Colitis: use of CT findings in differential diagnosis.

PURPOSE: To determine whether colitides can be differentiated based on computed tomographic (CT) features.

MATERIALS AND METHODS: The CT scans of 117 patients with documented colitis and colon wall thickening were reviewed. Features evaluated included mural thickness and homogeneity, distribution of bowel involvement, and associated mesenteric and small bowel disease.

RESULTS: The mean colon wall thickness in Crohn colitis (11.0 mm +/- 5.1) was significantly greater than in ulcerative colitis (7.8 mm +/- 1.9) (P < .002). Submucosal fat deposition, not observed in the acute colitides, was present significantly more often in ulcerative (61%) than in Crohn colitis (8%) (P = .0001). Exclusive involvement of the right colon and small bowel was most frequent with Crohn and infectious colitis. Abscess was associated almost exclusively with Crohn colitis (35%) but was seen in one patient with radiation colitis.

CONCLUSION: Although many CT findings in patients with colitis are nonspecific, some features are helpful in suggesting a specific diagnosis.