60 year old male presented with recurrent loose stools and abdominal pain. He underwent contrast enhancement CT scan of abdomen.

CT abdomen showed enhancing wall thickening of terminal ileum with inflammatory stricture, increased surrounding mesenteric vascularity, mucosal ulcers and hypertrophy of peri-ileal fat in right iliac fossa. There were focal areas of enteroenteric fistulae between the narrowed and dilated portions of inflamed terminal ileum. 

These features are consistent with acute-on-chronic Crohn disease with enteroenteric fistula.    

Assessing disease activity can be done by CT or MRI. MR enterography is useful in distinguishing between the stricture and transient narrowing of peristaltic segment of bowel. 

CT abdomen is also performed prior to capsule endoscopy to rule out bowel strictures, which are a contraindication to the use of a capsule endoscope.