What is a myocardial perfusion scan?
A myocardial perfusion scan is used to evaluate coronary artery disease, which is a narrowing of the blood vessels that supply oxygen to the heart muscle. As this disease progresses, the heart may not receive enough oxygen at times, especially when it's under stress. This may result in a chest pain called angina.
The scan uses radioactive substances (radionuclides), in the form of thallium and technicium, which can be used to produce pictures of a patient's heart. When the radionuclide is injected into the bloodstream, it travels to the heart muscle through the coronary arteries. This process can be visualized by a special camera.
How do I prepare for this test?
Do not eat or drink any products containing caffeine for twelve hours before the test. This includes coffee, tea, colas, and chocolate.
Do not eat anything at all for at least four hours before the test. If you are diabetic and are taking medication for diabetes, you may eat as you normally would.
You may drink water at any time.
Do not smoke three hours before the test.
Wear comfortable, low-heeled shoes or sneakers suitable for treadmill walking. If your clothing size is unusually large or small, please bring your own T-shirt and shorts or pants. You will be working hard during this test, and comfortable clothing will make it easier for you.
What happens during the test?
You will exercise by walking on a treadmill or if you are unable to adequately exercise, your cardiologist will administer medicine to simulate exercise.
Your heart rhythm will be monitored with an EKG (electrocardiograph machine) and multiple blood pressure readings will be taken. The radionuclide will be injected throughout an intravenous line approximately one minute before you stop exercising.
After the exercise portion of the test, images will be taken of your heart. You will lie on your back on an imaging table while a special camera circles slowly around your chest for thirty minutes.
After the first set of images has been taken, you may leave the examination room. You will be asked to return the next day for another injection of the radionuclide and a second set of pictures. These do not require exercise or medicine to simulate exercise. Because the size of your meal before the second set of images may affect their quality, please eat lightly and avoid caffeine. On occasion, your cardiologist may prefer a one (1) day protocol. This entails both portions of the exam the same day, with the resting exam first and the exercise to follow (2 injections and 2 scans).
How long will it take?
The first exercise and imaging session will take approximately one and a half hours. The second injection and imaging session will take approximately one hour. The one day combination will take approximately five hours.
Are radionuclides safe?
There are no adverse reactions to the injection we give you. You will not feel anything from this injection.
The radiation exposure from this test (.63 rem) is similar to most routine X-ray procedures.
How will I learn the results?
After the exam, a radiologist will evaluate the images and discuss them with your own physician. Your physician will explain the results to you.