How are Crohn’s disease and ulcerative colitis distinguished on cross-sectional imaging?
Comparison of Cross sectional Imaging Features of Crohns Disease and Ulcerative Colitis
| CROHN’S DISEASE | ULCERATIVE COLITIS | |
|---|---|---|
| Distribution | May involve any part of the gastrointestinal tract; most commonly affects small bowel, followed by colon, and less commonly esophagus, stomach, or duodenum | Involves colon starting at the rectum and moving proximally |
| Pattern of spread | Skip lesions | Continuous |
| Mean wall thickness | 12 mm | 8 mm |
| Wall morphology | Eccentric, segmental, sometimes with pseudosacculations | Diffuse, symmetric |
| Enhancement pattern | “Target” sign in active disease, “fat halo” sign in chronic disease | “Target” sign in active disease, “fat halo” sign in chronic disease |
| Terminal ileal involvement | 95% | 25% backwash ileitis in setting of pancolitis |
| Distribution of fibrofatty change | Mesenteric distribution | Perirectal distribution; associated with widening of the presacral space |
| Mesenteric lymphadenopathy | Yes | No |
| Complications | Fistulas, sinus tracts, and abscess formation (due to transmural extent of disease), stricture formation, colorectal cancer, lymphoma | Toxic megacolon, stricture formation, sclerosing cholangitis, colorectal cancer (higher risk than in Crohn’s disease), lymphoma |
What percent of patients with Crohn’s disease present with isolated colonic involvement?
20%.
