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;47:702–709.