Purpose: Monitoring Crohn's disease (CD) activity has a crucial importance, especially for evaluating treatment efficacy. Magnetic resonance enterography (MRE) and diffusion-weighted imaging (DWI) or their combination may represent potential non-invasive tools for this purpose. This study aimed to examine DWI and MRE for their potential to differentiate between different grades of ileocolonic CD activity.
Materials and methods: This retrospective study included 54 adult patients with a diagnosis of CD who underwent ileocolonoscopy and MRE including the DWI sequence. The severity of CD inflammation was categorized by Simple Endoscopic Score for Crohn's Disease (SES-CD) as inactive, mild, moderate and severe. In addition, following conventional MRE and DWI parameters were examined: bowel wall thickness, mural T2 hyperintensity, contrast enhancement, DWI signal intensity, and apparent diffusion coefficient (ADC) values.
Results: In patients with moderate to severe disease based on SES-CD, T2 hyperintensity score [1.68 ± 0.77 (1-3) vs. 2.19 ± 0.69 (1-3); p = 0.013] and mean DWI score [2.42 ± 0.58 (1-3) vs. 2.04 ± 0.69 (1-3); p = 0.037 ] were higher and mean ADC values [1.5 ± 0.4 (0.9-2.5) vs. 1.2 ± 0.3 (0.6-1.8)] were lower compared to patients with inactive to mild CD. ADC had a moderate diagnostic accuracy in predicting moderate to severe disease (AUC = 0.729, 95% CI = 0.591-0.841, p = 0.001), with a cut-off value of ≤1.47 × 10-3 mm2/sec yielded 88.5% (23/26) sensitivity, 57.1% (16/28) specificity.
Conclusion: DWI, ADC and T2 signal appear to differentiate moderate to severe CD from inactive to mildly active CD, based on SES-CD evaluation and may be useful in monitoring disease activity, particularly when evaluating treatment response.
Keywords: Crohn’s; Diffusion; Disease (CD); Disease Activity Score; MR Enterography.