RESUMO
Colorectal cancer remains one of the most common causes of cancer death in this country. This malignancy is ideally suited for screening because the detection and removal of the precursor adenomatous polyp can prevent most colorectal cancers from ever forming. The choice of a test for screening involves consideration of various individual parameters, including patient age and the presence of risk factors for the development of colorectal cancer. Computed tomographic colonography (CTC) has emerged as the leading imaging technique for colorectal cancer screening in average-risk individuals on the basis of the evidence presented in this paper. The double-contrast barium enema is an alternative imaging test that is appropriate particularly when CTC is not available. In 2008, the American Cancer Society guideline for colorectal cancer screening was revised jointly with the US Multi-Society Task Force on Colorectal Cancer and the ACR to include CTC every 5 years as an option for average-risk individuals. Computed tomographic colonography is also the preferred test for colon evaluation after an incomplete colonoscopy. Imaging tests including CTC and the double-contrast barium enema are usually not indicated for colorectal cancer screening in high-risk patients with polyposis syndromes or inflammatory bowel disease. This paper presents the new colorectal cancer imaging test ratings and is the result of evidence-based consensus by the ACR Appropriateness Criteria Expert Panel on Gastrointestinal Imaging.