Noninvasive monitoring with bowel ultrasound (NIMBUS) in paediatric inflammatory bowel disease: Feasibility in a single centre.

Objectives: Bowel ultrasound (BUS) is increasingly utilised for monitoring inflammatory bowel disease (IBD), a condition with stringent treatment targets to prevent complications. This study assessed the feasibility of BUS in paediatric IBD and its correlation with established monitoring markers.

Methods: A prospective study was conducted at a specialist paediatric IBD centre, including children aged 2-18 years with IBD diagnosed via modified Porto criteria. BUS parameters were based on paediatric ultrasound scoring systems, with imaging performed by a single paediatric radiologist. Biomarker data (faecal calprotectin, C-Reactive Protein, Erythrocyte Sedimentation Rate, White Cell Count, Ferritin and Albumin), and paediatric disease activity indices were recorded at time of BUS and again after a median follow-up of 2.8 months (interquartile range 1.8-4.1). Treatment changes were recorded, and ultrasound findings were correlated with clinical outcomes and inflammatory markers.

Results: Forty patients were included, 27 with ulcerative colitis (UC) or UC-type IBD-unclassified. BUS was feasible, with 98% retention (n = 39) and 96.5% measurable parameters (301/312). Poor-quality imaging occurred in 10.3%. In UC, bowel wall thickness (BWT, rho = 0.503, p = 0.039) and loss of haustration (rho = 0.490, p = 0.039) correlated with faecal calprotectin; no correlations were found for Crohn's disease or the total cohort. Activity index scores did not correlate with BUS parameters.

Conclusions: BUS shows potential as a noninvasive tool for assessing IBD activity in paediatric patients, especially in colitis where BWT correlates with calprotectin. However, image acquisition challenges highlight the need for expertise. Further studies across diverse cohorts are necessary to establish BUS's utility in paediatric IBD monitoring.

Clinical trial registration: Clinicaltrials.gov (21/12/2022): NCT05673278, https://clinicaltrials.gov/study/NCT05673278, IRAS ID: 8497/OCT/2022, Date of first enrolment: 01/05/2023.