Limitations in the CT diagnosis of acute diverticulitis: comparison of CT, contrast enema, and pathologic findings in 16 patients.

Pitfalls in CT diagnosis of acute diverticulitis were investigated in 16 patients with the disease who had misleading or equivocal CT features. The CT appearance was correlated with contrast enemas (13 cases) and with surgical assessment and pathologic evaluation of resected specimens (12 cases). Limitations in the CT diagnosis were related to (1) marked thickening of the colonic wall, between 1 and 3 cm in cross section simulating colonic neoplasm (all patients); (2) inability to visualize small amounts of fibropurulent exudate in the absence of pericolic inflammatory changes (eight patients); (3) failure to detect discrete intramural abscess (five patients). Resected surgical specimens available in 12 cases proved that colonic wall thickening was caused by muscular hypertrophy and various degrees of submucosal inflammation, edema, fibrosis, or focal organized inflammatory tissue. Contrast enema was useful in 10 out of 13 patients by excluding carcinoma of the colon and confirming the diagnosis of acute diverticulitis.