results: Blindly to the DSA, 25/27 aneurysms were detected and correctly localized, while 2 were depicted a posteriori. (mean size: 7.5 mm, range, 2.2±26 mm). 9 aneurysms were ruptured (2.9±7 mm; mean size 4.6 mm). The coronal stack images were superior to the transversal stack images in 2 cases, inferior in 6 cases and equal in 19 cases (p = 0.09). The coronal stack MIP was superior to the transversal stack MIP in 9 cases, inferior in 2 cases and equal in 16 cases (p = 0.016). In 3 cases, only the transversal stack images detected an aneurysm with enough confidence. In 3 other cases, the final diagnosis was only made with the coronal stack. In 8 aneurysms, different information was provided by each of the two stacks. Aneurysm necks were best measured in 23 cases on the coronal stack and in 16 on the transversal stack. Compared to 3D inflow, the double-stack technique was superior in 6 cases. Conclusions: The use of a double-plane acquisition in gadoliniumenhanced 3D T1-weighted MRA allows a more accurate depiction of aneurysms.

O70 Prevalence of unruptured intracranial aneurysms as shown by systematic application of MR angiography C. Colosimo, *F. Laschena, **A. Cerase, A. Tartaro, ***G. M. Dilella,****G. Maira Section of Neuroradiology, Inst. of Advanced Biomedical Technology, Ud'a. Chieti, Chieti, Italy *Idi, Iccrs, Rome, Italy **Neuroradiology Unit, Policlinico, Siena, Italy ***Dept. Of Radiology, U. C. S. C., Rome, Italy ****Inst. Of Neurosurgery, Rome, Italy Purpose: To define the prevalence of unruptured intracranial aneurysms (UIA) using MRA and to compare the detection rate of UIA on MRA and on coronal 3 mm-thick T2-wi. Materials and Methods: 1395 consecutive patients (742 females, 653 males; age range 2±87 years, median 52.3) without a history of SAH and examined for various clinical needs, were evaluated prospectively; all studies included 3 mm-thick coronal T2-wi and TOF 3D MRA. DSA was proposed in patients with defined or doubtful aneurysms.

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Results: 46 UIA were diagnosed in 40/1395 patients (2.86 %) on the basis of MRA; the MRA diagnosis was considered definite in 41 UIA and uncertain in 5 UIA. DSA was obtained in 19/35 patients with definite UIA and in 3/5 with uncertain UIA; DSA confirmed the MRA-based diagnosis of UIA in 21 patients; only in 1 patient with uncertain UIA was DSA negative. 38/46 (82 %) UIA were also demonstrated on thin section T2-w TSE coronal images. Conclusions: The prevalence of UIA was 2.86 % . On T2-wi 82 % of UIA and 100 % of UIA larger than 3 mm were detected. MRA screening of UIA cannot be proposed on a cost-effectiveness basis; however, careful scrutiny of thin T2-wi should increase the detection rate of UIA.

O71 Value of 3D contrast-enhanced magnetic resonance angiography in the diagnosis and follow-up of carotid and vertebral artery dissection L. Strada, N. Anzalone, G. Scotti Dept of Neuroradiology, Scientific Institute H San Raffaele, Milan, Italy Purpose: To verify the value of 3D gadolinium-enhanced MRA (Gd MRA) in the diagnosis and follow-up of cranio-cervical artery dissection. Material and Methods: 9 patients with acute clinical symptoms or color-Doppler sonography suspicious for cranio-cervical arteries dissection were evaluated with MR using a 1.5 unit (Siemens, Vision). All patients underwent Gd-MRA (3D FISP:TR5 /TE2/FA50) after intravenous Gd bolus injection at the onset of symptoms, at 1 month and at a median delay of 3 months. At the time of the first examination, 3DTOF MRA of intra- and extracranial arteries were also acquired. Source images and both MIP and MPR reconstruction were evaluated for image quality, presence of stenosis or occlusion, luminal irregularities and vascular wall anomalies. Results: Gd-MRA revealed the presence of 15 stenoses (13 carotid arteries and 3 vertebral arteries) and 1 carotid occlusion suggestive for dissection. Examination of axial reconstructions from source images showed that the intraluminal thrombus was not always well depicted, whereas 3D TOF MRA, though limited in the extent of vessel examination, better showed the intramural hematoma that confirmed the diagnosis. All patients were treated with anticoagulant therapy and all clinically improved. At the follow-up, contrastenhanced MRA showed the recanalization of stenotic vessels and confirmed the carotid artery occlusion. Conclusions: Gd-MRA is a fast and accurate technique in the evaluation of endoluminal alteration and the extent of carotid and vertebral artery dissections. Less evident intramural hematomas may require the acquisition of TOF MRA or conventional MR in doubtful cases.

O72 Craniocervical artery dissection: Diagnosis and follow-up with MR imaging and MR angiography *F. Gelal, **C. Calli, **O. Kitis, **N. Yunten, ***M. Uygur *Izmir State Hospital, Radiology Department, Izmir, Turkey **Ege University Radiology Department , Izmir, Turkey ***Izemar Imaging Center, Izmir, Turkey Purpose: To determine the value of MR imaging and MR angiography in the diagnosis and follow-up of internal carotid artery (ICAD) and vertebral artery dissections (VAD). Materials and Methods: 6 patients (four with ICAD, two with VAD; ages 34±55) are presented who were studied with three dimensional time-of-flight (TOF) MRA and T1W images with fat saturation, caudal and cranial saturation pulses. The patients, who

were either put on anticoagulation or simply observed, were followed up until complete resorption of the mural hematoma. Results: In all patients, 3D TOF MRA showed the narrowing of the dissected lumen; mural hematomas showed up as a band of high signal close to the vessel. Axial partitions of MRA and T1W images with fat saturation allowed direct visualization of the mural hematoma. On follow-up, mural hematomas gradually decreased in size while the patent lumen enlarged. Complete resorption of hematomas and normalization of flow were achieved between 2 to 7 months. Conclusions: We suggest that MRA accompanied by T1W images with fat saturation should be the method of choice in the diagnosis and follow-up of craniocervical artery dissections. Conservative medical treatment in these patients seems to be effective, obviating the need for aggressive treatment options. O73 Gd-enhanced MRA in the diagnosis of subclavian artery disease *N. Anzalone, *L. Strada, *C. Righi, **R. Castellano, ** R. Chiesa, *G. Scotti *Dept of Neuroradiology, Scientific Institute Hospital San Raffaele, Milan, Italy **Dept of Vascular Surgery, Scientific Institute Hospital San Raffaele, Milan, Italy Purpose: To verify the diagnostic value of Gd-enhanced MRA (GdMRA) in the diagnosis of subclavian artery stenosis or occlusion. Materials and Methods: 23 patients with ultrasound and clinical diagnosis of subclavian artery stenosis were evaluated with GdMRA (3DFISP:TR5,TE2,FA50) of the aortic arch performed in a 1.5 T unit (Vision, Siemens) with a body coil. A coronal volume centered at the level of the aortic arch was acquired after the power injection of a bolus of 20 ml of gadolinium at a rate of 2 ml/ sec. To obtain the arterial phase, a bolus test had been acquired previously. All patients underwent catheter artery DSA within two days from MRA. DSA was performed with catheterization of the aortic arch and in doubtful cases with selective catheterization of the subclavian artery. Both examinations were independently evaluated by two neuroradiologist. Results: All 23 Gd-MRA were considered diagnostic and were timed perfectly with the arterial phase. In 18 cases the presence of subclavian stenosis was demonstrated, in 5 cases a subclavian artery occlusion and in 1 case a subclavian aneurysm were disclosed. DSA confirmed the MRA diagnosis in all cases, although an overall Gd-MRA overestimation of the degree of stenosis was reported. Conclusions: Our data demonstrate a good correlation between Gd-MRA and DSA in the diagnosis of subclavian artery stenosis or occlusion. Gd-MRA appears to be a useful, non-invasive morphologic screening modality with which to plan surgical or endovascular intervention, limiting DSA to the treatment procedure. O74 MRA in the evaluation of the dural sinus thrombosis J. Tsitouridis, D. Melidis, S. Chondromatidou, M. Emmanouilidou, Ch. Papastergiou, A. Morichovitou, V. Souftas. Radiology Dept, Papageorgiou General Hospital, Thessaloniki, Greece Purpose: The aim of our study is to present problems encountered in the evaluation with MRA of 15 patients with partial or complete thrombosis of a dural sinus. Materials and Methods: MRA examinations were performed using a 1T Siemens Expert plus scanner. We obtained MRA images us-

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ing the fl2D±TOF technique (flip angle 35, TR 40 msec, TE 9,8 msec, 3 mm slice thickness, Dist Factor 0,30, NSA 1, matrix 215 ” 256, FOV 220 mm) and 3D TOF ± tun ± single ± slab (TR 33 ms, TE 9,6 msec, flip angle 20, slab thickness 75 mm, eff thick 1.25 mm, matrix 200 ” 512, FOV 210 mm, NSA 1, scan time 5 min 57 sec. In the second technique we localized the presaturation slab under the area of interest. Results: MRI findings of dural sinus thrombosis included the absence of high-flow signal from the sinuses, unusual prominent flow signals from the deep medullary veins, the delta sign in the conventional T1- and T2-weighted images as well the appearance of a collateral network of vessels around the sinus. Confirmation of the diagnosis was made with DSA in only 8 patients. All the patients were re-examined after two weeks with the two MRA techniques. Conclusions: Both MRA techniques were clearly diagnostic in a few cases (6/15) but in remaining 9 cases we found some limitations for each technique. In conclusion, we believe that MRA evaluation has some important limitations and that the solution to these problems is a combination of the MRA techniques.

Saturday O75±O88 O75 Persistant trigeminal artery causing cranial nerve deficits: MR diagnosis 1 J. W. Casselman, 1J. Ghekiere, 2W. Hoefnagels, 3W. Van Landegem, 4B. De Foer, 5J. Delbecq 1 A. Z. St.-Jan Brugge- Department of Radiology, Brugge, Belgium 2 St. Antonius Ziekenhuis- Department of Neurology, Vlissingen, The Netherlands 3 St. Augustinus Hospital, Department of Neurology; Antwerp, Belgium 4 St. Augustinus Hospital- Department of Radiology, Antwerp, Belgium 5 private neurologist, Lennik, Belgium Purpose: To review three cases of persistant trigeminal artery (PTA), illustrate the MR characteristics and demonstrate that these patients can present cranial nerve deficits. Materials and Methods: The cases of three patients, a 54-year-old woman with hemifacial pain, a 61-year old man with paroxysms of severe pain and an 11-year-old boy with proptosis and palsy of the right eyelid were reviewed. A cranial nerve MR-protocol was used to study these nerves from the brainstem to the peripheral branches. A T2-weighted brain study, Gd-enhanced coronal and axial high-resolution T1-weighted sequence and a high-resolution MR-angiography (512 matrix, 0.75 mm thickness) and gradientecho/fast spin-echo T2-weighted sequence (FOV 9.5 cm, matrix 256, thickness 0.7 mm) were used. Results: The three patients were found to have a PTA running from the C4 segment of the internal carotid artery (ICA) to the basilar artery, and passing laterally to the dorsum sellae. The first and last patient had an aneurysm at the origin of the PTA on the ICA. In the first two patients, the basilar artery was hypoplastic proximally to the junction with the PTA. In all three patients the diagnosis of PTA could only be made with high-resolution MRA and gradient-echo/fast spin-echo T2-weighted images. Conclusions: PTA must be excluded in patients presenting cranial nerve deficits (especially trigeminal neuralgia) and these deficits seem to occur more frequently than is reported in the literature. Upon MR, reliable diagnosis is possible only with high-resolution MRA and gradient-echo/fast spin-echo T2-weighted images.

O76 Cavernous hemangiomas of the skull: a review of the literature from 1975 through the year 2000 S. Heckl*, A. Aschoff, S. Kunze *German Cancer Research Center, Department of Oncological Diagnostics and Therapy Neurosurgical Department , University of Heidelberg, Germany Introduction: An extensive review was published by Barnes in 1984 regarding a period of 136 years, describing 123 intraosseous hemangiomas of the skull and 74 of the jaws. Unfortunately, the histological and radiological confirmation was not completely clear and some capillary hemangiomas were included. Methods: We reviewed the articles published in the literature since 1975 and, in addition, studied 4 of our own patients with respect of localisation and clinical symptoms. Results: There are 103 histologically proven intraosseous cavernous hemangiomas of the skull (including the 4 cases we report) and 22 of the jaws. The most frequent site was the frontal (39 %) lobe followed by the temporal one (16 %). In our patients, the localization of the cavernomas was supraorbital, parietal (2X) and occipital (diameter 15 to 25 mm). The patients presented slowly growing masses, tender to pressure, headaches and freely mobile skin above the site of cavernoma. MRI (hyperintensity on T2 and isointensity with brain on T1) and CT (osteolytic lesion with erosion of the tabula externa) confirmed the plain skull films showing the honeycomb or sunburst pattern appearance. Resections and postoperative course were uneventful. In three of our cases there was a coexistence with tumors (meningeoma, malignant lymphoma, malignant melanoma); none of these constellations had been described before. Conclusions: Cavernomas of the skull are rare. Symptoms may be absent but most often headaches occur which disappear after resection. O77 Odontogenic Keratocysts ± A 10-Year Radio-Clinicopathological Review N. Martin-Duverneuil, M. Auriol, Anthony Behin, F. Guilbert, J.-C. Bertrand, J. Chiras GH PitiØ Salpetriere ± Neuroradiologie Charcot, Paris, France Purpose: To determine the range of radiological semeiologic features of the maxillo-mandibular keratocysts and their recurrence in correlation with clinico-surgical and histopathologic findings. Materials and Methods: Retrospective, comparative and systematical analysis of 172 consecutive patients with keratocysts who underwent surgery over the past 10 years. Results: Inflammation was the most frequent initial symptom (40 %), followed by fortuitous radiological discovery (mandible : 28 %) and bone swelling (maxilla : 33 %) . In the maxilla, CT deformity of the thinned walls was revealed in 90 % of cases. The detection of histopathologic inflammation was correlated with definite CT features of the keratocyst shell, without any relation to clinical inflammation. In the mandible, a focal blowing was detected in 44 % of cases with a large presentation range (pseudo-odontogenic cysts: 23 %; pseudo-ameloblastomas: 12 %). Histopathologic inflammation was correlated with pericystic bony border intensity (86 %) and clinical inflammation with MR data. On the whole, there was no influence of the intensity of cystic keratinisation on the radiological features. Frequency, radiological features and histopathologic correlations of the recurrences were also evaluated. Conclusions: This study demonstrates the close link existing between radiological features and histopathologic inflammation; it also shows the extreme radiological diversity of these cysts in what

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is to our knowledge the largest group of patients reported in the imaging literature. O78 Presurgical CT study of the maxillofacial region in trans-rhinoseptal endoscopic neurosurgery L. Simonetti, G. Frank*, E. Pasquini**, R. Agati U.O. di Neuroradiologia, Ospedale Bellaria, Bologna, Italy *U.O. di Neurochirurgia, Ospedale Bellaria, Bologna, Italy **U.O. di Otorinolaringoiatria, Ospedale Maggiore, Bologna, Italy Purpose: The surgical literature recommends CT scanning of the maxillofacial region as part of the diagnostic work-up to trans-rhinoseptal endoscopy for sellar disease. The aim of this investigation is to disclose any anatomical abnormalities or pathological changes along the surgical route and to ascertain possible anatomical variants of the sphenoid sinus and its relations with the surgical target. Above all, the scan serves to display the bone planes as anatomical landmarks during the endoscopic procedure. Our study aimed to ascertain the true usefulness of CT examination in our patients. Materials and Methods: We reviewed the CT presurgical scans of the maxillofacial region done over the last two years (around 30 cases). Axial spiral CT scans were mostly performed followed by multiplanar reconstructions and volume rendering. CT information was verified in the light of surgical findings and compared with the data provided by presurgical MR scanning to investigate sellar disease. Results and Conclusions: We are currently processing our conclusions, which are open to discussion. O79 Bell's palsy and MRI. What is the prognostic value of quantitative measurements of signal intensity increases after contrast agent administration? 1 B. Kress, 2F. Griesbeck, 2A. Kornhuber, 1W. Bähren 1 Department of Radiology, 2Department of Neurology, Bundeswehrkrankenhaus, Ulm, Germany Purpose: The objective of this study was to assess the prognostic value of quantitative measurements of contrast enhancement. Materials and Methods: In a prospective study, MRI images with a slice thickness of less than 1 mm were obtained from 21 patients with Bell's palsy on the first day of inpatient treatment, and quantitative measurements of contrast enhancement of the nerve were conducted. Results: Initial MRI allowed the three patients whose palsy was to show no improvement in the course of their illness to be differentiated with certainty from the eighteen patients who were to exhibit a normal palsy. In none of the patients who had been diagnosed on the basis of initial MRI as having a normal palsy was the amplitude of the muscle compound action potential on the affected side reduced to less than 20 % of that of the normal side. Conclusions: The quantitative measurement of contrast enhancement was shown to be an important prognostic indicator and may provide a basis for differentiated therapy of facial paralysis.

O80 Diagnosis of facial nerve trauma with multidetector-array CT of the temporal bone 1 T. F. Gotwald, 2C. Pototschnig, 1R. Frank, 1A. Stoeger, 1T. Schuster, 2W. Thumfart, 1D. zur Nedden 1 Radiology, University Hospital, 2ENT-Department, Innsbruck, Austria Purpose: To evaluate the use of the newly available multidetector CT (MD-CT) technique in the imaging work-up of facial nerve trauma. Materials and Methods: Five patients with partial or complete facial nerve palsy after trauma to the temporal bone underwent MDCT scanning. From these CT datasets, multiplanar reconstructions and additional thin-slice (5 mm) maximum intensity projections (MIPs) were obtained. Two patients had undergone prior conventional CT exams. The imaging findings were compared to the findings in subsequent temporal bone surgery for facial nerve decompression. Results: Using MD-CT scanning, it was possible to correctly predict the specific location of facial nerve damage in three cases, as confirmed in subsequent ear surgery. One patient had multiple lesions; in this case MD-CT scanning predicted only one site of damage to the facial nerve. In another patient, MD-CT allowed more detailed evaluation of multiple temporal fractures as compared to the prior conventional CT exam. In yet another patient, thin-slice MIPs were useful to enhance a subtle fracture line not seen in conventional CT. Conclusions: Multidetector CT was extremely helpful in the differential diagnosis of facial nerve palsy in temporal bone trauma.

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O81 Role of 3D spiral SSD-reconstructed CT imaging in the diagnosis of midface fractures V. Magnano di San Lio, P. Romeo, S. Pappalardo, O. Pennisi, A. Vallone Imaging Department ± S.Vincenzo Hospital, Taormina, Italy Purpose: To evaluate the indications and limits of 3D spiral, Surface-Shaded Display (SSD) reconstructed CT imaging in fractures of the midface skeleton, in comparison to conventional and MPRreconstructed axial CT imaging. Materials and Methods: 59 patients with major facial traumas were studied; the study protocol included a single transversal-oriented helical CT scan. Subsequently, 3D SSD images were generated from helical raw data; these 3D SSD-reconstructed images were compared with 3D and MPR-reconstructed images from conventional axial CT scans. Results: Our experience included the six types of zygomatic fractures in the Knight and North classification, the three types of mascellar fractures in the Le Fort classification, as well as alveolar, ethmoido-orbital, maxillo-zygomatic and several other types of complicated fractures of the facial skeleton. Conclusions: Spiral 3D reconstructed CT imaging is a quick and easily feasible method for diagnostic imaging in the evaluation of traumatic injury to the facial skeleton. It provides the three-dimensional, surgical-like evidence of the spatial arrangement of midface fractures with dislocated, rotated, or comminute bony fragments: extremely helpful to surgeons in virtual preoperative planning of reconstructive work. The current limits of this method are detection of linear fractures without dislocated fragments, or analytic imaging of too thin or convolutely shaped bony laminae.

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O82 Cerebrospinal fluid (CSF) leakage: the role of CT and MR in the planning of endoscopic treatment G. Di Giulio 1, P. Castelnuovo 2, R. Dore 1, L.Sammarchi 1, V. Portugalli1, F. De Bernardi 2 1 Institute of Radiology, 2ENT Department University of Pavia, IRCCS Policlinico S. Matteo, Pavia, Italy Purpose: Endoscopic approaches to the repair of CSF leakage are now a well-established surgical procedure. In this study, we analyzed the role of imaging in the planning of this type of endoscopic surgery. Materials and Methods: 49 patients were treated with endoscopic surgery for CSF leakage. The fistulae were spontaneous in 21 pts, traumatic in 15 pts and iatrogenic in 13 pts. All patients underwent a CT scan only with coronal view, with sections of 1±2 mm thickness, without contrast medium. Axial spiral CT scans with coronal reconstruction were used in patients with dental artefacts. MR examination was used in patients with spontaneous or traumatic CSF leakage. Finally, pre-operative intrathecal injection of fluorescin was always used. Results: The cribriform plate and anterior ethmoid were the site of leakage in 33 pts (66 %), the posterior ethmoid and sphenoid sinus in 9 pts (16 %), while multiple sites were involved in 7 pts (14 %). In all patients, CT allowed a correct evaluation of bone defects (single or multiple), all of which were confirmed upon endoscopic surgery. Meningoceles were recognized only by gadolinium-MR (in 7 pts). Conclusions: Radiological planning requires both CT and MR, in that CT is more sensitive in detecting bone lesions and the site of leakage, but only MR can recognize meningoceles, thus allowing specific treatment. O83 Intrathecal gadolinium (gadopentetate dimeglumine)-enhanced MR cisternography in the evaluation of clinically suspected CDF rhinorrhea in human patients J. R. Jinkins1, M. Rudwan2, G. Krumina3, E. T. Tali 4 1 Department of Radiologic Sciences, Medical College of Pennsylvania-Hahnemann, Drexel University, Philadelphia, PA, USA 2 Department of Radiology, Ibn Sina Hospital, Kuwait City, Kuwait 3 Radiology Clinic, Education and Research Center, Riga, Latvia 4 Department of Radiology, Gazi University School of Medicine, Ankara, Turkey Purpose: To evaluate the utility of intrathecal gadopentetate dimeglumine: GD-enhanced magnetic resonance cisternography (GD-MRC) in the evaluation of cerebrospinal fluid (CSF) rhinorrhea. Materials and Methods: Fifteen adult patients who had experienced prior cranial trauma (n = 9), previous cranial surgery,(n = 3), or presented spontaneous CSF rhinorrhea (n = 3) were examined. Computed tomography (CT) showed evidence of anterior skull base fractures or erosions in each patient; preceding T2-weighted MR imaging had shown hyperintensity in the ethmoid-sphenoid air cells in all cases. Via lumbar puncture, a single dose of 0.5 cc/ml GD was injected into the subarachnoid space after mixing with 3±5 cc/ml of the patient's CSF. Immediate and delayed T1- and T2weighted MR imaging was then carried out in the three orthogonal planes with the patient prone. Results: Eleven patients showed leakage of GD through the cribriform plate into the ethmoid air cells. Two patients showed leakage of GD into the sphenoid sinus. No leakage was observed in two patients. Conclusions: This cooperative study shows the relative safety and feasibility of low-dose GD-MRC in confirming the presence and determining the focus of active CSF rhinorrhea.

O84 MR-based 3D surgical planning for venous malformations of the head and neck P. Held, A. G. Schreyer, Department of Radiology, Regensburg, Germany Purpose: To create MR-based 3D models of complex subcutaneous venous malformations (VM) within the neck and head for surgical- or intralesional laser therapy planning. Materials and Methods: We performed MR imaging in 4 patients with complicated VM of the neck. MRI was done on a 1.5T scanner (Symphony, Siemens). Fat suppressed T2-weighted FLASH and T1-weighted 3D FLASH sequences before and after i. v. GDDTPA application were acquired. MR data were 3D rendered on a computer workstation applying volume rendering algorithms. In addition, intensity-based segmentation was performed with manual fine tuning of the VM. Based on these imaging modalities, the decision to perform a surgical procedure or intralesional laser therapy was made interdisciplinarily. Results: All lesions were depicted clearly using MRI. 3D rendering of the volume of the surrounding anatomy was performed in real time without major post-processing. Only the VM had to be segmented manually because of their fuzzy appearance. The manual processing time for each case was approximately 30 minutes. Conclusions: 3D surgical planning based on MR imaging of head and neck lesions can be performed quickly and allows the surgeon to gain a better understanding of complex vascular malformations. Moreover, 3D models appear to be an excellent platform for interdisciplinary discussions among radiologists and surgical clinicians in determining therapeutical strategies. O85 Septic venous thrombosis of the lateral sinus: the challenge of diagnosis K. Marsot-Dupuch, D Ducreux, F Portier, M-C Petit-Lacour, P Lasjaunias Le Kremlin Bic†tre, France Purpose: To illustrate the difficulties in the diagnosis of septic thrombosis of the lateral sinus. It is important to underline that delayed diagnosis a principle contributor to the poor prognosis for patients with this rare condition, and thus to stress the need to perform MR/MRV in patients with underlying diseases putting them at risk. Materials and Methods: A retrospective study was conducted on three patients referred over the last three years (1998±2001) and who had undergone examinations with CT with and without contrast injection (soft tissue and bone window algorithms) and with MR/ MRV. Results: The clinical diagnosis was always underestimated at initial presentation, with the imaging modalities being requested following cerebral ischemic attack (2/3) or cephalalgia, photophobia and tinnitus (1/3). Initial imaging diagnosis was delayed (3-days to more than a week) in all cases, as patients had been referred for brain evaluation and possible carotid artery disease. One of the three patients is now deceased, while one had serious sequela of brain damage; the remaining patient recovered after antibiotherapy and anticoagulotherapy. Conclusion: Delayed diagnosis of septic thrombosis of the lateral sinus is probably related to its non-specific clinical symptoms. Therefore, in patients with a history of diabetes or of infection of the face or of the temporal bone, a careful examination of the skull base should be performed systematically to determine the permability of the venous sinuses, the integrity of the temporal and occipital bones and the normality of the related fatty spaces. Indeed,

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only a prompt diagnosis can allow the administration of an effective combination of antibiotherapy and anticoagulotherapy.

O86 Lemierre syndrome: use of CT to depict an extensive occult thrombophlebitis KV. Nguyen-Dinh, K. Marsot-Dupuch, B. Lamblin, F. Portier, P. Lasjaunias Services de Neuroradiologie et d'Oto-Rhino-Laryngologie, Centre Hospitalo-Universitaire de Bic†tre, Le Kremlin-Bic†tre Cedex, France Purpose: We report a patient presenting Lemierre syndrome or postanginal necrobacillosis, an uncommon but potentially lifethreatening condition characterized by a high rate of mortality in the absence of adequate antibiotherapy. Case report. A 26-year-old man presented with a left ulcero-necrotic pharyngotonsillitis, while a chest x-ray showed a left perihilar tumoral mass. Enhanced thorax CT showed bilateral peripheral lung micronodules with a necrotic mass in the culmen which was suggestive of septic emboli. An enhanced cervical CT performed a few hours after CDUS demonstrated an extensive thrombophlebitis involving the left internal jugular vein, the anterior jugular vein and the facial vein. Gas bubbles were present within the retrostyloid space and the jugular vein. Despite strong antibiotherapy, the septicaemia persisted and required cervical drainage. During surgery, a phlegmonous collection was found to be communicating freely with anterior and internal jugular veins. Conclusions: The extension of the infection to the parapharyngeal space occurs secondarily to the direct spreading of oropharyngeal infection or by tonsillar lymphatic or venous dissemination. Internal jugular vein thrombosis may result in septicaemia and septic emboli (in the lungs, joints, or bones). CT may contribute to diagnosis and establish the extent of thrombophlebitis.

O87 Bilateral subdural hygromas and hydrocephalus due to cerebral venous sinus and jugular vein thrombosis *S. Weidauer, **G. Marquardt, ***M. Adelmann, **V. Seifert, *F.E. Zanella *Institute of Neuroradiology and **Department of Neurosurgery, Johann Wolfgang Goethe ± University Frankfurt, Germany ***Department of Neurology, Klinikum Weilmünster, Germany Purpose: Bilateral subdural hygromas and hydrocephalus as initial manifestations of cerebral venous sinus and jugular vein thrombosis are rare neuroradiological features. The aim of the present study was to investigate the relationship between clinical and neuroradiological findings. Materials and Methods: We studied 4 patients with bilateral hygromas and 1 patient with acute hydrocephalus. All patients had serial CT and / or MR scans, MRA and 2 of them DSA. Results: 3 out of 4 patients with bilateral hygromas had a history of severe headache without trauma for at least one week before admission. Neurological examination revealed impairment of consciousness (3 of 4) and focal deficits (2 of 4); 2 had had seizures, but none of them had papilloedema. Two patients underwent neurosurgical treatment with burr hole aspiration. Early follow ± up examinations revealed relapsing hygromas in one case. MRA (4 of 4) as well as DSA (2 of 2) disclosed thrombosis of the cerebral venous sinus (3 of 4: transverse and sigmoid sinus, unilateral jugular vein; 1 of 4 bilateral jugular vein thrombosis) with complex collateralisation. The patient with acute hydrocephalus failed to improve after ventricular drainage. CT two days later revealed

intracerebral hemorrhage associated with sagittal sinus thrombosis in MRA. Conclusions: In cases without a history of head injury or infection, diagnostic investigations should rule out thrombosis of the cerebral venous sinus or jugular veins, especially when neurosurgical intervention is considered. We suggest malabsorption of CSF through the arachnoid villi followed by hydrodynamic disturbance of CSF outflow in case of increased venous pressure. O88 Guidelines and algorithms for head and neck imaging *F.Kainberger, **H. Czembirek *Department of Diagnostic Radiology, University of Vienna, **Central Institute of Radiology, Lainz Hospital, Vienna, Austria Purpose: With the Council Directive 97/43/Euratom recommendations concerning referral criteria for medical exposure, including radiation doses have to be implemented into national law of all EU member states. The quality of national guidelines in different European countries was evaluated. Materials and Methods: Out of all European member states 5 guidelines and algorithms for head and neck imaging accessible in the internet were evaluated with respect to contents, structure, evidence-based quality level, and fulfilments of Euratom recommendations. Results: None but one reached the quality level of evidence-based medicine, the others were consensus guidelines rather than of algorithms. The structure generally followed that of guidelines. A significant predominance of cross-sectional imaging modalities over conventional radiograms was observed. There was no specific reference to radiation exposure as recommended in EU directives. Conclusions: Along with historical analysis of radiation protection issues in Europe, conclusions can be drawn towards a more active role of European radiological societies to establish a new form of ªdiagnostic reasoningº and to deliver recommendations more actively.

Sunday O89±O139 O89 Multislice versus single-slice CT of the temporal bone L. Jäger, H. Bonel, M. Liebl, S. Srivastav, V. Arbusov, S. Lang, M. Reiser Institute of Clinical Radiology, University of Munich, Grosshadern, Munich, Germany Purpose: The aim of this study was to compare the image quality of multislice versus single-slice spiral CT in delineating anatomical structures of the temporal bone. Materials and Methods: 100 patients with suspected middle or inner ear pathologies were examined in a prospective study. The patients were randomly distributed and underwent single-slice spiral CT (Somatom Plus 4, Siemens, Erlangen) or CT scanning on a Somatom Plus 4 Volume Zoom scanner (Siemens, Erlangen). Finally, 50 patients were examined on each CT-scanner. Using the single-slice spiral CT axial and coronal images were acquired, whereas using the multislice spiral CT only axial images were acquired and from those reformatted coronal images were calculated. Two blinded radiologists carried out film readings to determine the visibility of anatomical landmarks on the axial and coronal images. For each patient only one temporal bone was evaluated, on the side without the pathology; a total of 25 left and 25 right temporal bones were evaluated with each examination modality.

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Results: On the axial images the multislice spiral CT was significantly superior to the single-slice spiral CT in delineating the anatomical subtleties of labyrinthine and tympanic structures. Even the reformatted coronal multislice images were significantly superior to the primarily acquired coronal single-slice images in depicting anatomical landmarks. Conclusions: High-resolution multislice spiral CT enables greater anatomical detail perceptibility than single-slice spiral CT. Even the reformatted multislice images guarantee diagnostic quality, and therefore the acquisition of CT-data in a second examinationplane is no longer needed to evaluate temporal bone pathology.

also performed, and a control MR study with the same sequences was performed one year later. Results: The correlation between the MR signs, the MR control study and the clinical evolution revealed 9 intra labyrinth schwannomas (3 intracochlear, 6 intravestibular), 5 cases of labyrinthitis and 3 cases of intralabyrinthine bleeding; for the latter 3 cases a differential diagnosis was made (with a spontaneous hyperintensity on the T1 without injection). Conclusions: MR intralabyrinthine enhancement is uncommon but must be known and well described, particularly in cases of sudden hearing loss.

O90 Virtual endoscopy of the middle ear: an ongoing study evaluating the clinical benefits of a standardised approach for radiological diagnosis and surgical planning 1 T. Rodt, 1S. Bartling, 2B.P. Weber, 1H. Becker Departments of Neuroradiology1 and Otorhinolaryngology2, Hannover Medical School, Hannover, Germany

O92 Sudden onset of MØni›re's disease and sensorineural hearing loss caused by liquor hypotension ? Two cases 1 J. W. Casselman, 2R.Kuhweide 1 Department of Radiology, 2Department of Otorhinolaryngology, A. Z. St.-Jan Brugge A. V., Brugge, Belgium

Purpose: Virtual endoscopy (VE) allows noninvasive endoluminal 3D-visualisation of the patient's individual anatomy and therefore can be helpful in conceptualising complex pathologies. The results of an ongoing study using a standardised examination algorithm are presented. Materials and Methods: Using a low-dosage protocol, Reconstructed Multi-Slice CT scans were obtained in 20 normal subjects and 43 patients with middle ear malformations, trauma, and prior surgery. VE and 3D images of the ossicles were generated using standardised post-processing algorithms as part of the routine clinical examination. The method was also evaluated in normal subjects. The clinical benefits for radiological diagnosis and surgical planning were evaluated. Results: Standardisation and evaluation in normal subjects enhanced the diagnostic reliability, as post-processing artifacts could be quantified. In 15/17 cases of malformation, VE and 3D visualisation led to a diagnosis which was surgically confirmed. In all patients with trauma or prior surgery, correct diagnosis was made with 2D images. 3D images confirmed diagnosis and provided additional information on spatial relationships among the individual structures which was useful for surgical planning. Conclusions: VE and 3D visualisation can be helpful in understanding the complex anatomy in cases of malformation, trauma and re-evaluation of surgery and, given these diagnostic benefits, are recommended as an additional routine examination in cases of malformation.

Purpose: The aim of this presentation is to review the MR and clinical findings in two patients with sudden sensorineural hearing loss (SNHL) and MØni›re's disease and to propose a hypothetical mechanism for the combination of symptoms and MR findings. Materials and Methods: Two women (ages 57 and 63) underwent a MR examination of the brain/inner ear because they had had an attack of MØni›re's disease and severe/fluctuating SNHL. The first patient had also had previousl MØni›re attacks on the opposite side, while the second patient mentioned tinnitus at presentation. T2-weighted brain images, thin 3DFT-CISS images and Gd-enhanced T1-images of the inner ear and posterior fossa were made. Results: Thickened meninges were seen on all sequences (thick and enhanced on Gd-enhanced T1 images, loss of fluid inside the IAC on CISS images) for both patients, along with narrowing of the prepontine cistern, low position of the tonsils and loss of normal calibre of the suprasellar cistern. Enhancement of the meninges could be followed deep into the internal auditory canal bilaterally. Conclusions: Liquor hypotension can probably cause SNHL and MØni›re-like symptoms in the absence of headache. The loss of CSF in the posterior fossa probably causes volume/pressure changes in the perilymph (over the cochlear aqueduct) and, as a result, an indirect hydrops of the scala media with MØni›re-like symptoms. This hypothesis is supported by MØni›re & SNHL attacks, which are known to occur after a number of lumbar punctures performed for anaesthesia (surgery). Treatment is the same as for liquor hypotension.

O91 Description and etiology of MR intralabyrinthine contrast enhancement F. Dubrulle, G. Labrot, J. Delomez, C. Vincent F. M. Vaneecloo, L. Lemaitre, Service de Radiologie Huriez -CHU Lille, LILLE, France Purpose: This study describes the signs of MR intralabyrinthine contrast enhancement, correlates these signs with the clinical information obtained and longitudinal control of the patients. The aim is to propose a radiological diagnosis and a description of the different pathologies possible. Materials and Methods: 17 patients with an inner ear contrast enhancement (posterior and/or anterior labyrinth) in Spin Echo T1 after gadolinium on 1.5 Tesla MR were included in the study. These patients presented asymmetric hearing loss in 9 cases, a sudden hearing loss in 5 cases and signs of MØni›re's disease in 3 cases. A 3D infra-millimeter T2 sequence (CISS sequence) was

O93 Visualization of inner ear dysplasias in patients with sensorineural hearing loss by high-resolution magnetic resonance imaging and volume-rendered reconstructions R. Klingebiel, N. Thieme, R. Lehmann Neuroradiology Section, Dept. of Radiology, CharitØ, Berlin, Germany Purpose: We evaluated a data acquisition and postprocessing (PP) protocol for inner ear (IE) assessment by magnetic resonance (MR) imaging in patients suffering from various labyrinth malformations. Materials and Methods: MR IE studies of 158 consecutive patients (n = 316 IEs), suffering from sensorineural hearing loss (SNHL) without evidence of an acoustic neurinoma, were reviewed for pathologies of the inner ear (IE) and internal acoustic meatus (IAM). HR MR data for all abnormal IE studies (n = 45) were postpro-

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cessed to previously standardized three-dimensional (3D) volumerendered (VR) reconstructions. Results: In 9 patients (5.7 %) the following IE dysplasias were detected: malformation of the cochlea (6 IEs), vestibulum (4 IEs), semicircular canals (SCCs) (12 IEs) and vestibular aqueduct (VA)/ endolymphatic sac (ES) (10 IEs). One patient showed evidence of an aplasia of the vestibulocochlear nerve (VCN). In 4 patients mutiple IE dysplasias were encountered. Comprehensive 3D visualization of all labyrinthine dysplasias was achieved by the use of two VR reconstructions. The overall time for bilateral IE assessment amounted to 30 ± 35 minutes. Conclusions: This imaging protocol allows for the rapid and comprehensive visualization of various inner ear dysplasias, based on a limited number of VR reconstructions. O94 Sialolithiasis: high-resolution sonography versus computed tomography F. Kainberger, S. Robinson, Ch. Czerny, C. Krestan, H. Imhof Department of Diagnostic Radiology, University of Vienna, Vienna, Austria Purpose: To determine the diagnostic value of a combined application of sonography (US) with computed tomography (CT) for diagnosis of sialolithiasis. Materials and Methods: 28 patients were investigated with highresolution US (HDI 5000, ATL, Bothell, WA.) and CT (Philips SR 6000 and Philips Secura; single slice 3/3 or spiral mode 3/3/2). US included investigation of all major salivary glands and ducts, CT was performed for either parotid or submandibular glands in axial direction without contrast media. Results: With US, abnormalities in the form of sialadenitis were found in 80 % with concrements in only 53 %. The most common cause of low sensitivity of detection of calculi was to mistake them with the calcified stylohyoid ligament and low sensitivity in finding small intraglandular stones. With CT, calculi were detected in 79 %. No abnormality was found with CT, if US was negative. Abnormalities indication glandular inflammation was only possible with CT in case of significant swelling. Conclusions: US and dedicated CT are complementary modalities that are readily accessible in clinical settings and can be used with low radiation exposure and without contrast media application. US is highly sensitive for the evaluation of glandular inflammation and CT is more sensitive for the detection of small calculi. O95 Histopathology in 28 cases of saccular cerebral aneurysm K. Tokunaga, C. Dallon, A. Dedashdi, K. Barath, G. P. Pizzolato, D. A. Rüfenacht, G. Gabbiani Neuroradiology, HUG, Geneva, Switzerland Purpose: To evaluate the histopathological appearance of 28 aneurysms. Materials and Methods: Aneurysm biopsies (8 cases) or autopsy materials (20 cases) of patients deceased as a result of aneurysm rupture or other reasons (aneurysm as an incidental finding) were evaluated histologically using a variety of stains to look for specific components of the aneurysm wall. The aspects evaluated included wall thickness, content and quality of smooth muscle tissue, signs of inflammation, signs of atheromatous changes, clot formation and signs of clot reorganization, content of collagen and elastic fibers, the presence of adventitial vessels and, where possible, evaluation of the rupture site. Results: The different stains applied in the study revealed that the aneurysm wall is not homogeneous and that it is variably con-

structed, when comparing different lesions. This included observations of a great variability in the amount, differentiation and organizational pattern of smooth muscle and collagen fibers. There were findings of inflammation and presence of clot reorganization, which may indicate local changes in aneurysm growth, wall repair or degeneration. Such changes could also lead to locally increased fragility and rupture. Conclusions: The histopathological evaluation of saccular cerebral aneurysms revealed a variety of wall changes, indicating that the aneurysm wall is a complex structure that may change during its growth. O96 3D rotational angiography in planning therapy of intracranial aneurysms *A. Hochmuth, **U. Spetzger, *A.Berlis, *J. Spreer, *J. Klisch, *M. Schumacher *Sektion Neuroradiologie, Neurozentrum, Universitaetsklinikum, Freiburg, Germany **Neurochirurgische Universitaetsklinik, Freiburg, Germany Purpose: To evaluate the diagnostic value of 3D rotational angiography (RA) compared to digital subtraction angiography (DSA) in the detection, categorization, and treatment-planning of ruptured intracranial aneurysms. Patients and Methods: Between September 1999 and September 2000, 53 patients with acute SAH underwent angiography (GE Advantx-E, GE, Milwaukee, USA) with both the RA and DSA methods. DSA was performed in 2 to 6 standard-projections. The 3D-datasets of the RA were evaluated using a GE Advantage workstation. DSA-films and 3D-datasets were analyzed retrospectively in terms of depiction of aneurysms (number and configuration) and impact on therapy-planning. Results: 49 aneurysms were detected in 42 patients, (1±5/pat, size 0.6±20.4 mm). However, RA revealed additional 7 aneurysms not seen on conventional DSA but failed to depict one. The delineation of the neck of the aneurysm was remarkably improved in RA in 70.5 % of all cases. In 45.0 %, respectively, a 50.0 % better depiction of the parent vessel and relationship to adjacent vessels was demonstrated. In 9/42 patients, an interventional procedure was proposed, while in 26/42 patients microsurgical therapy was proposed. In 7/42 patients, both options were rated as equal. Conclusions: In comparison to DSA, 3D-rotational angiography allows for a more exact depiction of anatomical details important in planning therapy of intracranial aneurysms. RA also identified more aneurysms. O97 3D Angio-CT: a useful tool in selection of methods for treatment of intracranial aneurysms M.L. Nowicki, J. Sikorska, K. Kordecki, A. Dowzenko, J. Walecki Diagnostic Radiology Dept., Central Clinical Hospital MSWiA, Warsaw, Poland Purpose: Presentation of our own experiences with 3D Angio-CT in the treatment of intracranial aneurysms. Materials and Methods: CT and Angio-CT were used in examination of 34 patients with acute subarachnoid hemorrhage (SAH). In all cases cerebral angiography (DSA) was also performed. 20 patients underwent endovascular embolisation of aneurysms. AngioCT was performed using HiSpeed CT/I (GE) and 3 D reconstruction by Advantage Windows 3.1 with option MIP, VR and Navigator for external and intraluminal artery examination. Results: In 32 patients both Angio-CT and DSA detected intracranial aneurysms. In 2 patients aneurysms were better visualized

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by Angio-CT than DSA. In 12 patients the Angio ±CT provided more information about the configuration of aneurysms than did DSA, and Angio-CT in these cases was especially helpful in selection of treatment strategy. 20 patients were treated by endovascular procedures and 14 by surgical clipping. Conclusions: 3D Angio-CT is a very helpful method in selection of treatment strategy in patients with intracranial aneurysms. O98 Three-dimensional simulation of coil-induced pulsatile flow changes in terminal cerebral aneurysms *C. Groden, *E. Bernd, **J. Laudan, **S. Gatchell, *H. Zeumer *Neuroradiologie, Hamburg, Germany **Hamburgische Schiffbau-Versuchsanstalt, Hamburg, Germany Purpose: To evaluate the effect in cerebral aneurysms of different percentages of coil mesh on pulsatile flow and pressure in the aneurysm neck. Materials and Methods: Geometric data on a basilar-tip aneurysm and vertebrobasilar arteries after subarachnoid hemorrhage were obtained by computer tomographic angiography. Intraarterial pressure was recorded with a pressure wire before and after aneurysm treatment with detachable coils. The pulsatile flow was simultaneously documented by ultrasound. A three-dimensional computer simulation of four conditions was created: a. Aneurysm before intervention, b. Aneurysm with a filling degree (FE) of 20 %, c. Aneurysm with a FE of 12 %, and d. Aneurysm with a FE of 12 % and simulation of a clotted aneurysm. Results: Relative pressure amplitudes neither increased nor decreased under the different simulated aneurysm-filling conditions. Condition b depicted complete cessation of inflow through the aneurysm neck. Condition c depicted incomplete deceleration of inflow through the aneurysm neck, showing remaining flow around the embedded platinum coils. Condition d, including additional clotting simulation of aneurysm dome, was not able to inhibit the persisting flow phenomena. Conclusions: Inserted platinum coils can immediately and decisively relieve the influx of pulsating blood, allowing initial clotting. To reach this effect a volume density of 20 % platinum coil mesh is required. O99 Endovascular treatment of intracranial aneurysms using Guglielmi detachable coils: analysis of mid-term angiographic and clinical outcomes P. Ng, M. S. Khangure, C.C. Phatouros, M. Bynevelt, T. ApSimon, W. McAuliffe Royal Perth Hospital, Perth, Australia Purpose: To analyse the angiographic and clinical outcomes of patients with intracranial aneurysms treated using GDC over an 8year period. Materials and Methods: 144 consecutive patients with 160 intracranial aneurysms were treated using GDC. Two neuroradiologists performed a consensus interpretation of the diagnostic angiogram, coil-embolisation-procedure angiogram, and follow-up angiograms, in all patients. Results: 81 patients (56 %) had ruptured and 63 (44 %) patients unruptured aneurysms. Of those with ruptured aneurysms, 22 were Hunt & Hess clinical grade I (27 %); 31 were grade II (38 %); 18 were grade III (22 %); 8 were grade IV (10 %); and 2 were grade V (3 %). Technical success was achieved in 131 of 144 patients (91 %). Of these aneurysms, there was complete occlusion in 46 %; residual body filling in 38 %; and residual neck filling in 16 %. Small neck remnants ( 2-mm) usually remained stable or im-

proved. Recanalisation occurred in 28 % of cases at 12 months. A narrow neck size (< 4 mm) correlated with a better angiographic outcome over time. At clinical follow-up after 2 years (available for 98.5 % of patients) 90 % of patients were clinically independent; 2 % remained disabled; 1 % had become disabled due to a rebleed; 1 % had died due to a rebleed; and 6 % had died due to other causes. The rebleed rate was 1.5 % (mean clinical follow-up of 48-months). Conclusions: Our results suggest that aneurysmal body filling tends to improve over time, especially after the first year; and that there is increasing angiographic stability up to 3 years after treatment. However, new recanalisation can occur up to 2 years after embolisation. O100 Endovascular treatment of cerebral aneurysms with a combination of metallic stents and Guglielmi detachable coils (GDC). M.E. Mawad, E. F. Ciceri*, R. P. Klucznik The Methodist Hospital, Baylor College of Medicine, Houston, Texas *Istituto Nazionale Neurologico ªC. Bestaº, Milan, Italy Purpose: To present our preliminary clinical experience in the treatment of complex intracranial aneurysms with a combination of a balloon-expandable stent and Guglielmi detachable coils (GDC). Materials and Methods: 15 patients harboring a complex intracranial aneurysm were treated. The technique used consists of deploying a metallic stent (S670 Medtronics, AVE) across the neck of the aneurysm, followed by the obliteration of the fundus with GDC. The balloon used to deploy the stent is kept in place and is inflated intermittently within the parent artery during the obliteration of the aneurysm. The inflation of the balloon serves the dual purpose of preserving the lumen of the parent artery and in densely packing the aneurysm with coils. Results: In four (4/15) patients we were unable to position the stent at the desired location due to the stiffness of the delivery system and/or the tortuosity of the parent artery. In one patient (1/15) the follow-up angiogram showed persistent filling of the aneurysm. One patient treated in the acute phase suffered a fatal re-rupture of the aneurysm one month following treatment. Conclusions: The use of a metallic stent can help in the endovascular treatment of complex aneurysms. O101 Performance of long J-shape coils in large and giant cerebral aneurysms: an in vitro study K. Tokunaga, N. Tanaka, K. Sugiu, J.-B. Martin, D. A. Ruefenacht Neuroradiology, Geneva University Hospital, Geneva, Switzerland Purpose: To evaluate performance of long J-shape coils (DCS-18, COOK) in in vitro models simulating large aneurysms. Materials and Methods: J-shape coils with a curved tip of 7- or 15mm diameter and a proximal 70-cm-long straight part exhibiting three different stiffnesses (soft, standard, and enforced) were evaluated. The capacity to negotiate a tortuous path was investigated in cerebral vessel models. The performance inside an aneurysm cavity was evaluated in silicone lateral wall type aneurysms with variable neck and dome diameters. The conformability to irregularly shaped aneurysms was compared with that of spiral coils. Results: Long J-shape coils easily passed through a microcatheter in tortuous vessels. In 12-mm spherical aneurysm models, knot formation was observed during withdrawal. In 15-mm aneurysms, delivery and retrieval were smooth, and standard-type coils demonstrated the best performance. In 20-mm aneurysms, good

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frameworks were obtained with standard and enforced-type coils, but soft-type coil masses were instable. In 30-mm aneurysms, softtype coils filled the aneurysmal lumen only partially, whereas enforced-type coils formed favorable frameworks. J-shape coil conformability to irregular aneurysms was superior to that of spiral coils. Conclusions: Long J-shape coils match the requirements needed to fill large and giant aneurysms and can shorten the time required for the procedure. O102 Treatment of large and giant aneurysms of the cavernous internal carotid artery with Cook detachable coils M. Leonardi, L. Simonetti, P. Cenni U.O. di Neuroradiologia, Ospedale Bellaria, Bologna, Italy Treatment of cavernous internal carotid artery aneurysms with direct surgical approaches is difficult because of the potential risk of profuse bleeding and cranial neuropathy. For these difficult aneurysms, surgical ligation or endovascular occlusion of the parent artery has long been performed as an effective and safe alternative. Nonetheless, even with meticulous pre-occlusion evaluation for possible ischemic complications, a small group of patients suffered neurologic complications after permanent occlusion of the parent artery. Selective occlusion of the aneurysm sacs with detachable balloons was then tried, but it had a higher complication rate than occlusion of the parent artery. Thanks to the advent of Gugliemi detachable platinum coils (GDCs), many surgically difficult or inoperable aneurysms can be treated safely and effectively by endovascular route. Treatment with detachable coils can allow surgically difficult cavernous ICA aneurysms to be eliminated without sacrificing the parent artery. However, this technique still represents a challenge to interventionists because these aneurysms are usually large in size and have a high incidence of recanalisation. We attempted to occlude cavernous aneurysms with the Cook detachable coils system (DCS) without sacrificing the parent artery, and evaluated on angiography the results of the treatment according to the size of aneurysms and on MR, on the basis of the presence of intrasaccular thrombosis or recanalisation. Six.cases of cavernous internal carotid artery aneurysms treated with DCS were selected for analysis; medical records, angiograms, endovascular treatment technique, and MR follow-up were analysed retrospectively. O103 Initial experience of cerebral avm embolisation with onyx: analysis of treatment in six patients M. Leonardi, L. Simonetti, Y. Cao, R. Agati U.O. di Neuroradiologia ± Ospedale Bellaria, Bologna, Italy The endovascular approach to arteriovenous malformations (AVM) using different embolising agents allows complete closure of the malformation in around a quarter of all cases reported, with significant variability by different authors. The incidence of major complications also varies widely because successful treatment is highly operator-dependent. The choice of cyanoacrylate dilution, the speed and technique of glue injection in relation to microcatheter position are empirical skills that are difficult to transmit from one operator to another and often applied on the basis of personal experience. The result is that, although acrylic glue is a valid embolising agent that has been applied for many years, it remains difficult to use and still poses significant risks for the patient. Another negative feature of this glue is the fact that, because of the potential risk of serious complications, acrylic glue manufacturers have not

given the product the EU mark of approval for endovascular use which is in fact included among the prohibited indications. This situation has recently created difficult working conditions, especially from the legal standpoint, despite widespread application for many years. This situation accounts for the ongoing search for safer alternative embolising agents whose application can be standardised within limits feasible for any interventional procedure. A new embolising material, Onyx (Onyx System MicroTherapeutics, Inc., MTI), was marketed some years ago as a ªfoamº with the theoretical feature of progressive occlusion rather than immediate gluing. We report the results obtained in the first six patients treated in our hospital with Onyx in the last six months, analysing the application technique and our impressions during treatment in relation to our past experience with cyanoacrylate glue.

O104 Transvenous embolization (TVE) for traumatic dural arterio-venous fistula (DAVF) *N. Fujimura, *M. Hirohata, *H. Morimitsu, **T. Abe, *T. Tokutomi, *M. Shigemori *Department of Neurosurgery, Kurume University School of Medicine, Kurume, Japan **Department of Radiology, Kurume University School of Medicine, Kurume, Japan Purpose: The usefulness of transvenous embolization (TVE) using detachable coils for traumatic dural arterio-venous fistula (dAVF) was studied. Materials and Methods: We treated four patients, including two direct carotid-cavernous fistulae (CCF) and two posterior fossae. All patients were treated with TVE of the arterio-venous (AV) shunt using detachable coils with or without transarterial embolization (TAE) of feeding arteries. Results: Two direct CCF and one of the posterior fossa dAVF were completely obliterated without any complications. Another patient who had multiple feeding arteries from bilateral carotid arteries and vertebral arteries with high flow AV shunt at the occipital sinus was treated with TAE of feeders and occipital sinus packing by transvenous approach. However, the AV shunt remained and developed massive intracerebellar hemorrhage a few days after the procedure. Conclusions: TVE using detachable coils is generally safe and effective for the treatment of traumatic dAVF. However, treatment for dAVF with multiple feeders and high flow AV shunt is still challenging.

O105 Intra-arterial papaverine infusion combined with hypertensive hypervolemic hemodilution (triple-H therapy) for cerebral vasospasm after subarachnoid hemorrhage 1 E. Keller, 2B. Schuknecht, 1N. Krayenbühl, 1J. Fandino, 1Y. Yonekawa, 2A. Valavanis 1 Dep. of Neurosurgery , 2Dep. of Neuroradiology, University Hospital, Zürich, Switzerland Purpose: To evaluate the role of selective intra-arterial papaverine hydrochloride infusion (PPV) in the multimodality treatment of postoperative cerebral vasospasm (CVS). Materials and Methods: 48 patients with symptomatic postoperative CVS were treated according to a standardized protocol. In all patients triple-H therapy was adapted to new volumetric systemic hemodynamic parameters (PICCO, Pulsion, Munich). If patients did not improve with triple-H, PPV was infused superselectively into vasospastic vessels (total dose of 300 mg). Patients with CVS

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resistant to 2 sessions of PPV infusion were treated with barbiturate coma and/or mild hypothermia. Results: 25 of 48 patients (52 %) improved with triple-H therapy alone. 19 patients were treated with PPV. 17 patients (89 %) improved after endovascular treatment. In 6 patients (31 %) CVS recurred after 2 days. 4 patients were successfully treated with a second endovascular intervention. In 4 patients CVS was resistent to triple-H and PPV; these patients were treated with barbiturate coma/hypothermia. 35 of 45 patients (77.8 %) had favourable outcome (GOS 4±5) after 3 months, 6 patients (13.3 %) were severely disabled (GOS 3) and 4 patients died (8.9 %). Conclusions: If carefully selected, 89 % of patients with postoperative CVS treated with triple-H therapy respond to PPV spasmolysis. Most studies evaluate isolated therapeutic modalities. This report suggests that different therapeutic steps are complementary. O106 Angioplasty of intracranial vasospasm after subarachnoid hemorrhage B. Turowski1, S. Weidauer1, R. du Mesnil1, J. Beck2, F. Zanella1 1 Institute of Neuroradiology University of Frankfurt, 2Clinic of Neurosurgery, University of Frankfurt, Frankfurt, Germany Purpose: The aim of this study was to demonstrate that intracranial angioplasty can be performed successfully without complications in cerebral vasospasm following aneurysmal subarachnoid hemorrhage. Materials and Methods: In six patients (3 males, 3 females, aged 30 to 68 years) seven intracranial angioplasties were performed with soft balloon catheters. One patient was treated twice in the same vessel. Indications for intracranial angioplasty were increasing Doppler-flow, worsening of clinical status, prolonged angiographic circulation time and proven spastic vessel. Results: In all patients the procedure was technically successful. The vessel diameter of the spastic segment was increased after dilatation between 2- and 5.8-fold (mean 3.9). There were no acute complications. Circulation time could be reduced markedly in all cases. Despite an initial good result, 15 days later a vasospasm recurred in the not completely treated segment and a second angioplasty was performed. Conclusions: Intracranial angioplasty after subarachnoid hemorrhage can be performed safely with a soft balloon-catheter. Further studies have to be done to assess the long term clinical impact of dilatation. O107 Cerebral angiography in the rat with mammographic equipment: a simple, cost-effective method for the evaluation of vasospasm in experimental subarachnoid hemorrhage (SAH) G.K. Ricciardi, S. Vinci, F. Granata, A. Pitrone, M. Longo Institute of Radiology, University Hospital ªG. Martinoº, Messina, Italy Purpose: The aim of this study was to evaluate post-subarachnoid hemorrhage (SAH) vasospasm and the effect of a new antivasospastic free radical scavenger (AVS) in rats, with an angiographic technique developed in our laboratory. Materials and Methods: The technique was tested on 40 rats divided equally into four groups: sham-operated + saline (Group I), SAH + saline (Group II), sham-operated + AVS (Group III) and SAH + AVS (Group IV). Single-exposure angiograms were acquired with mammographic equipment, using a 0.1-mm diameter focal spot and single emulsion mammographic films. Contrast medium was injected through a PE50 catheter placed within the

common carotid, while the external carotid was ligated. Measurements of the M1 and A1 tract and of the basilar trunk were made using the endovascular catheter as internal reference. Results: Single exposure angiographies made it possible to measure the calibre of the principle intracranial vessels in all animals investigated. The difference in vessel calibre between groups I and III was statistically significant for all the vessels measured (p < 0.05 sham + saline vs SAH + saline). The antivasospastic effects of AVS were statistically significant in all the evaluated cerebral vessels (p < 0.05 SAH + saline vs SAH + AVS), while there was no significant difference in vessel calibre between groups I and II (sham + saline vs sham + AVS). Conclusions: The technique we propose, which is cost-effective when compared to many recently reported ones, allowed us to detect intracranial vessel vasospasm in all non-treated SAH-induced rats, and to confirm the antivasospastic effects of AVS on all treated animals. O108 Endovascular treatment strategy for acute ruptured VA dissecting aneurysm (AN) *M. Hirohata, *H. Morimitsu, *N. Fujimura, **T. Abe, *T. Tokutomi, *M. Shigemori *Department of Neurosurgery, Kurume University School of Medicine, Kurume, Japan **Department of Radiology, Kurume University School of Medicine, Kurume, Japan Purpose: The proximal occlusion (PO) or occlusion of the dissected site (ODS) as treatment strategies for ruptured VA dissecting AN are still controversial. Based on our experience, the treatment strategy for ruptured VA dissecting ANs is discussed. Materials and Methods: We treated fourteen cases of ruptured VA dissecting ANs in the past 5 years. There were 6 men and 8 women with mean age of 55.7 years. The PICA originated from the proximal to the AN in six, distal to the AN in three, and mid portion of the AN in three cases. Another three cases did not have ipsilateral PICA. ODS was indicated with the 6 ANs located with distal to the PICA. Another 8 ANs were treated with PO. Results: One patient who was treated with ODS had intraoperative rupture. Another patient with the PICA originating from the mid portion of the AN had cerebellar infarction 4 months after PO. All had complete occlusion of the AN upon follow up study and none of them had rerupturing after embolization. Conclusions: PO is a safe and effective treatment for preventing rebleeding. However, ODS is preferable for ANs distal to the PICA. O109 MR-guided ablation of experimental brain tumors using a novel interstitial ultrasound applicator: a pilot study DF Schomer1, RJ Stafford1, CJ Diederich3, RE Price2, M Kangasniemi1, and JD Hazle1 1 Departments of Diagnostic Radiology and 2Veterinary Surgery & Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, USA 3 Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA Purpose: To provide real-time guidance for ultrasound thermal ablation of brain metastases in a canine model. Materials and Methods: An MR-compatible, three-sector intracavitary focused ultrasound array was introduced through a burr hole into the tumor. Catheter position was verified via T2-weighted FSE images parallel to the axis of the catheter. Applicator energy

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was focused on the tumor mass and heating was achieved over a 15-minute period by modulating the RF power (5±15 W) delivered to each of the segments with direct feedback from MR thermal imaging. Spatial-temporal temperature history obtained via MRTI was used to calculate the thermal dose using an Arrhenius integral method. Following post-treatment imaging, animals were euthanized and submitted for pathological examination. A second experiment was performed in a similar fashion except that the animals were euthanized three weeks after treatment to assess posttherapy management. Results: Placement of the ablation catheter into the center of each metastasis was accomplished without difficulty and confirmed with MR prior to ablation. The iGE-EPI MRTI sequence provided useful temperature estimates over the entire treatment volume during the course of the treatment, thus allowing the progression of thermal damage to be monitored and treatment parameters adjusted. Tissue injury on gross and histological review corresponded to the thermal dosimetry profiles predicted by MRTI Conclusions: MR temperature imaging was found to be useful for monitoring the delivery of thermal energy using a novel new MRcompatible, interstitial ultrasound applicator in a large animal brain tumor model.

performed with supraselective intraarterial infusion of urokinase (400,000±1,200,000 IU) and mechanical clot disruption. Exclusion criteria were coma duration > 6 hours and CT ischemic changes. After 3 months, clinical outcome was assessed using the modified Rankin scale (RS) and the distribution of chronic ischemic lesions was determined with brain MRI. Results: A complete basilar artery recanalization was obtained in 5 patients (55.5 %, mean age 54). Three patients were comatose and two somnolent at the beginning of treatment. At 3 months, 3 of them (33 %) had recovered to an RS of 1, and 2 (22 %) had recovered to an RS of 3. All had a distal clot location of embolic etiology. Time to thrombolysis was 6±14 hours (mean 7.8). None of the 4 patients (45.5 %, mean age 57) with incomplete recanalization (TIMI 0±2) survived. Three had a proximal and 1 had a midbasilar clot location. Three patients were comatose at the time of admission. Time to thrombolysis was 5±14 hours (mean 10.2). Two fatal hemorrhagic complications occurred in two patients with no recanalization and critical atherosclerotic stenoses. Conclusions: LIT of acute basilar artery thromboembolism significantly reduces mortality. A favorable outcome was achieved in patients with distal clot location and complete recanalization of the basilar artery. Time to treatment and clinical condition at presentation do not seem to significantly affect outcome.

O110 Stenting as emergency therapy in acute basilar artery occlusion *J. Spreer, **E. Oehm, * J. Klisch, * A. Berlis, **T. Els, *S. Ziyeh, * M. Schumacher *Neuroradiology, University Hospital, Neurozentrum, Freiburg, Germany **Neurology University Hospital, Freiburg, Germany

O112 Local intra-arterial thrombolysis: analysis with respect to the type of the thromboembolus H. Urbach1, A. Hartmann2, C. Pohl2, H. Omran3, S. Flacke1, H.H. Schild1, T. Kockgether Depts. of Radiology / Neuroradiology1, Dept. of Neurology2, Dept. of Cardiology2, University of Bonn, Bonn, Germany

Purpose: The prognosis in acute occlusion of the basilar artery (BA) is poor. Therapeutic options are limited if intraarterial thrombolysis (LIF) fails to reestablish a sufficient flow due to an underlying stenosis. We report our preliminary results with stenting in acute BA occlusion. Material and Methods: Four patients (3 men, 1 woman; age 54±77 years) presented acute occlusion of the BA. Duration of symptoms was 6±10 hours. LIF resulted in only incomplete recanalization and revealed severe stenosis of the BA (3 patients) or the distal left VA (1 patient with hypoplastic right VA) as the underlying cause. The patients were treated with primary (without previous dilatation) stenting. Results: In all cases stenting resulted in marked angiographic and hemodynamic improvement with antegrade flow in the BA. 3 patients had a favourable clinical outcome (2 x NIH stroke score 6, follow-up 9 months; 1 x NIHSS 5, follow-up 3 weeks). One patient died 10 days after the BA occlusion due to pontine infarction. Conclusions: Emergency primary stent application may improve the outcome in acute basilar artery occlusion, if intraarterial thrombolysis fails to reestablish a sufficient flow. Further studies concerning the long-term benefit are needed.

Purpose: To study whether recanalization by local intra-arterial thrombolysis depends on the type and age of the occluding thromboembolus. Materials and Methods: A retrospective evaluation of 58 patients treated with local intra-arterial thrombolysis in the carotid territory was conducted. Classification of the embolic source was made according to the TOAST-criteria; in addition, transoesophageal echocardiography (TEE) was required to assess left atrium and ventricle. Occlusion site, leptomeningeal collaterals, and recanalization were determined on digital subtraction angiograms; the time interval from onset of symptoms to onset of thrombolysis was measured in minutes. Results: Complete evaluations were available for 42 of 58 patients. Five patients had thromboembolic occlusions due to large artery atherosclerosis, while 23 patients suffered cardioembolic occlusions. Other embolic sources were found in four patients, two potential embolic sources in two patients, and no embolic source in 8 patients. Forward and backward unconditioned regression analysis revealed that the presence of a cardiac thrombus (p = 0.024, b = 2,788) affected recanalization. Thromboembolus location (p = 0.054) had a weak impact, while leptomeningeal collaterals and time interval had no impact. Conclusions: Recanalization of cardioembolic intracranial occlusions is significantly lower when transoesophageal echocardiography shows (pre-existing) cardiac thrombi.

O111 Local intraarterial thrombolysis in acute vertebrobasilar thrombosis R. Gasparotti, M. Pavia, L. Pinelli, S. Florio, R. Liserre Section of Neuroradiology, Dept. of Radiology, University of Brescia, Italy Purpose: Retrospective evaluation of a consecutive series of patients with acute basilar artery thrombosis treated with local intraarterial thrombolysis (LIT). Materials and Methods: Over an 18-month period, 9 consecutive patients (6 males, 3 women; mean age, 55 years; range 32±76 years) with acute basilar artery occlusion were treated using LIT. LIT was

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O113 Clinical outcome following intraarterial thrombolysis for acute stroke in patients less than 50 years of age J. W. Miller, E. Bourekas, G. Christoforidis, M. Notestine, A. Slivka The Ohio State University, Department of Radiology (NeuroInterventional), Columbus, Ohio, USA

Conclusions: Use of the device seems to be feasible in intra- and extracranial vessels. Limitations for the use of the cardiologic device include old thrombi and its lack of the flexibility necessary for access to intracranial vessels. An intracranial device is currently under evaluation.

Purpose: To evaluate the clinical outcome of intraarterial thrombolytic therapy for acute stroke in patients less than 50 years of age. Materials and Methods: From November 1995 to August 1999, 22 patients under 50 years of age (9 male and 13 female, range 15 ± 49 years) with stroke onset of less than 6 hours, underwent cerebral angiography. The National Institutes of Health Stroke Scale (NIHSS) score was determined at stroke presentation and the Rankin score was determined at discharge for all patients. Thrombolysis was performed on the patients with occlusions noted on angiography, using either urokinase or t-PA. Results: Ten of the 22 patients studied had occlusions in the middle cerebral, distal vertebral, or internal carotid arteries. Of the remaining patients, 11 demonstrated normal cerebral angiograms and one revealed a dissection. Of the ten patients treated with thrombolytics, five (50 %) had partial or complete recanalization. Of the five that recanalized, the median discharge Rankin score was 1 (range 0 ± 4) with three of the five patients having a score of less than two. The five without recanalization had a median discharge Rankin score of 4 (range 1 ± 5) with one of five patients having a score less than two. Two treated patients with recanalization had asymptomatic intracranial hemorrhage. Conclusions: A favorable clinical outcome was seen in stroke patients under the age of 50 who were treated with intraarterial thrombolysis. Forty percent of treated patients were asymptomatic (Rankin 0,1) at hospital discharge. Recanalization correlated with clinical improvement at discharge.

O115 Ex vivo angioplasty of an in-stent restenosis R. Ferdinandy, E. Vörös*, A. Palkó*, M. Szólics**, R. Sipka University of Szeged, Szeged, Hungary *University of Szeged, Dept. of Radiology, Szeged, Hungary; **Pµndy Kµlmµn County Hospital, Gyula, Hungary

O114 Experience with a waterjet thrombectomy device in cerebrovascular disease *T.E. Mayer, **G. F. Hamann *Neuroradiologie, **Neurologie, Klinikum Grosshadern, München, Germany Purpose: Recanalization by local or systemic fibrinolysis in thrombo-embolisms of brain-supplying or -draining vessels depends on the volume and composition of the clot. Moreover, thrombolysis can be time-consuming and this may affect the outcome. Fibrinolysis also has a considerable risk of bleeding and therefore contraindications. After approval of the ethics committee, we investigated the feasibility of using a rheolytic device based on the Bernoulli effect (Possis angiojet) that might improve the recanalization rate and time and avoid hemorrhage. Materials and Methods: Nine patients in emergency situations (five due to vertebro-basilar occlusion, one due to an acute thrombosis during a subclavian stent procedure and three due to dural sinus and cerebral vein thrombosis) were treated. Results: Access and recanalization were achieved in the subclavian stent and two occluded proximal vertebral arteries. The basilar artery was reached and recanalized only in two of four cases, once the device stopped in the intradural vertebral artery and once the atlas loop was not passed. Access to the sagittal sinus was possible in two of three cases. However, recanalization was only partially possible in one case due to a proven old thrombus in both patients. In the other patient the device stuck at the confluence of the sinuses. There was no device-related vessel injury.

Purpose: The incidence of restenosis after carotid angioplastystenting (CAS) and its management are still ill-defined. In one of our 17 patients, severe in-stent restenosis occurred which was treated with excision and graft placement. The purpose of our experiment was to prove that angioplasty can be an alternative to surgical treatment in patients with in-stent-restenosis. Materials and Methods: The ex vivo internal carotid artery specimen underwent angioplasty with a 4-mm balloon at 10 ATM pressure followed by a 6-mm balloon at 10 ATM and 18 ATM pressure. Ex vivo angiograms were obtained before and after each intervention. The specimen was then dissected to examine the intraluminar surface. Results: Complete resolution of stenosis was only achieved with the 6-mm balloon at 18 ATM pressure, revealing the rigidity of the restenosed vessel. The longitudinal dissection of the specimen showed a smooth, yellowish intraluminar surface similar to that of post-endarterectomy restenosis. Conclusions: As in-stent restenosis has a smooth intraluminar surface with little risk of thromboembolic events, repeated angioplasty with high-pressure balloons and/or stenting could be a safe alternative to surgical graft placement after CAS. O116 The necessity of C2 ganglionolysis in selected patients for the treatment of cervicogenic headaches: a safe and effective approach S. Kamran Saad Medical Center, Al Khobar, Saudi Arabia Purpose: To report the effectiveness and describe an approach for fluoroscopically guided C2 ganglionolysis for chronic headaches. Patients and Methods: 52 patients underwent cervical RFTC for cervicogenic headaches. All patients underwent diagnostic greater occipital nerve block (GO). Selected patients underwent RFTC of C2 (C2 ganglionolysis). Patients were then monitored for 6 months. Results: 6/52 patients were included in the study. Four patients reported partial (50 %) and two no headache relief after initial RFTC. The patients reported 100 % headache relief with GO block. These patients underwent selective C2 ganglionolysis (unilateral 4, bilateral 2). All patients reported complete headache relief. Conclusions: C2-induced headache, when mixed with cervicogenic headache, is difficult to separate. These patients may not obtain any or only partial relief with medial branch RFTC. GO block followed by C2 ganglionolysis can obtain complete headache relief. No procedure-related complications were reported.

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O117 The use of motor fMRI and neuro-navigational techniques in the resection of intracerebral tumours C. A. J. Romanowski, I.D. Wilkinson, D A. Jellinek, M. Radatz, G. Darwent, P. D. Griffiths Royal Hallamshire Hospital, Sheffield, UK Introduction: The preservation of motor function is important for post-surgical quality of life following the resection of intracerebral tumours. Functional MRI (fMRI) may provide a means of identifying eloquent areas of the cerebral cortex which can be used to guide neurosurgeons in their attempt to maximise tumour resection whilst minimising motor function damage. The aim of this work was to develop and provide an initial assessment of such a technique. Materials and Methods: Fifteen patients with frontal/parietal lobe mass lesions underwent fMRI at 1.5T (Eclipse, Marconi Medical Systems). A single-shot echo planar technique (TEeff = 40 ms; TR = 3 s) acquired 2 functional datasets: one examining right and the other left hand movement. The timecourse of each voxel was correlated with a smoothed square wave representing a model haemodynamic response. Data were used in conjunction with an intra-operative navigation system (BrainLAB) in 7 cases. Results: Statistically significant `activation' was attributed to the primary motor, primary somatosensory or supplementary motor cortex in 13/15 subjects. This information was used in pre-operative planning. No permanent changes in motor deficit were detected post-surgery (2 patients had transient neuro-deficits). Conclusions: The added information that was provided by fMRI, particularly when these data were incorporated into a neuro-navigation guided craniotomy, was deemed highly valuable to the neurosurgeon as it enabled safe resection of tumours in anatomical locations previously deemed to be too high-risk for safe resection using conventional (non-fMRI-guided) techniques. This observation was reinforced by the fact that no patients suffered permanent neurological deficits after radical tumour debulking (surgical estimates > 90 % tumour resection). O118 The combined study of language and sensorimotor regions using a single fMRI paradigm in patients with focal brain lesions S. Sunaert, G. Wilms, P. Van Hecke, G. Marchal Dept. of Radiology, University Hospitals Kuleuven, Leuven, Belgium Purpose: To develop a single fMRI paradigm that visualizes auditory, expressive and receptive language areas as well as the motor cortex in patients. Materials and Methods: Ten patients were scanned while performing three language tasks: a) verbal fluency, b) tone discrimination in which patients pressed a left/right key for high/low tones, and c) semantic decision-making in which patients pressed a left/ right key for objects/animals. Results: Contrasting the a + b + c tasks versus rest activated the global language network: the superior temporal gyrus bilaterally, the left angular gyrus, the left medial and inferior frontal gyrus, and the cingulate gyrus bilaterally. The MR signal profile in these regions disentangled auditory from receptive and from expressive language regions. Contrasting left and right key responses (events) during the language tasks significantly identified the primary motor cortex of the hand. Conclusions: A single fMRI paradigm allowed us to study both the language network and the sensorimotor cortex of the hand. The differential response of the regions in the language network enabled us to differentiate auditory, expressive and receptive regions. Event-related analysis of the patients' motor responses to the lan-

guage tasks identified sensorimotor cortex. This paradigm reduced scan time in patients with lesions adjacent to both the language and motor cortex. O119 Neuroanatomic correlates of stuttering revealed by functional MRI *C. Preibisch, *P. Raab, **K. Neumann, ***A.W. von Gudenberg, ****H.A. Euler, *H. Lanfermann, *F. Zanella *Department of Neuroradiology, **Department of Oto-RhinoLaryngology, University of Frankfurt, Frankfurt, Germany ***Kasseler Stotertherapie, **** Department of Psychology, Kassel, Germany Purpose: To establish functional MRI for the investigation of brain function and monitoring of therapy effects in stuttering people. Materials and Methods: 20 healthy volunteers and 21 adult stutterers were studied during overt sentence reading. For suppression of speech-related artefacts, an event-related experimental design was used (78 events, presentation duration 3 sec, fixed inter-stimulus interval 15.5 sec, TR 3 sec). GE-EPI was used for data acquisition. Evaluation employed SPM99: correction for slice timing and motion, spatial normalization, calculation of statistical parametric maps. Results: The applied event-related experimental design allowed the successful suppression of speech-related artefacts. Healthy subjects displayed consistent activation in speech-related and motor areas. Compared to healthy subjects, stutterers showed increased activation in the right frontal (superior, middle and inferior frontal, and precentral gyrus), parietal (left/right inferior parietal lobule, right precuneus) and limbic (left anterior cingulate) areas. Decreased activation was found bilaterally in the brainstem and cerebellum, left inferior frontal (Broca) and middle temporal gyrus (Wernicke), right limbic lobe (posterior cingulate) and left thalamus (anterior nucleus). Conclusions: These results closely resemble those obtained in earlier neuroimaging studies on stuttering and language processing. Thus, fMRI seems to be adequate to study neurophysiological correlates of stuttering. O120 Functional MR imaging of the auditory cortex after non-invasive electrical stimulation of the auditory nerve *C. Preibisch, *P. Raab, **K. Neumann, *H. Lanfermann, *F. Zanella *Department of Neuroradiology and ** Department of Oto-RhinoLaryngology, University of Frankfurt, Frankfurt, Germany Purpose: To investigate the reliability and reproducibility of noninvasive electrical stimulation of the auditory nerve for objective and non-invasive evaluation of the auditory pathway function. Materials and Methods: A modified MEDEL electro-audiometer was used for electrical stimulation. For safety reasons this device electrically decouples the stimulation electrodes during scanning via photo resistors. The stimulation electrode (silver ball) was placed in the saline filled external auditory canal. To check for reproducibility two healthy volunteers were investigated twice. 10 deaf patients were examined prior to a cochlear implant. Functional imaging employed GE EPI (matrix 128 or 64, FOV 230 mm, 4 slices, thickness 4 mm, TE 66 ms, TR 4 sec, number of measurements 88 or 128). Results: The quality of the EPI images was not degraded by the electrodes. In both volunteers we found reproducible activation in the contralateral primary auditory cortex (one also ipsilateral). In most patients activation maps were severely degraded by motion artefacts. Only six out of ten subjects showed detectable activation.

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Conclusions: Investigation of healthy volunteers showed that an objective and non-invasive evaluation of the auditory pathways using electrical stimulation and functional MRI is feasible and reproducible. However, patient compliance is a major problem which is not easily resolved. O121 Correlation between fmri in cochlea implantation candidates and their post-operative outcome in 21 deaf patients A.M. Schmidt, B.P. Weber, M. Witt, R. Zacharias, M. Vahid, T. Wöllner, T. Lenarz, H. Becker Department of Neuroradiology and Otorhinolaryngology, Medical School of Hannover, Germany Purpose: An objective evaluation of the auditory pathway prior to cochlea implantation (CI) is very desirable. We have shown that functional MRI (fMRI) using promontory stimulation has a good correlation with subjective promontory testing used in CI-candidates. The objective of the current study was to compare pre-operative fMRI activation with post-operative speech perception abilities. Methods: 21 patients were examined. Pre-operative fMRI (at 1.5 Tesla) was performed using an EPI pulsesequence (TE 40 ms, 128 ” 128 matrix, slice-thickness 5 mm) and post-processed with the Functool programme (GE). Post-operative outcome over at least 6 months was evaluated using performance tests including a telephone test, consonant-, vowel-, monosyllabic- and word testing. Results: 15 patients with good activation patterns had good speech-perception results. Of the two patients with poor activation, one had poor and one acceptable results. Of the four patients who had no activation, two showed good results and two no open set understanding. In other words, we had two false negative ± but so far no false positive± results. Conclusions: fMRI using promontory activation appears to correlate well with post-operative performance. The method is promising and may be a useful clinical tool for use in the objective evaluation of cochlear implant candidates. Larger patient populations will need to be evaluated to gain further information about the usefulness of this method. O122 Posterior corpus callosum and interhemispheric transfer of somatosensory information: an fmri study G. Polonara, M. Fabri*, T. Manzoni, U. Salvolini Servizio di Neuroradiologia, *Istituto di Fisiologia, Università degli Studi, Ospedale Umberto I, Torrette di Ancona, Ancona, Italy Purpose: To study the activation pattern evoked by mechanical tactile and painful unilateral stimulation and to verify the callosal role in the interhemispheric transfer of somatosensory information. Materials and Methods: Cortical activation evoked by unilateral tactile stimulation was investigated with fMRI in twelve normal volunteers and in twelve patients submitted to resection of the corpus callosum to control drug-resistant epilepsy. Cortical activation evoked by mechanical painful unilateral stimulation was investigated in six normal volunteers and three patients with complete resection of the corpus callosum. Results: In normal subjects, unilateral tactile stimulation of the hand evoked activation of area SI in the contralateral hemisphere and activation of areas PPC and SII in both hemispheres. In subjects with total or subtotal callosotomy, the same stimulation evoked activation of controlateral areas SI, PPC and SII. In subjects with partial callosotomy where the posterior third of the body

of the commissure was intact, the same stimulation evoked the activation of contralateral SI, and of bilateral PPC and SII. In normal subjects, unilateral noxious stimulation of the hand evoked activation of contralateral SI and of bilateral SII. In subjects with total callosotomy, the same stimulation evoked activation of contralateral SI and of bilateral SII. Conclusions: Activation of ipsilateral SII and PPC after unilateral tactile stimulation of the hand is mediated by somatosensory areas of the contralateral hemisphere, through the corpus callosum. Callosal fibres activating ipsilateral SII and PPC cross the posterior third of the body of the commissure. Activation of ipsilateral SII after unilateral painful stimulation of the hand is at least partially independent of callosal transmission.

O123 The cortical representation of the motor tongue area: comparison of fMRI and intraoperative mapping G. Fesl1, J. Ilmberger2, H. J. Reulen3, T. A. Yousry1 Abteilung für Neuroradiologie 1, Abteilung für Physikalische Medizin2, Klinik für Neurochirurgie3 Klinikum Groûhadern, Ludwig-Maximilian-Universität, München, Germany Purpose: We wanted to compare the anatomical location of the cortical representation of the motor tongue area (MTA) defined by fMRI with the area defined by intraoperative mapping (IOM). Materials and Methods: Ten patients with astrocytoma (6 men, 4 women, age: 15±49 y, 6 WHOII, 4 WHOIII) were studied. fMRI: 65 scans were acquired with a 1.5T scanner using T2*-weighted EPI sequences. During the active phases the patients had to move their tongue horizontally. Postprocessing was performed with SPM96. The results were presented on a 3D-surface. IOM: Stimulated areas were defined as active when the patients were not able to move the tongue. All stimulated areas were marked and photographed. The intraoperative images were matched with those of the fMRI/ 3D surfaces. Results: The MTA was identified by intraoperative stimulation in 7 patients in the lower precentral gyrus. fMRI showed significant activations (p < 0.001) in the lower pre- and postcentral gyrus bilaterally in 10 patients. The intraoperative stimulation points were always included in the areas defined by fMRI. Conclusions: The anatomic location of the MTA as defined by IOM can be reliably identified by fMRI. fMRI therefore reliably locates the MTA preoperatively.

O124 Reorganization of brain activation after spinal cord injury *H. Al Kadhi, **A. Curt, * G. R. Crelier, *** M.-C. Hepp-Reymond, *S. S. Kollias, *A. Valavanis *Institute of Neuroradiology, University Hospital Zurich, Zurich, Switzerland **Paraplegic Centre, University Balgrist, Zurich, Switzerland ***Institute of Neuroinformatics, University and ETH, Zurich, Switzerland Purpose: Neurophysiological studies showed that deafferentation and deefferentation induce reorganization within central somatosensory and motor representations. We report changes in brain activation patterns during movements of unaffected body parts in chronic paraplegic patients after spinal cord injury (SCI). Materials and Methods: Eight SCI patients and 12 healthy controls underwent BOLD-sensitive functional MRI during sequential finger-to-thumb opposition, flexion and extension of wrist and elbow and horizontal movements of the tongue. Single-subject and group

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analyses were performed and the activation volume, maximum tvalue and center of gravity determined. Results: The somatotopical organization within the contralateral primary motor cortex (M1) was preserved in the SCI patients, and no shift towards the deafferented and deefferented lower limb area was detected. However, during finger movements the SCI patients showed an increased volume of activation in contralateral M1 and in the cerebellum that was not seen during wrist, elbow and tongue movements. Additionally, an increased activation was found in non-primary motor and parietal areas for all movements tested. Conclusion: These results suggest that, in paraplegic patients, alterations of the normal input-output patterns of preserved movements between the central motor system and its target muscles may be induced by spinal lesions. These changes show no somatotopical rearrangement but indicate a reorganization of brain areas involved in central motor control. O125 Functional dynamics of the visual processing in the dorsal stream examined by fMRI *F. Di Salle, **E. Formisano, *** L. Trojano, ***S. Maugeri, ****D. Linden, *S. Cirillo, **R. Goebel, *R. Elefante *University of Naples ± Neuroradiology, Naples, Italy **University of Maastricht, The Netherlands ***Institute of Telese, Italy ****University of Frankfurt, Germany Purpose: Cortical processing of visual information exhibits a subdivision between the morphological analysis of visual objects, mainly located in the ventral-stream along the inferior surface of the occipital lobe, and the analysis of spatial features, which is located in the dorsal stream of the parietal lobe. The processing of mental images follows a similar pattern, and a principal area active in performing spatial operations on mental images has been located along the intraparietal sulcus (IPS). This activity also requires the participation of frontal areas (DLPFC and SMA). The present study was aimed at analysing this cortical pattern, in order to understand the specific role of the areas involved in the processing of mental images. Materials and Methods: We studied 6 healthy volunteers using an event-related fMRI method, analysing the temporal behaviour of each area and the features of the BOLD response. The latter were correlated to the behavioural responses, evaluating whether or not an increasing reaction-time corresponded to a similar variation of the BOLD response. Results and Conclusions: All the considered parameters indicated a strong specificity of the activity in the IPS for the generation of mental images and their spatial manipulation, and allowed us to hypothesise detailed temporal dynamics for information-processing along the dorsal stream. O126 Integration of fMRI in presurgical planning and neuronavigation P. Raab1, C. Preibisch1, R. Krishnan2, H. Yahya2, H. Lanfermann1, F. Zanella1 1 Department of Neuroradiology, University of Frankfurt, Germany 2 Department of Neurosurgery, University of Frankfurt, Germany Purpose: To validate preoperative fMRI of language and motor functions for surgical planning and intraoperative navigation. Materials and Methods: A total of 58 patients with intracranial tumours underwent functional MRI prior to neurosurgery. According to the location of the tumour they either performed a motor (37 patients; alternating movements of tongue, fingers and toes) or language task (21 patients; modified Wilde intelligence test and

word generation). Imaging employed GE EPI. Pre-processing (3D motion correction, smoothing) and correlation analysis were performed using BrainVoyager. Thresholded statistical maps were finally imported into the BrainLab VectorVision2 intraoperative neuronavigation system. When the tumour adjoined the central sulcus, electrophysiological mapping was performed during surgery. Results: Localisation of motor function was more successful (28 out of 39) than of language function (13 out of 22). Successful fMRI in each case improved presurgical planning. In 24 patients the acquired functional maps were used for intraoperative navigation. In 23 patients electrophysiological mapping confirmed motor locations detected by fMRI. Conclusions: The quality of the functional maps and electrophysiology indicate reliable mapping of motor function by fMRI. The transfer of fMRI data into the operating room is easy. Intraoperative access to functional data facilitated identification of spatial relationships between functionally relevant regions and the lesion. O127 Hippocampal asymmetry in rolandic epilepsy demonstrated by 1H MR spectroscopy *R. Raininko, **S. Lundberg, ***J. Weis, **O. Eeg-Olofsson *Department of Radiology, University Hospital, Uppsala, Sweden **Section of Pediatrics, Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden ***Department of Biomedical Engineering, University Hospital, Uppsala, Sweden Purpose: We previously reported that patients with rolandic epilepsy (benign childhood epilepsy with centrotemporal spikes) may show pathological changes on MRI. Hippocampal abnormalities were most common, and were found in 6/18 children (33 %). The purpose of the present study was to analyze the hippocampi with MR spectroscopy in patients with rolandic epilepsy. Materials and Methods: Eleven patients with rolandic epilepsy and 15 healthy age-matched volunteers underwent H1 MR spectroscopy. The voxels, 2 ” 2 x4 cm each, were placed to include the entire hippocampus with a minimal amount of surrounding tissues. A PRESS sequence with TR 2000 ms and TE 32 ms was used. The amounts of total N-acetylaspartate (tNAA), glutamine and glutamate (Glx) and total choline (tCho) were related to total creatine (tCr), and asymmetry indexes (AI) were calculated. In the controls, the results were not age-related and means and SD for asymmetry indexes were calculated. Mean + 2 SD was defined as the upper limit of normal variation. Results: AIs for tNAA/tCr and Glx/tCr were above the 2-SD limit in 11/11 and 5/11 patients, respectively. AIs for tCho/tCr were not very different in the controls and the patients: only one patient fell out of the 2-SD variation. Conclusions: Hippocampal asymmetry is common in rolandic epilepsy. O128 Correlation between quantitative histomorphology of tumor cell nuclei in gliomas and preoperative proton-MR-spectroscopic data R. Nafe 1, S. Herminghaus 1, S. Raab 1, H. Lanfermann 1, W. Schlote2, F. Zanella 1 1 Dept. of Neuroradiology, 2Edinger Institute for Neurology, Clinics of Johann Wolfgang Goethe-University, Frankfurt am Main, Germany Purpose: A comparison between proton MR spectroscopy (1HMRS) and histomorphology of brain tumors based on morphometric data has not been reported up to now. Therefore, the

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question of whether there are significant correlations between the special variables of each methods must be answered. Material and Methods: The primary surgical glioma specimens (glioblastomas, astrocytomas, oligodendrogliomas) examined were from 47 patients with tumor grades II±IV according to the WHO classification and who had been evaluated by means of a digital image analysis system using Ki-67-immunostained paraffin sections. Nuclear density, Ki-67-proliferation index, nuclear area and shape variables (roundness factor, Fourier-amplitudes) were determined on 200 randomly selected tumor cell nuclei in each tumor specimen. These data were then correlated with preoperative data from 1HMRS using Spearmans correlation analysis. Results: A positive correlation between Fourier-amplitudes, choline peak and lipid peak was observed, as well as a negative correlation between these variables and the nuclear roundness factor. This result indicates higher choline and lipid peaks with increasing irregularity of nuclear outlines. Proliferation index Ki-67 was positively correlated with the lipid peak, while nuclear density showed a positive correlation with the choline peak. Glioblastomas (n = 29) showed an additional positive correlation between mean nuclear size and total creatine. Conclusions: The results demonstrate a significant correlation between nuclear morphology and 1HMRS of gliomas, supporting the biological significance of both histomorphometry and proton MR spectroscopy for the evaluation of these tumors. O129 Prognostic impact of choline compounds and lipids in patients with neuroepithelial brain tumors *S. Herminghaus, **M. Setzer, *U. Pilatus, **J.M Lang, *H. Lanfermann, **V. Seifert, *F.E. Zanella *Institute of Neuroradiology, Frankfurt, Germany **Clinic of Neurosurgery, Frankfurt, Germany Purpose: Proton MR spectroscopy allows the assessment of choline compounds (Cho) and lipids (Lip), which are typically enhanced during cell replication and necrotic transformation of tumor tissue, respectively. Since mitotic figures and tumor-necrosis are essential for histological tumor-grading. Cho and Lip might be of prognostic impact. Materials and Methods: 31 patients (mean age 52.8 years) with histologically confirmed supratentorial neuroepithelial brain tumors were included in the trial. In all cases ± due to location or unfeasibility of complete resection ± only stereotactic biopsies were performed. Low-grade tumors were monitored at 3 to 6 month intervals, while high-grade tumors received focal radiation therapy (60 Gy). MRS studies (PRESS, TE 135, TR 1500) were performed at the time of the initial diagnosis. After correction for coil loading, number of acquisitions and voxel size, Cho and Lip concentrations were expressed in institutional arbitrary units. Statistical analysis included Kaplan Maier curves, log-rank test, and hazard regression models. Results and Conclusions: An increase in Cho-compounds exceeding an approximate level of 140 % of physiological values is associated with the risk of progression from stable to progressive disease. Patients with highly elevated Cho-levels (256 % + /-95.8) but without Lip consistently showed progressive disease and reduced mean survival time (29.8 month). Appearance of Lip in addition to already elevated Cho-levels was accompanied by an even worse prognosis (mean survival time 6.8 months).

O130 H-MR Spectroscopic Imaging-guided surgery: assessment of brain tumor heterogeneity and infiltration and correlation with neuropathology A. Bizzi, U. Danesi, B. Pollo, G. Castelli, G. Broggi, M. Savoiardo Istituto Nazionale Neurologico ªCarlo Bestaº, Milan, Italy Purpose: Evaluate H-MRSI in detecting tumor heterogeneity and infiltration before pre-operative planning. Determine whether elevated choline correlates with cellular density, proliferation and/or grade. Methods and Materials: Twenty-five patients (mean age: 43 yrs.) with untreated intracranial mass were examined preoperatively with multivoxel PRESS technique (TR/TE = 1500/136). H-MRSI coordinates of surgical specimens were recorded using an intraoperative neuronavigation device. The following histopathological diagnosis were made: 16 high grade gliomas, 8 low grade gliomas, 1 PNET. Cho/NAA, Cho/Cr and Cr/NAA ratios for voxels within and around the T2-w. signal abnormality were calculated. Lesions were classified in homogeneous or heterogeneous, well-defined or infiltrating/multicenter by H-MRSI and MRI. Results: Cho was elevated in all tumors. In 6 patients Cr and Cho were elevated with Cho/Cr ~1: all cases were astrocytomas (grade II and III). LGG had homogeneous abnormal spectra with welldefined borders; AA showed an infiltrating appearance. GBM subdivided in two groups with well- and ill-defined borders. Elevated nCho best correlated with cellular density. Conclusion: 1) H-MRSI is a sensitive tool to depict tumor heterogeneity and borders and it is more specific than conventional MRI. H-MRSI-guidance may improve pre-operative planning in heterogeneous, infiltrating lesions. 2) A new H-MRS profile was identified: the elevation of Cr with Cho was seen only in astrocytomas and it may suggest a specific tumor type. 3) Choline is elevated in all tumors and best correlates with cellular density. O131 Single-voxel proton MRS using the PRESS sequence in preoperative evaluation of pediatric brain tumors: a proposed model for differentiation between low-grade and high-grade tumors K. Zakrzewski1, J. Kreisel 2, T. Bieganski 2, P. P. Liberski 3, E. Nowoslawska 4, L. Polis 4 1 Department of Neurosurgery, Polish Mother Memorial Hospital, Research Institute (PMMH RI), Lodz, Poland 2 Department of Pediatric Radiology PMMH RI, Lodz, Poland 3 Department of Molecular Biology, Chair of Oncology, Medical Academy Lodz, Poland 4 Department of Neurosurgery PMMH RI, Lodz, Poland Purpose: The aim of this study was to detect correlations between proton MRS spectra of pediatric brain tumors and their malignancy. Materials and Methods: Seventy-four children with brain tumors were evaluated preoperatively on 1.5 T MR scanner using singlevoxel (8 cm3) proton MRS with PRESS sequence. Among them, there were 44 patients with low-grade tumors (WHO grade I and II), and 30 patients with high-grade tumors (WHO grade III and IV). Spectra were evaluated for Cho, Cr, NAA and Lac-Lip concentrations and Cho/NAA, Cho/Cr, NAA/Cr and Lac-Lip/Cr ratios. Results: The most significant correlation between the measured parameters and tumor malignancy was detected for Cho concentration and Cho/NAA ratio. The percentage of correct diagnoses was 89 %, sensitivity 0.95, specificity 0.8 with 8 incorrect diagnoses. Six of the misdiagnosed cases were high-grade tumors (all germinomas), while two others were low-grade tumors. The results of differentiation using the proposed model differed according to the location of tumors within the brain. For cerebral hemispheric tu-

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mors (26 cases) the percentage of correct diagnoses was 88 %, sensitivity 0.85, specificity 0.9 with 3 incorrect diagnoses. On the contrary, all the cerebellar tumors (29) were diagnosed correctly. For parasellar region tumors (10) and pineal region tumors (6) the proposed model seemed to be of very limited use. Conclusions: In our opinion, the postulated model may be helpful in preoperative differentiation between low-grade and high-grade tumors in children, particularly for tumors located within the posterior fossa.

O132 Preoperative 1h mrs study of uncertain zones in gliomas: predictive value of the method 1 J. Walecki, 1Z. Mariak, 1E. Tarasów, 1B. Kubas, 3P. Pieniazek, 4S. Skrzyæski 1 Akademia Medyczna Bialystok, 3Instytut Onkologii, Gliwice, 4 CSK WAM, Warsaw, Poland Purpose: Assessment of uncertain zones in glial tumors plays a crucial role in proper therapy planning and enables prediction of the follow-up. Intraoperative and preoperative (in CT and MRI) determinations of tumor boundaries are not very sensitive. 1H MR spectroscopy provides the best available demonstration of uncertain zones. The aim of the present study was to evaluate the value of 1H MRS in assessment of uncertain zones and the predictive possibilities of the method in patients with glial tumors. Materials and Methods: 26 patients with glial tumors verified upon histological examination (WHO stages: II-9, III-11, IV-6) were studied using CT, MR and MRS both before surgery and 1 to 3 months after surgery. The patients remained under clinical observation over 1 year. The MR studies were performed on 1.5 and 2.0 T systems, with and without gadolinium. 1H MRS studies, single voxel PRESS sequence (TE-35 msec., TR-1500 msec., NSA192), were used to obtain spectra of the tumor, of the tissue close to the tumor and of the edema surrounding the lesion. Results: Initial results show a correlation between time of recurrence (or tumor progression in partially resected gliomas) and alterations in spectrum obtained from uncertain zones. The most important parameters were lip/NAA, Cho/NAA, lac/NAA. Conclusions: There is a significant difference between these ratios and ratios from tumors and normal brain.

O133 Can 1HMRS be useful in radiotherapy monitoring? P. Pieniazek*, M. Sokól*, J. Walecki**, P.Grieb***, E. Tarasow**, E Kluczewska* * Institute of Oncology, Gliwice, Poland **Radiology Department, Medical Academy, Bialystok, Poland ***Laboratory for Experimental Pharmacology, Polish Academy of Sciences Medical Research Centre, Warsaw, Poland Purpose: CNS tumors of glial origin still pose a considerable challenge both to neurosurgeons and radiotherapists. Surgical removal of a tumor is routinely followed by external beam radiation. Regardless of any treatment plan modifications, irradiation afflicts not only the tumor bed but usually brain tissue free of tumor cells. Moreover, recurrence is not a rare event. The aim of this study was to evaluate the usefulness of 1HMRS in radiotherapy monitoring. Materials and Methods: The authors studied 20 patients who underwent total tumor resection, and postoperative radiotherapy. MRI images and 1H MR spectra were sequentially recorded before therapy onset, after 50 % and 100 % of total planned dose, and one month after therapy completion. Volumes of interest on the base of treatment plan were placed close to the tumor bed (High-

Dose Area), and distant to it (Low-Dose Area). Their locations were the same for a given patient throughout the study. Results: The results of spectra approximation (presented as metabolite ratios: NAA/Cr, Cho/Cr, Cho/NAA, mI/Cr, Lac/NAA, Lip/NAA) were subjected to statistical analysis. The statistical analysis revealed significant differences between data obtained in the groups of patients who did and did not develop early tumor recurrence. Conclusions: Although the studied group consisted of only 20 patients, the results obtained show a potential predictive value of 1 HMRS in radiotherapy and in early tumor recurrence detection. O134 Short TE 1HMRS spectral patterns of postradiation changes and early tumour recurrence in the human brain in vivo P. Pieniazek*, M. Sokól*, J. Walecki**, P.Grieb***, E. Tarasow**, E. Kluczewska* * Institute of Oncology, Gliwice, Poland **Radiology Department, Medical Academy ± Bialystok, M.Sklodowskiej-Curie 24A, Bialystok, Poland ***Laboratory for Experimental Pharmacology, Polish Academy of Sciences Medical Research Centre, Warsaw, Poland Purpose: Fractionated radiotherapy is routinely employed as an adjuvant treatment for patients who undergo surgical removal of primary CNS tumours. Tumour recurrence is not a rare event, especially in tumours of glial origin. Differentiation of early postoperative and radiation-induced changes is often difficult or even impossible by means of MRI including contrast-enhanced scans. 1 HMRS, a direct and moreover non-invasive ªbiochemical biopsyº, allows tissue metabolic profiles to be defined. The aim of this study was to determine spectral patterns of radiation-induced changes versus early stages of tumour recurrence. Materials and Methods: With the use of an Elscint Prestige 2T MRI/MRS system, 55 patients aged 28±51 who underwent surgical resection of primary CNS neoplasm (WHO III and IV) were studied. On each patient MRI and 1H single voxel spectroscopy were performed before the beginning of radiotherapy (4±6 weeks after surgery), after half of the total dose, total dose, 1 and 6 months after therapy completion. VOI1 was placed near the tumour bed, so that high-dose area (60 Gy) was included, and VOI2 in a distant region of the brain (total dose up to 30Gy), according to the treatment plan. Each VOI was constant for a given patient during the study. During the time of observation 19 patients developed tumour recurrence, while the others showed only postoperative and radiation-induced changes. Results and Conclusions: Statistical analyses of spectral patterns for both groups are presented and show characteristic changes allowing for differentiation between recurrence and post-radiation changes. Spectral changes compatible with neoplastic processes were observed at least 4±6 weeks before any imaging signs of tumour recurrence. O135 Neuroborreliosis: MR and 1H MR spectroscopy findings A. Ustymowicz*, E. Tarasow*, J. Zajkowska**, B. Kubas*, W. Dzienis*, J. Walecki *Dept. of Radiology, **Dept of Infectious Diseases, Medical Academy Hospital, Bialystok, Poland Purpose: To assess the central nervous system (CNS) with MR and H MR spectroscopy in neuroborreliosis patients. Materials and Methods: In 44 patients (27 women and 17 men; aged 18±75 years) MR examinations of CNS were performed. Additionally, 12 of them were examined with 1H MR spectroscopy 1

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(PRESS 35). Metabolite peaks and ratios were evaluated in spectra acquired from normal-appearing (MR) white matter of frontal lobes and were compared with a control group of 32 cases. Results: MR images were abnormal in 50 %. Most patients presented cortico-subcortical atrophy (86 %), hyperintense foci (T2weighted images) in white matter (41 %) and the brain stem (9 %). 1 H MRS examinations (n = 12) revealed an increase in Cho/Cr and Lip/Cr. In 5 patients a decrease in NAA/Cr was also found. Four of these patients presented MR changes: brain atrophy (n = 1) and brain atrophy with white matter focal lesions (n = 3). One patient with Lyme encephalopathy did not reveal abnormalities on MR study. Conclusions: 1) Central nervous system changes observed with MR in neuroborreliosis are not specific; Lyme disease has to be considered when patients present brain atrophy and foci of hyperintense signal (T2-weighted images) in white matter and the brain stem. Metabolite parameters in neuroborreliosis are altered; an increase in lipids and choline suggest demyelination and/or inflammatory processes; a decrease in NAA in some patients may correspond to axonal loss. O136 H-MR-spectra (MRS) in patients with acute and chronic hydrocephalus prior and after CSF-shunting *W. Reiche, **M. Kiefer, *C. Diem, *Dr. M. Backens, *C. Krick, *Prof. Dr. W. Reith *Department for Neuroradiology, Saar University Hospital, Homburg / Saar, Germany **Clinic for Neurosurgery, Homburg/Saar, Germany Purpose: To study H-MR-spectra (MRS) in patients with acute and chronic hydrocephalus prior and after CSF-shunting and to compare results with data of controls. Materials and Methods: In 54 patients (average age 52.4  20.7) and in 12 controls (average age 37  8.7) a total of 83 MR investigations (consisting of conventional MRI and H-MRS) were acquired. In 12 of these, MRS data prior to and after CSF shunting were available. A single volume technique was applied for H-MRS using a spin-echo sequence (TE 135 ms, TR 1500 ms). MRS volumes were positioned in the central/paracentral region. For evaluation of MRS, peak ratios [NAA/Cr, NAA/Cho, NAA/(Cho + Cr) and Cho/Cr] were calculated and assigned to the following clinical diagnoses: acute occlusive hydrocephalus (AOH) (n = 7), longstanding CSF-shunted AOH (n = 12), NPH (n = 15), longstanding CSF-shunted NPH (n = 8), chronic occlusive hydrocephalus (COH) (n = 7) and brain atrophy (n = 5). Results: The MRS peak ratios showed no difference between AOH and controls. Patients with longstanding CSF-shunted AOH revealed a slight decrease of NAA/Cr (U-test p = 0.027). Compared to controls NAA/Cr was clearly reduced in patients with chronic hydrocephalus (NPH, longstanding CSF shunted NPH and COH) (p < 0.006) and in patients with brain atrophy (p = 0.027). There was no significant difference between patients with NPH and longstanding CSF-shunted NPH compared to brain atrophy. NAA/Cr was slightly lower in the COH group as compared to atrophy (p = 0.01). MRS prior to and post CSF shunt implantation showed no changes. Conclusions: The decrease in the NAA/Cr ratio indicates loss of neurones, which is more severe in chronic hydrocephalus and atrophy than in longstanding CSF-shunted AOH. Using H-MRS , it is not possible to distinguish NPH from atrophy.

O137 1H MRS evaluation of brain metabolism in patients with type 1 diabetes mellitus *Z. Rozhkova, *V. Rogozhyn, **B. Mankovsky, **O. Lipskaya *Radiological Center of the Academy of Medical Sciences of Ukraine, Kiev, Ukraine **Institute of Endocrinology, Kiev, Ukraine Purpose: Our goal was to investigate the cerebral metabolism in patients with long-term type 1 diabetes mellitus on the basis of the analysis 1H MR in vivo spectra of the brain. Materials and Methods: Two groups of patients were examined with a 1.5 T Magnetom Vision Plus System (SIEMENS). The 1 st group included 12 diabetic patients without overt neurological disorders, ranging in age from 20 to 40 years old, with diabetes duration from 9 to 20 years; HbA1 c: 8.4  1.35 %, mean  SD. The 2 nd group included 19 healthy volunteers, aged 23 to 40 years old. 1 H MR spectra were recorded in both hemispheres of the occipital lobe and in the frontal lobe with the STEAM sequence (TR/ TE = 1365/135, 20; 1500/270 ms), VOI = 8 cm3, NS = 128. Results: In the 1H spectra of patients with diabetes, the following signals were identified: N-acetylaspartic acid (NAA), total creatine (Cr), choline (Cho), glucose (Glx), myo-inositol (mI), scylloinositol (sI), lactate (Lac) and an additional peak with a 2.14 ppm chemical shift. Statistical analysis was performed using Student's paired test. For the patients in the 1 st group, a significant decrease in NAA and Cr peak areas was observed as compared to the patients in the second group. The amount of Cho-containing metabolites was not statistically significant in both hemispheres. Furthermore, the signals of Glx and Lac in the spectra of diabetic patients were detected more frequently than in the spectra of volunteers. The presence of Lac is essential for the diabetic state. Conclusions: 1H MRS is very useful for evaluating disturbances of the brain metabolism in patients with long-term diabetes.

O138 Normal appearing white matter in patients with acute disseminated encephalomyelites: a proton magnetic resonance-chemical shift imaging study L.S. Politi, M. Moretti, C. Tessa, F. Lolli, L. Guerrini, S. Salti, F. Salvi, G. Pellicanò, M. Mascalchi Radiodiagnostics, University of Florence, Florence, Italy Purpose: Proton magnetic resonance (MR) spectroscopy demonstrates lowering of the N-Acetyl-Aspartate (NAA)/Creatine(Cr) ratio in normal appearing white matter (NAWM) of patients with multiple sclerosis (MS). We evaluated whether NAWM in patients with acute disseminated encephalomyelites (ADEM) is truly normal or exhibits microscopic damage. Materials and Methods: Five patients (mean age 39  12 years) with ADEM were examined 6  2.5 years after the acute phase. Twelve (mean age 35  11 years) healthy subjects served as controls. Each subject underwent a conventional MR imaging study and chemical shift imaging (CSI) with a TSE-PRESS sequence with TE 136 ms. Two 20-mm thick slices, FOV 12 ” 9 cm, 32 ” 32 matrix, at mid-ventricular and supraventricular level were acquired. NAA/Cr, NAA/Choline (Cho) and Cho/Cr ratios were computed in 6 areas of NAWM in the patients and 16 corresponding areas in control subjects. Results: The Mann-Whitney test did not show significant differences in NAA/Cr, NAA/Cho and Cho/Cr between the NAWM of patients and controls. Conclusions: Our results, in line with those of diffusion and magnetization tranfer MR imaging (Inglese M et al., 2000), indicate that, at variance of MS, the NAWM in patients who suffered

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ADEM does not show signs of damage even at the microscopic level.

O139 1H-MRS to evaluate the neuroprotective effects of gabapentin in Huntington's disease *J.O. Heidenreich, *A. Schilling, *D. Bonekamp, **J. Priller, ** H. Meierkord, *K.-J. Wolf *Dept. of Radiology, UKBF, Freie University Berlin, Berlin, Germany **Dept. of Neurology, Humboldt University, Berlin, Germany Purpose: In patients with Huntington's disease (HD) and in asymptomatic gene carriers, a reduction in N-acetylaspartate (NAA) and an increase in lactate have been demonstrated in the frontal and occipital cortex as well as in the caudate nucleus. In this study we evaluated the neuroprotective effects of gabapentin in HD by means of magnetic resonance spectroscopy (1H-MRS). Materials and Methods: 22 patients with genetically proven HD were enrolled in this prospective study. To date, 8 patients have been examined initially and after six to twelve months of treatment with Gabapentin and compared to normal controls. Spectra were acquired from 8 ml voxel positioned in the frontal and occipital cortex and the caudate nucleus with a STEAM-sequence. Results: HD patients initially showed, as compared to controls, a reduction in the neuron marker NAA in the frontal and occipital cortex and caudate nucleus. In these regions a median increase in lactate was detected, although not in all patients. After treatment with gabapentin, in HD patients the median reduction in lactate was found to be 25 % in the frontal cortex, 60 % in the occipital cortex and 50 % in the caudate nucleus. A median increase in choline was measured in the frontal cortex. For all regions a median increase in the Glx-components (glutamine, glutamate and GABA) was found. Conclusions: It was shown that the median lactate concentration decreased in the frontal and occipital cortex and caudate nucleus under treatment with gabapentin. This may be a result of the neuroprotective effects of gabapentin on the brain energy metabolism in HD. The increase in choline might reflect gliosis, which has been

described in HD, especially in the brain region with the lowest reduction in lactate. O140 Proton Magnetic Resonance spectroscopic imaging in first episode schizofrenia: involvement of hippocampus and dorsolateral prefrontal cortex A. Bertolino1,2,3, T. Scarabino2, D. Sciota1, F. Brudaglio1, M. Altamura1, G. Blasi1, J. H. Callicott3, D. R. Weinberger3, M. Nardini1 Dipartimento di Scienze Neurologiche e Psichiatriche, Bari, Italy, University of Bari, Bari, Italy 2. Neuroradiologia, Ospedale Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy 3. Clinical Brain Disorders Branch, National Institute of Mental Health, Bethesda, MD, USA Background and Purpose: Previous studies with proton magnetic resonance spectroscopy (1H-MRS) in chronic patients with schizophrenia have reported selective neuronal pathology (as shown by reduction of N-acetylaspartate, NAA, a marker of neuronal integrity) in the hippocampal area (HIPPO) and in dorsolateral prefrontal cortex (DLPFC). The purpose of the present study was to assess with 1H-MRS imaging (1H-MRSI) the selectivity of NAA reductions in patients experiencing a first episode of schizophrenia. Materials and Methods: We studied 16 patients (10 males, age 24.6 + 5.1) with schizophreniform disorder (DSM-IV). Twelve patients were being treated with antipsychotics at time of scanning. Studies were performed on a 1.5T GE scanner using a previously described 1H-MRSI pulse sequence (TE = 272 msec, TR = 2200 msec). Regions of interest (ROIs) were identified on coplanar T1 weighted images in HIPPO, DLPFC and several other cortical and subcortical ROIs. Results and conclusions: ANOVA revealed selective reductions of NAA/CRE in HIPPO (p < 0.001) and in DLPFC (p < 0.03) of the patients. No effect was found in all ROIs for all other metabolites. These results suggest selective reductions of NAA levels in HIPPO and DLPFC of patients at disease onset. Therefore, neuronal pathology as shown by reduced NAA levels does not seem to be an epiphenomenon of chronicity.