Ultrasound Shear Wave Elastography Helps Discriminate Low‐grade From High‐grade Bowel Wall Fibrosis in Ex Vivo Human Intestinal Specimens

Abstract

OBJECTIVES: To determine whether bowel wall fibrosis can be detected in freshly resected human intestinal specimens based on ultrasound-derived shear wave speed. METHODS: Seventeen intact (>3-cm) bowel segments (15 small and 2 large intestine) from 12 patients with known or suspected inflammatory bowel disease were procured immediately after surgical resection. Ultrasound shear wave elastography of the bowel wall was performed by two methods (Virtual Touch Quantification [VTQ] and Virtual Touch-IQ [VT-IQ]; Siemens Medical Solutions USA, Inc, Mountain View, CA). Eighteen short-axis shear wave speed measurements were acquired from each specimen: 3 from the 9-, 12-, and 3-o'clock locations for each method. Imaging was performed in two areas for specimens greater than 10 cm in length (separated by ≥5 cm). A gastrointestinal pathologist scored correlative histologic slides for inflammation and fibrosis. Differences in mean shear wave speed between bowel segments with low and high inflammation/fibrosis scores were assessed by a Student t test. Receiver operating characteristic curve analysis was performed. RESULTS: High-fibrosis score (n = 11) bowel segments had a significantly greater mean shear wave speed than low-fibrosis score (n = 6) bowel segments (mean ± SD: VTQ, 1.59 ± 0.37 versus 1.18 ± 0.08 m/s; P= .004; VT-IQ, 1.87 ± 0.44 versus 1.50 ± 0.26 m/s; P= .049). There was no significant difference in mean shear wave speed between high-and low-inflammation score bowel segments (P > .05 for both VTQ and VT-IQ). Receiver operating characteristic curves showed areas under the curve of 0.91 (95% confidence interval, 0.67-0.99) for VTQ and 0.77 (95% confidence interval, 0.51-0.94) for VT-IQ in distinguishing low-from high-fibrosis score bowel segments. CONCLUSIONS: Ex vivo bowel wall shear wave speed measurements increase when transmural intestinal fibrosis is present.