Quantified small bowel motility assessment on magnetic resonance enterography in paediatric inflammatory bowel disease - does it reflect clinical response?

Background Quantified small bowel motility assessment using cine magnetic resonance enterography (MRE) has shown promise as a biomarker in adult inflammatory bowel disease. Whether quantified motility corresponds to treatment response in paediatric inflammatory bowel disease is unknown. ObjectiveTo test whether changes in motility reflect response. Materials and methods Local ethics approval was granted for this single-institution, retrospective study. All children < 18 years with confirmed inflammatory bowel disease, who had more than one MRE between Jan 2011-Jan 2022, were included. Simplified MaRIA (sMaRIA) and motility index (quantified motility) at all terminal ileum and diseased non-terminal ileum segments were independently assessed by two radiologists each with >= 9 years' experience. Change in (Delta) motility index was compared to clinical (gastroenterologist physician's global assessment) and consensus radiological reference standard (response = decrease in sMaRIA of more than or equal to 2 points) in responders versus non-responders using the Mann-Whitney test. Sensitivity and specificity of Delta motility index more than zero were compared to decrease in sMaRIA of 2 or more points for identifying clinical response. Results Of 64 children aged 5-16, 21 out of 64 (33%) were responders, 37 out of 64 (58%) were non-responders and 6 out of 64 (9%) had inactive disease according to clinical reference standard. Delta Motility index by both radiologists was higher in responders (+ 16, + 39) than non-responders (-43, -44), P = 0.04, P = 0.01 each radiologist, respectively. Motility index was more sensitive (57% versus 24%), but less specific (67% versus 93%) than sMaRIA in identifying clinical response. Conclusion Motility index on cine MRE corresponds to clinical response, and is more sensitive at detecting response compared to sMaRIA in paediatric inflammatory bowel disease.