Single photon emission computed tomography (SPECT) can identify which patients will benefit more from undergoing percutaneous coronary intervention (PCI) than receiving medical therapy alone for blocked coronary arteries, according to late-breaking clinical trial results presented at the American Heart Association’s Scientific Sessions 2007.Myocardial perfusion SPECT (MPS) is a nuclear imaging technique that assesses blood flow in the heart by taking a series of pictures around the chest after injecting a radioactive tracer into the blood.