Identifying the inflammatory and fibrotic bowel stricture: MRI diffusion-weighted imaging in Crohn's disease

PurposeTo identify inflammatory and fibrotic mural stricture in Crohn's disease (CD) using MR diffusion-weighted imaging (DWI) and to compare DWI findings with those of enteroscope and histological markers.Method and materialsThirty-one patients with CD (18 males, 13 females; mean age, 38.9 years) were recruited in this approved retrospective study and an informed consent was obtained from each subject. All subjects underwent bowel MRI examination with conventional and DWI sequences at 3.0 T. Colonoscopy results were distributed within 24 h after examination. According to the endoscopic manifestations and pathological results, the patients were divided into two groups: inflammatory (21/31) and fibrotic (10/31).ResultsIn the group of inflammatory stricture, the mean ADC value of stricture bowel was 1.4 ± 0.23 × 10−3 mm2/s, whereas 0.8 ± 0.16 × 10−3 mm2/s in the group of fibrotic stricture. Inter-group independent sample t-test was performed. A statistically significant difference was observed (t = 7.403, P < 0.05). The area under receiver-operating characteristic curve was 0.981 (95% confidence interval, 0.943–1.000), with 1.11 × 10−3 mm2/s as the cutoff point. The sensitivity of low ADC values in detecting inflammatory bowels was 90.5%, and the specificity of high ADC values in excluding inflammatory bowels was 100%.ConclusionDecreased ADC values in inflammatory stricture bowel may be resulted from multiple factors, including an increase in cellularity, presence of edema, micro-abscesses and increased perfusion. Meanwhile, fibrotic tissue deposition was indicated to lead to restrictions in diffusion. Distinguishable ADCs were observed between inflammatory and fibrotic bowel stricture, where DWI sequence could contribute to the identification.