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.