Definition of MIBG scintiscan:

An MIBG scintiscan is an imaging test that uses a radioactive substance (called a tracer) and a special scanner to find or confirm the presence of pheochromocytoma and neuroblastoma, which are tumors of specific types of nervous tissue.

See also: Nuclear scan

How the test is performed:

A radioisotope (MIBG, iodine-131-meta-iodobenzylguanidine) is injected into a vein. This compound attaches to specific tumor cells.

Later that day (or the next day) you lie on a table that is positioned under the arm of the scanner. The abdomen is scanned. You may be asked to return for repeated scans for 1 - 3 days. Each scan takes 1 - 2 hours.

Before or during the test, you may be given an iodine solution to prevent the thyroid from absorbing too much of the radioisotope.

How to prepare for the test:

You must sign an informed consent form. You will be asked to wear a hospital gown. However, loose-fitting clothing may be allowed. Remove jewelry or metal objects before each scan.

How the test will feel:

There is a sharp needle prick when the material is injected. The table may be cold or hard. You must lie still during the scan.

Why the test is performed:

This test is done to confirm pheochromocytoma or neuroblastoma.

Normal Values:

There are no signs of a tumor.

What abnormal results mean:

Most often, this test is used to locate pheochromocytoma. It may be very useful to detect multiple tumors or tumors that are located outside the adrenal tissues.

Additional conditions under which the test may be performed include multiple endocrine neoplasia (MEN) II

What the risks are:

There is some exposure to radiation from the radioisotope. Because the radiation from this radioisotope is fairly high compared to most others, some precautions may be necessary for a few days after the test. Your health care provider will tell you about specific precautions, which may include flushing the toilet twice after each use (to dilute radioactive material excreted in the urine).

Before or during the test, you may be given an iodine solution to prevent excess iodine from being absorbed into the thyroid.

This test should NOT be done on pregnant women because of the danger to the fetus from radiation.

Special considerations:

The radioisotope is costly and may not be available in all medical facilities.

Because the radiation from this radioisotope is fairly high compared to most other radioisotopes, some precautions may be necessary for a few days after the test.

Your health care provider will tell you about specific precautions, which may include flushing the toilet twice after each use (to dilute any radioactive material that passed out through the urine).