BackgroundMagnetic resonance entero-colonography enables accurate assessment of ileocolonic Crohn's disease, but the need for bowel cleansing and rectal enema limits considerably its use in daily practice. AimWe evaluated the accuracy of diffusion-weighted magnetic resonance entero-colonography with neither bowel cleansing nor rectal enema to assess endoscopic activity. MethodsForty-four Crohn's disease patients underwent prospectively and consecutively diffusion-weighted magnetic resonance entero-colonography [with apparent diffusion coefficient (ADC) and Clermont score calculation] and ileocolonoscopy [with Crohn's Disease Endoscopic Index of Severity (CDEIS) and Simplified Endoscopic score for Crohn's Disease (SES-CD) calculation]. ResultsMean ADC was inversely correlated with total CDEIS (=-0.40; P=0.0067) and total SES-CD (=-0.33; P=0.032). Considering the 194 segments, ADC was inversely correlated with segmental CDEIS (-0.48; P<0.001) and segmental SES-CD (-0.44; P<0.001). ADC values were lower in segments with deep ulcers (1.300.23) or superficial ulcerations (1.75 +/- 0.64) than in non-ulcerated segments (2.15 +/- 0.5) (P=0.001). Using a receiver operating curve, we determined that segmental ADC <1.42 detected endoscopic deep ulcerations with sensitivity=0.91 and specificity=0.83 (Area under the curve=0.84; P<0.001). Segmental ADC <1.88 detected endoscopic superficial ulcerations with sensitivity=0.64 and specificity=0.75. The segmental ADC values decreased when the ulcerations size increased (P=0.0001). Clermont score correlated with ileal CDEIS (0.63; P<0.05) and ileal SES-CD (0.58; P<0.05). Clermont score was higher in ulcerated segments (23.3 +/- 8.4) than in non-ulcerated segments (12.4 +/- 10.0) (P=0.006) and increased with ulcers size (P=0.012). Clermont score >18.9 detected ulcerations with sensitivity=0.79 and specificity=0.73. ConclusionDiffusion-weighted magnetic resonance entero-colonography using apparent diffusion coefficient and Clermont score was effective to indirectly detect endoscopic ulcerations in ileocolonic Crohn's disease.