Nuclear Medicine Scans
A nuclear medicine scan is a test in which radioactive material is taken into the body and is used to create an image of a specific organ or bone.
The purpose of a nuclear medicine scan is to locate areas of impaired function in the organ or bone being scanned. Nuclear medicine scans are widely used for diagnosis and monitoring of many different conditions. In the diagnosis and treatment of cancer, nuclear medicine scans are used to identify cancerous sites, for tumor localization and staging, and to judge response to therapy.
A nuclear medicine scan is an extremely sensitive test that can provide information about the structure and function of specific parts of the body. Types of nuclear scans include bone scans, heart scans, lung scans, kidney and bladder scans, thyroid scans, liver and spleen scans, and gallbladder scans. Brain scans are done to detect malignancy.
In a nuclear medicine scan, a small amount of radioactive material, or tracer, is injected or taken orally by the patient. After a period of time during which the radioactive material accumulates in one area of the body, a scan is taken by a special radiation detector, called a radionuclide scanner. This machine produces an image of the area for analysis by the medical team.
This test is performed in a radiology facility, either in a hospital department or an outpatient x-ray center. During the scan, the patient lies on his or her back on a table, but may be repositioned to the stomach or side during the study. The radionuclide scanner is positioned against the body part to be examined. Either the camera, the table, or both, may change position during the study. Depending on the type of scan, the procedure may take anywhere from 15 to 60 minutes. It is important for the patient not to move except when directed to do so by the technologist.
The required preparation for nuclear medicine scans ranges from slight to none. The doctor may advise that certain prescription medications be discontinued before the test or that the patient not eat for three to four hours before the test. Depending on the type of test, a reference scan or specialized blood studies may be done before the scan is taken. Jewelry or metallic objects should be removed.
The patient should advise the doctor of any previously administered nuclear medicine scans, recent surgeries, sensitivities to drugs, allergies, prescription medications, and if there is a chance that she is pregnant.
No special care is required after the test. Fluids are encouraged after the scan to aid in the excretion of the radioactive material. It should be almost completely eliminated from the body within 24 hours.
The risks of nuclear medicine scans are very low. Most scans use the same or less amount of radiation as a conventional x ray and the radioactive material is quickly passed through the body. Side effects or negative reactions to the test are very rare.
A normal result is a scan that shows the expected distribution of the tracer and no unusual shape, size, or function of the scanned organ.
Depending on the tracer and technique used, the scan can identify and image particular types of tumors or certain cancers. Too much tracer in the spleen and bones, compared to the liver, can indicate potential hypertension or cirrhosis. Liver diseases such as hepatitis may also cause an abnormal scan, but are rarely diagnosed from the information revealed by this study alone.
In a bone scan, a high concentration of tracer occurs in areas of increased bone activity. These regions appear brighter and may be referred to as "hot spots." They may indicate healing fractures, tumors, infections, or other processes that trigger new bone formation. Lower concentrations
Wilson, Michael, ed. Textbook of Nuclear Medicine. New York:h5Raven Press, 1998.
Society of Nuclear Medicine. 1850 Samuel Morse Dr., Reston, Virginia 20190. (703) 708-9000. Fax (703) 708-9015. <http://www.snm.org>.
Virtual Hospital: Iowa Health Book: Diagnostic Radiology: Patient's Guide to Nuclear Medicine. 25 Mar. 2001. 27 June 2001. <http://www.vh.org/Patients/IHB/Rad/NucMed/PatGuideNucMed/PatGuideNucMed.html>.
Ellen S. Weber, M.S.N.
Paul A. Johnson, Ed.M.
—A radioactive, or radiation-emitting, substance used in a nuclear medicine scan.
QUESTIONS TO ASK THE DOCTOR
- How long will my scan take?
- How long will the tracer stay in my body?
- Will repeat scans be necessary?