Curriculum based clinical review: small bowel imaging in Crohn's disease

Abstract

The multidisciplinary management of patients with small bowel Crohn's disease is complex with an increasing reliance on imaging to guide management. The use of barium fluoroscopy is in decline with a shift towards the cross-sectional modalities. This article provides an overview of the various techniques used to image the small bowel, and highlights the clinical scenarios where imaging tests are most useful.

Keywords: CROHN'S DISEASE; RADIOLOGY; SMALL INTESTINE.

Figure 1

A 19-year-old woman with right iliac fossa pain and diarrhoea. Barium small bowel follow-through with pneumocolon. Spot image shows subtle mucosal ulceration within the terminal ileum (white arrows), plus further ulceration and distortion of the medial aspect of the caecal pole and appendix. The early changes in the terminal ileum would be difficult to appreciate on MR or CT. Findings were confirmed via ileocolonoscopy, with biopsies suggestive of Crohn's disease.

Figure 2

Coronal CT enteroclysis image shows markedly thickened segment of terminal ileum with mural oedema and mucosal hyperenhancement (solid white arrow) plus more subtly diseased segment of proximal ileum (dashed white arrow). Note excellent jejunal distension with enteroclysis.

Figure 3

(A, B) Coronal T2 fat saturated image of the right iliac fossa (A) shows a segment of thickened terminal ileum with mural oedema (solid white arrows). Coronal T1 VIBE postgadolinium image (B) shows marked mucosal hyperenhancement as compared with other bowel loops giving a layered appearance to the bowel wall with deep linear ulcers (dashed white arrows), findings seen in active disease.

Figure 4

(A, B) A 35-year-old man with known Crohn's disease and left upper quadrant pain. Axial T2 HASTE image (A) shows a short segment of thickened jejunum in the left upper quadrant (solid white arrows). Axial diffusion weighted image (B) shows corresponding high signal diffusion restriction in this loop (dashed white arrows) (b=750 s/mm²). Jejunal disease can be difficult to evaluate, and in conjunction with other sequences findings were useful to help confirm active disease. HASTE, half-fourier acquired single-shot turbo spin echo.

Figure 5

(A–D) Longitudinal US image (A) shows thickened segment of terminal ileum with loss of the normal mural layer pattern (solid white arrows) and a fistulous tract (dashed white arrow). Transverse colour Doppler image (B) shows increased vascularity within the loop. Transverse image (C) shows a fistulous connection (dashed white arrows) between the terminal ileum and transverse colon, with marked oedema in the adjacent mesenteric fat (*). A coronal image from a CT performed several days later (D) confirmed active terminal ileal disease with colonic fistulation (dashed white arrow) and deep ulceration (solid white arrow).

Figure 6

A 27-year-old man with Crohn's disease admitted with severe abdominal pain, raised inflammatory markers and peritonism. Axial CT image of the pelvis shows segment of markedly thickened and distended ileum with local perforation and adjacent abscess formation (white arrow). The patient had extensive peritonitis at surgery, and required a significant small bowel resection.

Figure 7

Multiple choice question 2.