Correlation and Assessment of Small Bowel Lesions Using Cross-Sectional Imaging Techniques Compared With Small...

Guidelines endorse intestinal ultrasound (IUS) for small bowel (SB) Crohn's disease (CD) monitoring but lack clarity on when to use magnetic resonance enterography (MRE) or computed tomography enterography (CTE). Small intestinal contrast ultrasound (SICUS) may improve detection, yet its added value-especially for proximal disease and treatment decisions-has not been prospectively validated against MRE/CTE in real-world settings.

This prospective study at a high-volume tertiary gastroenterology center recruited established patients with CD (18-75 years) requiring SB evaluation. The accuracy of IUS followed by SICUS was assessed against CTE/MRE (within 24-48 hours) for detecting activity, extent, bowel wall thickness, length, complications, and treatment impact.

A total of 407 patients (median age 36 years; 60.2% male) underwent IUS/SICUS followed by CTE (n = 215) or MRE (n = 192). SICUS showed sensitivity/specificity of 95.3%/93.0% for disease activity and 90.7%/90.5% for extent. It significantly improved stricture detection over IUS (86.8% vs 71.3%, P = 0.0005), with sensitivity of 91.7% for fistulas and 87.5% for abscesses. SICUS correlated strongly with CTE/MRE for bowel wall thickness (Spearman rho, R = 0.667) and disease length ( R = 0.839) ( P < 0.001). Most missed lesions (n = 17) and strictures (n = 22) were in the proximal/mid-SB. Cross-sectional imaging changed management in 9.3% (n = 38), mainly for surgical planning, therapy escalation, or stricture intervention.

IUS is a highly accurate, noninvasive tool for monitoring SB CD, with SICUS enhancing stricture detection. Although CTE/MRE remains essential for evaluating proximal and mid-SB disease and surgical planning, the limited overall incremental impact support a scalable, ultrasound-first approach (ClinicalTrials.gov: NCT06125678).