MR Enterographic Findings as Biomarkers of Mucosal Healing in Young Patients With Crohn Disease.

OBJECTIVE: The purpose of this study was to investigate the MR enterographic findings that best correlate with mucosal healing assessed with ileocolonoscopy.

MATERIALS AND METHODS: Patients with Crohn disease who underwent two ileocolonoscopic examinations and also underwent MR enterography close in time to the second endoscopic examination were included in a retrospective study. Two pediatric gastroenterologists blinded to the imaging findings reviewed the endoscopic examinations to assess for mucosal healing, defined as resolution of inflammation within a bowel segment at subsequent ileocolonoscopy. Two radiologists blinded to endoscopic and clinical data interpreted the MR enterographic images. Sensitivity, specificity, and accuracy for mucosal healing were calculated for several imaging features.

RESULTS: A total of 30 patients (15 female patients, 15 male patients; age range, 8-24 years; mean, 17.2 ± 3.2 years) with pediatric-onset Crohn disease were examined. The average time between MR enterography and the second ileocolonoscopic examination was 12.7 ± 7.9 days. A total of 202 bowel segments from the terminal ileum to rectum were evaluated in the 60 ileocolonoscopic examinations. Forty-four bowel segments exhibited mucosal healing, and 37 segments exhibited persistent inflammation. At imaging, the MR index of activity score in mucosal healing segments was 6.6 ± 3.4, compared with 13.7 ± 9.7 in segments without mucosal healing (p = 0.0001). The average bowel wall thickness in healing segments was 2.7 ± 0.9 mm compared with 4.7 ± 3.1 mm in persistently inflamed segments (p = 0.0004). An MR index of activity score less than 8 had the highest accuracy for mucosal healing (accuracy, 74%; sensitivity, 84%; specificity, 62%; p < 0.0001). Mucosal hyperenhancement (72%, 98%, 41%), mesenteric hypervascularity (72%, 98%, 41%), bowel wall edema (72%, 93%, 46%), and bowel wall thickness less than 4 mm (72%, 84%, 57%) were also strongly associated with mucosal healing (p < 0.0003).

CONCLUSION: In this study MR enterography was accurate for assessing mucosal healing, an important therapeutic endpoint in pediatric patients with Crohn disease.