Posters: Musculoskeletal Subjects and Methods: Forty healthy female volunteers evenly distributed between age 20 and 81 (median age 45) were assessed with endoanal and endovaginal 1.5 T MRI. Axial PDw, 3D GRE and sagittal and coronal T2w TSE images of the pelvic floor were obtained with both methods. The essential anatomical structures were evaluated. Results: The exquisite soft tissue contrast combined with the high local resolution due to the endoluminal coil provided the ideal access to the study of this complex region. Multiplanar information on the posterior areas of the pelvic floor obtained with the endoanal coil was completed with information on the anterior areas obtained with the endovaginal coil. The key anatomical structures with clinical importance, with particular reference to surgical evaluation are illustrated. Optimal MR endoluminat coil use and specific sequences to evaluate individual structures in the perineum are suggested. Conclusion: The use of MR endocavitary coils in pelvic imaging allows a thorough understanding of the complex anatomical structure and is essential for pathology detection and surgery planing.

Fast MRI in the diagnosis of pelvic floor dysfunctions V. Piloni ~, G. Valeri-', C. Ferrara 2, P. Ercolani2, S. Ciarrocchi3, L. Spazzafumo ~, A. Giovagnoni4, E. De Nigrisk IDepartment of Radiology, AZ

7, Ancona: ZMR Center. University of Ancona: 3Department of Statistics, INRCA, Ancona; aDepartment of Radiolngy, Unirersit)' of Modena. Italy Purpose: To provide objective and reproducibile data in the diagnosis of pelvic floor dysfunctions before treatment.

Subjects and Methods: Twenty-six patients (six males, 20 females, aged 29-87 years, mean 62.8 years) with associated urinary, genital and anorectal dysfunctions, were examined with both fast MRI and conventional videorecorded cysto-colpo-proctography. MR1 studies were performed on a 1.0 T superconducting system using a pelvis phased array coil. Images were analyzed for evidence of various abnormalities including cystocele and hypermobile bladder neck (anterior compartment); vaginal vault prolapse, elitrocele and edrocele (middle compartment); recto-anal intussusception, rectocele, enterocele and sigmoidocele (posterior compartment). Films from conventional and fast MRI were compared side-by-side and analyzed for three characteristics including (a) image quality, (b) organ definition, (c) number and conspicuity of abnormalities. Three independent reviewers performed comparison and rated the three characteristics by using a relative three-point scaleLfast MRI were rated as better than same as or worse then conventional studies. The frequency with which fast MRI were rated as better was tested in a total of 52 case reviews. In addition, the distance from the pubococcygeal line was taken as a reference for measurement of descendent on straining of: (1) the anorectal junction; (2) the bladder neck: and (3) the vaginal vault. Finally, the anorectal angle (ARA) and the angle between the vaginal axis and the reference line, were calculated at rest and on straining. Measurements were independently performed twice by two radiologists. Statistics included calculation of intra-interobserver agreement, average resting and training values and correlation between parameters. Results: Overall quality of MRI was judged superior to that of conventional imaging in 38 on 52 (73.1%); organ definition in 41 on 52 (78.9%) and identification of abnormalities in 45 on 52 (86.2%) with a confidence of P <0.01. Both intra-interobserver indices were always greater than 80% (range 8493%). Average resting and training values of the various parameters were as follows: anorectal junction 0.64 mm_+ t4 and - 21.8 ram_.+25; vaginal vault 47.5 mm _+ 13.4 and 13.9 mm +_ 0: bladder neck 23.5 ram + 10.4 and 1.4 mm _+21.6; ARA 97.4~ + 18 and 110.2~ _+21.1; vaginal angle 99.3 ~ _+ 15.2 and 59.5 ~ + 21.1, respectively. A close correlation between resting and straining values was seen to affect ARA ~ and the bladder neck-to-reference line distance (Pearson coefficient 0.493, P < 0.05 and 0.615 P < 0.01, respectively). In addition, ARA ~ was correlated with almost all other parameters (Pearson coefficient ranging from 0.552 to 0.706, P < 0.01). Conclusions: Fast MRI is an attractive alternative to fluoroscophy prior to pelvic floor re-education and/or surgical planning.

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149

our study was to compare MRI and arthroscopy for evaluation of normal and degenerative cartilage. Material and Methods: Eighty six patients with knee osteoarthrosis (OA) were examined with 0.5 T magnet (Gyroscan T5-NT, Philips Medical Systems, Best. Netherlands) (the routine examination consisted of T~-weighted SE coronal 600\20, 3 - 4 mm section thickness with 0.5 mm intersection gap: gradient echo transaxial 550\27, flip 35. 3 - 4 mm section thickness with 0.5 mm intersection gap; proton and T 2 sagittal 1500',20, 85 3 - 4 mm section thickness with 0.5 mm intersection gap: 3DFFE 23,14, flip angle 10-50; 1.5 mm section thickness. A 16-20 cm FOV. 256/128 axial or 256/256 sagittal, coronal matrix, two signals acquired were used. In all patients arthroscopy were performed. The Kellgren and Lawrence classification for knee OA was used to diagnose tibiofemoral OA. Forty nine (52%) from 86 inspected patients had no definitions for radiographic OA. On the contrary 'a focus behind a focus' (only 18 foci) and "a joint behind a joint' was compared. The yardsticks of a rating were: morphologic structure of surface, homogeneity and intensity of MR-signal. Results: MRI has allowed to identify normal and degenerative cartilage. The homogeneity of MR-signal correlated with arthroscopically normal cartilage in 93.1% of cases; in invariable nonhomogeneous morphology was by tag of the earliest stage of an arthrosis exhibited at arthroscopy by its softening and loss of elasticity. Degenerativ changes detected by arthroscopy in 85.7% of cases, were exhibited with MR signal nonhomogeneity. Conclusion: OA and the cartilage degeneration are visible image with MR as intracartilaginous signal changes, superficial erosions, diffuse cartilage thinning and cartilage ulceration. Thus noninvasive identification of the early pathological cartilage changes is possible before radiological arthrosis demonstration.

•]

Wrist MR-arthography in the evaluation of triangular fibrocartilagineous complex

G. Valeri l, P. Ercolani ~, A. Soccetti2, A. Giovagnoni2, E. De NigrisL IMR

Center, Institute of Orthopaedics, Unicersity of Ancona, hair; 2hzstitute of Radiology. University of Modena. Italy

Purpose: To verify the clinical utility of magnetic resonance arthrography (MR-arthrography) of the wrist in the evaluation of suspected triangular ,fibrocartilagineous complex (TFC) lesions. Subjects and Methods: Thirty-five patients with clinically suspected lesions of TFC underwent MR and MR-arthrography. In all patients an intrarticular (monocapartimental radio-carpal joint) injection of 2 - 1 0 ml of a t0 mmol saline solution of Gd-DTPA was injected. Two radiologists evaluated independently the visualisation of the triangular fibrocartilagineous complex expressed in a semiquantitative scale with three grades. In MR images the grade 0 was considered the complete visualisation of the triangular fibrocartilagineous complex, the grade 1 its partial visualisation and grade 2 absence of visualisation. In MR-arthrography images the grade 0 was considered the absence of contrast medium passage through the triangular fibrocartilagineous complex, the grade 1 minimal passage and grade 2 complete passage. Results: In MR images the triangular fibroeartilagineous complex was normal in 27 cases (76%) and partially visualised in eight cases (24%1. In MR-arthrography images the triangular fibrocartilagineous complex was normal in 13 cases (37%) and with partial lesions in 22 cases (63%). There were no severe side-effects to contrast medium injection or severe complications. Conclusion: The results show that MR-arthrography must be considered a useful method compared to MR without contrast medium in the visualisation of triangular fibrocartilagineous complex and in the detection of its lesions.

Perfusion analysis of the patellar cartilage with dynamic MRI after contrast administration: differences between control subjects and patients with anterior knee pain of patenar origin Luis Marti-Bonmati, Daniel Montaner Alonso, Asunci6n Torregrosa. Victoria Higueras, Miguet Sanfeliu. Departments of Radiology and Traumatology, Doctor

Peset University Hospital. Valencia, Spain

Comparison of the MRI and arthroscopy for osteoarthrosis in early diagnostics L. Luchikhyna, A. Baev. "Basseinovaia"Hospital, MRI Department of 'Medic-

ina' Hospital, Moscow, Russia

Introduction:The early diagnosis of an arthrosis is based on revealing the initial changes of a cartilage before radiological findings. One of the earliest changes at an experimental arthrosis is a matrix cartilage hyperhydratation. The aim of

Introduction: It is hypothesized that patellar chondromalacy can be secondary to altered vascularization in the subchondral bone tissue which could secondarily involve the deeper layers of the cartilage. Our objetive was to evaluate the differences in the articular patellar cartilage and subchondral bone perfusion characteristics with dynamic MR imaging after contrast administration. Material and Methods: Seventeen patients were consecutively included in the study, 11 of them were diagnosed of probably patellar chondromalacy while six constituted the control group. All patients had an MR study with intravenous gadolinium chelate administration. By digital analysis of the dynamic series of images, parametric images were constructed in a pixel-by-pixel basis providing

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150

images, parametric images were constructed in a pixel-by-pixel basis providing data on the perfusion characteristics. Maximum enhancement, average enhancement and maximum velocity of enhancement parametric images, both in the arlicular patellar cartilage and the subchondral bone, were latter analyzed with ROI measurements. These measures were statistically compared uning the Student's t-test for independent samples. A qualitaty analysis was also performed looking for differences in the brightness in the cartilage and bone with the different parametric images and the results were compared with the ;(2 test. Results: Maximum enhancement and maximum velocity of enhancement values in the more external side of the patellar cartilage were higher in patients with chondropathy than in the control group (40.96 + 24.62 vs. 23.28 + 4.61 and 30.36 _+ 17.71 vs. 17.45 + 2.64, respectively, P < 0.04). Qualitative analysis also showed a higher cartilage's perfusion brightness in patients with anterior knee pain (P = 0.009). Discussion/Conclusion:The differences observed in the enhancement of the patellar cartilage suggest that in patellar chondropathy exists some vascular alterations in the deeper layers of the articular cartilage, having an increased perfusion.

concomitantly the intensity of the IH D Q F signal increases, rma~ becomes shorter, and the decay becomes steeper. t5Intact r. t-

O >

13W

10

r n"

5 e-

M R I evaluation of muscular dystonias d e n e r v a t i v e process

and therapeutic

r" 0

E. Fanucci 1, V. Varrucciu ~, G. Sodani l, S. Masala =, G. Simoneni 2. ~Radiology

.01

Department, S. Eugenio Hospital, ASL, Rorna C, Italy; 2University of Rome 'Tor Vergata ", Italy

Purpose: To demonstrate the efficacy of MRI in comparison with other techniques (US and CT) in evaluation of muscular dystonias and therapeutic denervative process. Materialsand Methods: Twelve subjects with muscular dystonias (ileopsoas and piriformis muscle syndrome) underwent US, CT and MRI before and after percutaneous therapy with botulinic toxin causing denervative process at 2, 7 and 60 days. MRI was performed using SET1, TSET2 and STIR T" sequences; ultrasound was performed at rest and with dynamic clinical manouvres. A 20 G, 10 cm length was used for botulinic toxin injection: a dose of 100 UI was injected inside piriformis muscle and 200 UI inside ileopsoas muscle, all under CT guidance. Results: No complication of the procedure were registred. Ultrasound and CT evidenced only subtle muscle variation: lower echogenigity, normal aspect in CT density and, sometimes increased muscle diameter. MRI particularly STIR sequences well evidenced denervative process in 9/12 patients with increased signal intensity of affected muscle (60 days after procedure). Conclusion:Therapy of muscular dystonias with CT guided botulinic toxin injection is a feasible technique allowing a new therapeutic approach. MRI offers the better evaluation of muscular dystonias particularly in the follow-up and it proposed as a possible alternative to elettromiography in deep muscles.

~

.t

1

10

Creation time (ms) Fig. 1. ]H DQF signal intensity of regenerated Achilles tendon as a function of r. All samples were prepared from rabbit Achilles tendon, 3, 9, 13 and 21 weeks after the tenotomy. Means and standard errors are shown for the intact tendon (n = 6). The details of the healing process were also followed by DQF images. Three weeks after the rupture, the AT is not observed at r = 0.4 ms. After 9 weeks gradient echo images are almost identical to those obtained for uninjured legs. DQF images clearly show the pathology even after 18 weeks. The results obtained follow closely the known stages of the healing [3] and are in good accordance with our previous T 2 relaxation and anisotropy measurements of tenotomized tendons [4]. Conclusions: In this work we have shown that IH DQF spectroscopy is a sensitive technique for detecting the different phases during the healing process of ruptured Achilles tendon.

References [1] Tsoref L, et aL MRM 1998;39:11. [2] Tsoref L, et at. MRM 1998;40:720. [3] Enwemeka CS. Phys Ther 1989;69:816. [4] Takamiya H. et al. Trans Ortho Res Soc 1999;24:1078.

Monitoring the healing process of ruptured achilles tendon by t H D Q F M R S a n d M R I

Yoshiteru Seo I, Kazuya lkoma =, Hisatake Takamiya 2, Yoshiaki Kusaka 2, Liat Tsoref3, Uzi Eliav4, Hadassah Shinar4, Gil Navon 4. IDepartment of Physiology

and 2Orthopedic Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan; 3School of Physics and 4School of Chemistry, Tel Aviv University, Tel Aviv, Israel

Introduction:Tendons and ligaments are difficult to observe by MRI due to

their short transverse relaxation times. We have recently developed a method, which detects water interacting with ordered structures. We report here the application of this method - - ~H double quantum filtering (DQF) [1,2] - - to follow the healing process of ruptured (tenotomized) Achilles tendons (AT). The method detects exclusively water in anisotropic environments and resolves different ordered tissues by using a creation time (T) contrast. Materials and Methods:Male Japanese white rabbits (2.5 kg) were anesthetized by pentobarbital (50 mg/kg i.p.), and lower leg including the Achilles tendon was dissected en bloc with surrounding tissues. The specimen was inserted in an N M R tube with the longitudinal axis of the Achilles tendon aligned parallel to the static magnetic field. After the leg was imaged, the AT was removed and inserted in the NMR tube, as described above, for spectroscopic measurements. In order to follow the healing process of the Achilles tendon, specimens from different rabbits were obtained 3, 9, 13 and 21 weeks after the tenotomy. Six intact Achilles tendons that did not undergo a tenotomy were also measured for comparison. Results: DQF spectra of the regenerated part of the Achilles tendons were measured as a function of the creation time T. The results obtained at various stages of the healing, as well as the results obtained for the intact tendons are summarized in Fig. 1. The DQF signal of healthy intact tendon reached maximum intensity at rm=~ = 0.4 ms. Three weeks after the tanotomy, the DQF signal was very weak. Its maximum was obtained at r~,~ = 1.6 ms and the decay of the intensity was very slow. At further stages of the healing process,

Magnetic resonance imaging and reflex sympathetic dystrophy following t o t a l k n e e replacement J.C. Kinmont, R. Tayar, T.G. Kavanagh. St. Helier Hospital, Carshalton,

Surrey, UK Purpose/Introduction: Reflex sympathetic dystrophy (RSD) involving the lower limb is a recognised complication of total knee replacement (TKR), but the pathogenesis is still poorly understood. The importance of early diagnosis of RSD and prompt initiation of treatment has been stressed. Initially, confusion and delay in post-operative diagnosis may occur until local venous thrombosis and infection have been excluded. Magnetic resonance imaging (MRI), particularly of the upper limb, has been shown to be of value in the early diagnosis and staging of RSD, though regarded only as an adjunct to clinical findings, plain radiographs and a bone scan. The presence of artifact due to the metal prosthesis, adversely affecting image interpretation in the affected limb, has been considered a deterrent to MR imaging following TKR. Subjects and Methods: MR imaging following TKR was undertaken in patients with excessive pain and stiffness, in whom serology, venogram and bone scan were not strongly suggestive of infection or thrombosis. Coronal and axial FSE and FMPIR imaging sequences of the thigh and calf were used. Objective evidence of RSD was sought using those signs described by Schweitzer et al. [1]. Further imaging in affected cases was repeated to assess response to treatment. Results: Despite the presence of local artifact from the large ferromagnetic prosthesis, adequate imaging of the lower limbs was achieved, so that the periprosthetic bone and soft tissues could be adequately assessed. FMPIR imaging sequences of the thigh were particularly instructive. Discussion/Conclusion:Not previously reported, we have found that MR imaging of the post-operative lower limb, employing a FMPIR sequence, can facilitate the management of RSD. We present three eases of RSD following

t00

Posters: Musculoskeletal TKR and demonstrate the value of MRI in the early diagnosis, staging and monitoring of response to treatment.

References [1] Schweitzer ME, et al. Radiology 1995; 195:211-214.

Meniscal and ligamentous tears diagnosed with M R u n a g i n g o f the knee joint

73.7, 68.4. For sequences SAG: SENS: 56.1, 46.3, 57.3, 57.3: SPEC: 63.2, 71.1, 71.1, 78.9. These values were significantly different between both M R sequences (P < 0.001). Kappa values for intraobserver agreement were 0.679 and 0.751 for ACR sequences, and 0.43 and 0.63 for SAG sequences. Kappa values for interobserver agreement were 0.593 and 0.499 for ACR sequences, and 0.335 and 0.266 for SAG sequences. Conclusion: Para-sagittal series parallel to the main axis of the acromion (ACR) is the best orientation for acromial categorization by MR imaging. We recommend this series to be included in the routine shoulder protocol.

Relationship between bone marrow changes of the mandibular condyle and inflammatory arthritis, arthrosis and joint effusion

B Drugowi 1, R. Druga z, L. Janougkovhz. IRadiodiagnostic Department, Hospi-

tal Na Homolce, Prague 5: -'Department of Functional Anatomy, 2nd Medical Faculty, Charles University, Prague, Czech Republic

Introduction:The goal of presented study is to find optimal combination of MR sequences for assesment of the meniscal tears, complete or partial tear of the anterior cruciate ligament (ACL), and medial collateral ligament (MCL) injury. Results of the MR examination were compared with arthroscopic and surgical findings. Subjects and Methods: A total of 173 patients (91 male patients, 82 female patients) underwent MR examination of the knee joint. MR imaging was performed by means of a IT imager (Magnetom Impact Expert System IT, Siemens). Tl-weighted images, T2 weighted images and TI flash 2D FS images were obtained in all 173 cases in sagittal and coronal planes. Results: Meniscal tears: imaging protocol included TI- and T2-weighted coronal and sagittal sequences. The diagnosis of the meniscal tear is based on an abnormal intrameniscal signal intensity on Tl-weighted images also without a corresponding abnormality on T2-weighted images. High signal intensity on T2-weighted images indicates acute meniscal tear. Meniscal tears diagnosed with using of this protocol were confirmed arthroscopically or surgically in 85% of cases. Tears of the ACL: diagnosis of the ACL tear is primarily based on hyperintense signal within a disrupted ligament in both T1- and T2-weighted sagittal images. In addition discontinuity of the ACL and angulation of the PCL ligament may be also used as useful criteria. Bone bruising of the tibial plateau or lateral femoral condyle is indicative for complete acute tear. Tears of the ACL demonstrated with using of these criteria were arthroscopically or surgically confirmed in 90% of cases. Tears of the MCL: on the coronal MR images there is an increased signal, deformity and loss of continuity of the ligament fibers on T1- and T2-weighted images. T2-weighted images are more efficient for imaging of the acute lesions. Tears of the MCL were confirmed arthroscopically or surgically in 88% of cases. In 45% of male patients and in 35% of female patients tears of the ACL were associated with medial meniscus lesions. Conclusion: MR imaging is an accurate, noninvasive, and cost-effective method for the evaluation of acute and chronic lesions of the knee joint ligaments and menisci. Comparison of MR examination with arthroscopic and surgical findings in group of 173 patients indicates high specifity of MR imaging for assessment of meniscal and ligamentous injuries. Acromial characterization by MRI: evaluation of two different para-sagittai sequences F.

Saezl ~, G.

Tabernero 1, J.A.

Larena l,

J.I.

Martin j,

L.

Larrea ~.

E. Ellzagaray2, D. Grande 2. 1Radiology Department, Hospital Cruces; Radiology Department, Hospital Basurto, Bilbao, Spain

Purpose: Categorization of acromial morphology into the three recognized types defined by Bigliani has proved elusive by MR imaging, with published results of poor inter- and intra-observer agreement. We have performed this study to try to establish the best sagittal plane for the evaluation of acromial morphology by MR imaging. Subjects and Methods: A total of 120 patients have been referred to our Radiology Departments for imaging evaluation because of 'painful shoulder'. MR imaging, plain films and CT with 3D-reconstruction were performed on all patients, after informed consent was obtained. MR imaging (0.5 T) study included the classical para-coronal, axial, and para-sagittal (perpendicular to the main axis of the supraspinatus muscle: SAG) orientations. Apart from these series we added another parasagittal (ACR), this time parallel to the main axis of the acromion. CT was acquired by means of overlapping slices (2.5 mm thick, 2 mm gap) and 3D reconstruction. MR imaging findings were separately evaluated by two groups of radiologists who were blinded to the 3D-CT findings (gold standard). The acromion was categorized into three Bigliani types according to the geometry of its inferior surface: type I, fiat; type II, concave; type III, concave with a hook. Results: Sensitivity (SENS) and specificity (SPEC) values for differentiating between acromion types I and II versus type III are shown, for the different sequences (ACR and SAG) and observers (two readings and two groups of readers): for sequences ACR: SENS: 93.3, 81.7, 86.6, 84.1; SPEC: 81.6, 78.9,

151

Ewa Mafikowska, Hubert Wanyura, Jerzy Walecki, Robert Knorr. Hanna Markiewicz. Department of Maxillo-Facial Radiology, WarsawMedical Univer-

sity, Poland

Purpose/Introduction: It has been estimated that almost 60% of the Polish population has been affected by different dysfunctions of the temporomandibular joint (TMJ). The most common disturbances seem to be internal derangements in the course of arthrosis, inflammatory arthritis - - both with and without joint effusion, disc displacement and/or deformity and congenital anomalies. The goal of this paper was to analyze the relationship between bone marrow changes of the mandibular condyle and inflammatory arthritis, arthrosis, joint effusion and other forms of internal derangements. Subjects and Methods: With respect to internal derangement, joint effusion and inflammatory disease magnetic resonance (MR) images of the 15 patients with MR evidence of bone marrow oedema or sclerosis were compared to 15 control patients with normal bone marrow. Results: Seven of 15 patients with bone marrow changes had normal bone and eight had inflammatory arthritis. All joints with bone marrow changes as well as 12 of the controls had different forms of disc displacement. Bone marrow changes were associated with more advanced stage of internal derangement. Discussion/Conclusion: Since nearly one-half of the joints with bone marrow changes had no inflammatory arthritits, it seems that bone marrow changes can be present without any inflammatory arthritis. More joint effusion and more advanced stage of internal derangement in joints with bone marrow changes indicates a strong association between these diseases entities. C o r r e l a t i o n between M R i m a g e s of the temporomandibular

joint and arthroscopic findings Ewa Mafikowska. Hubert Wanyura, Jerzy Walecki, Robert Knorr. Department

of Maxill-Facial Radiology, Warsaw Medical University, Poland

Purpose/Introduction: The different forms of temporomandibular joint (TMJ) dysfunction affect approximately 60% of Polish population. After radiological and MR diagnosis most of those people require diagnostic evaluation and/or arthroscopic procedure which is the safest and the most effective way of both diagnosis and treatment. The goal of this paper is to evaluate the correlation between MR images of the TMJ and arthroscopic findings. Subjects and Methods: The group of 12 patients with the TMJ dysfunction were diagnosed by MR. The average age was 35.7, eight were female and three male. According to MR images, five patients were diagnosed as reducing anterior disc displacement, three as internal derangements caused by inflammatory arthritis, two as arthrosis and two were normal. These two patients with normal MR images of the TMJ and five with reducing anterior disc displacement were further managed in conservative way (rehabilitation) and the group of five patients underwent diagnostic arthroscopy. Results: The arthroscopic findings of all five cases were very similar to the MR images. The only one important difference between MR and arthroscopic findings which were found during arthroscopy and were not noticed on MR images were adhesions. Discussion/Conclusion: Since arthroscopic findings of the TMJ were very similar to MR images it seems that MRI should be the method of choice in the diagnosis of patients with many TMJ dysfunctions before they are qualified for arthroscopic procedure. ~-~

Dynamic contrast-enhanced MRI of patellar tendon autograft for anterior cruciate ligament (PTA-LCA) reconstruction: an index of l i g a m e n t i z a t i o n ?

E. Rosso l, B. Guadagni l, G. Burastero 2, F. Giacco2, L. Felli 2, F. Sardanelli ~.

tDepartment of Diagnostic Imaging; '-Department of Orthopaedics, University of Genoa, Italy

Posters: Musculoskeletal

152

Purpose: To evaluate take and ligamentization the PTA-LCA with dynamic

Subjects and Methods: We studied with MRI in 34 patients with persistent pain,

MRI.

not related to a trauma, localized at the level of the ankle and foot. The MRI examinations have been performed with a high field (1.5 T Vision Plus Siemens) and with a small bore dedicated equipment to the studying of the limbs (0.2 T Artoscan Esaote), using T1, T2, GE and fat suppression. Results: In nine patients an osteoid osteoma was present and one patient underwent a previous surgical treatment on the base of another clinical suspect. The other patients presented RSDS (reflex sympatetic dystrophic syndrome), osteonecrosis, stress fractures, dissecans osteocondrites, villonodular synovites, sinus tarsi inflammations, impingement syndromes and infective process. Discussion/Conclusion: In our experience MRI permitted to clearly depict the nidus of osteoid osteoma in the contest of the lesion even if is very important to choose the right sequences because the reactive marrow edema may obscure the lesion. MRI permitted a correct differential diagnosis in front of the other alterations with clinical symptoms similar to the ones of osteoid osteoma.

Methods and Materials: Thirteen patients were examined at 1.5 T 1-3 and 18-24 months after surgery. A sagittal spin-echo sequence ( T R , T E = 198/12 ms. 94 mm slices; 2562 matrix) was acquired before and every minute after intravenous injection of 0.2 mmol/kg Gd-DTPA (total, nine measurements). Percent enhancements of PTA-ACL, posterior cruciate ligament (PCL), and native patellar tendon (NPT) were calculated [1-5]. Results: At I - 3 months, the median enhancement of PTA-ACL was 197 at 1 min and 445 at 8 min, of PCL 30 and 151, of NPT 57 and 134. respectively, at 18-24 months, 21 and 159. 37 and 173, 11 and 104, respectively. At 18-24 months, the enhancement of PTA-ACL was reduced at both 1 and 8 min (P = 0.0003, Mann-Whitney), of NPT only at 1 min (P = 0.0003), while that of PCL did not change. We found a significant difference between PTA-ACL and PCL at I - 3 months at both I and 8 min (P = 0.0015), while at 18-24 months we did not. At both examinations. PTA-ACL and NPT enhancements were different (P < 0.0017). Conclusion: Early after surgery, PTA-ACL and NPT showed a strong enhancement. Later, PTA-ACL enhancement was reduced becoming similar to PCL, but higher than NPT, suggesting a neovascularization supporting the ligamentization of PTA-ACL.

References [1] [2] [3] [4] [5]

Howell SM, et al. Am J Sport Med 1995~23:42-48. Howell SM, Taylor MA. J Bone Jt Surg 1993:75A:1044-1055. Lane JG, et al. Arthroscopy 1993;9:149-153. McFarland EG. Orthopaedics 1993:16:403-410. Shino K, et al. Arthroscopy 1991;7:171-176.

Meniscal lesions of the knee: MR plain images and MR arthrography with saline solution or diluted paramagnetic contrast agent E. Rosso ~. R. Ferrando t, B. Guadagni t, F. Giacco2, L. Felli2, F. Sardanelli 1.

IDepartment of Diagnostic Imaging, 2Department of Orthopaedics. University of Genoa. Italy

Purpose: To compare MR plain images and arthrography with saline solution or diluted paramagnetic contrast agent. Subjects and Methods: Ten patients underwent 1.5 T examination: (1) plain images, SE Tlweighted images (TI-Wl) and gradient echo T*-WI: (2) T*-WI after a first intraarticular injection (saline solution, 10 ml); (3) T~-WI after a second injection (1:100. Gd-DTPA/saline solution). All sequences (coronal planes; 4 mm slices; matrix 256-': FOV 160 cm) were acquired with and without magnetization transfer (MT). The eight different sequences were qualitatively ranked by two readers, by consensus [1-4]. Results: Arthroscopy revealed seven meniscal tears and one meniscocapsular lesion: in two patients no meniscal lesion was arthroscopically detected. In a general way, MR examination showed the seven meniscal tears (four grade II and three grade III), three degenerative meniscal lesions (not detetected at arthroscopy), and the menisco-capsutar lesion. For meniseal tears, the best results were obtained with T*-WI with saline solution (non-MT better than MT), mean with T~-W1 with Gd (non-MT similar to MT), worse with plain images (non-MT better than MT). Conclusion: In evaluating meniscal tears, T.,*-Wl with intraarticular saline solution seem to be better than plain images and than TI-WI with Gd. Moreover MT seems to be not useful for detecting meniscal lesions.

References [1] [2] [3] [4]

Chandnani VP. et al. Radiology 1991;178:557-561. Gylys-Morin VM, et al. AJR 1992:148:1158-1 | 65. Vinemsen UF, et al. Radiology 1996;201(P):156. Wolff SD, et al. Radiology 1991;179:623-628.

The importance of MRI for the diagnosis of osteoid osteoma of the foot and for a correct surgical treatment M. Mastantuono. E. Bassetti, L. Di Giorgio, V. Vittiglio, F. Trenta, L. Francone, R. Passariello. Department of Radiology, H chair University "La

Sapienza" Rome

Purpose/Introduction: Diagnosis of intraarticular and cancellous lesion may be difficult with conventonal X-ray and CT due to absent or poor reactive osteosclerosis. The location of the lesions before surgery or other treatment methods is very important to avoid recurrence due to incomplete excision. We report our experience in dfflerential diagnosis with MRI of these kind of lesions.

Quantitative dynamic MR imaging in multiple myeloma Hans Hawighorst, Thomas M6hler, Heinz P. Schlemmer, Gerhard van Kaick.

Department of Radiology. German Cancer Research Center, INF 280, 69120 Heidelberg, and Department of Hematology and Ontology, Unit'ersity of Heidelberg, Germany Purpose: To evaluate if angiogenesis is increased in patients with multiple myeloma as estimated by quantitative, dynamic MR imaging and to assess the role of quantitative, dynamic MR imaging for lesion detection, characterization, and therapy monitoring of multiple myeloma. Methods: Pharmacokinetic parameters (amplitude A, exchange rate constant k20 were calculated from contrast-enhanced dynamic MR imaging series in 18 patients with biopsy-proven monoclonal gammopathy (MGUS) and multiple myetoma (MM) and compared with normal controls (n = 7). All MRI data were compared with various histomorphological and serum markers of tumor angiogenesis (e.g. microvessel density, expression of VEGF). In addition, in five patients serial quantitative, dynamic MR images were acquired prior and after anti-angiogenic treatment. Results: Quantitative evaluation of the dynamic MR parameters revealed a statistically significant (P < 0.01) 6.7-fold increase in the mean of parameter A as well as a 6.2-fold increase in the mean tissue exchange rate constant k21 in bone marrow lesions of patients with newly diagnosed MM as compared to normal controls. Patients with MGUS revealed a pattern in between MM and normal controls. Monitoring after antiangiogenie treatment (Tbalidomid) revealed a significant reduction or normalization in the pharmacokinetic parameters. Conclusion: We conclude from our preliminary results that quantitative, dynamic MR imaging may prove to be a new imaging modality to localize and to characterize patients with hematological disorders, Evidence suggest that tumor angiogenesis is increased in patients with MGUS and MM. Furthermore, antiangiogenic treatment may be proven to be a rational therapeutic strategy and can be monitored by quantitative, dynamic MR imaging.

Uncommon fnding of internal derangement of the temporomandibular joint: the posterior disk displacement with reduction J. Widelec 1'2, P. Peetrons 1. IDepartment of Medical Imaging, Centre Hospitalier MoliOre-Longchamp: 2Department of Medical Imaging, lnstitut J. Bordet, Centre des Tumeurs de I'ULB, Brussels, Belgium Purpose: To report three cases of the posterior disk displacement (PDD) with reduction in two patients suffering for internal derangement of the temporomandibular joint (TMJ) and to describe imaging criteria of PDD of the TMJ. Materials and Methods: Two patients underwent a bilateral MR study of the TMJs for internal derangement including coronal and sagittal acquisitions with a dedicated surface coil. Results and Conclusion: The first study demonstrated clearly a symptomatic anterior disk displacement without reduction on one side and a non symptomatic PDD on the other side. In the second patient both disks were posteriorly displaced but only one side was painful. In both these cases, the disk and its posterior band were located along the posterior border and the condyle. According to the normal 12 o'clock disk position [1], the diagnosis of PDD was made. The reduction occurred on the open-mouth position while the disk recovered its normal position between the top of the condyle and the articular eminence of the temporal bone. To our knowledge, the PDD is considered exceedingly rare [2,3]. Case reports and descriptions in textbooks have documented this finding. The estimated prevalence of PDD of the TMJ in our series is evaluated at 0.3%. PDD is indeed uncommon but can easily be recognized on MR studies. Moreover, like other TMJ disk displacements, the PDD can also be an incidental finding.

Posters: lnterventional

Re~rences [1] Drace JE, Enzmann D. Defining the normal temporo-mandibular joint: closed-, partially open-, and open-mouth MR imaging of asymptomatic subjects, Radiology 1990;177:67-71. [2] Westessou P-L, Katzberg RW. Temporomandibular joints, In: Som PM. Curtin HD, editors. Head and Neck Imaging, vol. 1, 3rd edn. St. Louis: Mosby. 1996, pp. 373-433. [3] Westesson P-L. Larheim TA, Tanaka H. Posterior disc displacement in the temporomandibular joint. J Oral Maxillofac Surg 1998;56:1266-1273.

Posters: Interventional ~-~

3D correction of image distortion for interventional M R I

v. Daanen. L. Nicol, G. Sergent, P. Bourel, F. Godart. C. Vasseur, J. Rousseau. General Hospital, Sciences UniversiU' and Siemens Medical Svs-

tenT. Lille, France

Introduction: In interventional MRI, the systems designed to help the surgeon during biopsy need the accurate knowledge of the positions of the target but also of the needle entry point on the skin of the patient, lr some cases, this needle entry point can be outside the Bo homogeneity area, or in the vicinity of this area, there where the distortions may be larger than few millimetres. perhaps centimetres. In that case a major correction of geometrical deformations has to be performed. MRI geometrical deformations have been well studied by many authors for a long time, but only inside the area of the main magnetic field homogeneity: distortions induced by fiducial markers used for stereotactic neurosurgery or field heterogeneity caused by susceptibility effects lbr example. The aim of this work is to study the needs of an image correction according to the position of the needle entry point. A fast method for 3D co-ordinates correction is also presented. The influence of some different parameters on the accuracy of the correction result is discussed. Materials and Methods: All experiments have been performed on a resistive 0.2 T OPEN (Siemens Medical Systems, Germany) specially designed for interventional MRI. We have used a parallel epipedie calibratior phantom (42 x 32 x 24 cm) which consists on seven parallel plans distant of 30 ram. Each plan contains 100 glass marbles (15 mm diameter) disposed as a regular 30 mm square pattern. The phantom is disposed inside the body coil in such a manner that the lateral side of the FOV, in front of a MR interventional operator, can be studied. Axial and coronal slices (matrix 256 • 256, FOV 250 x 250 ram, slice thick 7 mm) have been obtained using SE, TSE and Flash 2D sequences, with different acquisition parameters. An image processing (filtering, thresholding. barycenter determination ...) automatically extracts the 3D coordinates of the marbles in the images and associates them to their real 3D coordinates in order to obtain 3D distortion matrixes. Then, a correction algorithm, based on a linearity hypotheses, enables us to calculate the real 3D coordinates of any point in the images. We have evaluated the necessity of distortion correction and the effectiveness of the correction algorithm according to the conditions of image acquisition and according to the position in the FOV. Results: Results show that maximum geometrical distortion is lower than 2 mm inside a 300 mm diameter sphere, whatever the imaging sequence used: consequently, we consider that correction is not necessary in this area. Outside this region, the 3D correction algorithm have to be used and we obtain an accuracy in the order of 2 mm inside a 360 mm diameter sphere. For larger FOV. correction is not possible. Discussion and Conclusion: The methods, described in the literature, are often based on the identification of the deformation model using magnetic field distribution knowledge. Our method does not need complex computation but only hypotheses of distortion linearity and our algorithm is restricted to the calculation of 3D co-ordinate of a given point in the image. The magnitude of the observed distortions of the image in the external area of usual FOV's shows that these distortion obligatory have to be corrected in an interventional MR context, especially if the determination of accurate position of the entry point of biopsy needle is needed.

~'~

MR-guided catheter tracking: assessment of passive visualisation in an open low-field system

F. Wacker l, K. Reither I, M. Wendt 2, K.-J. Wolf I. 1Department of Radiology, Benjamin Franklin Hospital, Free University, Berlin, Germany; -'Case Western Reserve University, Cleveland, Ohio, USA

Purpose: Magnetic resonance imaging (MRI) offers many potential advantages over conventional X-ray techniques for guiding and monitoring interventions.

153

The purpose of this study was to demonstrate the feasibility of passive visualisation techniques to perform MRl-guided vascular interventions in an animal model using an open magnet system. Subjects and Method: All animal experiments (n = 4) were performed in a 0.2 Tesla open whole body MR-scanner (Magnetom OPEN, Siemens, Erlangen) under general anaesthesia. Prior to the MR-guided interventions a contrastenhanced MRA was performed. Based on the 3D-MRA data set, the catheter positioning was performed using a single-slice true FISP sequence with a frame rate of 1.3 s. Susceptibility-based prototype catheters and guidewires (Somatex, Germany) were introduced in the aorta and selectively advanced in the splenic and renal arteries under MR-guidance. Results: The catheters were advanced in the aorta and introduced in the renal and splenic arteries under MRI-guidance without complications. The visualisation of the catheters was easy and reliable in the aorta and in the proximal parts of the renal and splenic arteries. In the distal parts of these vessels the visualisation was difficult due to complex anatomy and to a relatively low contrast to the surrounding structures. The use of three slices allowed a better catheter tracking in complex anatomical structures. Conclusion: Passive catheter tracking may be a valuable and technically robust alternative to active tracking methods which requires no additional MR hardware and can be implemented in any open MR system. It may be especially helpful for specific applications like tumor-embolisation or TIPS. where tomography combined with angiography and MR catheter tracking could be essential.

A s s e s s m e n t of image artifacts of an MR-compatible carbon

fiber cannula J.R. Reicbenbach, S. Wurdinger, S. Pfleiderer, W.A. Kaiser. Institute of Diag-

nostic and Intert'entional Radioh~gy. Friedrich-Sehiller University Jena. Germany

Purpose/Introduction: Minimally invasive interventional and surgical techniques under MRI guidance have rapidly evolved during the last few years. Susceptibility effects associated with the instruments can cause position errors and signal cancellation. Carbon fibre composites represent an attractive biomedical material for use in interventional MRI because of the low density, high strength and stiffness. The magnetic susceptibility is close to that of water although the exact value depends on details of geometry and fabrication. Another advantage is the reduced electrical conductivity compared to devices containing bulk metal. The aim of this study was to assess susceptibility artifacts of novel coaxial, carbon fibre based cannulas and a conventional. MR-compatible biopsy needle using different MR sequences. Subjects and Methods: A non-ferromagnetic, 14-G titanium alloy puncture needle trocar (C.R. Bard. Germany) and two novel carbon fibre coaxial cannulas (C.R. Bard, NJ, USA) with diameters of 18 G and 14 G were used for phantom studies. The whole assembly of the new sets consists of a two-part puncture needle trocar with a carbon composite outer sheath and an inner metallic needle. For the experiments only the cannula was used with the inner needle styles removed. Imaging was performed on a 1.5 T MR scanner (Gyroscan ACS II, Philips Medical Systems. Best, NL) using a linearly polarized receive-only head coil. The phantom consisted of a bowl of margarine fixed within a special breast biopsy frame. The cannulas were placed parallel to each other within the same imaging plane and perpendicular to the static field. The experiments were performed with 2D, spin echo (SE), fast spin echo (FSE) and if-spoiled gradient-echo (FFE) sequences. Images were acquired with the readout direction parallel and perpendicular to the main field (FOV 200 mm, matrix 256, BW/pixel 250 Hz). SE images were acquired with TR/TE/TH 130/16/3. NEX I. Parameters of the FSE sequence were TR/TE/ TH 4000/300/3, ETL 35. EST 16.7, NEX 2. For the FFE sequence the parameters were: TR/TE/x,'TH 50/8/30/3. Symmetric echo sampling was performed and full k-space was acquired. To estimate the size of the signal voids for different cannulas, intensity profiles across the cylinder shafts were calculated using coronal images with the readout direction parallel and perpendicular to the needles. Results: The carbon fibers produced much smaller artifacts compared to the conventional titanium alloy coaxial cannula for all MR sequences. The gradient echo sequence yielded larger artifacts compared to the spin-echo and fast spin echo sequences independent of the direction of the readout gradient. No distinct image differences between the SE and FSE sequences were observed. however, the artifacts are dependent on the readout gradient orientation. Discussion/Conclusion: We have shown that carbon fibre cannulas produce smaller artifacts and signal cancellations compared to a conventional, MRcompatible, non-ferromagnetic coaxial system. The size of the artifacts is strongly dependent on the particular MR sequence used. Carbon fibre composites are promising materials for the design and construction of MR-compatible instruments and devices, especially in the field of MR-guided interventional procedures. This may have important implications for further optimization at various fields, although the final challenge for finding the optimal trade-off between safety aspects, effectiveness, machinability, and cost-effectiveness will certainly continue into the near future.