Metaiodobenzylguanidine (MIBG) Scan
A Metaiodobenzylguanidine (MIBG) scan is a nuclear scintigraphic imaging test that uses the radiopharmaceutical metaiodobenzylguanidine (MIBG) labeled to Iodine-123 or Iodine-131 to help locate and diagnose certain types of cancer in the body.
MIBG is a substance that gathers in some tumours, particularly neuroblastoma tumours. When MIBG is combined with radioactive iodine (tracer), it provides a way to identify primary and metastatic (spread) disease.
MIBG scans are helpful for locating both bone and soft tissue tumours.
The test is performed by injecting a small amount of radioactive dye (tracer) through an IV. Pictures are then taken under a scanner that is similar to a CT scan. The scans may occur 24, 48, or 72 hours after the tracer is given. Doctors are looking for bright spots on the scan, these indicate cancer cells.
Why an MIBG Scan is Done
An MIBG scan may be done to find or confirm the presence of neuroblastoma or pheochromocytoma, which are tumours of specific types of nervous tissue.
Performing the Procedure
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 undergoing an MIBG scan will have to take a special medicine before, during and after the MIBG scan to help keep the radioactive substance out of the thyroid gland. Medicine must be taken 1–2 days before the MIBG injection and continued for 5–7 days.
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 other 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 undergoing the MIBG lies down on the narrow exam table and is asked to stay very still for the duration of the scan. A safety belt may be used to strap the person to the table.
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 makes buzzing and clicking sounds, but does not hurt and does not produce any radiation.
After the scan, the radioactive material 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.
Published on May 19, 2014
MIBG Treatment for Childhood Neuroblastoma
MIBG, called meta-iodobenzylguanidine, is a chemical that started as a blood pressure medicine. It was found to be preferentially picked up by neural crest cells which give rise to, among other things, parts of your adrenal glands. Neural crest cells can also give rise to a type of cancer called neuroblastoma. Neuroblastomas are in a class of tumors (called neuro-endocrine tumors) that will take up MIBG and can respond to treatment with MIBG. Read more about MIBG Treatment HERE
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 radiopharmaceutical is given they will feel a sharp prick when the needle is inserted then some slight pressure or tugging when the radiopharmaceutical 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 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.