Nuclear Cardiology

Nuclear cardiology involves diagnostic tests using radioactive substances. These tests can provide a variety of useful information about the heart and how it functions.

Multiple-gated acquisition scanning (MUGA), also known as radionuclide ventriculography, is a test that uses radioactive tracers to produce an image of the heart’s chambers and the major blood vessels leading to and from it. This test can measure the heart’s function and the amount of blood reaching the heart muscle.

The radioactive substance thallium or technetium (sestamibi) is injected into a vein in the arm, after which a special camera or scanner is used to view the amount of the tracer that reaches the heart muscle. Areas of the heart that have good blood flow will absorb the tracer, while areas of the heart that have severely reduced blood flow will not adequately absorb the tracer. This scan is used to diagnose coronary artery disease and can determine the area of heart muscle that has sustained damaged.

PET Scan

A PET scan is a highly accurate method for diagnosing coronary artery disease and the extent of heart muscle damage. During a PET scan, a small amount of radioactive glucose is injected into the body, which travels through the blood stream to the heart. This tracer uses radioactive positrons (positively charged particles) to detect the metabolic activity of the cells. The tracer accumulates in areas of the heart that are damaged or not working properly — areas that have a different metabolic rate than normal tissue. A special scanner measures the concentration of the tracer in this tissue, providing a detailed three-dimensional image of the heart’s function. This differs from other nuclear tests in that it does not produce a detailed picture of the heart’s anatomical structure. PET scans are also be used to detect disease in other parts of the body.

Thallium Stress Test

A thallium stress test determines the blood flow to the heart muscle, both at rest and during stress. The radioactive substance, thallium, is injected into a vein shortly after the heart has been stressed by exercise and images of the heart’s blood flow are taken. After the patient has rested for several hours, another series of images of the heart’s blood flow are taken. The resting images and stress images are compared. Areas of the heart not receiving good blood flow can be identified.