A cardiac pet scan is a diagnostic imaging procedure that is done using radioactive substances to visualize the blood flow to the heart and the functioning of the heart muscles. A cardiac pet scan stress test is more accurate at assessing the blood flow (perfusion) defects as well as assessing the functioning of the left ventricle.
A cardiac PET scan is an elective procedure.
A cardiac pet scan is usually done after an echocardiogram or a cardiac stress test, especially if the results from these tests are inconclusive or need further evaluation.
Before performing a cardiac PET stress test the following may be done
Before the start of the procedure, an ECG is done and an IV line is put in place and a radiotracer is injected through it. The radiotracer agent that is used could be thallium(TI-201) or technitium (Tc-99), the individual is then shifted to the PET scan machine room after about 20-45 minutes, which is the time it takes for the radiotracer to be absorbed and circulate in the body. The individual is then made to lie on a table that glides into the cardiac PET scan machine. The cardiac PET scan machine has a revolving gamma camera that takes images of the coronary arteries, the heart muscle. A vasodilator may then be injected to study the response of the heart to the drug, and another series of images are taken. ECG recordings are also done during the procedure. Once the images are recorded, and the testing is completed, the table is moved out from the PET scan machine and the connected ECG leads and the IV line is removed.
As physical activity and exercise place additional stress on the heart muscle, increase the heart rate, blood pressure, and increase the requirement of blood flow to it, a stress test is a procedure that can induce ischemia (absence of blood flow) in the heart muscle if there is a presence of coronary artery disease. A cardiac PET scan stress test may be done by making the individual perform physical activity (such as cycling or walking on a treadmill) to increase the heart activity while monitoring the ECG and the blood pressure, and then injecting the radiotracer to capture images of the blood flow and the heart muscle. The radiotracer is injected at the peak of exercise or shortly after a drug to simulate physical activity is injected. Images are taken immediately after the injection of the radiotracer and again after a gap of 3-4 hours (called delayed imaging). Areas of the heart muscle that are at risk of damage are seen to be filled with the radiotracer in the delayed imaging while dead heart tissue does not take up any radiotracer (called as a fixed defect). This helps to differentiate between the areas of the heart that are damaged beyond repair due to a previous myocardial infarction (heart attack) and the ones that are at risk of damage due to a future myocardial infarction.
A cardiac PET scan is an outpatient procedure and the individual is free to leave after the test is completed. Soreness at the site of insertion of the IV line and the back muscles may be noticed. The reports of a cardiac PET stress test are usually available in a day or two after the procedure for interpretation by the attending specialists.
There are no complications after a cardiac PET scan which is a very safe procedure.
Cardiac PET scans are safe procedures and no complications are seen. They are useful in the detection of the severity and extent of known or suspected coronary artery disease, as well as the after-effects of a heart attack.
Hospitalization is not required for a cardiac PET scan.