Isotope study
Alternative names:
nuclear scan; PET (isotope) scan of the brain; radioactive uptake; radioisotope; radionuclide organ imaging; scintillation
How the test is performed:
A radioactive isotope needs to be introduced into the body. This is done several ways. - Through a needle into a vein (usually the inside of the elbow).
- Through a catheter, that is inserted into a vein or artery and is then guided to the organ being tested.
- Ingestion (for example, to test the thyroid, the patient drinks radioactive iodine).
When the isotope has had sufficient time to be absorbed by the organ, the patient is placed on a table (called a gantry) under the scanner. This may be a rectilinear scanner or gamma camera (devices which detect the gamma rays that are emitted by the isotope). The patient is required to remain still to produce an accurate image. The camera then transmits the information to a computer, which displays an image of that organ or region. A "picture" can be reproduced onto an X-ray film, and a computer printout is usually generated. For some tests, a counter is placed over the organ, and the amount of radioactivity or intensity of radioactivity is recorded.
A technician interprets the information as it is transmitted to the computer and can guide the camera to specific locations to get a better image.
How to prepare for the test:
You must sign a consent form.
Fast overnight before the test. Depending on the region being scanned, you may need to wear a hospital gown. Remove jewelry, dentures, and other metal that may affect the scan.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
How the test will feel:
If the isotope is injected, there will be a sharp prick when the needle is inserted. If a catheter is inserted, the site of insertion is usually numbed with an anesthetic. You will first feel a prick when the needle is inserted but will feel little more than slight pressure or tugging during the injection of the isotope. If the isotope is ingested, the flavor of the liquid may be unpleasant, but no pain is involved.
For patients who are extremely sensitive to the isotope, there may be nausea, headache, or vomiting. Discuss allergies with the health care provider or technician before the test.
Why the test is performed:
This test shows the size, shape, position, and some functions of an organ. If another test has indicated cancer or other abscesses, this test can help support that diagnosis. If other tests show cancer or infection, this test can indicate the location. Therapy can be monitored and evaluated.
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