Abstract： SPECT myocardial perfusion imaging is a noninvasive method of assessment of coronary heart disease (Myocardial Ischemia). As a new type of myocardial imaging agent, 99Tcm-tetrofosmin is easy to label with 99mTc, background removed fast, effectively shorten the waiting time for examination, and better in diagnosis of myocardial ischemia/infarction, but is underestimate the activity of myocardial cells. 18F-FDG PET myocardial perfusion imaging is an effective method in evaluation of myocardial activity. Since the low penetration, high cost and a certain rate of failure in examination, it is not widely used. 99Tcm-HL91 is a hypoxia tissue imaging agent and can be combined with hypoxia tissue directly, obviously ingested by hypoxia myocardium, seldom ingested by normal myocardium and barely ingested by necrotic myocardium. SMI is a kind of performance in the development process of coronary heart disease, which is one of the most dangerous factors of coronary heart disease. Hypoxia imaging with 99Tcm-tetrofosmin and 99Tcm-HL91 in SMI patients play a positive role in the judgment of range of myocardial ischemia and myocardial activity, the choice of reasonable treatment plan, and the judgment of prognosis and reducing the financial burden for patients.