A gallium scan is a nuclear medicine imaging test that uses a special camera to look for areas of inflammation or infection in the body and take images of specific tissues in the body.
Several days before the test is performed, a radioactive (radiopharmaceutical) isotope or tracer called gallium citrate Ga 67 is injected into the body via a vein in the arm. Over the next 2-3 days, the tracer travels through the body and builds up in locations where there is a build-up of white blood cells.
Areas of inflammation or rapidly dividing cells show up especially well because they “take up” more gallium than normal tissue.
Why a Gallium Scan is Done
Positron emission tomography (PET) scans are being used more frequently these days to evaluate cancers, so gallium scans are not done very often. A gallium scan may be done, however, if a PET scan is not available.
A gallium scan is done to find areas of infection or inflammation in the body when a person has an unexplained fever; detect infection or inflammation in the lung or mediastinum (the space in the chest between the lungs), especially in people whose immune systems are not working well (immunosuppression); evaluate and monitor certain infections or inflammatory diseases (such as tuberculosis.
Gallium Scans may also be done to diagnose and stage certain cancers – lymphoma, lung, osteosarcoma, Ewing sarcoma, soft tissue sarcoma, and rhabdomyosarcoma. It can also evaluate how well cancer treatment is working
Performing the Procedure
The scan is usually done as an outpatient procedure in the nuclear medicine department of a hospital. An individual booked to have a scan may be asked to wear clothing that has no metal zippers, belts or buttons. They may be asked to change into a gown during the test and remove glasses, jewellery or objects that could interfere with the test.
An enema may be given before the scan to prevent stool from interfering with the test; a laxative may be given the night before or an enema may be given 1–2 hours before the test. The enema may be uncomfortable, but does not cause pain.
Check with the nuclear medicine department to see if there are any other special instructions to follow before the test.
The gallium scan has 2 stages: the gallium is given by injection, and then the person is scanned with a camera that detects gallium.
Giving the Gallium
A small amount of gallium is injected into a vein in the hand or arm. The gallium travels through the blood and spreads throughout the body. Giving the gallium usually takes about 15 minutes.
Taking the Gallium Scan
Scans are taken at a specified time, usually 24, 48 or 72 hours after the injection. The scan usually takes 1–1.5 hours.
The person lies very still on a narrow table. A safety belt may be used to strap the person to the table. One can breathe normally during the scan but may be asked to move into different positions while some images are taken.
Scanning may involve several close-up views of certain parts of the body or the entire body may be scanned, which means that the large scanning camera may come very close to the body to take images. The camera does not produce any radiation.
After the scan, the gallium quickly loses its radioactivity. It passes out of the body through the urine or stool (faeces). Depending on the type of radiopharmaceutical used, it may take a few hours or days to completely pass out of the body.
Drinking fluids after the procedure helps flush the radiopharmaceutical from the body. Special instructions may be given to take special precautions after urinating, to flush the toilet twice and to wash the hands thoroughly.
Potential Side Effects
The dose of x-rays or radioactive materials used in nuclear medicine imaging can vary widely. Dose depends on the type of procedure and body part being examined. In general, the dose of radiopharmaceutical given is small and people are exposed to low levels of radiation during the test. The potential health risks from radiation exposure are low compared with the potential benefits. There are no known long-term adverse effects from such low-dose exposure.
Some potential side effects that might occur include:
- Bleeding, soreness or swelling may develop at injection site.
- Allergic reactions to the radiopharmaceutical may occur, but are extremely rare.
Special Considerations for Children
Being prepared for a test or procedure can reduce anxiety, increase cooperation and help your child develop coping skills. Parents or caregivers can help prepare children by explaining to them what will happen, including what they will see, feel and hear during the test.
Explain to your child that when the gallium is given they will feel a sharp prick when the needle is inserted then some slight pressure or tugging when the gallium is injected.
Check with the doctor to find out if food or liquids are restricted before the scan.
Children need to lie still on the exam table during the scan, which may be unpleasant for them. Some children may need sedation to lie still for the whole test. Some children may like to hold a special toy or blanket during the scan or listen to music or a story during the scan.
You can stay with your child while they have their scan to calm them and help them lie very still. Pregnant women cannot stay in the room during the scan.
If your child feels closed-in when the scanner passes over their body, reassure them that the scan does not hurt and will not last very long.
Instructions may be given for special precautions that need to be taken when caring for children during the first 6–24 hours after the test:
- If the caregiver is pregnant, someone else should do most of the child care.
- Wear disposable, waterproof gloves when handling the child’s urine, stool or vomit, including diaper changes.
- Change sheets or clothing that has vomit, urine or stool smears on it. Wear disposable, waterproof gloves when handling sheets or clothing. Sheets and clothing can be washed in the regular laundry.
- Flush the toilet immediately after use by the child.
- Place diapers in the outside garbage.