High b-value computed diffusion-weighted imaging for differentiating bowel inflammation in Crohn's disease

Abstract

Purpose This study evaluated whether high b-value computed diffusion-weighted imaging (cDWI) can improve detection and differentiation of bowel inflammation in patients with Crohn's disease (CD).Methods Fifty-four consecutive CD patients who had undergone magnetic resonance enterography (MRE) and ileocolonoscopy (ICS) or balloon-assisted enteroscopy (BAE) were retrospectively studied; cDWI with a b-value = 1500s/mm2 (cDWI1500) was generated using DWI acquired with b-values of 0 and 800 s/mm2 (aDWI800). Overall, 366 bowel segments were evaluated. The signal intensities (SIs) of the bowel lumina were visually assessed on DWI. Bowel wall-to-iliopsoas muscle SI ratios on aDWI800 and cDWI1500 images and apparent diffusion coefficient (ADC) values were measured; visual assessments for lesion detection were performed using a 5-point Likert-like scale on plain MRE with aDWI800, plain MRE with cDWI1500, and contrast-enhanced (CE)-MRE without DWI. The area under the receiver-operating characteristic curve (AUC) was calculated to compare quantitative and qualitative assessments.Results SIs of the intraluminal fluid were shown as comparable to, or lower than background SIs on 157 (44.7 %) and 345 (98.3 %) of 351 segments on aDWI800 and cDWI1500, respectively. AUCs of SI ratios on cDWI1500 images (82.0 %, [95 % confidence interval: 76.6–87.3 %]) were greater than on aDWI800 (75.2 %, [68.2–82.3 %]; p < 0.001), and were close to the ADC values (81.5 % [76.3–86.7 %]; p = 0.76). The AUCs of CE-MRE images were largest, followed by plain MRE with cDWI1500, and plain MRE with aDWI800.Conclusions As it suppresses the SIs of intraluminal fluid and improves contrast between severe and non-severe inflammation, cDWI1500 helps with CD evaluation.