During a CT scan of the body, the area being studied is positioned inside a cylinder that is part of the CT scanner. The cylinder can tilt and the X-ray scanning devices within it can rotate to obtain the views needed. CT scanning can be used to obtain information about almost any body organ (such as the liver, pancreas, intestines, kidneys, adrenal glands, lungs, and heart), blood vessels, the abdominal cavity, bones (especially of the spine), and the spinal cord. For more information about CT scanning of the brain and skull, see the medical test CT Scan of the Head and Face. For more information about spinal CT, see the medical test CT Scan of the Spine.
A dye that contains iodine (contrast material) is often injected into the blood (intravenously) during a CT scan of the body. The dye makes blood vessels and certain structures or organs inside the body more visible on the CT scan pictures. The dye may be used to evaluate blood flow, detect some types of tumors, and locate areas of inflammation. Intravenous contrast material is often used to obtain images of the chest, abdomen, and pelvis. If an abdominal CT scan is done, a contrast material is usually given by mouth (orally).
Why It Is Done
CT scans are used to study many areas of the body, including the:
- Chest (thorax): A CT scan of the chest can detect infection, lung cancer, pulmonary embolism, and a bulge in a blood vessel (aneurysm). It can also be used to help determine whether cancer has spread (metastasized) into the chest from other locations in the body.
- Abdomen: A CT scan of the abdomen can help detect several conditions, including cysts, abscesses, infection, tumors, an aneurysm, enlarged lymph nodes, foreign objects, bleeding into the abdominal cavity, diverticulitis, inflammatory bowel disease, and appendicitis. It can also help determine whether cancer has spread from another place in the body to abdominal organs or lymph nodes.
- Urinary tract: A CT scan can detect kidney stones, blockage, abnormal growths, infection, structural problems, and some diseases of the urinary tract.
- Liver: A CT scan can detect liver tumors, bleeding from the liver, and some liver diseases. It can also help determine the cause of jaundice.
- Pancreas: A CT scan can detect a tumor in the pancreas or inflammation of the pancreas (pancreatitis).
- Gallbladder and bile ducts: A CT scan can be used to investigate blockage of the bile ducts. Gallstones occasionally show up on a CT scan, but an ultrasound test is usually used to detect gallstones.
- Adrenal glands: A CT scan can detect tumors in the adrenal glands.
- Spleen: A CT scan can be used to evaluate injury to the spleen.
- Spine and spinal bones (vertebrae): A CT scan can detect tumors, injuries, deformities, narrowing of the spinal canal (spinal stenosis), and other problems of the spine. The test can also identify a ruptured (herniated) disc of the spine and help determine if thinning of the bones (osteoporosis) is severe and affecting the spine. For more information, see the medical test CT Scan of the Spine.