Baseline terminal ileal CT and MRI measurements are associated with imaging outcomes in pediatric Crohn's disease: a cohort study.

BACKGROUND

Cross-sectional imaging is increasingly used for both initial diagnosis and long-term monitoring of Crohn's disease. The quantitative morphology of the terminal ileum may predict treatment response.

OBJECTIVE

We aimed to identify baseline qualitative and quantitative imaging features that are associated with clinical and radiologic treatment response in a large cohort of children with Crohn's disease.

MATERIALS AND METHODS

This was a retrospective study of the RISK cohort study in pediatric Crohn's disease. This multicenter study included 1,136 children <18 years from 28 sites in North America. Subjects enrolled with newly diagnosed Crohn's disease who underwent endoscopy with baseline and follow-up CT or MRI were considered for this study. Exclusion criteria were incomplete data or surgical resection prior to follow-up imaging. Imaging analysis included assessing a qualitative terminal ileum (TI) categorical score based on SAR-AGA consensus definitions ((1) normal, (2) inflammation only without luminal narrowing, (3) inflammation with luminal narrowing, or (4) stricture with pre-stenotic dilation ≥3 cm) and quantitative measurements (maximum bowel wall thickness and maximum/minimum lumen diameter). Two endpoints were considered: (1) clinical response (off corticosteroids and quiescent Physician Global Assessment at follow-up imaging) and (2) CT and MRI response (follow-up imaging normalization). Multivariable logistic regression analyses were developed for each endpoint.

RESULTS

Ninety-six subjects were included. Clinical response endpoint was achieved in 38% (n=36) of participants, and imaging normalization was achieved in only 20% (n=19) of participants. Follow-up imaging showed disease progression in 24 (25%) patients, 7 (7%) of whom were radiologically normal at baseline (7%). A higher baseline TI categorical score was associated with lower odds of imaging normalization during follow-up (OR 0.4 [0.2, 0.8], P=0.009). Larger TI minimum lumen diameter (OR 1.1 [1.01, 1.3], P=0.04) and smaller maximum bowel wall thickness at baseline (OR 0.8 [0.6, 0.97], P=0.03) were associated with imaging normalization. There were no baseline imaging measurements associated with clinical response.

CONCLUSIONS

Baseline increased terminal ileal minimum lumen diameter and decreasing wall thickness were associated with imaging normalization at follow-up, but not clinical response.