ª Springer Science+Business Media, LLC 2012
Abdom Imaging (2012) DOI: 10.1007/s00261-012-9858-6
Abdominal Imaging
Chronic diverticulitis vs. colorectal cancer: findings on CT colonography Stefaan Gryspeerdt, Philippe Lefere Virtual Colonoscopy Teaching Centre, Akkerstraat 32 c, 8830 Hooglede, Belgium
Abstract Purpose: The purpose of this update article is to evaluate findings on CT colonography in patients with chronic diverticulitis and to compare the findings in patients with colorectal carcinoma. Materials and methods: Different morphological criteria retrieved from a literature review were retrospectively analyzed in a series of 13 patients with proven chronic diverticulitis. The findings were compared with a series of 10 patients with colorectal carcinoma. Results: Overall, the findings in chronic diverticulitis resemble the findings in acute diverticulitis. The advantage of virtual CT colonography in differentiating both entities relies in the combination of morphological features previously described on axial computed tomography and double contrast barium enema. The single strongest morphological feature pointing towards the diagnosis of chronic diverticulitis is the presence of diverticula in the affected segment. In the presence of diverticula in the affected segment, a long segment (‡10 cm), thick fascia sign without adenopathies, mild bowel wall thickening, tapered margins, and distorted but preserved mucosal folds are likely to further improve accuracy of diagnosing chronic diverticulitis. Conclusion: The single strongest morphological sign to differentiate chronic diverticulitis from colorectal cancer is the presence of diverticula in the affected segment. Key words: Diverticulitis—Chronic—Tumor—Colon— Virtual CT colonoscopy In Western countries the presence of diverticular disease has increased over the past century. The prevalence of diverticulosis is similar in man and woman, increasing with age ranging from approximately 10% in adults
Correspondence to: Stefaan Gryspeerdt; email: stefaan.gryspeerdt@ skynet.be
younger than 40 years of age to 50–70% among those 80 years of age or older [1–7]. The terms diverticulosis and diverticular disease are used to describe the presence of an uninflamed diverticulum. Diverticulitis indicates inflammation of the diverticulum, accompanied by gross and microscopic perforation. It is a common condition with an estimated incidence of 25%. Of those patients who experience an attack of diverticulitis one-third will have recurrent symptoms and another third will have a subsequent episode [8–10]. The inflammatory changes and associated fibrosis cause distortion of the bowel wall. Abdominal CT has been shown to reveal wall thickening and pericolic inflammatory stranding and associated inflammatory collections or abscesses in patients with colonic diverticulosis associated with one or more episodes of diverticulitis [11]. The main difficulty in the diagnosis of diverticulitis, being it acute, recurrent or chronic, is to exclude the possibility of colon cancer: both diseases are endemic in the aged population and results of previous studies have indicated that there is an overlap in the CT appearance between acute diverticulitis and colorectal cancer. Even the combination of findings results frequently in unequivocal differentiation between acute diverticulitis and tumor [12–19]. To our knowledge there has been only one limited report describing chronic diverticulitis on CT [20] and double contrast barium, with no report describing the appearances of chronic diverticulitis on virtual CT colonography. It is the purpose of this article to review and determine CT signs helpful in differentiating between chronic diverticulitis and colon cancer.
Materials and methods In the first part a review of the literature was performed to identify different signs of diverticulosis/diverticulitis, possibly useful to differentiate chronic or recurrent diverticulitis from colorectal cancer.
S. Gryspeerdt, P. Lefere: Chronic diverticulitis vs. colorectal cancer
Patients In the second part of the study we retrospectively reviewed the reports of virtual CT colonography studies sent for review to a tele-radiology site in Hooglede, Belgium, between 2008 and 2010. All examinations were interpreted and reported in consensus by two radiologists with an experience of >5000 CTC (S.G. and P.L.). Based on these reports, studies that showed imaging findings compatible with chronic diverticulitis, sigmoidal cancer or studies that concluded equivocal findings of chronic diverticulitis or sigmoidal cancer were retrieved. The medical data of these patients were retrospectively evaluated and final diagnosis of chronic diverticular disease as well as the exclusion or presence of colon cancer was considered confirmed by means of the following: clinical course and ultimate clinical outcome in the patient at medical chart review performed at least 2 years after virtual CT colonography, colonoscopy, and biopsy, or surgery.
CT scanning All patients underwent a colonic preparation consisting of a low residue diet, cathartic colon cleansing, and fecal tagging with barium and iodine. After smooth muscle relaxation with buthylscopalamine (Buscopan, BoehringerIngelheim, Paris, France) colonic insufflation was obtained with an automated carbon dioxide insufflator (PROTOC02L, E-Z-EM, Princeton, USA). Data were obtained with patients in the supine and prone positions. All examinations were performed with multidetector-row CT scanners that had a minimum of four rows.
Review of images Data of eligible patients were reloaded on a dedicated workstation (Vitrea, version 6.0, Vital Images, Plymouth, MN). All images were reviewed for radiographic imaging findings identified on the basis of literature review. Axial, coronal, and sagittal images, as well as tissue transition projection (TTP) images were used.
Results
fascia sign [18], lymph nodes and lymph nodes size [16], wall thickness and pattern of thickening (luminal mass [19], concentric wall thickening or eccentric wall thickening [17]), morphology of the margins (tapered or coneshaped vs. abrupt with shoulder forming) [20], morphology of the mucosal folds (distorted but preserved or distorted) [20], intestinal obstruction [20]. Pathology typically associated with chronic recurrent diverticular disease: mucosal prolapse syndrome and inflammatory polyps [21]. The degree and patterns of contrast enhancement (target sign or halo sign, homogeneous, heterogeneous [22]), as well as visualization of engorged mesenteric veins [17] have also been described as differentiators between colonic diverticulitis and colon cancer but were not withhold for this study since no contrast was administered in any of the virtual CT colonography examinations. Signs typically found in the setting of acute diverticulitis were not withhold for analysis because our purpose was the evaluation of signs present in chronic/recurrent diverticulitis, and, more importantly, in the setting of virtual CT colonography, none of the patients presented with acute abdominal pain or tenderness suggestive for acute diverticulitis. Therefore, the following signs were not tabulated for evaluation: free fluid, free air, abscesses, fistulae. All these signs are typically seen in the setting of acute diverticulitis [18–20].
Patients Based on retrospective analysis of the reports that showed imaging findings compatible with chronic diverticulitis, sigmoidal cancer or studies that concluded equivocal findings of chronic diverticulitis or sigmoidal cancer, we were able to retrospectively withhold a confirmed diagnosis of tumor or chronic diverticular disease in 23 patients. Based on medical data, clinical course, and ultimate clinical outcome a confirmed diagnosis of chronic diverticulitis was found in 13 patients: exclusion of colon cancer by negative clinical follow-up during at least 2 years in 5 patients, biopsy showing chronic inflammatory disease in another 5 patients. Chronic diverticulitis was diagnosed in 3 patients at surgery. In 10 patients final diagnosis of colorectal cancer was established at surgery.
Review of literature
Analysis of CT findings
Review of the literature revealed following signs possibly helpful in differentiating chronic diverticulitis from colorectal cancer on virtual CT colonography: involved length [16], presence or absence of diverticula (normal or inflamed, with or without arrowhead sign in the affected segment [17, 18]), degree of luminal narrowing [19], pericolic infiltration [17] (grouping imaging features described as stranding and pericolic edema [16]), thick
The prevalence of the findings studied is shown in Tables 1 and 2 for patients with final diagnosis of chronic diverticulitis and carcinoma, respectively. Calculated sensitivity, specificity, positive predictive value, negative predictive value, and accuracy are detailed in Table 3. Although the series are definitely too small to get enough statistic power (reflected in a wide range of lower
S. Gryspeerdt, P. Lefere: Chronic diverticulitis vs. colorectal cancer
Table 1. Prevalance of findings on virtual CT colonography in patients with chronic diverticulitis Chronic diverticulitis
1
2
3
4
5
6
7
Length (mm) Diverticula in affected segment Luminal narrowing (mm) Pericolic infiltration Thick fascia sign Lymph nodes (if present max. size mm) Bowel wall thickening (mm) Luminal mass Concentric wall thickening Eccentric wall thickening Tapered margins Overhanging edge—shoulder forming Distorted but preserved mucosal folds Distorted mucosal folds Mucosal prolapse Inflammatory polyp
70 x Complete x x 10 22
58 x Complete x x 6 17
80 x 7 x x
70 x Complete x x
90 x complete x x 6 10
270 x 13 x x
36 230 x 10 8 x x 8 14 9
17 10
x
x
x x
x x
x x x
x
9
10
11
60 107 250 x x x Complete 23 10 x x x 6 13 8 7 x
x
x
x
10
8
x x
x
x x
x x
x
x
x
x x
12 13 Av/% 91 x 5 x x
59 x 9 x x
15 6 x
x
x
x x
x
x
x
x
x
x
x
113 mm 92% 85% 77% 12 mm 30% 41% 41% 67% 38% 85% 23%
x x
Av average
Table 2. Prevalance of findings on virtual CT colonography in patients with colorectal cancer Cancer
1
2
3
4
5
6
7
8
9
10
Av/%
Length (mm) Diverticula in affected segment Luminal narrowing (mm) Pericolic infiltration Thick fascia sign Lymph nodes (if present max. size mm) Bowel wall thickening (mm) Luminal mass Concentric wall thickening Eccentric wall thickening Tapered margins Overhanging edge—shoulder forming Distorted but preserved mucosal folds Distorted mucosal folds
45
89
18
32
28
39
27
40
25
5
34 mm 0%
12
7 x
17
Complete x
3 x
Complete x
19
26 x
Complete x
8 17
16
Complete x x 8 8
13
22 x
7 27
8 23
x
x
x
10 22
6 14
9 x
x x x x
x
x x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
60% 10% 17 mm 20% 50% 40% 10% 90% 0% 100%
Av average
and upper limits, tabulated in Table 3), we were able to retrieve some clear tendencies (Figs. 1, 2, 3, 4). Single morphological features. When we evaluate single morphological signs, a single strong discriminator was the presence or absence of diverticula in the affected segment. Presence of diverticula in the involved segment was found in all but one (92%) patients in the group of chronic diverticulitis whereas diverticula in the involved segment were found in none of the patients with final diagnosis of colon carcinoma. Presence of diverticula in the affected segment showed 92% sensitivity, 100% specificity, 100% positive predictive value, 91% negative predictive value, and 96% accuracy for chronic diverticulitis. The series evaluated is, however, small, resulting in a relative wide range of lower limits (Table 3).
Other morphological criteria None of the tumors showed preserved mucosal folds; whereas mucosal folds were judged preserved in 76% of cases with chronic diverticulitis.
Chronic diverticulitis tended to be longer compared to tumor: the mean length for chronic diverticulitis was 11 cm, compared to 3.4 cm for tumors. When we arbitrarily divided groups in lesions ‡10 cm and <10 cm, a 100% specificity for chronic diverticulitis is obtained for lesions ‡10 cm. Complete luminal narrowing on virtual CT colonography was found in 40% of patients for both groups. Pericolic infiltration was indicative for chronic diverticulitis rather than tumor, being present in 85% of patients with chronic diverticulitis, compared to 60% in the group of patients with tumoral disease. Thick fascia sign was found to be a strong discriminator, being present in 77% of patients with chronic diverticulitis compared to only 10% of patients with tumoral disease. Lymph nodes with variable diameter ranging from 2 to 10 mm were found in 38% of patients with chronic diverticulitis, whereas larger lymph nodes with variable diameter ranging from 7 to 10 mm were found in 60% of patients with tumoral disease. Bowel wall thickening was more pronounced in the group with tumoral disease (mean 17 mm) compared to
S. Gryspeerdt, P. Lefere: Chronic diverticulitis vs. colorectal cancer
Table 3. Statistical analysis of findings on virtual CT colonography for chronic diverticulitis and colon cancer Sensitivity
Chronic diverticulitis Length (>10 cm) Diverticula in affected segment Luminal narrowing (complete) Pericolic infiltration Thick fascia sign Lymph nodes absent Bowel wall thickening (<2 cm) Luminal mass Concentric wall thickening Eccentric wall thickening Tapered margins Distorted but preserved mucosal folds Cancer Length (<10 cm) No diverticula in affected segment Luminal narrowing (incomplete) No pericolic infiltration No thick fascia sign Lymph nodes present Bowel wall thickening(>2 cm) Luminal mass Concentric wall thickening Eccentric wall thickening Overhanging edge—shoulder forming Distorted mucosal folds
Specificity
LL
UL
0.31 0.92 0.38 0.85 0.85 0.62 0.92 0.08 0.38 0.46 0.62 0.77
0.09 0.64 0.14 0.55 0.55 0.32 0.64 0.00 0.14 0.19 0.32 0.46
0.61 1.00 0.68 0.98 0.98 0.86 1.00 0.36 0.68 0.75 0.86 0.95
1.00 1.00 0.60 0.60 0.90 0.60 0.40 0.20 0.50 0.40 0.90 1.00
0.69 0.69 0.26 0.26 0.55 0.26 0.12 0.03 0.19 0.12 0.55 0.69
1.00 1.00 0.88 0.88 1.00 0.88 0.74 0.56 0.81 0.74 1.00 1.00
PPV
LL
UL
1.00 1.00 0.60 0.30 0.90 0.60 0.40 0.80 0.50 0.60 0.90 1.00
0.69 0.69 0.26 0.07 0.55 0.26 0.12 0.44 0.19 0.26 0.55 0.69
1.00 1.00 0.88 0.65 1.00 0.88 0.74 0.97 0.81 0.88 1.00 1.00
0.31 0.92 0.38 0.38 0.85 0.62 0.92 0.92 0.62 0.54 0.62 0.77
0.09 0.64 0.14 0.14 0.55 0.32 0.64 0.64 0.32 0.25 0.32 0.46
0.61 1.00 0.68 0.68 0.98 0.86 1.00 1.00 0.86 0.81 0.86 0.95
NPV LL
UL
1.00 1.00 0.56 0.61 0.92 0.67 0.67 0.33 0.50 0.60 0.89 1.00
0.40 0.74 0.21 0.36 0.62 0.35 0.41 0.01 0.19 0.26 0.52 0.69
1.00 1.00 0.86 0.83 1.00 0.90 0.87 0.91 0.81 0.88 1.00 1.00
0.53 0.91 0.43 0.43 0.82 0.55 0.80 0.67 0.50 0.40 0.64 0.77
0.29 0.59 0.18 0.18 0.48 0.23 0.28 0.09 0.19 0.12 0.35 0.46
0.76 1.00 0.71 0.71 0.98 0.83 0.99 0.99 0.81 0.74 0.87 0.95
Accuracy LL
UL
0.53 0.91 0.43 0.60 0.82 0.55 0.80 0.40 0.38 0.46 0.64 0.77
0.29 0.59 0.18 0.15 0.48 0.23 0.28 0.19 0.14 0.19 0.35 0.46
0.76 1.00 0.71 0.95 0.98 0.83 0.99 0.64 0.68 0.75 0.87 0.95
1.00 1.00 0.56 0.56 0.92 0.67 0.67 0.60 0.62 0.54 0.89 1.00
0.40 0.74 0.21 0.21 0.62 0.35 0.41 0.36 0.32 0.25 0.52 0.69
1.00 1.00 0.86 0.86 1.00 0.90 0.87 0.81 0.86 0.81 1.00 1.00
LL
UL
0.61 0.96 0.48 0.61 0.87 0.61 0.70 0.39 0.43 0.52 0.74 0.87
0.39 0.78 0.27 0.39 0.66 0.39 0.47 0.20 0.23 0.31 0.52 0.66
0.80 1.00 0.69 0.80 0.97 0.80 0.87 0.61 0.66 0.73 0.90 0.97
0.61 0.96 0.48 0.48 0.87 0.61 0.70 0.61 0.57 0.48 0.74 0.87
0.39 0.78 0.27 0.27 0.66 0.39 0.47 0.39 0.34 0.27 0.52 0.66
0.80 1.00 0.69 0.69 0.97 0.80 0.87 0.80 0.77 0.69 0.90 0.97
Clopper–Pearson exact 95% confidence interval for a proportion (based on binomial distribution) LL lower limit, UL upper limit, PPV positive predictive value, NPV negative predictive value
the group with chronic diverticulitis (mean 12 mm). Bowel wall thickening of more than 2 cm was found in 30% of tumoral lesions compared to only 0.1% in the group with chronic diverticulitis. Eccentric wall thickening and tapered margins were present in, respectively, 46% and 67% patients with chronic diverticulitis vs. 40% and 0% in patients with tumoral disease. Overhanging edges or shoulder formation was found in all but 2 patients with tumoral disease (90%) (identified mainly on the basis of TTP images), and in only 38% of patients with chronic diverticulitis. Interestingly, we did not find signs of obstruction in any patient at time of virtual CT colonography. Finally, pseudopolypoid images (caused by mucosal prolapse) and inflammatory polyp were both found in a single different patient with final diagnosis of chronic diverticular disease. Combined morphological signs. The number of subjects was too low to perform multivariable analyses. Indeed, a minimum of 10 subjects in the least occurring category per independent variable has been recommended [23]. Inclusion of too many predictors leads to overfitting of the data. Indeed, in a smaller series a perfect diagnostic accuracy can often be obtained combining different findings. In this study, an excellent accuracy (96%) was observed
with a single finding, i.e., ‘diverticula in affected segment’. To obtain such high accuracy level in a larger series, adding information from other findings could be required. The results indicate findings which are candidates as additional predictors. Following findings showed an accuracy >70%: presence or absence of thick fascia sign and evaluation of the mucosal folds (preserved or distorted). Other findings showed an accuracy >50%: evaluation of the length of the affected segment (< or ‡10 cm), presence or absence of adenopathies, bowel wall thickening (< or ‡2 cm), margins of the lesions (tapered or shoulder forming.
Discussion Diverticular disease and colorectal neoplasia share similar epidemiological features and risk factors. An increased risk for sigmoid location of tumors in patients with diverticula as compared to comparable groups has been reported. Similarly, the prevalence of advanced adenomas in the sigmoid colon has been reported as well as the association of diverticulosis with colorectal neoplasia. A common explanation for the similar development of diverticulosis and colorectal neoplasia is related to the slow colonic transit time for both conditions.
S. Gryspeerdt, P. Lefere: Chronic diverticulitis vs. colorectal cancer
Fig. 1. Typical chronic diverticulitis: axial CT images. Axial CT images show a long segment with tapered margins (arrow in A), distorted but preserved folds (arrows in B), the thick
Fig. 2. Typical chronic diverticulitis: TTP image shows a long segment with distorted but preserved mucosal folds (arrows).
Furthermore, there is the possibility that patients with a prior history of diverticulitis have a higher risk of colorectal carcinoma because of the chronic inflammation in the mucosa contributing to carcinogenesis [24–26].
fascia sign (arrow in C), and the presence of diverticula in the affected segment (arrow in D).
Although elective sigmoid resection is frequently recommended after the two episodes of uncomplicated diverticulitis because of the serious complications of recurrent colonic diverticulitis many authors have also shown that symptomatic patients, responding well to medical treatment for uncomplicated diverticulitis, would be expected to do well without elective colectomy [8, 27, 28]. Since virtual CT colonography has gained acceptance as possible examination tool for screening the patient at average risk for colorectal cancer and diverticular disease and colorectal neoplasia share similar epidemiological features and risk factors, differentiating chronic or recurrent diverticulitis from tumoral disease is likely to become more and more important. There have been several studies describing the CT features of diverticulitis and colon cancer. Many of the studies described overlapping CT features of those two diseases. Review of the literature shows that significant points of overlap include wall thickening, associated soft tissue masses, and luminal narrowing [12–14].
S. Gryspeerdt, P. Lefere: Chronic diverticulitis vs. colorectal cancer
Fig. 3. Typical tumor. A Typical axial image shows a short segment with pronounced wall thickening, shoulder forming, and no in-lying diverticula (arrows). B Virtual double contrast
Fig. 4. Usefulness of detecting in-lying diverticula for diagnosing chronic diverticulitis. A TTP image shows short 3.6 cm segment with preserved mucosal folds but shoulder forming at the proximal margin. Unequivocal findings: preserved folds are indicative for chronic diverticulitis but short segment with shoulder forming indicates tumor. B Axial image demonstrates in-lying diverticula, one with presence of hyperdense fecalith (f), indicating chronic diverticulitis (arrows). Additional finding: thick fascia sign, also suggestive for chronic diverticulitis (arrowhead).
barium enema images show short segment with shoulder forming and distorted mucosal folds (arrows).
Chintapalli [15] found that in case the length of the involved segment is more than 10 cm in the presence of pericolonic stranding with no colonic lymph nodes adjacent to the segment, the most likely diagnosis is diverticulitis. In case pericolonic lymph nodes are present, most likely diagnosis was reported to be colon cancer [14]. Our series confirmed that a long affected segment (‡10 cm) is more likely to be found in chronic diverticulitis. We found a tendency of pericolic infiltration suggesting chronic diverticulitis but could not find a tendency of lymph nodes pointing towards diagnosis of tumoral disease. The latter can probably be explained by the nature of chronic diverticulitis: chronic disease is likely to cause more adenopathies, detected by CT, compared to acute diverticulitis. The finding of shoulder forming being suggestive for tumoral disease in our series is also in concordance with results published by Chintapalli [16]. Kircher [18] reported pericolic infiltration (fat stranding) to be found in 95% of patients with diverticulitis, and thick fascia sign in 50% of patients. Comparably, we found pericolic infiltration or thick fascia sign to be present in 75% of cases. To our knowledge only one study reported upon radiographic findings in case of chronic diverticulitis [20]. In that study barium enema examinations were reported to reveal a relatively long segment of circumferential narrowing in the sigmoid colon with spiculated contour and tapered margins. CT revealed findings of sigmoid diverticulitis with localized wall thickening and pericolic fat stranding in 90% of the patients in whom CT was performed; CT revealed inflammatory collections in three and fistulas in another 3 patients.
S. Gryspeerdt, P. Lefere: Chronic diverticulitis vs. colorectal cancer
Findings suggestive of chronic diverticulitis.
1. 2. 3. 4. 5. 6. 7. 8.
Fig. 5.
Wall thickening (milder). Long segment (> 10 cm). Tapered margins. Distorted but preserved folds. Pericolonic infiltration. No pericolonic adenopathies. Thick fascia sign . Diverticula adjacent to and in the affected segment.
Findings suggestive of maligant tumor.
1. 2. 3. 4. 5. 6. 7. 8.
Wall thickening ++ (> 2 cm). Short segment . Shoulder forming. Distorted folds. No pericolonic infiltration. Pericolonic adenopathies. No thick fascia sign . Diverticula adjacent to but NOT IN the affected segment.
Differential diagnosis between chronic diverticulitis and adenocarcinoma.
The authors concluded that the CT findings in patients with chronic diverticulitis are similar to those in patients with acute diverticulitis.
Our study confirmed that, based on axial imaging only, the findings are in line with findings in patients presenting with acute diverticulitis.
S. Gryspeerdt, P. Lefere: Chronic diverticulitis vs. colorectal cancer
Using TTP images obtained at virtual CT colonography, our study confirmed that tapered margins and presence of markedly separate spiculated folds without distortion point towards the diagnosis of chronic diverticulitis. Obstruction has been reported in acute diverticulitis, tumor as well as chronic diverticulitis [18, 20]. In our series, however, none of the patients presented with signs of obstruction. The explanation for this is a patient selection bias residing in the fact that we examined a cohort of patients examined with virtual CT colonography, a recent technique not eligible to evaluate patients with acute abdominal symptoms. The most important discriminator to differentiate between chronic diverticulitis and tumoral disease, however, was the finding that in our small series the presence of diverticula in the affected segment clearly points towards the diagnosis of benign disease rather than tumoral pathology. This finding was previously described by Shenet al. [17]. It is important to note that diverticula in close relation with the affected segment were found in both groups, (more precisely in 3 patients with chronic diverticulitis and 2 with tumoral disease), a finding also reported by Shen et al. In line with the findings of other authors [16–18] we also found long segments being indicative for chronic diverticulitis, short segments being indicative for tumoral disease. However, the high sensitivity for tumoral disease using cut-off of 10 cm in this series is surprising and to be attributed to the small number of tumors, e.g., by chance. Although our series is too small for multivariate analysis, we can theoretically evaluate our results and look for signs with accuracy >50% for both tumor and chronic diverticulosis. In this way it is reasonable to expect that evaluation of the length of the affected segment, presence or absence of thick fascia signor adenopathies, bowel wall thickening, margins of the lesions, and evaluation of mucosal folds further enhance the diagnostic capability of presence or absence of diverticula in the affected segment. Especially, evaluation of thick fascia sign and morphology of the mucosal folds are promising candidates as additional predictors. Bringing together all signs, it seems reasonable to theoretically conclude that, in the presence of diverticula in the affected segment, a long segment (‡10 cm), thick fascia sign without adenopathies, mild bowel wall thickening, tapered margins, and distorted but preserved mucosal folds are likely to improve accuracy of diagnosing chronic diverticulitis. In the absence of diverticula, a short segment (<10 cm), absence of thick fascia sign, presence of diverticula, pronounced bowel wall thickening (>2 cm), shoulder forming, and distorted mucosal folds are likely to improve the accuracy of diagnosing tumor (Fig. 5) A combination of all these findings and multivariate analysis would be worthy to be investigated in larger series.
The use of combined findings of presence or absence of lymph nodes, pericolonic inflammation and edema were comparably found in the study by Chintapalli [15, 16]. This study has several serious limitations. First of all this is a retrospective study with inherent selection bias as well as well as interpretation bias. The small number of patients included in the series does not give the results enough statistical power. Therefore, we can only conclude for tendencies. Furthermore, final diagnosis of chronic diverticulitis is based on the mixture of clinical as well as pathological basis. Therefore, we cannot exclude the presence of small slow-growing tumoral foci in what clinically appears to be chronic diverticulitis. However, our findings are consistent with previously reported series and show that the strength of virtual CT colonography in differentiating chronic diverticulitis from tumoral disease relies in the combination of findings previously reported on axial computer tomography as well as those reported on barium enema studies. The single strongest morphological feature pointing towards the diagnosis of chronic diverticulitis is the presence of diverticula in the affected segment. In the presence of diverticula in the affected segment, a long segment (‡10 cm), thick fascia sign without adenopathies, mild bowel wall thickening (<2 cm), tapered margins, and distorted but preserved mucosal folds are likely to further improve accuracy of diagnosing chronic diverticulitis. Acknowledgments. The authors acknowledge the following colleagues for their help with clinical follow-up of the patients: Leroux K, MD Radiology Department, Ziekenhuis Maas en Kempen, B-3680 Maaseik, Belgium; Ardies Ph, MD Radiology Department, AZ Sint-Jozef, B2390 Malle, Belgium, Clybauw A, MD Radiology Department, AZ Maria Middelares, B-9050 Gentbrugge, Belgium; Grignard F, MD Radiology Department, Sint-Elizabeth Ziekenhuis, B-9620 Zottegem, Belgium; Louagie A, MD Radiology Department, AZL Algemeen Ziekenhuis Lokeren, B-9160 Lokeren, Belgium; Perdieus D, MD Radiology Department, Imelda Ziekenhuis, B-2820 Bonheiden, Belgium; and Sieleghem D, MD Radiology Department, AZ Sint Blazius, B-9200 Dendermonde, Belgium. The authors also acknowledge Fieuws S, Ir, Biostatistical Centre, Katholieke Universiteit Leuven, Kapucijnenvoer 35, B-3000 Leuven, Belgium for advice with statistical analysis.
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S. Gryspeerdt, P. Lefere: Chronic diverticulitis vs. colorectal cancer
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