In-vivo monitoring of acute DSS-Colitis using Colonoscopy, high resolution Ultrasound and bench-top Magnetic Resonance Imaging in Mice

Objective The aim of this study was to establish and evaluate (colour Doppler-) high-resolution-ultrasound (hrUS) and bench-top magnetic resonance imaging (btMRI) as new methods to monitor experimental colitis. Materials and methods hrUS, btMRI and endoscopy were performed in mice without colitis (n=15), in mice with acute colitis (n=14) and inmice with acute colitis and simultaneous treatment with infliximab (n=19). Results Determination of colon wall thickness using hrUS (32 MHz) and measurement of the cross-sectional colonic areas by btMRI allowed discrimination between the treatment groups (mean a vs. b vs. c – btMRI: 922 vs. 2051 vs. 1472 pix- el, hrUS: 0.26 vs. 0.45 vs. 0.31mm). btMRI, endoscopy, hrUS and colour Doppler-hrUS correlated to histological scoring (p <0.05), while endoscopy and btMRI correlated to post- mortem colon length (p<0.05). Conclusions The innovative in vivo techniques btMRI and hrUS are safe and technically feasible. They differentiate be- tween distinct grades of colitis in an experimental setting, and correlate with established post-mortem parameters. In addi- tion to endoscopic procedures, these techniques provide infor- mation regarding colonwall thickness and perfusion. Depend- ing on the availability of these techniques, their application increases the value of in vivo monitoring in experimental acute colitis in small rodents.