A novel identification system combining diffusion kurtosis imaging with conventional magnetic resonance imaging to assess intestinal strictures in patients with Crohn's disease

Purpose To determine the utility of diffusion kurtosis imaging (DKI) for assessing bowel fibrosis and to establish a new magnetic resonance imaging (MRI)-based classification based on DKI and conventional MRI parameters for characterizing intestinal strictures in Crohn's disease (CD) using the histological evaluation of resected intestine samples as the reference standard. Methods Thirty-one patients with CD undergoing preoperative conventional MRI and diffusion-weighted imaging (DWI) (bvalues = 0-2000 s/mm(2)) were consecutively enrolled. We classified the mural T2-weighted signal intensity and arterial-phase enhancement patterns on conventional MRI. We also measured DWI-derived apparent diffusion coefficients (ADCs) and DKI-derived apparent diffusion for non-Gaussian distribution (D-app) and apparent diffusional kurtosis (K-app). A new MRI-based classification was established to characterize intestinal strictures in CD. Its performance was validated in nine additional patients with CD. Results Histological inflammation grades were significantly correlated to T2-weighted signal intensity (r = 0.477;P < 0.001) and ADC (r = - 0.226;P = 0.044). Histological fibrosis grades were moderately correlated toK(app)(r = 0.604,P < 0.001); they were also correlated toD(app)(r = - 0.491;P < 0.001) and ADC (r = - 0.270;P = 0.015). T2-weighted signal intensity could differentiate between no-to-mild and moderate-to-severe bowel inflammation (sensitivity, 0.970; specificity, 0.479).K(app)could differentiate between no-to-mild and moderate-to-severe bowel fibrosis (sensitivity, 0.959; specificity, 0.781). The agreement between the new MRI-based classification and the histological classification was moderate in the test (kappa = 0.507;P < 0.001) and validation (kappa = 0.530;P < 0.001) sets. Conclusions DKI can be used to assess bowel fibrosis. The new MRI-based classification can help to distinguish between fibrotic and inflammatory intestinal strictures in patients with CD.

Automated summary

DKI is effective in evaluating bowel fibrosis in patients with CD, and a new MRI-based classification using DKI and conventional MRI parameters can help distinguish between fibrotic and inflammatory intestinal strictures. The new classification shows moderate agreement with histological classification.