What is a Gallium Scan?
A gallium scan is a diagnostic test that looks for infection, inflammation, and tumors. Gallium is a radioactive metal, so the scan is generally performed in the nuclear medicine department of a hospital.
The gallium is mixed into a solution. It is injected into your arm and moves through your blood, collecting in your organs and bones. Your body will then be scanned to see where and how the gallium has accumulated in your body.
Although gallium is radioactive, the risk of radiation exposure from this procedure is lower than from an X-ray or CT scan. Aside from the injection, the test is painless and requires very little preparation. However, the scan takes place several hours after the gallium injection, so schedule your procedure accordingly.
Purpose of a Gallium Scan
Your doctor may order a gallium scan if he or she suspects that you have cancer or to help determine the source of unexplained pains or fever. The scan is also used as a follow-up test for patients who have been diagnosed or treated for cancer. A gallium scan of the lungs can help to diagnose of a variety of lung diseases and infections.
Preparation for a Gallium Scan
There is no need to fast and—aside from the gallium—no other medications are required for this test. In some cases, you may need to use a laxative or an enema to clear your bowels before the scan so that stool does not interfere with the test results.
Notify your doctor if you are pregnant, think you may be pregnant, or are nursing. Tests involving radiation are not recommended for women who are pregnant or nursing and should not be performed on very young children if an alternative test is available.
How a Gallium Scan Works
This is an outpatient procedure, which means that you can go home on the day of the test.
When you arrive at the hospital, a technician will inject a gallium solution into a vein in your arm. You may feel a sharp prick and the site may be tender for a few minutes.
After the injection, you will be able to leave the hospital as the gallium begins moving through your bloodstream, collecting in your bones and organs. You will be instructed to return to the hospital at a specific time for the scan, usually between six and 48 hours after you receive the injection.
When you return, you will change in to a hospital gown, remove all jewelry and other metal, and lie on your back on a firm table. A scanner will slowly move around your body while a special camera detects where the gallium has collected in your body. The camera’s images can be viewed on a monitor.
The scanning process takes between 30 and 60 minutes. It is important that you remain completely still during the scan. The scanner does not touch you directly and the procedure is painless. Some people find the hard table uncomfortable and have trouble remaining still. If you think you will have trouble lying still, tell your doctor before the test. The doctor may give you a sedative or antianxiety medication to help.
In some instances, the scan may be repeated over the course of several days. In this case, you will not need to have additional gallium injections.
Interpreting Your Results
A radiologist will review your scans and send a report to your doctor.
Normally, the gallium will collect in your bones, liver, breast tissue, spleen, and large bowel. Gallium is taken up by cancer cells and other compromised tissues more readily than by healthy tissues. So, gallium that collects in other sites could be a sign of:
Gallium Scan of the Lungs
In a gallium scan of the lungs, your lungs should appear normal in size and texture and should have collected very little gallium. Abnormal results could indicate:
- sarcoidosis (when chronic inflammatory cells form nodules on multiple organs)
- respiratory infections
- tumors in the lung
- scleroderma of the lung (an autoimmune disease that damages vital organs)
- pulmonary embolus (an arterial blockage)
- primary pulmonary hypertension (high blood pressure in the arteries of your heart)
This test is not foolproof. It is important to note that not all cancers or small defects will show up in the gallium scan.
Is a Gallium Scan Dangerous?
There is a small risk of complications from radiation exposure, but it is less than the risk involved with X-rays or CT scans. The risk increases if you have many gallium scans over time.
Your body will eliminate the gallium naturally, though a trace amount may remain in your tissues for a few weeks.