Medical Content Created by the Faculty of the
Harvard Medical School
CT scans are pictures taken by a specialized x-ray machine. The machine circles your body and scans an area from every angle within that circle. The machine measures how much the x-ray beams change as they pass through your body. It then relays that information to a computer, which generates a collection of black-and-white pictures, each showing a slightly different "slice" or cross-section of your internal organs. Because these "slices" are spaced only about a quarter-inch apart, they give a very good representation of your internal organs and other structures. Doctors use CT scans to evaluate all major parts of the body, including the abdomen, back, chest, and head.
A CT scan is an excellent way to view the organs inside your abdomen. It is especially useful for looking at solid organs, such as the liver, pancreas, spleen, kidneys, and adrenal glands. It is also excellent for viewing the large blood vessels that pass through the abdomen (the aorta and vena cava) and for finding lymph nodes in the abdomen. Organs that can change their shape when they are empty or full, such as stomach and intestines, are harder for a CT scan to evaluate well, because it is sometimes difficult for a doctor to tell for sure if they are abnormal. Often the CT can give some information about these organs, though. Abdominal CT scans are often used to look for signs of inflammation or infection inside the abdomen in different organs, to look for cancer, or to look for injury to one or another internal organ.