Diffusion kurtosis MRI versus conventional diffusion-weighted imaging for evaluating inflammatory activity in Crohn's disease.

ABSTRACT

PURPOSE: To assess the efficacy of diffusion kurtosis imaging (DKI) and to compare DKI-derived parameters with that of conventional diffusion-weighted imaging (DWI) for grading the inflammatory activity of Crohn's disease (CD). MATERIALS AND METHODS: In all, 38 patients with CD underwent 3T magnetic resonance enterography (MRE) with DKI (b values of 0-2000 s/mm2 ). The inflammatory activity of the bowel segments was graded by magnetic resonance index of activity (MaRIA) as inactive (<7), mild (≥7 and <11), or moderate-severe (≥11). Apparent diffusion for non-Gaussian distribution (Dapp ) and apparent kurtosis coefficient (Kapp ) on DKI as well as apparent diffusion coefficient (ADC) on DWI were compared. RESULTS: In all, 86 bowel segments including inactive (20), mild (19), and moderate-severe (47) CD were analyzed. The differences in Kapp , Dapp , and ADC among inactive, mild, and moderate-severe CD were significant (all P < 0.05). Kapp (r = 0.862), Dapp (r = -0.755), and ADC (r = -0.713) correlated well with MaRIA in all segments. Stronger correlation with MaRIA in moderate-severe CD was found for Kapp (r = 0.647) than that of Dapp (r = -0.414) and ADC (r = -0.580). Receiver operating characteristic (ROC) curve analysis showed high accuracy of Kapp , Dapp , and ADC for differentiating active from inactive CD (AUC 0.953 for Kapp , 0.944 for Dapp , 0.907 for ADC) as well as differentiating inactive-mild from moderate-severe CD (AUC 0.946 for Kapp , 0.887 for Dapp , 0.846 for ADC). The threshold Kapp of 0.731 allowed differentiation of active from inactive CD with 89.4% sensitivity and 95% specificity. CONCLUSION: DKI of CD is clinically feasible and might be superior to conventional DWI for grading the inflammatory activity of CD. LEVEL OF EVIDENCE 2 Technical Efficacy Stage 2 J. Magn. Reson. Imaging 2018;47702-709.