Ultrasound Elasticity Imaging for Detecting Intestinal Fibrosis and Inflammation in Rats and Humans With Crohn's Disease

Abstract

Intestinal fibrosis causes many complications of Crohn's disease (CD). Available biomarkers and imaging modalities lack sufficient accuracy to distinguish intestinal inflammation from fibrosis. Transcutaneous ultrasound elasticity imaging (UEI) is a promising, noninvasive approach for measuring tissue mechanical properties. We hypothesized that UEI could differentiate inflammatory from fibrotic bowel wall changes in both animal models of colitis and humans with CD. Female Lewis rats underwent weekly trinitrobenzene sulfonic acid enemas yielding models of acute inflammatory colitis (n = 5) and chronic intestinal fibrosis (n = 6). UEI scanning used a novel speckle-tracking algorithm to estimate tissue strain. Resected bowel segments were evaluated for evidence of inflammation and fibrosis. Seven consecutive patients with stenotic CD were studied with UEI and their resected stenotic and normal bowel segments were evaluated by ex vivo elastometry and histopathology. Transcutaneous UEI normalized strain was able to differentiate acutely inflamed (-2.07) versus chronic fibrotic (-1.10) colon in rat models of inflammatory bowel disease (IBD; P = .037). Transcutaneous UEI normalized strain also differentiated stenotic (-0.87) versus adjacent normal small bowel (-1.99) in human CD (P = .0008), and this measurement also correlated well with ex vivo elastometry (r = -0.81). UEI can differentiate inflammatory from fibrotic intestine in rat models of IBD and can differentiate between fibrotic and unaffected intestine in a pilot study in humans with CD. UEI represents a novel technology with potential to become a new objective measure of progression of intestinal fibrosis. Prospective clinical studies in CD are needed.