Magnetic resonance imaging of Crohn disease: early recognition of treatment response and relapse.

A patient with active Crohn disease was evaluated by MRI at admission, clinical remission, and a new relapse. The MRI-estimated disease extension correlated with surgical findings, whereas ultrasonography underestimated and a small bowel series overestimated the extension. MRI disclosed the disappearance of intestinal edema at the time of clinical remission and, in contrast to ultrasonography, showed an abscess and a fistula, confirmed by surgery, at the new relapse.