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Positron Emission Tomography (PET)

How It Is Done continued...

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.

How It Feels

You will not feel pain during the test. The table you lie on may be hard and the room may be cool. It may be difficult to lie still during the test.

You may feel a quick sting or pinch when the IV is put in your arm. The tracer is unlikely to cause any side effects. If you don't feel well during or after the test, tell the person who is doing the test.

You may feel nervous inside the PET scanner.


There is always a slight chance of damage to cells or tissue from radiation, including the low levels of radiation used for this test. But the chance of damage is usually very low compared with the benefits of the test.

Most of the tracer will be flushed from your body within 6 to 24 hours. Allergic reactions to the tracer are very rare.

In rare cases, some soreness or swelling may develop at the IV site where the radioactive tracer was put in. Apply a moist, warm compress to your arm.


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 radiologist may discuss preliminary results of the PET scan with you right after the test. Complete results are usually available in 1 to 2 days.

Positron emission tomography (PET)

Blood flow is normal and organs are working well. The flow and pattern of the tracer shows normal distribution in the body.

Abnormal: Heart:
  • Decreased blood flow and increased glucose metabolism may show that the blood vessels are narrowed or blocked. This may mean coronary artery disease (CAD) is present.
  • Decreased blood flow and glucose metabolism may mean that heart tissue is scarred and damaged, such as from a heart attack.
Tumor detection:

Areas of increased glucose metabolism may mean a tumor is present.

WebMD Medical Reference from Healthwise

Last Updated: September 09, 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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