This is a test in which a small amount of radioactivity is used to obtain pictures of your heart with a gamma camera. These pictures will show how well your heart is pumping blood around your body and it will help your doctor make a diagnosis.
To perform the test, stannous (Tin) ions are injected into the patient's bloodstream. The stannous ions make the red blood cells 'sticky' and a subsequent intravenous injection of the radioactive substance, Technetium-99m-pertechnetate, labels the red blood cells in-vivo. With an administered activity of about 800 MBq, the effective radiation dose is about 8 mSv. The patient is placed under a gamma camera, which detects the low-level gamma radiation being given off by technetium-99m. As the gamma camera images are acquired, the patient's heartbeat is used to 'gate' the acquisition. The final result is a series of images of the heart (usually sixteen), one at each stage of the cardiac cycle.
The resulting images show the blood pool in the chambers of the heart and the images can be analyzed on a computer to calculate the ejection fraction of the heart together with other useful clinical parameters. This scan gives an accurate and reproducible means of measuring and monitoring the ejection fraction of the left ventricle.
For a patient that has had a heart attack, or is suspected of having another disease that affects the heart muscle, this scan can help pinpoint the position in the heart that has sustained damage as well as assess the degree of damage.