A PET scan is an imaging test that helps doctors to see how your heart and its tissues are working at the cellular level. The test is most often used to diagnose heart conditions such as coronary artery disease (CAD). The results allow doctors to see 1) if there is any significant blockage of the coronary artery by performing a stress (perfusion) test, and 2) the degree of heart damage, if any, after a heart attack.

How does it work?

The PET scanner is a large, tunnel-shaped machine. You will lie on a narrow examination table, which slides through the center of the PET scanner. Before the scan, leads that monitor your heart rhythm are attached to your chest and a very small amount of a radioactive material (called a radiotracer) is injected into a vein in your arm. The radiotracer collects in your organs and tissues as it moves through your body. The scanner detects the energy that the radiotracer gives off, and then a computer is used to create 3D images representing whether there is enough blood flow to different parts of your heart muscle and whether there is any scar due to prior heart attack.

What should I expect?

A PET scan is done on an outpatient basis, meaning you will not have to stay overnight in the hospital. Depending on the type of test your cardiologist requests, the test may take between 1 and 4 hours.

Patients are usually told not to eat anything 4 to 6 hours before the test. You may drink water but it is important to avoid any caffeinated beverages (such as coffee, tea, soda, chocolate) for at least 12 hours before the test. If you have diabetes, you should talk to your doctor about your food and insulin intake, because not eating can affect your blood sugar levels (especially if the test is ordered to detect the presence or absence of any heart damage).

Talk to your doctor about any medicines (prescription, over-the-counter, or supplements) that you are taking, because he or she may want you to stop taking them before the test. It is important to avoid any theophylline-containing medications for at least 48 hours prior to the PET scan. Consult with your cardiologist about your specific medications. It is always helpful to make a list of your medicines and bring it with you to the procedure, so that doctors know exactly what you are taking and how much.

You will be asked to put on a hospital gown. Then, you will lie down on a table, which will be slowly moved through the center of the PET scanner. You will be asked to lie still, because too much movement will make the images blurry. The radiotracer usually takes about 45 minutes to 1 hour to travel throughout your body, and the PET scan itself may take up to 1 hour. If you are having the test because your doctor suspects you have heart disease, you may also undergo a stress test, where you are given medicines that have the same effect on your body as exercise does. After the test, you may go about your normal activities.

PET scanning is a very safe test. The amount of radiation you receive is within the acceptable limit that is commonly given to patients. Some people could have an allergic reaction to the radiotracer, but this is extremely rare. You can help flush the radiotracer out of your body by drinking lots of liquids after the test.

After the test, the nuclear cardiologist that is specially trained in this area will review the data and a full report will be sent to your cardiologist.

If you are pregnant, or think you might be pregnant, or if you are nursing, you must tell your doctor. The radiation exposure can be harmful to a fetus or a nursing infant.