Assessment of dynamic contrast enhancement of the small bowel in active Crohn's disease using 3D MR enterography

Abstract

Purpose: To retrospectively compare the dynamic contrast enhancement of the small bowel segments with and without active Crohn's disease at 3D MR enterography (MRE).

Materials and methods: Thirteen patients (five men, eight women; mean age 41.2 years; range 29-56) were imaged on a 1.5-T MR scanner (Sonata, Siemens Medical) with standard MR sequences after having ingested 1000 ml of a 3% mannitol solution. Subsequently, high resolution 3D gradient-echo (volumetric interpolated breath-hold examination=VIBE) data sets were obtained pre-contrast and 20-40s, 60-80s, and 120-140 s after i.v. Gd-DOTA administration (0.2 mmol/kg). Signal enhancement was measured on single slices both in normal and histologically confirmed (12/13) inflamed small bowel wall segments as well as in the aorta, the psoas muscle, and the background to calculate signal-to-noise (SNR) and contrast-to-noise ratios (CNR).

Results: Small bowel wall enhancement was significantly higher (p<0.05) in inflamed compared to normal segments at 20-40s (SNR inflamed: 58.7+/-33.8 vs normal: 36.0+/-19.8; p=0.048; CNR inflamed: 34.8+/-23.4 vs normal: 16.3+/-11.2; p=0.017) and at 60-80s (SNR: 60.3+/-25.1 vs 41.9+/-20.0; p=0.049; CNR: 34.9+/-15.1 vs 19.3+/-13.2; p=0.01) after i.v. contrast administration, respectively. Even at 120-140 s CNR was still increased in inflamed segments (33.7+/-16.0 vs 18.1+/-13.2; p=0.04), while differences in SNR did not attain statistical significance (63.0+/-26.2 vs 45.3+/-23.3; p=0.15).

Conclusion: In active Crohn's disease, histologically confirmed inflamed small bowel wall segments demonstrate a significantly increased early uptake of gadolinium on 3D VIBE sequences compared to normal small bowel segments.