A 55-year-old woman with known inflammatory bowel disease undergoes small bowel MRI (MR enterography). The terminal ileum shows mural thickening greater than 4 mm with a layered 'target' sign of mural stratification, restricted diffusion on DWI, and marked mural and perienteric hypervascularity on post-contrast images. Mesenteric fat shows fibro-fatty proliferation. What do these findings collectively indicate?

• A Chronic fibrotic stricture with upstream dilatation
• B Active inflammation of Crohn's disease ✓
• C Intestinal tuberculosis with ileocaecal involvement
• D Carcinoid tumour of the terminal ileum

Explanation

MR enterography reliably distinguishes active inflammatory disease from fibrotic stricture, which is critical for management in Crohn's disease. Active inflammation manifests as mural thickening with preserved layering (target sign), increased mural and perienteric enhancement, markedly increased vascularity of the vasa recta (comb sign), restricted diffusion, and perienteric oedema. Fibrotic stricture shows loss of mural stratification, reduced enhancement, and dilatation upstream without perienteric hyperaemia. These active inflammatory findings favour medical therapy, while fibrotic strictures typically require surgical or endoscopic intervention.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.