In vivo endoluminal ultrasound biomicroscopic imaging of colon lesions in mouse models of cancer and inflammation

Colorectal cancer (CRC) is the third most common cancer in the world and the third leading cause of cancer-related mortality in United States. Most malignant tumors are cured if diagnosed and properly treated during the disease early stage. CRC risk increases in patients with inflammatory bowel disease (IBD), a chronic inflammatory condition affecting about five million people worldwide. Mice models of CRC and IBD are used to understand the pathogenic mechanisms, to establish therapeutic and preventive measures and to evaluate diagnostic tools. The development of minimally invasive tools to detect and monitor colon diseases could improve the studies in mice models for IBD and CRC. This has motivated the use endoluminal ultrasound biomicroscopy (eUBM) to image colon lesions in mice models for CRC and IBD, in vivo. An eUBM system was employed using a 40 MHz transducer attached to a microcomputer controlled front-end electronics. The transducer rotates inside a catheter and ultrasound cross-sectional colon images were obtained with the catheter inserted into the working channel of flexible bronchofiberscope. Water, injected through the catheter, was the ultrasound coupling medium. All colonic tissue layers in control mice (mucosa, muscularis mucosae, submucosa and muscularis externa) were detected by eUBM. Small adenomas and invasive adenocarcinomas were well visualized in eUBM images of CRC and IBD mouse models. All eUBM images correlated well with the post-mortem colon histology sections.