Background: Mucosal healing is hitherto the most popular therapeutic endpoint in Crohn's disease (CD) and is currently defined as no endoscopic ulcers. Magnetic resonance imaging (MRI)is an accurate examination for assessing activity in CD. To date, magnetic resonance index of activity (MaRIA) and Clermont score (CS) are the two main MRI indices available in grading CD severity.
In the present study, we aimed to compare the performances of Clermont score  and MaRIA  in assessing mucosal healing in CD.
Methods: In this prospective study, all the patients underwent consecutively magnetic resonance entero-colonography (MREC) including diffusion-weighted sequences with no bowel cleansing and with no rectal enema, and colonoscopy (with CDEIS and SES-CD calculation) within 4 weeks (mean interval=17±11 days). Radiologists were blinded from endoscopic findings and endoscopists were blinded from radiologic findings.
Results: Overall, 44 CD patients were included (Table 1).
Considering the 194 segments (ileum=37, colorectal=159), CS correlated with segmental CDEIS (0.48; p<0.001) and segmental SES-CD (0.44; p<0.001). MaRIA correlated also with segmental CDEIS (0.48; p<0.001) and segmental SES-CD (0.45; p<0.001). According to the established cut-off values i.e. MaRIA >7 and CS >8.4, the sensitivity of each index was 0.53 and 0.56, and the specificity was 0.80 and 0.82, respectively. The sensitivity for detecting deep ulcerations was 0.90 and 0.91 for the MaRIA and Clermont indices, respectively, with a specificity of 0.79 and 0.80.
Taking into account the 44 included patients, deep MRI remission predicted mucosal healing with sensitivity=0.60,specificity=0.76 and negative predictive value=0.85 according to Barcelona criteria (no segmental MaRIA >7), and sensitivity=0.50, specificity=0.88 and negative predictive value=0.86 according to Clermont criteria (no Clermont score >8.4). In addition, MRI remission predicted mucosal healing with sensitivity=0.50, specificity=0.85 and negative predictive value=0.85 according to Barcelona criteria (no segmental MaRIA >11), and sensitivity=0.50, specificity=0.80 and negative predictive value = 0.84 according to Clermont criteria (no Clermont score >12.5).
Conclusions: MaRIA and Clermont score are equally effective in detecting endoscopic ulcerations in Crohn's disease. Accordingly, MRI remission or deep MRI remission defined according to Barcelona or Clermont criteria are highly predictive of mucosal healing supporting their use in clinical trials and daily practice.
 Hordonneau et al., (2014), Am J Gastroenterol
 Rimola et al., (2009), Gut