Computed tomography colonography: a well-known but poorly utilized screening method.

Abstract

Radiol Bras. 2014 Mai/Jun;47(3):V–VI Malignant colon neoplasm is the third cause of death for cancer in the United States of America. Many of such deaths could be avoided with the introduction of an effective screening schedule. The ideal screening test is the one that allows for an early diagnosis and, consequently the management of the disease at its early stages. The effectiveness of a screening test depends on three factors, namely: 1) the disease must be common; 2) early detection of the disease; 3) acceptance of the test by the patient. Different factors predispose to large bowel neoplasia: 1) family history of disease or large adenomatous polyp (diagnosed before the age of 60); 2) inflammatory bowel disease; 3) family history of adenomatous polyposis or nonpolypoid hereditary colorectal cancer syndromes; 4) previous history of adenomatous colon polyps. Despite the existence of specific predisponent conditions, in approximately 75% of cases it is not possible to identify a specific risk factor. Before the introduction of computed tomography colonography (CTC), several screening tests were available to detect colon polyps or neoplasms, namely, fecal occult blood test, rectosigmoidoscopy, a combinations of the mentioned methods, double contrast barium enema and colonoscopy. In 2008, the American Cancer Society, in association with the US Multi-Society Task Force on Colorectal Cancer (representing the three major American gastroenterological societies – American Society of Gastroenterology, American College of Gastroenterology, and American Society of Endoscopy) and the American College of Radiology placed CTC as a screening test for colorectal carcinoma (CRC) in association with colonoscopy, as a modality for primary prevention and early detection. Virtual colonoscopy or CTC is a relatively recent investigation method, initially described in 1994 amongst the available options for screening CRC. It is a minimally invasive computed tomography (CT) modality utilizing low radiation doses,