Positron emission tomography (PET) is a scan that examines biological chemistry at the cellular level using radioactive tracers to show whether or not different parts of heart muscle are alive, working, vascularized, and healthy. A PET scan creates a three-dimensional picture of heart tissue and shows the heart at work. Cardiologists use PET scans to look for adequate blood flow to the heart, damage to the heart after a heart attack, and the effectiveness of a treatment plan.
How It Works
PET scanning uses a radioactive substance that is injected into the bloodstream. This substance is absorbed by cells in which tissue is either damaged or not working properly – areas with changes in metabolic activity. The PET scan machine uses hundreds of radiation detectors to find the radioactive substance in the body, measure it, and create the pictures of the heart (or other body tissues).
What To Expect
Patients receive protocols from their doctors regarding eating, drinking, and smoking prior to the test and regarding taking medication before the test, including insulin and inhalers. Patients with diabetes may have additional instructions.
A technician applies electrodes, leads, an intravenous line, monitoring devices, and a ring of detectors on the patient’s chest. The PET scanner is a large machine that has a short, open-ended tube in the middle (like a very short tunnel). The patient lies on a scanning table, which slides through the middle of the PET scanner. Pictures are taken for 15 to 30 minutes before the radioactive substance is injected. After the radioactive substance is injected, the patient waits about 45 minutes for the substance to move through the bloodstream and into the heart. Another set of pictures is then taken.
Different medications may be given during the scanning to cause the heart to respond in different ways. These medications may cause a warm, flushing feeling or a mild headache. Patients should report such feelings to the lab technicians, especially discomfort; shortness of breath; dizziness; lightheadedness; or any other unusual symptoms. Technicians will watch for any changes on the ECG monitor that suggest the test should be stopped.
PET scanning may be used for patients who are unable to exercise on a treadmill or stationary cycle. The appointment will take three to four hours. After the test, the patient resumes normal activities.
Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Diag/dipet.cfm
The Cleveland Clinic www.clevelandclinic.org/heartcenter/pub/guide/tests/nuclear/pet.htm