The role of spiral computed tomography in sigmoid diverticulitis and the diagnostic-therapeutic implications

PURPOSE: Colonic diverticula are saccules made of colonic mucosa and submucosa that herniate from the colonic lumen through the muscular layer of the wall where straight vessels penetrate. Diverticula are localized in the sigmoid colon in 95% of cases. Bacteria pooling in the lumen may cause lumen erosion and eventually perforation. CT is a useful technique in this condition because it can demonstrate intra- and/or extramural inflammation. Aim of this retrospective study was to assess the capabilities of contrast-enhanced helical Computed Tomography (CT) in sigmoid diverticulitis, especially relative to selection of the appropriate treatment. MATERIAL AND METHODS: We retrospectively reviewed the findings of 41 patients referred to our emergency department for diverticulitis. CT scans were performed 65 seconds after i.v. injection of nonionic contrast material (3 mL/s, 120 mL in all) administered by a CT-power injector. The following 7 CT findings were considered at least suggestive of acute diverticulitis: focal wall thickening, intramural abscess, inflammatory changes in the sigmoid mesentery root, pericolic fat inflammation or pericolic abscess formation, fistula, peritonitis. CT results were compared with surgical and physical findings. RESULTS: Based on CT findings, diverticulitis was classified as mild (25 patients) or severe (15 patients). In mild diverticulitis we found: focal sigmoid wall thickening (6 patients), intramural abscess (3 patients), sigmoid mesentery root thickening (5 patients), edema fluid (8 patients) and phlegmon (3 patients). In severe diverticulitis we found: sigmoid mesentery abscess (6 patients), fistula (5 patients) and peritonitis (4 patients). CT findings were questionable in 1 case and thus we could not exclude a perforated carcinoma. CONCLUSION: Contrast-enhanced helical CT is the imaging modality of choice in assessing mild or severe acute diverticulitis because it provides useful information for appropriate treatment planning in the emergency setting. This technique is most useful in questionable cases and in patients with suspected severe diverticulitis where a choice must be made between different treatment options.