Positron Emission Tomography
(PET)En Español (Spanish Version)
Positron emission tomography (PET) produces images that show the amount of functional activity in the living tissue being studied.
PET Scans of the Brain
© 2008 Nucleus Medical Art, Inc.
Parts of the Body Involved
PET can be performed on a variety of body tissues, including:
- Whole body
Reasons for Procedure
A PET scan may be done for a number of reasons, including to:
- Look for tumors or assess tumor level of activity after treatment
- Assess causes for memory disorders such as Alzheimer’s disease
- Determine the cause of seizures
- Determine if patients with uncontrolled seizures might benefit from surgery
- Assess brain metabolism in patients with chronic fatigue syndrome
- Learn how blood is flowing in the heart to assess for coronary artery disease and to check for heart muscle damage
- Help understand how drugs are processed by the body
Risk Factors for Complications During the Procedure
If you are allergic to the radioactive substance administered for a PET scan, you may be at risk for complications.
What to Expect
Prior to Procedure
- Wear comfortable clothes.
- Do not eat or drink anything except water for at least four hours before the scan.
- Check with your doctor about taking your regular medications.
- If you have diabetes , ask the doctor for specific diet recommendations for test day since accurate results depend on normal body chemistry levels.
- Tell your doctor if you might be pregnant.
You will lie still on a table while the scan takes place.
No anesthesia is necessary.
Description of the Procedure
A nurse or technologist administers a radioactive substance. This may be done through an injection, or in some cases, you will be asked to breathe in a gas with the substance. The compound travels through the blood to the area of the body under study. It takes between 30 to 90 minutes for the substance to be absorbed by the tissue under study. Once the substance has been absorbed, the scan can take place.
You lie on a table and are moved into a machine that looks like a large, square-shaped doughnut. This machine detects and records the energy levels emitted from the substance that was injected earlier. The images are viewed on a nearby computer monitor. The scan lasts about 30 to 45 minutes. You may be asked to perform specific tasks before or during the test. For example, during a heart PET scan, you may be asked to walk on a treadmill.
Drink plenty of fluids to help the radioactive substance pass from your body.
How Long Will It Take?
The whole procedure takes at least two hours.
Will It Hurt?
Except for the pinprick associated with the injection, a PET scan is a painless procedure. People who are claustrophobic (uncomfortable in closed or tight spaces) may experience some anxiety.
The only possible complication is an allergic reaction to the radioactive substance.
Average Hospital Stay
You will not be admitted to the hospital for a PET scan. It is an outpatient procedure.
No special post-procedure care is necessary.
The images show activity levels as different colors or degrees of brightness. If the test has been ordered to look for a cancer, brighter colors may indicate a tumor. A radiologist with training in PET interpretation will review the images and send the results to your doctor. It may take a few days for your doctor to receive the report.
RadiologyInfo, Radiological Society of North America
Society of Nuclear Medicine
University Helath Network
National Institutes of Health website. Available at: http://www.nih.gov/ .
Primary Care Medicine . 4th ed. Lippincott, Williams, and Wilkins; 2000.
Radiological Society of North America website. Available at: http://www.rsna.org/ .
Last reviewed November 2007 by Rosalyn Carson-DeWitt, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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