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Positron emisson tomography
PET (positron emission tomography or cardiac viability study): This imaging procedure uses radioactive tracers to create three-dimensional pictures of the tissues inside the body. It is used for patients unable to exercise on a treadmill or stationary cycle.
A PET helps your doctor:
- Determine if there is adequate blood flow to the heart
- Assess the amount of damage to the heart after a heart attack
- Evaluate the effectiveness of your treatment plan
To prepare:
- Do not eat or drink anything except water after midnight before your test. If you must take medications, drink only small sips of water to help you swallow your pills.
- Do not drink or eat caffeine products for 24 hours before the test, including over-the-counter medication such as Excedrin, Anacin, diet pills, and NoDoz.
- Ask your physician if you should take all of your heart medications on the day of the test. Do not discontinue any medication without first talking with your doctor.
- If you are diabetic, ask your physician how to adjust your medications the day of your test. If you own a glucose monitor, bring it with you to check your blood sugar levels before and after the test. If you think your blood sugar is low, tell the lab personnel immediately.
- Wear comfortable clothes. You may be asked to wear a hospital gown during the test.
What to expect:
During a PET scan, a technician will attach 10 electrodes with adhesive pads to the skin of your chest. Men may have chest hair shaved to allow a better connection. The electrodes are attached to an electrocardiograph (EKG) monitor, which charts your heart's electrical activity during the test.
An intravenous (IV) line will be inserted into a vein in your arm. The technician will perform a resting EKG, measure your resting heart rate and take your blood pressure.
The technician will ask you to lie on the exam table under a camera. A small amount of rubidium will be injected into the IV. Rubidium is a radioactive tracer that allows the physician to view the blood flow in your heart when you are at rest. It is not a dye.
The physician or nurse will administer a medication called dipyridamole into the IV for about four minutes. The medication will cause your heart to react as if you were exercising. It may cause a warm, flushing feeling and, in some cases, a mild headache.
At regular intervals, the lab technicians will ask how you are feeling. Tell them if you feel chest, arm, or jaw pain or discomfort; shortness of breath; dizziness; lightheadedness; or any other unusual symptoms. The technicians also will watch for any changes on the EKG monitor that suggest the test should be stopped.
After all the medication has entered your bloodstream, a small amount of rubidium will again be injected into the IV. The rubidium allows the physician to view the blood flow to the heart muscle while it is in stress. The IV will be removed from your arm once all the medication has entered your bloodstream.
The appointment will take about three to four hours. The first part of the test will take about one hour. The second part will take about two hours, with the usual exercise time taking between seven and 12 minutes.
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