Detecting inflammation in inflammatory bowel disease — how does ultrasound compare to magnetic resonance enterography using standardised scoring systems?

Background Magnetic resonance enterography (MRE) is the current gold standard for imaging in inflammatory bowel disease, but ultrasound (US) is a potential alternative. Objective To determine whether US is as good as MRE for the detecting inflamed bowel, using a combined consensus score as the reference standard. Materials and methods We conducted a retrospective cohort study in children and adolescents <18 years with inflammatory bowel disease (IBD) at a tertiary and quaternary centre. We included children who underwent MRE and US within 4 weeks. We scored MRE using the London score and US using a score adapted from the METRIC (MR Enterography or Ultrasound in Crohn’s Disease) trial. Four gastroenterologists assessed an independent clinical consensus score. A combined consensus score using the imaging and clinical scores was agreed upon and used as the reference standard to compare MRE with US. Results We included 53 children. At a whole-patient level, MRE scores were 2% higher than US scores. We used Lin coefficient to assess inter-observer variability. The repeatability of MRE scores was poor (Lin 0.6). Agreement for US scoring was substantial (Lin 0.95). There was a significant positive correlation between MRE and clinical consensus scores (Spearman’s rho = 0.598, P =0.0053) and US and clinical consensus scores (Spearman’s rho = 0.657, P =0.0016). Conclusion US detects as much clinically significant bowel disease as MRE. It is possible that MRE overestimates the presence of disease when using a scoring system. This study demonstrates the feasibility of using a clinical consensus reference standard in paediatric IBD imaging studies.