Computed Cleansing for CT Colonography Using a Three-Material Transition Model

Virtual colonoscopy is a non-invasive technique for the detection of polyps. Currently, a clean colon is required; as without cleansing the colonic wall cannot be segmented. Enhanced bowel preparation schemes opacify intraluminal remains to enable colon segmentation. Computed cleansing (as opposed to physical cleansing of the bowels) allows removal of tagged intraluminal remains. This paper describes a model that allows proper classification of transitions between three materials: gas, tissue and tagged intraluminal remains. Using a twomaterial transition model leads to polyps that may be missed if located at these junctions or artefacts that may be misjudged as polyps. The computed cleansing effectively detects and removes the remains from the data. Inspection of the 'clean' wall is possible using common surface visualization techniques.