A Nuclear Medicine Thallium Viability Scan is a test used to evaluate the blood flow to the heart. After a heart attack (myocardial infarction), some of the heart muscle may be permanently damaged or scarred. Once this occurs, the area affected will cease to function properly. Other parts of the heart may be injured, but not permanently scarred. These areas may be “hibernating”, and may not be detectable through traditional imaging studies, such as an echocardiogram. These damaged areas of the heart may still be “viable”, but may not have completely recovered. As a result, the heart may temporarily function at a much reduced level.You doctor may want to identify these “hibernating” areas because restoring blood flow to that area of the heart may restore proper function and prevent permanent damage from occurring. Using this test the cardiologist can determine if there is an adequate amount of this “hibernating” or “stunned” tissue, verses heart tissue that is permanently damaged.This will help the cardiologist determine which type of treatment is best suited for your case.
A viability scan is accomplished by taking pictures of your heart at various intervals after an injection of a special radioactive drug called Thallium 201.Over a period of time the thallium will be taken into the “good” healthy heart muscle but will not be taken up by any scarred or “bad” heart muscle.Pictures are taken at 30 minutes, 6 hours and the next morning at 24 hours after the injection to see if the amount of the thallium tracer in the heart has changed.