Nuclear stress myocardial perfusion imaging (MPI) is a nuclear cardiology test that shows how well blood flows to the muscle of the heart (myocardium). This test is used to diagnose the presence or absence of coronary artery disease.
A radioactive tracer (sestamibi) is injected into the patient’s bloodstream and is taken up by the heart tissue. A single photon emission computed tomography (SPECT) camera detects the radiation released by the tracer to produce images of the heart. Two sets of images are taken, one after an injection at rest and another after an injection during a stress test – either exercise stress on a treadmill or drug-induced stress with Lexiscan medication, which simulates exercise.