The noninvasive diagnostic imaging process known as computed tomography (CT scan or CAT scan) creates horizontal, or axial, pictures of the body (commonly referred to as slices) using a mix of X rays and computer technology. Any portion of the body, including the bones, muscles, fat, organs, and blood arteries, are clearly seen in a CT scan. Compared to traditional X rays, CT scans are more detailed CT scans can be performed with or without contrast. Contrast is a chemical administered orally or injected into an intravenous (IV) line that enhances the visibility of the specific organ or tissue being studied. You might need to fast before a contrast examination for a specified amount of time.