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Positron Emission Tomography (PET)

How To Prepare

  • Before you have a PET scan, tell your doctor if:
    • You have diabetes. If you take medicine to control diabetes, you may need to take less than your normal dose. Talk with your doctor about how much medicine you should take.
    • You take any medicines, supplements, or herbal remedies. You may need to stop taking some medicines or change your dose before this test.
    • You are or might be pregnant.
    • You are breast-feeding. The radioactive tracer used in this test can get into your breast milk. Do not breast-feed your baby for 2 days after this test. During this time, you can give your baby breast milk you stored before the test, or you can give formula. Discard the breast milk you pump for 2 days after the test.
    • You have a fear of enclosed spaces.
  • Do not smoke or drink caffeine or alcohol for 24 hours before this test.
  • Do not eat or drink for at least 6 hours before this test.

You may be asked to sign a consent form.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done or what the results mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

A positron emission tomography (PET) scan is done in a hospital nuclear medicine department or at a special PET center by a radiologist or nuclear medicine specialist and a technologist. You will lie on a table that is hooked to a large scanner, camera, and computer.

During the test

The radioactive tracer is usually given in a vein (IV). You may need to wait 30 to 60 minutes for the tracer to move through your body. During this time, you may need to avoid moving and talking.

The PET scanner, which is shaped like a doughnut, moves around you. The scanned pictures are sent to a computer screen so your doctor can see them. Many scans are done to make a series of pictures. It is very important to lie still while each scan is being done. At some medical centers, a CT scan will be done at the same time.

For a PET scan of the brain, you will lie on a bed. You may be asked to read, name letters, or tell a story, depending on whether speech, reasoning, or memory is being tested. During the scan, you may be given earplugs and a blindfold (if you do not need to read during the test) to wear for your comfort.

If you are having a PET scan of your heart, electrodes for an electrocardiogram (EKG, ECG) will be put on your body.

During the test, you will be alone in the scanner room. The technologist will watch you through a window and you will be able talk to him or her through a two-way intercom at all times.

The test takes 1 to 3 hours.

After the test

After the test, drink lots of fluids for the next 24 hours to help flush the tracer out of your body.

WebMD Medical Reference from Healthwise

Last Updated: January 28, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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