The PET stress test is performed with the person lying down in the PET scanner, a large "doughnut" shaped machine similar to a CT scanner. The person receives an injection of tracer medication called rubidium-82, (Rb-82) which allows a special camera to visualize and measure blood flow through the heart at rest.
The patient next receives an injection of a drug that increases blood flow in normal coronary arteries but not in blocked or narrowed arteries or in heart tissue that has been damaged. Rb-82 is again injected and the camera takes a picture of the heart during increased blood flow, or “stress”. The differences in blood flow are used to create an image of the blood flow in the heart. This image will indicate if there is a blockage present.
More details on what patients undergoing an Rb-82 PET scan experience
Before the PET scan, one or more members of the medical staff will explain the procedure to the patient. They are more than happy to answer patients' questions before, during, and after the procedure.
At the beginning of the test, patients receive an injection in the arm of a chemical compound that contains a small amount of a radioactive substance (Rb-82). The scanner then takes images of the heart for eight minutes. By the end of this scanning, the radioactive substance has disappeared completely from the patient's body. This procedure-the "at rest" portion of the test-is repeated one more time.
Next, for the "stress" portion of the test, the patient receives an injection of a drug that increases the flow of blood through normal, healthy arteries. (Arteries that are blocked and tissue that is damaged do not accommodate an increased blood flow.) Following another injection with a small amount of the radioactive substance, the patient undergoes a PET scan to detect any differences in blood flow.
By comparing the patterns of blood flow from the at-rest and stress portions of the test, the physician determines whether significant disease is present. If disease is detected, the physician can also determine whether it is due to reversible blockages in the coronary arteries or to permanent scarring of the heart muscle.
This PET scan process typically takes 1 to 1½ hours. Results are usually reviewed the same day as the test, and a report is sent to the referring physician the following day.
When weakening in the overall function of the heart is detected, doctors often order an additional test, F-18 FDG, to determine the extent of permanent or reversible damage to the heart muscle. This testing takes an additional 1½ hours. In this test, the patient receives sugar intravenously, and the blood sugar is measured several times. Next, the patient is injected with F-18 FDG. After resting for approximately 45 minutes, the patient undergoes the PET scan, which lasts, in this case, about 20 minutes.