Cardiac PET Scan

A cardiac PET scan is an accurate, noninvasive test that creates images of your heart. A healthcare provider can use these images to make decisions about the next steps in your heart care. They can judge how healthy your heart muscle is and decide how to treat it. A cardiac PET scan uses a small amount of radiation.


A type of cardiac PET scan showing which areas of your heart have good blood flow
A type of cardiac PET scan can show which areas of your heart have good blood flow.

What is a cardiac PET scan?

A cardiac PET (positron emission tomography) scan creates images of your heart using a scanning machine and an injection of radioactive tracers. The test’s radioactive tracers release energy. Depending on the specific type of tracer and the conditions under which a healthcare provider injects it, the pattern with which the tracer lights up your heart can give providers information about how healthy your heart is.

A PET scan of your heart is a noninvasive, accurate test that creates images of your heart from every angle. By looking at what your body’s cells are doing, a cardiac PET scan can provide information other imaging tests can’t. And it can find problems earlier than other tests can.

A combined PET/CT (computed tomography) scanner can take both types of images one after the other with the same machine.

When is a cardiac PET scan performed?

A provider performs a PET scan of your heart when they need to know:


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Test Details

How does a cardiac PET scan work?

During the test:

  • Your healthcare provider injects a small amount of radioactive tracer into an IV in your vein. The tracer isn’t a dye or contrast. Depending on the tracer, it can stay in your body for a couple of minutes or a few hours.
  • A special camera, called a PET scanner, detects the radiation energy the tracer releases.
  • The PET scanner creates 3D computer images of your heart based on the energy it detects.

How do I prepare for a cardiac PET scan?

Your healthcare provider will give you specific instructions. Be sure to follow them for the most accurate results. In general, you can expect the following to prepare for your heart PET scan:

Eating and drinking
  • Don’t eat or drink anything except water for four hours before the test.
  • Don’t have anything that contains caffeine for 24 hours before the test. This includes coffee, tea, cola and other sodas, chocolate and strawberries (these contain a small amount of caffeine). It also includes decaffeinated and caffeine-free products (these contain small amounts of caffeine). Caffeine affects test results.
  • Eat foods high in fat and low in carbohydrates for 24 to 48 hours before your heart PET scan if your provider is checking for cardiac sarcoidosis or infection. These are rare tests. People who get a cardiac PET scan for other reasons won’t need to follow this diet.

Don’t do strenuous exercise for 24 hours before your cardiac PET scan.

Using tobacco products

Don’t smoke on the day of your cardiac PET scan. Nicotine affects the test results.

Taking medications

Bring a list of all medications and supplements you take, including over-the-counter products you buy without a prescription.

Medications with caffeine: Don’t take any over-the-counter medication that contains caffeine (such as pain relievers and diet pills) for 24 hours before your cardiac PET scan. Talk to your provider if you have questions about other medications that may contain caffeine.

If you have asthma: Your provider will likely tell you not to take theophyllinefor 48 hours before your heart PET scan.Bring your asthma inhaler with you to the test.

If you have diabetes: If you take insulin, ask your provider how much you should take on the day of your cardiac PET scan. You may need to take 50% of your usual morning dose and eat a light meal four hours before the test.

If you take pills to manage your blood sugar, your provider will likely tell you not to take your medication before the test. Bring your diabetes medication with you so you can take it after you finish the test. Don’t take your diabetes medication and skip a meal before your heart PET scan.

If you own a glucose monitor, bring it with you to check your blood sugar levels before and after your test. If you think your blood sugar is low, tell your provider right away. Plan to eat and take your medication after your heart PET scan.

If you take heart medications: Ask your provider about changes you need to make to your medications before your cardiac PET scan. Don’t stop taking any medication unless your provider tells you to. You should only take these medications on the day of the test if you have chest pain:

How long does a cardiac PET scan take?

The appointment will take about one to three hours. However, the machine may only scan you for a total of 30 minutes.

What to expect during a cardiac PET scan

After replacing your shirt with a hospital gown and having a blood pressure check, you’ll:

  1. Have an electrocardiogram (EKG) before and during the test to keep track of your heart’s electrical activity. Painless, sticky patches on your body collect this information.
  2. Get an IV in your arm or hand so you can receive medication and a radioactive tracer during the test.
  3. Lie still on the exam table with a camera above you in the middle of a large, donut-shaped machine.
  4. Receive a small amount of radioactive tracer through your IV so your provider can scan to check your blood flow while you rest.
  5. Receive medication through your IV to make your heart react as if you were exercising. You may feel warm or cold and may have a mild headache.
  6. Get another small amount of tracer so your provider can scan to check your blood flow while you’re “active.” Your provider will compare the two scans (resting and active).

Depending on the disease your provider is checking for, the steps above may differ.

Your healthcare team will ask you how you’re feeling several times during the test. Tell them if you feel:

What to expect after a cardiac PET scan

A provider will remove the IV from your arm or hand at the end of the test. You can change out of your hospital gown and go home. Someone will need to drive you home if you had a sedative.

Be sure to drink a lot of water over the next 24 hours so you can flush the tracer out of your system.

What are the risks of a cardiac PET scan? Are there side effects?

Side effects

Side effects may include:

  • Some temporary redness and pain on the skin where you had your IV.
  • An allergic reaction to the radiotracers’ radiation. This is very rare and the amount of radiation exposure is low.


Risks for certain people include:

  • A cardiac PET scan can harm a fetus or infant, so let your provider know if you’re pregnant or nursing.
  • People who have diabetes may not get accurate test results.
  • People who feel anxious in small spaces may be uncomfortable during the scan. However, you can ask for a sedative before your scan.
  • People who have a body mass index (BMI) above 30 may need a special scanner that some hospitals may not have.


Results and Follow-Up

What type of results do you get and what do the results mean?

The provider reviewing your heart (cardiac) PET scan can help your referring provider make a diagnosis. Results discuss which areas of your heart muscle may improve with treatment and which may not. Your provider uses this information to decide whether procedures would help your heart pump better. Improving this also improves shortness of breath.

When should I know the results of a cardiac PET scan?

Your provider should receive the results of your cardiac PET scan in 24 to 48 hours. Then, they’ll share them with you, along with any treatment recommendations.

If the results are abnormal, what are the next steps?

Depending on the condition of your heart muscle, your provider may decide you need:

If these procedures wouldn’t help you because of the extent of heart muscle damage, your provider may recommend that you continue taking medication instead.

When should I call my doctor?

Contact your healthcare provider if:

  • You haven’t received results after several days.
  • You have questions about the treatment they recommend.
  • Your symptoms have gotten worse since your cardiac PET scan.

A note from Cleveland Clinic

Lying inside a large machine with a small opening can be unsettling, but a cardiac PET scan can provide answers about your heart’s health. This noninvasive, accurate test can provide answers other tests can’t. The sooner you have answers, the sooner you’re on your way to a healthier heart.

Medically Reviewed

Last reviewed on 04/25/2023.

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