Skip to content
My WebMD Sign In, Sign Up

Information and Resources

Font Size

Positron Emission Tomography (PET)

Positron emission tomography (PET) is a test that uses a special type of camera and a tracer (radioactive chemical) to look at organs in the body. The tracer usually is a special form of a substance (such as glucose) that collects in cells that are using a lot of energy, such as cancer cells.

During the test, the tracer liquid is put into a vein (intravenous, or IV) in your arm. The tracer moves through your body, where much of it collects in the specific organ or tissue. The tracer gives off tiny positively charged particles (positrons). The camera records the positrons and turns the recording into pictures on a computer.

PET scan pictures do not show as much detail as computed tomography (CT) scans or magnetic resonance imaging (MRI) because the pictures show only the location of the tracer. The PET picture may be matched with those from a CT scan to get more detailed information about where the tracer is located.

A PET scan is often used to evaluate cancer, check blood flow, or see how organs are working.

See pictures of a PET scanner camera and PET scans of the brain camera.

Why It Is Done

A positron emission tomography (PET) scan is done to:

How To Prepare

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.

Tell your doctor about any medicines and herbal remedies you take. You may need to stop taking some medicines or change your dose before this test.

WebMD Medical Reference from Healthwise

Last Updated: July 28, 2011
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.

Hot Topics

Health Solutions From Our Sponsors

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

Close up of eye
What's robbing your focus?
Woman sitting in front of UV lights
What you need to know.
Ra Management Get A Personalized Report
Assess your symptoms.
finger blood test
Ask questions and get answers.
Psoriasis
Bumps, rashes, and hives.
nurse helping woman on crutches
How much time to recover?
woman stretching
Must-see diet and fitness info.
fruit drinks
Foods that can help you focus.
child brushing his teeth
Your kids will find them.
man with cold on couch
How to feel better fast.
mother with children in park
Parenting tips for every age.
MS Overview
Recognizing symptoms.

Women's Health Newsletter

Find out what women really need.