Intestinal Ultrasound Measures are Strongly Correlated With Small Bowel Endoscopic Lewis Score in Active Crohn's Disease

Background: Small bowel video capsule endoscopy (SB-VCE) assesses mucosal inflammation in Crohn's disease (CD), while intestinal ultrasound (IUS) examines transmural involvement. We aimed to correlate SB-VCE with IUS in evaluating active CD and monitoring treatment response over time.

Methods: Patients with active SB-CD who initiated biologics were prospectively followed with fecal calprotectin (FC), SB-VCE, and IUS at baseline and after 14 and 52 weeks. The Lewis score (LS), Limberg index (LI), and terminal ileum bowel wall thickness (TI-BWT) were documented, and the International Bowel Ultrasound Segmental Activity Score (IBUS-SAS) was retrospectively calculated. Biochemical, endoscopic, and ultrasonographic remission were defined as FC < 150 μg/g, LS < 135, and LI < 2 + TI-BWT ≤ 3 mm, respectively. A therapeutic response for each index was defined as a 25% reduction compared to baseline.

Results: Seventy-one patients were included (median age: 30 years [23-43], 49.3% male). The median interval between SB-VCE and IUS was 3 days (0-25). Initially, the LS strongly correlated with TI-BWT (r = 0.647, P < .001), LI (r = 0.597, P < .001), and IBUS-SAS (r = 0.647, P < .001), but these correlations weakened over time (TI-BWT: r = 0.344, P = .002; LI: r = 0.471, P = .001; IBUS-SAS: r = 0.236, P = .122). Moderate agreement was found between ultrasonographic and endoscopic treatment responses (LS and TI-BWT: K = 0.51, P = .015; LS and LI: K = 0.44, P = .063), with fair agreement for remission (K = 0.27, P = .006). TI-BWT best cutoffs for mild (LS ≥ 135) and moderate-to-severe (LS ≥ 790) inflammation were 2.25 mm and 3.6 mm, respectively.

Conclusions: IUS measures are strongly correlated with VCE-inflammatory LS in active CD and may provide an assessment of endoscopic response and remission over time.