Quantitative assessment of terminal ileum motility on MR enterography in Crohn disease: a feasibility study in children.

Objectives: Investigate the relationship between quantified terminal ileal (TI) motility and histopathological activity grading, Crohn Disease MRI Index (CDMI) and faecal calprotectin.

Methods: Retrospective review of children with Crohn disease or unclassified inflammatory bowel disease, who underwent MR enterography. Dynamic imaging for 25 patients (median age 12, range 5 to 16) was analysed with a validated motility algorithm. The TI motility score was derived. The primary reference standard was TI Endoscopic biopsy Assessment of Inflammatory Activity (eAIS) within 40 days of the MR enterography. Secondary reference standards: (1) the Crohn Disease MRI Index (CDMI) and (2) faecal calprotectin levels.

Results: MR enterography median motility score was 0.17 a.u. (IQR 0.12 to 0.25; range 0.05 to 0.55), and median CDMI was 3 (IQR 0 to 5.5). Forty-three percent of patients had active disease (eAIS > 0) with a median eAIS score of 0 (IQR 0 to 2; range 0 to 5). The correlation between eAIS and motility was r = - 0.58 (p = 0.004, N = 23). Between CDMI and motility, r = - 0.42 (p = 0.037, N = 25). Motility score was lower in active disease (median 0.12 vs 0.21, p = 0.020) while CDMI was higher (median 5 vs 1, p = 0.04). In a subset of 12 patients with faecal calprotectin within 3 months of MR enterography, correlation with motility was r = - 0.27 (p = 0.4).

Conclusions: Quantified terminal ileum motility decreases with increasing histopathological abnormality in children with Crohn disease, reproducing findings in adults. TI motility showed a negative correlation with an MRI activity score but not with faecal calprotectin levels.

Key Points: • It is feasible to perform MRI quantified bowel motility assessment in children using free-breathing techniques. • Bowel motility in children with Crohn disease decreases as the extent of intestinal inflammation increases. • Quantified intestinal motility may be a candidate biomarker for treatment efficacy in children with Crohn disease.