Virtual colonoscopy or computed tomographic (CT) colonography is a recent radiological technique enabling detection of tumoral lesions in the colon. As in the past two decades its radiological predecessor, double-contrast barium enema (DCBE), has lost most of its adherents, CT colonography constitutes a real opportunity for gastrointestinal radiologists to play a preponderant role in the diagnosis and treatment of colorectal
cancer and the adenoma. Since its introduction by David Vining in 1994, CT colonography has very rapidly shown its virtues as a possible substitute for DCBE. The first important study on CT colonography by Helen Fenlon from the Boston Medical Center, published in 1999 in the New England Journal of Medicine, reporting very good lesion detection, underscored this aspiration. Since then CT colonography has dramatically evolved by the refi nement of existing techniques and the introduction of new ones: faecal tagging with the option of reducing the cathartic or laxative part of the preparation, the use of carbon dioxide to infl ate the colon, the introduction of multi-detector CT scanners producing spectacular images with isotropic resolution and reducing the examination time for the patient, the use of ultra-low-dose scan protocols reducing the radiation burden, improvement of the image post-processing with fast three-dimensional functions, and computer-aided diagnosis (CAD). These technical improvements help both the radiologist and the patient. For the former there is an improvement of the reading conditions, possibly improving diagnostic accuracy; for the latter the preparation and examination are more comfortable.