Gallium scan of the body

Encyclopedia of Medicine by Teresa G. Norris

A gallium scan of the body is a nuclear medicine test that is conducted using a camera that detects gallium, a form of radionuclide, or radioactive chemical substance.

Most gallium scans are ordered to detect tumors in the body or to study the liver. Gallium is known to settle in certain organs and tissues, and also to accumulate in inflamed tissues and abnormal organs. Gallium scans are sometimes used to evaluate cancer following chemotherapy or radiation therapy.

Children and women who are pregnant or breastfeeding are only given gallium scans if the potential diagnostic benefits will outweigh the risks.

The patient will usually be asked to come to the testing facility 24-48 hours before the procedure to receive the injection of gallium. Sometimes, the injection will be given within only four to six hours of the study or as many as 72 hours before the procedure. The timeframe is based on the area or organs of the body being studied.

For the study itself the patient lies very still for approximately 30-60 minutes. A camera is moved across the patient's body to detect and capture images of concentrations of the gallium. The camera does not give off radiation, but picks up signals from any accumulated areas of the radionuclide. In most cases, the patient will be lying down throughout the procedure. Back (posterior) and front (anterior) views will usually be taken, and sometimes a side (lateral) view is used. The camera may occasionally touch the patient's skin, but will not cause any discomfort. A clicking noise may also be heard throughout the procedure, but this sound is only the scanner's registering of radiation.

The intravenous injection of gallium is done in a separate appointment prior to the procedure. Generally, no special dietary requirements are necessary. However, sometimes the physician will ask that the patient have light or clear meals within a day or less of the procedure. Many patients will be given laxatives or an enema prior to the scan to eliminate any residual gallium from the bowels.

There is generally no aftercare required following a gallium scan. However, women who are breastfeeding who have a scan will be cautioned against breastfeeding for four weeks following the exam.

There is a minimal risk of exposure to radiation from the gallium injection, but the exposure from one gallium scan is generally less than exposure from x rays.

A radiologist trained in nuclear medicine or a nuclear medicine specialist will interpret the exam results and compare them to other diagnostic tests. It is normal for gallium to accumulate in the liver, spleen, bones, and large bowel.

An abnormal concentration of gallium in areas other than those where it normally concentrates may indicate the presence of disease. Concentrations may be due to inflammation or the presence of tumor tissue. Often, additional tests are required to determine if the tumors are malignant or benign.

Even though gallium normally concentrates in organs such as the liver or spleen, abnormally high concentrations will suggest certain diseases and conditions. For example, Hodgkin's or non-Hodgkin's lymphoma may be diagnosed or staged if there is abnormal gallium activity in the lymph nodes. After a patient receives cancer treatment, such as radiation therapy or chemotherapy, a gallium scan may help to find new or recurring tumors or to record regression of a treated tumor. Physicians can narrow causes of liver problems by noting abnormal gallium activity in the liver. Gallium scans also can diagnose lung diseases or a disease called sarcoidosis, in the chest.

• Books
• Fischbach, Frances T. A Manual of Laboratory and Diagnostic Tests. Philadelphia, PA: Lippincott-Raven Publishers, 1996.
• Illustrated Guide to Diagnostic Tests. Springhouse, PA: Springhouse Corporation, 1998. Organizations
• American Cancer Society. 1599 Clifton Road NE, Atlanta, GA 30329. (404) 320-3333. http://www.cancer.org.
• American College of Nuclear Medicine. P.O. Box 175, Landisville, PA 31906. (717) 898-6006.
• American Liver Foundation. 1425 Pompton Avenue, Cedar Grove NJ 07009. 1-800-GO LIVER (465-4837). http://gi.ucsf.edu/ALF/serv.html.
• Society of Nuclear Medicine. 1850 Samuel Morse Drive, Reston, VA 10016. (703) 708-9000. http://www.snm.org. Other
• A Patient's Guide to Nuclear Medicine. University of Iowa Virtual Hospital. http://www.vh.org/Patients/IHB/Rad/NucMed/PatGuideNucMed/PatGuideNucMed.html.>