Fig. 27

Chron’s Disease. Plain abdominal CT shows the fat halo sign (arrows) in the wall of the D3 (a) and D4 (b), in a patient with quiescent Crohn’s disease. CT enterography (c) of a CD patient with active disease who previously had a segmental enterectomy—note the surgical clips at the ileal-ileal anastomosis (curved arrows). There is a fistula between the thickened ileal segment near the anastomosis and the duodenum. MIP coronal reformation (d) shows mesenteric engorgement (asterisks) and adenopathy (arrowhead) near a thickened bowel wall segment (arrows). Abdominal CT of another patient with active disease (e) shows gastric outlet obstruction (asterisk) and a stricture in D2 that shows the target sign (arrow). Barium study of the same patient (f) shows the short stricture (arrow) and dilatation of the proximal duodenum (asterisk)