Positron emission tomography scan, also called PET scan or PET imaging, is a highly specialized nuclear imaging test that uses small amounts of radioactive substances to produce powerful images of the body’s biological function. A PET scan is non-invasive and usually painless.
How does a PET Scan Work?
PET scan uses a special camera and a radioactive chemical tracer to view organs in the body. The radionuclide’s used in PET scans are chemical substances such as glucose, carbon, or oxygen used naturally by the particular organ or tissue during its metabolic process.
During the test, the tracer liquid is put into a vein (intravenous, or IV) in your arm. The tracer may also be swallowed or inhaled depending on what part is being imaged. The tracer moves through your body, where much of it collects in a specific organ or tissue. The tracer gives off tiny positively charged particles called positrons.
The camera records the positrons and turns the recording into pictures on a computer.
PET scans may be performed to:
- Detect cancer
- Determine if cancer has spread to other parts of the body
- Assess the effectiveness of cancer treatments
- Evaluate the brain after trauma to detect blood clot, bleeding, and/or perfusion of the brain tissue
- Assess damage to the heart muscle after a heart attack
Before the Procedure:
- Notify the radiologist or technician of any medications you are taking and if you are allergic to or sensitive to contrast dye, iodine, or seafood.
- Fasting for a certain period of time prior to the procedure is required, usually for at least four hours.
- Notify your physician if you are pregnant or breastfeeding.
During the Procedure:
- You will be positioned on an examination table. An IV line will be inserted into your arm if needed. The radiotracer will then be injected into your vein, swallowed or inhaled depending on the imaging needed.
- You may have to drink a contrast liquid that helps the radiologist interpret the imaging results. The radiotracer takes about 30 to 60 minutes to concentrate in the organs. During this time, you will be asked to lie still and not talk.
- After 30-60 minutes, you will be moved into the scanner for imaging.
You will be instructed to drink plenty of fluids and empty your bladder frequently for 24 to 48 hours after the test to help flush the remaining radionuclide from your body.
If you notice any pain, redness, and/or swelling at the IV site, you should notify your physician.
Advantages & Disadvantages
- PET scans provide information about both structure and function of the tissues.
- It helps detect cancers or areas of spread which have not been identified by other imaging studies such as a CT or MRI.
- Since it provides information on cellular activity, it helps in the early detection of disease.
Risks and Complications
- The amount of the radionuclide used for the procedure is small enough that there is no need for precautions against radioactive exposure.
- The injection of the radionuclide may cause some slight discomfort.
- Allergic reactions to the radionuclide are rare, but may occur.