The value of small bowel wall contrast enhancement after sulfur hexafluoride-filled microbubble injection to differentiate inflammatory from fibrotic strictures in patients with Crohn's disease

We analysed the value of contrast-enhanced ultrasound to differentiate inflammatory from fibrotic ileal strictures in patients with Crohn's disease (CD). Twenty-eight patients (17 male and 11 female; mean age ± SD, 48.5 ± 17.17 years) with a biopsy-proven diagnosis of CD were included. In each patient, the terminal ileal loop was scanned by a convex-array probe (2-5 MHz) before and after sulphur hexafluoride-filled microbubble injection. The digital cine-clip registered after microbubble injection during the first-pass dynamic enhancement was quantified in gray-scale levels by a dedicated software through manually drawn regions-of-interest (ROIs) encompassing the anterior bowel wall. Time-intensity curves from patients with inflammatory and fibrotic ileal strictures, fitted according to the theoretical gamma variate curve, were compared. Inflammatory vs. fibrotic ileal strictures differed in the percentage of maximal enhancement (45.86 ± 5.32 vs. 37.33 ± 16.24%; p < 0.05) and area under the enhancement curve (1168.25 ± 437.65 vs. 570.47 ± 323.08; p < 0.05), whereas the difference in time to peak enhancement was found not significant (9.25 ± 4.21 vs. 12.01 ± 7.34 s; p > 0.05). The quantitative analysis of small bowel wall contrast enhancement after microbubble contrast agent injection may differentiate inflammatory from fibrotic ileal strictures in patients with CD.