PET-CT examination is the most expensive examination in Sichuan province, with a local cost of 6800 RMB and a whole body examination of 9800 RMB. First of all, PET machine has higher input cost, and its cyclotron-accelerated positron drug is short half-life type with higher production cost, and the cost of molecular imaging is higher compared with ordinary CT or MRI. Since PET-CT is a whole-body examination, it has diagnostic effects on the head, neck, chest and the whole body extremities; and it is a molecular imaging examination, which can reflect more the fusion of functional imaging and structural anatomy from the metabolic point of view.