Jonathan Russell Dillman MD, Presenter: Research support, Bracco Group Research support, General Electric Company Research support, Siemens AG

Ryan W. Stidham MD, Abstract Co-Author: Research funded, Siemens AG

Peter Higgins MD, Abstract Co-Author: Nothing to Disclose

David Moons, Abstract Co-Author: Nothing to Disclose

Laura Johnson BS, Abstract Co-Author: Nothing to Disclose

Jonathan Matthew Rubin MD, PhD, Abstract Co-Author: Equipment support, ZONARE Medical Systems, Inc Research Grant, General Electric Company Equipment support, General Electric Company Equipment support, Koninklijke Philips Electronics NV Consultant, Koninklijke Philips Electronics NV

To determine if acoustic radiation force impulse (ARFI)-derived bowel wall shear wave velocity (SWV) can discriminate inflamed from fibrotic bowel segments in a well-established Crohn disease animal model.

This study was approved by our institutional Committee on the Use and Care of Animals. Lewis rats underwent intra-rectal administration of trinitrobenzenesulfonic acid (TNBS). An acute colitis (inflammation) model of Crohn disease was produced by a single TNBS enema, and animals were imaged 2 days following treatment (n=6). Colonic fibrosis was achieved by repeated weekly TNBS enemas over a 4-week period, and animals were imaged 7 days following treatment after resolution of acute inflammation (n=7). Nine bowel wall SWV measurements (Virtual Touch Tissue IQ/modified S2000 ultrasound machine/9L4 transducer; Siemens Medical Solutions, USA–Issaquah, WA) were obtained from the rectosigmoid junction of the colon in all rats without and with applied strain to the anterior abdominal wall (≤40% applied strain). Mean bowel wall SWVs were compared between the two animal groups without and with applied strain, and the ratio of SWV to applied strain (SWVR) also was used to differentiate between inflamed and fibrotic rat intestine.

Mean bowel wall SWVs were significantly higher for fibrotic vs. acute inflammation cohort rats at 0% (3.42 vs. 2.30 m/s; p=0.047) and 30% (6.27 vs. 3.61 m/s; p=0.021) applied strain. Both acute inflammation and fibrotic cohort rats demonstrated a linear increase in mean SWVs to applied strain, with no overlap of the 95% confidence intervals (see graph) despite one outlier rat in the fibrotic cohort that did not develop bowel wall fibrosis. The mean slopes (p=0.049) of these linear relationships were significantly different, and y-intercepts nearly so (p=0.079). The c-statistic of the SWVR for differentiating inflamed from fibrotic bowel was 0.818.

Intramural SWV can be used to accurately distinguish inflamed from fibrotic bowel segments in the rat TNBS model of Crohn disease.

Increased bowel wall shear wave velocity correlates with tissue fibrosis in an animal model of Crohn disease, a finding that may allow noninvasive characterization of intestinal strictures in humans.

Dillman, J, Stidham, R, Higgins, P, Moons, D, Johnson, L, Rubin, J, Intramural Shear Wave Velocity Discriminates Inflamed from Fibrotic Bowel Segments in a Crohn Disease Animal Model.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043562.html