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

PurposeTo 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 methodsThirteen 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 20–40 s, 60–80 s, 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).ResultsSmall bowel wall enhancement was significantly higher (p < 0.05) in inflamed compared to normal segments at 20–40 s (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 60–80 s (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).ConclusionIn 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.