PET-CT for coronary artery disease is achieved by abnormal uptake of the tracer 18F-FDG (a glucose analogue) by the lesion site of coronary artery disease. High glucose utilization at the lesion site relative to the normal site results in high 18F-FDG uptake, indicating that the myocardial cells are in an ischemic state, and if they are completely necrotic, 18F-FDG uptake cannot occur. With severe coronary stenosis, its blood flow will be severely reduced, when myocardial perfusion imaging is a ‘fixed defect’. On FDG myocardial metabolic imaging, if there is FDG uptake at these ‘fixed defect’ sites, the myocardium is still alive. If there is no FDG uptake, the myocardial cells are necrotic. The advantages of PET-CT cannot be replaced Although ECG exercise tests and ambulatory ECG can also help diagnose the disease, they have strict indications and contraindications and are not very accurate. PET-CT provides both anatomical and functional information, which improves the accuracy of diagnosing coronary artery disease. It has an accuracy of over 90% in diagnosing coronary heart disease and can detect early atherosclerosis that cannot be detected by other tests.