MR enteroclysis in a 21-year-old man with active Crohn’s disease. Coronal true-FISP (a) and Haste (b) images show mucosal irregularity (arrows) as thin lines of high signal intensity, longitudinally, or transversely (fissure ulcers) orientated within the thickened in the terminal ileum consistent with diffuse ulcerations in Crohn’s ileitis. Axial true-FISP sequence (c) detects wall thickening of terminal ileum as well as the cecal wall (arrows). Axial fat-suppressed T2 Haste sequence (d) MR image shows high signal intensity bowel wall (arrows) and fluid surrounding the distal ileum (small arrow). Coronal (e) and axial (f) contrasts GRE T1 with fat saturated images show marked contrast enhancement, with avid enhancement of the mucosa of the terminal ileum and cecal walls. Note the high signal intensity linear structure due to increased vascularity (small arrows in (e)) close to the mesenteric border of the involved small bowel segment, the so-called comb sign. These MR findings are indicative of active Crohn’s disease.