Activity evaluation of Crohn disease with DWI

Objective: To assess the diagnostic value of DWI and ADC in evaluating activity of Crohn disease (CD). Methods: Conventional MR enterography (MRE) and DWI findings of 47 patients with CD were retrospectively analyzed. Mural thickness, T2WI signal intensity, contrast enhancement and DWI signal intensity were qualitatively scored respectively (0-3). ADC values were measured in bowel wall on ADC maps. Taking Crohn disease activity index (CDAI) as reference of CD activity, the relationships between CDAI and both of DWI signal intensity and ADC value were analyzed. Results: There were 25 cases of active CD (CDAI≥150) and 22 cases of inactive CD (CDAI<150). DWI score of active CD was significantly higher than that of inactive CD (P<0.001). ADC value in inflamed segment of active CD was significantly lower than that of inactive CD (P<0.001). DWI signal intensity correlated positively with CDAI (r=0.74, P<0.001) while there was negative correlation between ADC value and CDAI (r=-0.71, P<0.001). ADC value and DWI signal intensity showed well diagnostic accuracy for CD activity with ROC analysis (AUC=0.98, 0.91, respectively). Taking ADC value of 1.17×10^-3 mm²/s as threshold, the diagnostic sensitivity and specificity was 100% and 88.0%, respectively. Conclusion: Both of DWI and ADC value are helpful to diagnose the activity of Crohn disease with high accuracy.