Computed tomography (CT) colonography or virtual colonoscopy uses special x-ray equipment to examine the colon and detect abnormalities such as polyps and cancer. CT colonography is used to examine the colon and rectum, and detect abnormalities such as polyps and cancer. Polyps are growths in the lining of the colon that protrude into the intestinal canal can be identified and tested to determine whether they are completely benign or potentially malignant.
During the exam, a small tube is inserted a short distance into the rectum to allow for inflation with air while CT images are taken. CT colonography, also known as virtual colonoscopy, uses low dose radiation CT scanning to obtain an interior view of the colon (the large intestine) that is otherwise only seen with a more invasive procedure where an endoscope is inserted into the rectum and passed through the entire colon.
Conventional colonoscopy and double contrast barium enema are the main methods currently used for examining the entire colon. The bowel must be empty before either of these procedures is performed. In contrast, CT colonography is less invasive than a conventional colonoscopy. It involves using a CT scanner to produce 2- and 3-dimensional images of the entire colon and rectum.