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A gallium scan is a nuclear medicine imaging test that uses a radioactive isotope (radiopharmaceutical) called gallium citrate Ga 67 to look for areas of inflammation or infection in the body. A special camera takes images of the body’s tissues. 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 to evaluate cancers, so gallium scans are not done very often. However, a gallium scan may be done if 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)
- diagnose and stage certain cancers
- Ewing sarcoma
- soft tissue sarcoma
- evaluate how well cancer treatment is working
How a gallium scan is done
The scan is usually done as an outpatient procedure in the nuclear medicine department of a hospital.
- It is important for a woman to tell the nuclear medicine staff if she is breast-feeding, pregnant or thinks she may be pregnant before having any nuclear medicine test.
- The person 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.
- 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.
- The person may breathe normally during the scan.
- The person may be asked to move into different positions while some images are taken.
- A large scanning camera will come close to the person’s body and take images.
- The camera does not produce any radiation.
- Scanning may involve several close-up views of certain parts of the body or the entire body may be scanned.
After the scan, the gallium quickly loses its radioactivity. It passes out of the body through the urine or stool (feces). It may take a few hours or days for the gallium to completely pass out of the body.
- Drinking fluids after the procedure helps flush the radiopharmaceutical from the body.
- Instructions may be given for special precautions that need to be taken after urinating, such as 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.
What the results mean
The special camera detects areas where gallium normally builds up, including bones, liver, spleen, large intestine and breast tissue. Other areas of increased uptake of gallium may indicate:
- active infection or inflammation
- certain types of cancer
- other medical problems
Not all cancers show up on a gallium scan. Other tests are often needed to determine whether an area of increased uptake of gallium is non-cancerous (benign) or cancerous (malignant). Recent blood transfusions, chemotherapy and radiation therapy may affect the distribution of gallium in the body.
What happens if a change or abnormality is found
The doctor will decide whether further tests, procedures, follow-up care or additional treatment are needed.
Special considerations for children
Being prepared for a test or procedure can reduce anxiety, increase cooperation and help the 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.
- Check with the doctor to find out if food or liquids are restricted before the scan.
- Explain to children that when the gallium is given they will feel:
- a sharp prick when the needle is inserted
- slight pressure or tugging when the gallium is injected
- 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.
- Children could listen to music or a story during the scan.
- The parent or caregiver can stay with the child and help them lie very still.
- Reassure children that what they see and hear is normal.
- They may hear a clicking noise during the scan.
- The camera may touch their skin, but it will not hurt.
- Some children feel closed-in when the scanner passes over their body. Let them know that the scan will not take 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 the child uses it.
- Place diapers in the outside garbage.
The preparation for a gallium scan depends on the age and experience of the child. Find out more age-specific information on helping children cope with tests and treatment.