Abstract
Myocardial perfusion imaging is a routine study that helps to see if the blood flow to the heart muscle is normal or abnormal. There are three parts to myocardium imaging; the resting scan with the radioactive tracer, the stressing of the myocardium, and the stress scan with the radioactive tracer. With the resting scan, a radioactive tracer is injected into the patient to obtain the first set of images of the myocardium at rest. After the rest scan, comes the stressing of the myocardium. There are two different ways to stress the myocardium for the stress test. The first way is to have the patient exercise on a treadmill following a specific exercise protocol, and the second method is to use a pharmacologic stressing agent if the patient cannot exercise. Pharmacologic stress agents produce coronary artery vasodilation and increased myocardial blood flow. During exercise stress, the heart rate should preferably reach 85% of the maximum heart rate and the patient should be symptomatic or fatigued, the technologist injects the patient with the radioactive tracer at peak stress and then obtains a second set of stress images . Of the two different ways to stress the myocardium, the physical stressor is preferred to pharmacologic stress testing in conjunction with myocardial perfusion imaging.
