Diffusion weighted imaging to predict longer term response in Crohn's disease patients commencing biological therapy: Results from the MOTILITY Trial.

Objectives: Predicting longer term response to biological therapy for small bowel Crohn's disease (SBCD) is an unmet clinical need. Diffusion-weighted MR imaging (DWI) may indicate disease activity, but its predictive ability, if any, is unknown. We investigated the prognostic value of DWI for one year response or remission (RoR) in SBCD patients commencing biologic therapy, including incremental value over C-reactive protein (CRP) and faecal calprotectin (FC).

Methods: A subset of participants in a prospective, multicentre study investigating the predictive ability of motility MRI for one-year RoR in patients starting biologic therapy for active SBCD, underwent additional DWI at baseline and post-induction (12-30 weeks). CRP and FC were collected in a subgroup. RoR at one year was evaluated using clinical and morphological MRE parameters. We calculated sensitivity and specificity to predict RoR and Quality of life (QoL) at one year, comparing apparent diffusion coefficient (ADC) value, Clermont score and CRP using multivariable logistic regression.

Results: 25 participants were included (mean 36.9 years, 32% female). ADC changes and Clermont score had poor sensitivity (30.0% [95%CI: 6.7-65.2] and 40.0% [95%CI: 12.2-73.8] respectively) and poor-to-modest specificity (50.0 [95%CI: 27.2-72.8] and 65.0% [95%CI: 40.8-84.6]) for RoR. None of Clermont score, CRP or FC predicted QoL.

Conclusions: DWI has inadequate sensitivity and specificity for RoR at one year. There is no significant incremental prognostic value of DWI over CRP and FC to predict RoR and/or QoL at one year.

Advances In Knowledge: Early post-induction DWI has no prognostic value for RoR at one year.