Evaluating the inflammatory activity in Crohn's disease using magnetic resonance diffusion kurtosis imaging

Objectives: To explore the feasibility of diffusion kurtosis imaging (DKI) for evaluating inflammatory activity in Crohn's disease (CD).

Materials and methods: In all, 51 CD patients were included, who were performed with consecutive enteroscopy, MR and DKI (b values = 0-2000 mm²/s). The lesions of bowel segments were graded as inactive (0-2), mild (3-6), and moderate-severe group (> 6) based on simplified endoscopic activity score for Crohn's disease (SES-CD), The abilities of the parameters of DKI and DWI in grading different activity lesions were compared.

Results: One hundred and twenty-seven bowel segments including inactive (15), mild (45) and moderate-severe (67) were analyzed. ADC (r = - 0.627, p < 0.001), D_app (r = - 0.381, p < 0.001) and K_app (r = 0.641, p < 0.001) were correlated with SES-CD. These parameters were significantly different among the three groups (all p < 0.001). ROC analysis found ADC had the highest accuracy (AUC = 0.884, p < 0.001) to differentiate inactive from active group with the threshold at 0.865 × 10^-3 mm²/s, which was slightly higher than K_app (AUC = 0.867, p < 0.001) with the threshold at 0.645, and was obviously higher than D_app (AUC = 0.726, p = 0.005). Similarly, ADC also had the highest accuracy (AUC = 0.846, p < 0.001) to differentiate inactive-mild from moderate-severe group with the threshold at 0.825 × 10^-3 mm²/s, and minimally higher than K_app (AUC = 0.843, p < 0.001) with the threshold at 0.695, and obviously higher than D_app (AUC = 0.690, p < 0.001).

Conclusion: DKI is feasible and comparable to conventional DWI for the evaluation of inflammatory activity in CD.