MR-enterography in Crohn’s disease: what MRE mural parameters are associated to one-year therapeutic management outcome?

Objective: To investigate the association of mural parameters of MR-enterography (MRE) with one-year therapeutic management of Crohn’s disease (CD) patients. Methods: CD patients, undergone MRE with diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps between January 2017 and June 2018, were retrospectively enrolled. Extramural complications represented an exclusion criterion because of their potential influence on the intrinsic characteristic of the bowel wall. Two groups of patients were defined on the base of the therapeutic management adopted at 1-year follow-up: Medical-group and surgical-group. The following MRE parameters were evaluated: wall-thickening, longitudinal-extension, T2-fat-suppression-mural-signal, ulcers, mural-oedema, wall-enhancement-rate/pattern, DWI-scores, ADC-values, strictures. Results: 70 CD patients were enrolled. 57/70 (81.4%) were included in Medical-group and 13/70 (18.6%) in Surgical-group. ADCmean and strictures resulted to be significantly (p < 0.01) different between the two groups. The ADCmean showed to be significantly associated to conservative management [p < 0.01; OR: 0.0003; 95% CI (0.00–0.13)], while the strictures to surgical management [p < 0.01; OR: 29.7; 95% CI (4.9–179.7)]. ROC curves for ADCmean showed that AUC was 0.717 [95% CI (0.607–0.810), p < 0.01] with an optimal cut-off value of 1.081 × 10−3 mm2 s−1. A negative predictive value of 90.2% was observed associating ADCmean values > 1.081 × 10−3 mm2 s−1 to conservative therapy. 13/17 (76%) strictures with an ADCmean > 1.081 × 10−3 mm2 s−1 benefited of conservative therapy. Conclusion: ADCmean values calculated on DWI-MRE may be associated to 1-year conservative medical therapy in patients with CD without extramural complications. Advances in knowledge: ADC maps may be proposed to select CD patients with a lower burden of mural active inflammatory cells and/or fibrosis benefiting of 1-year conservative treatment.