Diffusion-weighted magnetic resonance enterocolonography in assessing Crohn disease activity

Diffusion‑weighted magnetic resonance imaging has the potential to identify inflamed bowel segments in patients with Crohn disease (CD).

We aimed to determine diffusion‑weighted imaging (DWI) value to predict active CD and compare apparent diffusion coefficients (ADCs) with endoscopic and conventional indices of magnetic resonance imaging of CD activity.

Overall, 229 patients with suspected and diagnosed CD prospectively underwent magnetic resonance enterocolonography (MR‑EC) with DWI sequence and ileocolonoscopy. The magnetic resonance activity index (MaRIA), Clermont index, and CD endoscopic index of severity (CDEIS) were calculated.

The clinical diagnosis of CD was confirmed in 100 out of 229 patients. A DWI score of 2 or higher had 96.9% sensitivity and 82.3% specificity for diagnosing CD. A threshold ADC value of 1.3 × 10-3 mm2/s could distinguish between normal and inflamed bowel segments with a sensitivity of 73.8% and a specificity of 98%. For the MaRIA, a threshold ADC value of 1.32 × 10-3 mm2/s with a sensitivity of 97.9% and a specificity of 97.8% was established. There were significant differences in the DWI scores and ADC values comparing patients with inactive, mild, and moderate-to-severe disease (P <0.01). ADCs inversely correlated with the MaRIAglobal (r = -0.69; P = 0.001), Clermontglobal (r = -0.722; P = 0.001), and CDEIS (r = -0.69; P = 0.001).

DWI is a valuable tool that is capable of identifying inflamed bowel segments as accurately as the conventional MaRIA score and of discriminating between mild and moderate-to-severe CD.