Sigmoid Stenosis caused by diverticulitis versus carcinoma: Can they be differentiated by ultrasound?

Transcription

1 Sigmoid Stenosis caused by diverticulitis versus carcinoma: Can they be differentiated by ultrasound? T Ripollés, MD; MJ Martínez, MD; C Fernández, MD; J Vizuete, MD; D Gómez, MD; G Martín, MD. Department of Radiology, Hospital Universitario Dr Peset, Valencia, Spain.

2 INTRODUCTION Colonoscopy is warranted in every patient with diverticulitis subjected to conservative management to exclude carcinoma. The differentiation of these two entities is crucial for appropriate clinical management especially in the emergency setting, where it is not possible to perform colonoscopy or CT-colonography to exclude carcinoma until inflammatory changes have subsided.

3 PURPOSE To evaluate the usefulness of ultrasound as the initial diagnostic method for differentiating diverticulitis from colon cancer in patients with sigmoid colon stenosis.

4 MATERIAL & METHODS Retrospective analysis Period: February 2006 to January 2013 Review of the reports of the Radiology Department with diagnosis of sigmoid stenosis by CT, barium enema, colonoscopy or ultrasonography. We included patients with chronic, acute or recurrent diverticulitis, sigmoid cancer or equivocal findings of these entities. Imaging techniques evaluated: Ultrasound and CT Scan 52 patients with sigmoid stenosis had a confirmed diagnosis of tumor or diverticular disease

5 MATERIAL & METHODS Morphological ultrasound criteria were retrieved from the literature review to differentiate between inflammatory versus tumoral stenosis of colon. Off-site, two radiologists reviewed each ultrasound criteria in all patients. Length and thickness of the affected segment Concentric or eccentric wall thickening Internal wall layered preserved or no Morphology of the margins (tapered or abrupt) Preserved or distorted mucosal folds Thickening of muscular layer Presence of diverticula in the affected segment Presence of regional lymph nodes Pericolonic stranding fat Collection or fistula presence

6 MATERIAL & METHODS Based in these criteria the stenosis were classified by each reader, who were unaware of the diagnosis, as benign, malignant or indeterminate (with equivocal findings). Benign criteria included: Bowel wall thickening < 15 mm Length > 10 cm Concentric wall thickening Preserved mucosal folds Tapered margins Thickened muscular wall layer Preserved internal layers Diverticula in affected segment Malignant criteria included: Bowel wall thickening > 15 mm Length < 10 cm Eccentric wall thickening Distorted mucosal folds Overhanging edge Loss of layered wall Regional lymph nodes Absence of diverticula

7 Bowel wall thickening (< or > 15mm) A The maximum measurement of the wall was calculated in the stenotic segment. In A was 30 mm and 12 mm in B. A sigmoid carcinoma was proved with surgery in both cases. B 12 mm

8 Length of involved segment (> or < 10 cm) F Acute diverticulitis. US scan demonstrates a long segment (14 cm) of sigmoid colon with thickened walls and multiple diverticula. Inflammatory changes are seen in the pericolonic fat (F). A B Annular scirrhous carcinoma. A short sigmoid segment with pronounced stenosis. White arrows in US image (A) shows an abrupt stenosis with loss of layers. Corresponding CT scan (B) depicts an intraluminal foreign body in the stenosis (black arrow).

9 Eccentric or concentric wall thickening A B Axial US scan of the sigmoid colon. A) Typical eccentric wall thickening secondary to tumour. B) Symmetric thickening of the sigmoid wall caused by diverticular disease. The arrows point to the hyperechoic intestinal lumen.

10 Morphology of the margins Tapered Abrupt US image shows a segment with tapered margins (white arrows) and preserved layers. Diverticula (yellow arrow). Typical US longitudinal study of a tumor, with wall thickening and abrupt margins (arrows).

11 Thickening of muscular layer F ii F A B F ii Longitudinal (A) and axial (B) US views of a stenotic sigmoid colon shows prominent muscular layer (arrows) and preserved internal layers (ii). Inflammatory pericolonic fat (F) is demonstrated. US diagnosis was benign process. Pathological specimen (C) demonstrated the thickened muscular layer (arrows) and proliferative fat (F) in chronic diverticulitis with inflammatory changes.

12 Layered wall: preserved or loss * A A. Longitudinal US view of a wellstratified thickening wall of the colon in a patient with sigmoiditis. B B. Longitudinal US view of an stenotic hypoechoic segment of the colon with loss of layered wall (*), abrupt margins and nonhaustral folds.

13 Layered wall: preserved or loss A D * B B C A) Longitudinal US image shows a long segment with thickened walls. Between yellow arrows the wall present a stratified structure. Between white arrows wall layers are lost. B and C) Corresponding axial US view. D) CT scan demonstrates the stenotic segment. Yellow arrows points the inflammatory process. White arrows corresponds to the tumoral segment. Note the extension to the adjacent bowel (*).

14 Preserved or distorted mucosal folds A A) Longitudinal US image of a long segment with thickened walls shows the mucosal folds preserved (arrows). B) Corresponding CT scan with contrast enema demonstrates the stenotic segment and distorted folds. C) Pathologic specimen depicts an inflammatory process with thickened muscular layer (arrow) and preservation of haustral folds (HF). No tumor was found. C HF B

15 Preserved internal layers A B m Axial (A) and longitudinal (B) US image of a thickened segment of sigmoid colon shows preserved internal layers (white arrows) and thickened external hypoechoic muscular layer (m). (C) CT coronal image shows a short segment with pronounced wall thickening, shoulder forming (black arrows), and no in-lying diverticula, findings suggestive of malignant tumor. Colonoscopy ruled out the presence of cancer. m C

16 Preserved internal layers A B C D US image (A and B) of a long segment of sigmoid colon with thickened wall in a patient with previous diverticulitis. The preserved structure of the internal layers (arrows) -a sign of benign process- is clearly shown. C) Coronal contrast-enhanced CT scan illustrates the inflamed sigma with preserved folds and internal enhanced mucosal layer. D) Corresponding contrast barium enema shows long segment of narrowing with spiculated folds and tapered margins in the sigmoid colon. Note additional scattered diverticula.

17 Regional lymph nodes A large lymph node (n) is seen adjacent to a stenotic segment of sigmoid colon (S). Note the absence of internal layers manifested in a short section with hypoechoic thickened walls (between arrows) corresponding to a neoplasm which was confirmed at surgery. The distal portion keeps the layered structure of the wall (w).

18 Diverticula in affected segment The presence of diverticulum within the thickened wall is a fairly reliable sign of benign stricture. Axial US image shows a diverticulum (arrow) within a thickened muscular layer in a patient with acute diverticulitis. A f B C D Patient with acute diverticulitis. Axial US (A) and enhanced CT (B) demonstrates thickening of sigmoid colon with inflamed diverticula (white arrow) and pericolonic inflammatory fat (f). C) and D) the same patient two years later shows a tumoral stenosis in the same segment with diverticula (white arrows in D). Note the loss of stratification in US image (yellow arrow in C) and the absence of internal layers. (S) sigmoid colon. A diverticulum (white arrow) without inflammatory signs can be identified. This is an exceptional finding in tumoral stenosis.

19 Fistula Chronic diverticulitis with enterovesical fistula. A) Coronal CT scan demonstrates an stricture on the colon and a soft tissue mass in the bladder wall (arrow). The absence of diverticula, the abrupt margins and the short length of the stenosis suggested a tumoral condition. B) US image shows an echogenic tract (arrow) between the sigmoid colon (sigma) and the bladder (VEJIGA) representing an enterovesical fistula. The preserved layers of the colon suggested the US diagnosis of a benign process.

20 Pericolonic stranding fat F * Longitudinal US scan. Homogeneous wall thickening of a long-segment of the sigmoid colon, with preserved internal layers depict a benign process with inflammatory changes in the adjacent fat (*) Pericolonic stranding fat (F) is defined in this US study. The loss of stratification and the eccentric thickening of the wall are typical signs of the malignant colonic stenosis. A carcinoma was proved at surgery

21 Collection A B w * Perforated carcinoma. A short segment of sigmoid colon (Sigma) in the US image in A shows an asymmetric wall thickening (w) with loss of folds, absence of the differentiated layers and stranding fat (*). Bladder (V) is seen. Corresponding US axial image in B, shows an adjacent collection (c) C C) Corresponding CT scan with rectal contrast demonstrates the collection (c) with air level adjacent to the thickened sigma (S). c S

22 Collection C) and D) endovaginal US image demonstrates an stratified wall with thickening of the * muscular layer, (m) m c inflammatory fat (f) and diverticula (not C shown). Note in D A B an interruption of the wall by a gas-filled A 87-year old woman with lower abdominal pain and collection. leukocytosis. A) Axial image from contrast-enhanced Peridiverticular CT shows a thickened distal sigmoid colon with abscess was diverticula and pericolic inflammatory changes. The identified in surgery margins are non-well-defined and abrupt edges are and non neoplastic shown (arrows). B) Sagittal view depicts a gas-filled process was collection (c) adjacent the thickened sigmoid colon demonstrated in the and a soft-tissue mass (*) located behind the process. pathological analysis D An indeterminate diagnosis was made. of the specimen. c f

23 MATERIAL & METHODS Finally, a diagnosis in consensus by the two radiologists was made as benign, malignant or indeterminate. A) Typical sigmoid stenosis secondary to DIVERTICULITIS: US scan shows a long segment with distorted but preserved mucosal folds (arrows). A B) Typical sigmoid stenosis secondary to tumor: US longitudinal image shows a long segment with pronounced wall thickening, loss of normal layer structure and shoulder forming (arrows). B

24 MATERIAL & METHODS Statistical analysis: Sensitivity, Specificity, Accuracy, Positive predictive Value, Negative Predictive Value. 95% Confidence Interval. The diagnosis determined with the two imaging techniques was compared with the histopathology examination or clinical follow up of at least one year. The interobserver agreement for each sonographic sign and the final diagnosis was calculated by the kappa statistics.

25 RESULTS CLINICAL VARIABLES CATEGORY FREQUENCE Age range years (75±13) n=52 Men 30 (57%) Gender Women 22 (43%) CT scan 5 (9,6%) Initial diagnosis of Ultrasound 29 (55,7%) stenosis Colonoscopy 14 (26,9%) Barium enema 4 (7,7%) Final diagnosis Diverticulitis 30 (58%) Neoplasia 22 (42%)

26 RESULTS Statistical analysis of sonographic findings for diverticular disease DIVERTICULITIS (n=30) Sensitivity Specificity Preserved mucosal folds 90% 95% Thickening of muscular layer 90% 80% Preserved internal layers 89% 95% Diverticula in affected segment 73% 86% Pericolic stranding fat 67% 14% Collection 24% 73% Fistulas 33% 64%

27 RESULTS Statistical analysis of sonographic findings for colon cancer NEOPLASIA (n=22) Sensitivity Specificity Loss of the layered structure 87% 87% Length of segment < 10 cm 82% 63% Eccentric thickening 59% 73% Abrupt margin 82% 87% Regional lymph nodes 32% 100% Bowel wall thickening > 15 mm 32% 93% Absence of diverticula in affected segment 70% 88%

28 RESULTS Results with combined morphological criteria for neoplasia NEOPLASIA Sensitivity Specificity Abrupt margin + Regional lymph nodes 77% 87% Abrupt margin + Absence of diverticula in affected segment 71% 91%

29 RESULTS Results with combined morphological criteria for diverticulitis DIVERTICULITIS Sensitivity Specificity Thickening of muscular layer + Preserved internal layers 93% 86% Preserved mucosal folds + Diverticula in affected segment 90% 91%

30 RESULTS Range of Kappa coefficient of the lecture of sonographic criteria: between 0,441 (length <10 cm) and 0,903 (regional lymph nodes) - Kappa >0,8 in 5 out of 13 features: Abrupt margin 0,859; preserved mucosal folds 0,834; lost of the layered structure 0,803; preserved internal layers 0,801; and lymph nodes 0,903. Overall kappa coefficient: 0,782 (Substantial) Agreement in the diagnosis of malignant or benign stenosis: 88% (46 / 52) 3 indeterminate cases of each reader Off-site US diagnosis of carcinoma, excluding 3 indeterminate cases, oscillated between 93,9 and 98% of accuracy or 94,7 and 100% of sensitivity

31 CONCLUSION Our experience suggests that diverticulitis can often be differentiated from colon carcinoma using some US findings described in the literature. The combination of all of these US criteria could reach a high accuracy.

32 CONCLUSION BENIGN MALIGNANT -Preserved mucosal folds -Thickening of muscular layer -Preserved internal layers -Diverticula in affected segment -Loss of the layered structure -Length of segment <10 cm -Eccentric thickening -Abrupt margin -Regional lymph nodes -Wall thickening > 15 mm -Absence of diverticula in affected segment