QUANTITATIVE SMALL BOWEL MOTILITY ASSESSMENT ON MAGNETIC RESONANCE ENTEROGRAPHY IN PEDIATRIC CROHN’S DISEASE: ASSOCIATIONS WITH CLINICAL PHENOTYPE AND SURGICAL OUTCOME

Abstract The natural history of pediatric Crohn’s disease (CD) can lead to complications such as strictures and fistulae, increasing the risk of surgery. Magnetic resonance enterography (MRE) is unique in its ability to provide anatomic and functional characterization of intestinal morphological abnormalities. Prior adult studies have linked altered small bowel motility to strictures and fibrosis, but pediatric data are limited. In addition, it is unclear if motility can predict surgical risk in children with CD. Our study aims to evaluate motility in the small bowel and its association with clinical phenotype and surgical outcome in pediatric CD and compare it to patients with irritable bowel syndrome (IBS) and healthy controls (HC). In this single-center retrospective study we included pediatric CD patients with macroscopic ileal involvement (Paris classification L1 or L3) who underwent cine-MRE from 2012-2024. The images were anonymized and uploaded to the Entrolytics.io website by Motilent. Two pediatric radiologists identified the proximal, distal, and terminal ileum on dynamic cine-MRI sequences to attain GIQuant motility scores., Clinical, laboratory and additional MRE parameters were collected. GIQuant scores were collected also for patients with IBS and HC, who had radiologically normal studies. Patients who had more than one MRE for follow up were included in a subcohort to analyze longitudinal changes in intestinal motility. Descriptive and regression statistical analysis was performed. 33 pediatric CD patients (median age 14.7 years), 38 IBS patients and 9 HC were included. In the CD cohort, 79% had L3 ileocolonic and 21% L1 ileal disease, and 24% were inflammatory, 39% stricturing and 37% both stricturing and penetrating. Ileal and ileocolonic CD patients had lower mean terminal ileum GIQuant score (148.3±94.4) than IBS (271.3±112.4) and HC (269.6±74.7) (p < 0.01), while the mean proximal ileum GIQuant score was lower in CD (293.68±106.83) vs IBS (372.31±117.89) (p < 0.05). CD patients who underwent surgery showed similar terminal ileum scores to those who did not undergo surgery (median 120.3 (IQR (87.1-145.5)) vs 130.7(111.5-221.7)) but more frequently had mesenteric fatty proliferation (79% vs 29%). GIQuant scores did not differ significantly between complicated phenotypes (B2 or B2/B3) and inflammatory (B1) ones. In the longitudinal analysis (n = 12), an increase in terminal ileum GIQuant correlated with an increase in albumin. Ileal motility is reduced in children with CD compared to IBS and HC, consistent with prior studies. In our cohort, motility differences across CD phenotypes and surgical outcome were minimal. Additional studies are necessary to understand how quantitative motility assessment can provide complementary information on disease characterization in pediatric CD. Figure 1:GIQuant scores in the proximal, distal and terminal ileum of children with Crohn’s disease (CD), irritable bowel syndrome (IBS) and healthy controls (HC).