Computed Axial Tomography (CAT Scan)


Reviewed by Joseph Maloney, M.D.

“CAT” scans allow doctors to view bones, blood vessels and soft tissue.

Detailed Description

Computed Axial Tomography, also known as “CAT” scanning, provides detailed cross-section of various organs and other body parts, such as the lungs, liver, kidneys, pancreas, brain, spine, blood vessels, and extremities. CAT scans allow doctors to view bones, blood vessels and soft tissue. The CAT scan combines the use of a digital computer together with a rotating X-ray device. The X-ray principle governs CAT: as X-rays pass through the body, they are absorbed or weakened at different levels, creating a profile of X-ray beams of different strength. The X-ray registers on film and creates an image.

Unlike other imaging techniques such as MRI and X-ray, CAT scans can image a combination of soft tissue, bone, and blood vessels. Physicians view the CAT images on the computer monitor to look at the soft tissue, then the bone and the blood vessels, as needed. A conventional X-ray, on the other hand, can only show the dense bone structures of the head and neck and not the soft brain tissue. MRI clearly shows soft tissue and blood vessels, but gives no details of the bony structures, such as the skull. X-ray angiography of the head only depicts the blood vessels of the head and neck and not the soft-brain tissue.

CAT is the tool of choice for studying the lungs and abdomen. CAT also is useful in the diagnosis of cancer. CAT images and CAT angiography applications are also increasingly used in the diagnosis and treatment of heart disease, acute stroke, and vascular diseases. Furthermore, physicians use CAT to measure bone-mineral density for the detection of osteoporosis. All dedicated shock—trauma centers also have CAT scanners, as doctors use this application in trauma and emergency cases. Inner ear and sinus problems also are detected using a CAT scan. For many patients, the CAT is an outpatient procedure which requires no hospital stay.

Last updated: 14-Jul-09


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