Evaluation of dynamic contrast-enhanced magnetic resonance imaging and diffusion-weighted imaging for predicting muscular hyperplasia/hypertrophy in Crohn's disease

Abstract

Objectives: The existence of smooth muscle alteration in Crohn's disease (CD) is often neglected. It has been found that muscular hyperplasia/hypertrophy rather than fibrosis was the primary component of bowel wall thickening. This study aimed to assess the value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion weighted imaging for the characterization of histopathologic tissue composition of CD, particularly smooth muscle hypertrophy, as well as inflammation and fibrosis.

Methods: The study included patients diagnosed with CD who received MRI examination 30 days before resection from August 2016 to December 2020. A semiquantitative histological grading scheme was employed to evaluate the pathological tissues. Resected sections were matched with MRI according to pathological marks. Parameters evaluated included: mural thickness, T2 ratio, apparent diffusion coefficient value; and maximum enhancement, initial slope of increase, perfusion parameters of DCE-MRI and enhancement pattern. These parameters were compared with location-matched histopathological grade.

Results: Ninety-one sections were enrolled in this retrospective study. When active inflammation is moderate or severe, volume transfer coefficient (K^trans), maximum enhancement (ME) and initial slope of increase (ISI) are lower, mural thickness is higher when a certain degree of smooth muscle alteration is present. When active inflammation is absent or mild, ME, mural thickness and ISI can differentiate the presence of predominant muscular alteration. By combining ME and thickness comparisons against their cutoff values to create a combined ordinal parameter, the area under the curve value for whether significant muscular alteration coexists with moderate or severe active inflammation was found to be 0.953.

Conclusions: MRI predicts the degree of inflammation, and can distinguish the degree of muscular alteration coexists with moderate or severe active inflammation with reasonable accuracy.

Keywords: Crohn disease; Inflammatory bowel disease; Magnetic resonance imaging; Pathology.