CT Scan A CT or CAT scan is a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, organs, and blood vessels. CT scans may be done with or without contrast. "Contrast" refers to a substance injected into an intravenous (IV) line that causes the particular organ or tissue under study to be seen more clearly. Some studies require the patient to drink “Oral Contrast” prior to their exam. You may want to ask your physician about the amount of radiation used during the CT procedure and the risks related to your particular situation. It is a good idea to keep a record of your past history of radiation exposure, such as previous CT scans and other types of x-rays, so that you can inform your physician. Learn more about the tests.