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Metaiodobenzylguanidine (MIBG) scan
An MIBG scan is a nuclear imaging test that uses the radiopharmaceutical metaiodobenzylguanidine (MIBG) to help locate and diagnose certain types of cancer in the body.
An MIBG scan may be done to find or confirm the presence of pheochromocytoma or neuroblastoma, which are tumours of specific types of nervous tissue.
An MIBG scan is usually done as an outpatient procedure in the nuclear medicine department of a hospital.
- It is important for women to tell the nuclear medicine staff if they are breast-feeding, pregnant or think they may be pregnant before having any nuclear medicine test.
Some special preparation is needed before the scan.
- Some medicines can interfere with the scan. Avoid taking the following medicines for 7 days before the MIBG:
- cold, cough, sinus and allergy medicines
- nasal sprays
- The person will take a special medicine before, during and after the MIBG scan.
- The medicine is either super-saturated potassium iodide (SSKI) or Lugol’s solution.
- It helps keep the radioactive substance out of the thyroid gland.
- The person starts taking the medicine 1–2 days before the MIBG injection and continues to take it for 5–7 days.
- A 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.
The MIBG scan has 2 stages: MIBG is given by injection, and then the person returns later for scans.
Giving the MIBG
The radiopharmaceutical MIBG is injected into a vein in the hand or arm.
- The radiopharmaceutical travels through the blood and collects in the body.
- Giving the MIBG usually takes 15 minutes.
Taking the MIBG scan
Scans are taken after the body has absorbed the MIBG (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 hold the person on the table.
- A large camera will come close to the person’s body and take pictures.
- Imaging may involve several close-up views, whole-body scanning or tomography.
- The camera makes buzzing and clicking sounds, but it does not hurt.
After the scan, the radioactive material quickly loses its radioactivity. It passes out of the body through the urine or stool (feces). It usually takes a few hours or days for the MIBG 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.
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.
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.
- Explain to children that when the radiopharmaceutical is given they will feel:
- a sharp prick when the needle is inserted
- slight pressure or tugging when the radiopharmaceutical is injected
- Check with the doctor to find out if food or liquids are restricted.
- 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.
- Let children know that they might hear a clicking noise during the scan.
- Some children feel closed-in when the scanner passes over their body.
- Let them know that the camera may touch their skin, but will not hurt.
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 an MIBG scan depends on the age and experience of the child. Find out more age-specific information on helping children cope with tests and treatment.