A gallium scan is a nuclear medicine test that can check for problem areas in certain tissues in your body.
A radioactive tracer (tracer) called gallium citrate is injected into a vein in your arm. It moves through your bloodstream and into certain tissues. These tissues include your bones, liver, and intestine, and areas that are inflamed or have a buildup of white blood cells. After the tracer builds up in your body, a special camera takes pictures. The pictures show the areas where the amount of tracer is higher than normal. These areas are called hot spots.
It often takes the tracer a few days to build up. So the pictures (scans) are usually taken at 2 days and again at 3 days after you get the tracer. The tracer stays in you until your body gets rids of it through urine or stool (feces).
Why It Is Done
A gallium scan is done to:
- Find the source of an infection that is causing a fever.
- Look for an abscess or certain infections, especially in the bones.
- Check the response to antibiotic treatment.
- Diagnose inflammatory problems such as pulmonary fibrosis or sarcoidosis.
- Find certain types of cancer (such as lymphoma). The scan also may be done to see if cancer has spread (metastasized) to other areas of the body. Or it may check how well a cancer treatment is working.
How To Prepare
Before this test, tell your doctor if:
- You are or might be pregnant.
- You are breastfeeding.
- If you plan to no longer feed your baby your breast milk after the test, stop breastfeeding 2 weeks before the test. The radioactive tracer will not build up in your breast tissue.
- If you will continue to breastfeed after the test, talk with your doctor about how long to wait to use your milk after the test. Many doctors suggest waiting 4 weeks before you give your breast milk to your baby. This is because the tracer can pass to your baby. Some doctors may advise you to stop breastfeeding completely after this scan.
- Within the 4 days before the scan, you have:
- Had an X-ray test using barium contrast material. This includes a barium enema.
- Taken a medicine that contains bismuth, such as Pepto-Bismol.
Barium and bismuth can affect the test results.
Gallium builds up in the large intestine before your body gets rid of it as stool. So you may need to take a laxative the night before the scan. You may also need an enema 1 to 2 hours before the scan. This is to help your doctor more clearly see the areas of your body that are being studied.
Talk to your doctor about any concerns you have about the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form( What is a PDF document? ).
How It Is Done
The technologist will clean a site on your arm and then inject a small amount of radioactive tracer. You will need to come back for the scans. Gallium scans are usually done 24 hours (1 day), 48 hours (2 days), and 72 hours (3 days) after the tracer is injected.
When you come in for the scan, you may need to remove your jewelry. You may also need to take off all or most of your clothes. It depends on which area is being examined. You will be given a cloth or paper to cover yourself during the test.
You will lie on your back on a table. A large camera will be close above you. The camera will scan for radiation released by the tracer. It will make pictures of the tracer in your tissues. The camera may move slowly above and around your body. The camera does not produce any radiation, so you are not exposed to more radiation while the scan is being done.
You may be asked to move into different positions so the area of interest can be viewed from other angles. You need to lie very still during each scan to avoid blurring the pictures. You may be asked to hold your breath briefly during some of the scans.
Each scan may take about 60 to 90 minutes.
How It Feels
You may feel nothing at all from the needle puncture when the tracer is injected. Or you may feel a brief sting or pinch as the needle goes through the skin. Otherwise, a gallium scan usually causes no pain. You may find it hard to stay still during the scan. Ask for a pillow or blanket to make yourself as comfortable as you can before the scan begins.
Allergic reactions to the tracer are rare.
Your injection site may swell or be sore. To get relief, you can apply a moist, warm compress to your arm.
Anytime you're exposed to radiation, there's a small chance of damage to cells or tissue. That's the case even with the low-level radioactive tracer used for this test. But the chance of damage is very low compared with the benefits of the test.
Most of the tracer will leave your body through your urine or stool within a day. So be sure to flush the toilet right after you use it, and wash your hands well with soap and water. The amount of radiation in the tracer is very small. This means it isn't a risk for people to be around you after the test.
A gallium scan is a nuclear medicine test. A special camera takes pictures of certain tissues in the body after a radioactive tracer makes the tissues able to be seen. The test results are usually ready within 2 days after you had the scans.
The collection and activity of gallium in the bones, liver, spleen, and large intestine is normal. No areas of unusual amounts of gallium are seen.
An abnormally high amount of gallium (hot spot) is present in one or more areas of the body. This could mean inflammation, infection, or a tumor.
What Affects the Test
You may not be able to have the test, or the results may not be helpful, if:
- You are pregnant. A gallium scan is not usually done during pregnancy because the radiation could harm the baby (fetus).
- You have barium or bismuth in your system. If a gallium scan is needed, it should be done before any tests that use barium (such as a barium enema). Taking a medicine (such as Pepto-Bismol) that contains bismuth can also affect the test.
- You can't stay still during the test.
What To Think About
- A gallium scan is used for certain types of cancers. Mainly it's for cancers of the lymph nodes, bones, or bone marrow. A normal scan does not rule out the possibility of cancer, though. That's because some types of cancer don't show up on a gallium scan. This type of scan also can't tell if a tumor is cancerous (malignant) or noncancerous (benign).
- Your doctor will interpret the results of the scan along with the results of other tests, such as a physical exam, blood tests, and X-rays. In many cases, results from an MRI test or positron emission tomography (PET) scan may be as accurate as the results from a gallium scan.
- If other nuclear scanning tests need to be done, they should be scheduled before a gallium scan. This is because the gallium tracer stays in the body longer than other tracer compounds.
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.