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Abstract
Colorectal cancer is one of the most frequent neoplasms in western countries with an estimated 400.000 deaths per year’s world wide. Colorectal cancer has a high prevalence and a long asymptomatic premalignant phase and readily treatable when detected early. It is therefore an inherently suitable disease for screening. (2)
Most colorectal cancers evolve from adenomatous polyps, this pathogenesis makes colorectal cancer to a large extent preventable, and thus screening for colorectal polyps with subsequent polypectomy has been shown to constitute an effective approach for decreasing the incidence of colorectal cancer.Currently, a number of methods are used to detect colorectal mass lesions (tests for occult blood in fecal material, tumor markers tests, hydrocolonic ultrasonography, single and double contrast barium enema studies and colonoscopy), however., none fulfill all of the essential requirements needed for a screening test which are, High diagnostic accuracy (particularly with regard to negative Value), low cost, high patient acceptance and compliance. This has stimulated interest in the development of cross sectional imaging as a Tool for the detection of colorectal masses. Proposed modalities include computed tomography (CT) and magnetic resonance (MR) colonography
[CT Virtual colonography], as a new technique being developed for imaging of colorectal polyps and cancer. (4)