CAT SCAN (CT SCAN)
Last Updated : 7/5/2010
Dr. Ira Shah
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What is a

CAT scan

?

A computerized axial tomography scan is more commonly known by its abbreviated name, CAT scan or CT scan. CAT scanning is computer generated images of various parts of the body by exposure to various electromagnetic radiations. CAT scan can identify normal and abnormal structures and thus help to find the pathology in an organ. It is also used to guide procedures such as angiography and biopsies.

How is the CAT scan done ?
CAT scanning is painless. A large donut-shaped X-ray machine takes X-ray images at many different angles around the body. These images are processed by a computer to produce cross-sectional pictures of the body. In each of these pictures the body is seen as an X-Ray "slice" of the body, which is recorded on a film. This recorded image is called a tomogram. Sometimes patients may be given a contrast to delineate the organs better. Patients with a history of allergy to iodine or contrast materials should notify their physicians and radiology staff.

Why are CAT scans done ?
CAT scans are done to see the internal structures of various parts of the body. The common areas where the CAT scan is done is the head to look for bleeds, stroke, infections and accumulation of fluid (hydrocephalus), subdural collections and abscesses. In the abdomen, assessment of tumors, lumps and abscesses including visualizing the liver, gallbladder, pancreas, spleen, aorta, kidneys, uterus, and ovaries can be detected better with CAT scan. CAT scans are also used in the chest to identify tumors, cysts, or infections that may be suspected on a chest X-ray. Draining of abscesses and needle biopsies are done with CAT scan. Thus minimal invasion can be achieved to a procedure that would need surgery routinely.

How is a CAT scan performed ?
Fluids and food are restricted for several hours prior to the CAT scan. All metallic materials and certain clothing around the body are removed because they can interfere with the clarity of the images. Patients are asked to lie down on a table and the table is slide into the center of a large donut-shaped machine which takes the X-ray images around the body. The actual procedure can take from a half an hour to an hour and a half. If specific tests, biopsies, or intervention are performed by the radiologist during CAT scanning, additional time and monitoring may be required. It is important during the CAT scan procedure that the patient minimize any body movement by remaining as still and quiet as is possible. This significantly increases the clarity of the X-ray images.

What are the

complications of a CAT scan

?

A CAT scan is a very low-risk procedure. The most common problem is an allergic reaction to intravenous contrast material. Intravenous contrast is usually an iodine-based liquid given in the vein, which makes many organs and structures, such as the kidneys and blood vessels much more visible on the CAT scan. There may be resulting itching, a rash, hives, or a feeling of warmth throughout the body and rare instances an anaphylaxis reaction that can lead to difficulty in breathing. Radiation exposure is more than that of an X-ray but still is quite safe and not known to cause any problems. However repeated CAT scans should be avoided frequently to prevent high exposure to radiation.



Contributor Information and Disclosures

Dr. Ira Shah
Consultant Pediatrician, B.J.Wadia Hospital for Children, Mumbai, India


First Created : 4/2/2001

References

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