digestive disorders
Colorectal Cancer Screening
Computed Tomography (CT) Colonography
 CT Colonography (virtual colonoscopy) generates two- and three-dimensional images of the colon by using a special CT scan technique. In this technique, people drink a contrast agent and their colon is inflated with gas from a tube inserted in the rectum. Viewing the high-resolution three-dimensional images somewhat simulates the appearance of regular colonoscopy, hence the name. Virtual colonoscopy may be an option for people who are unable or unwilling to undergo the regular colonoscopy procedure, but it is less accurate and highly dependent on the skill and experience of the radiologist. This test does not require sedation but still requires a thorough bowel preparation, and the inflation of the colon with gas may be uncomfortable. Additionally, unlike with regular colonoscopy, lesions cannot be removed for examination under a microscope (biopsied) during the procedure. If a polyp or cancer is found during virtual colonoscopy, a regular colonoscopy is needed to remove the polyp or biopsy the cancer. Virtual colonoscopy can show whether cancer has spread outside of the colon to the lymph nodes or liver but is not good for detecting small polyps in the colon. This test is done every 5 years. 