Viscoelastic properties of small bowel mesentery at MR elastography in Crohn’s disease: a prospective cross-sectional exploratory study

Abstract Background Creeping fat is a pathological feature of small bowel Crohn’s disease (CD), with literature suggesting that bowel resection with extended mesenteric resection is related to less postoperative recurrences. Conventional imaging is unable to accurately quantify the disease involvement (i.e., fibrosis) of creeping fat. Quantification of disease involvement could be useful in decision-making for additional extended mesenteric resection. We investigated the feasibility of magnetic resonance elastography (MRE) of the mesentery and if MRE is capable to detect fibrotic disease involvement of mesentery in active CD. Methods Multifrequency MRE yielded spatial stiffness (shear wave speed, SWS, |G*|) and fluidity maps (φ). Viscoelastic properties of seven CD patients’ mesentery were compared to age- and sex-matched healthy volunteers (HV) (Mann–Whitney U-test). Within CD patients, the affected and “presumably” unaffected mesentery were compared (Wilcoxon-signed rank test). Repeatability was tested in 15 HVs (Bland–Altman analysis, coefficient of variation [CoV]). Spearman rank correlations were used to investigate the relation between microscopically scored amount of mesenteric fibrosis and viscoelastic parameters. Results SWS, |G*|, and φ of affected mesentery in CD were higher compared to HV (p = 0.017, p = 0.001, p = 0.017). Strong correlations were found between percentage of area of mesenteric fibrosis and SWS and |G*| (p