Abstract
Background and Objectives: To retrospectively assess the value of magnetic resonance enterography (MRE) parameters derived from conventional and diffusion weighted imaging (DWI) sequences to differentiate fibrotic strictures from inflammatory ones in adult patients with Crohn’s disease (CD), using surgical specimens as the histopathological reference standard. Material and Methods: Twenty-three patients with CD who had undergone surgical resection of ileal strictures with full-thickness histopathologic analysis within 3 months from preoperative MRE were included. Two radiologists blinded to histopathology in consensus evaluated the following biomarkers on MRE images matched to resected pathological specimens: T1 ratio, T2 ratio, enhancement pattern, mural thickness, pre-stenotic luminal diameter, and apparent diffusion coefficient (ADC). A blinded pathologist graded stricture histological specimens with acute inflammation score (AIS) and fibrosis score (FS). MRE measurements were correlated with the reference standard. Results: Inflammation and fibrosis coexisted in 78.3% of patients. T2 ratio was reduced in patients with severe fibrosis (p = 0.01). Pre-stenotic bowel dilatation positively correlated with FS (p = 0.002). The ADC value negatively correlated with FS (p < 0.001) and was different between FS grades (p < 0.05). The area under the receiver operating characteristic curve for discriminating between none and mild/moderate–severe bowel wall fibrosis was 0.75 for pre-stenotic bowel dilatation (sensitivity 100%, specificity 44.4%) and 0.97 for ADC (sensitivity 80%, specificity 100%). Conclusions: Inflammation and fibrosis often coexist in CD bowel strictures needing surgery. The combination of parameters derived from conventional MR sequences (T2 ratio, pre-stenotic dilatation) and from DWI (ADC) may provide a contribution to detect and grade bowel fibrosis in adult CD patients.
Highlights
Crohn’s disease (CD) is a chronic autoimmune systemic progressive and relapsing inflammatory disorder that can affect any part of the gastrointestinal tract
Our study demonstrated that pre-stenotic dilatation, T2 ratio and mean apparent diffusion coefficient (ADC) value correlated with bowel wall fibrosis in adult patients with CD
This result is consistent with another previous retrospective study conducted on 20 pediatric CD patients by Barkmeier et al [1] in which the authors found strictures with >3 cm upstream dilatation being highly associated with transmural fibrosis
Summary
Crohn’s disease (CD) is a chronic autoimmune systemic progressive and relapsing inflammatory disorder that can affect any part of the gastrointestinal tract. The inflammatory process can involve the whole thickness of the intestinal wall and may progress to mural fibrosis over time [1]. Both inflammation and fibrosis cause abnormal narrowing of the intestinal lumen with the formation of stenosis. It is estimated that within 10 years of initial diagnosis, about 70% of patients with CD develop a stricturing or perforating complication [3] and 50% need surgical intervention [4]. Strictures are referred to as localized constant luminal narrowing diagnosed radiologically, endoscopically or surgically, whose functional effects may be judged from an unequivocal pre-stenotic (upstream) dilatation (i.e., ≥3 cm) [5,6,7]. Strictures lead to obstructive symptoms (abdominal pain, constipation, vomiting), decreasing patient’s quality of life
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