The difference between pulmonary arteriography and CTPA is as follows: 1. Pulmonary arteriography: It is actually an invasive interventional test, in which a catheter is placed through a punctured peripheral vein and finally selectively enters the left and right pulmonary artery trunks, and then a contrast agent is injected into the pulmonary artery via the catheter to visualize the pulmonary artery, with the aim of seeing whether there are lesions in the pulmonary vessels and where the lesions are located, mainly for the diagnosis (treatment) of acute pulmonary embolism. It can also look at the presence of aneurysms, arteriovenous fistulas, etc. in the pulmonary arteries. The advantage is that the image is very intuitive and can be both diagnosed and treated; the disadvantage is that the operation is more complicated, the operation environment is more demanding, and the price is also high; 2. CTPA: CT angiography for pulmonary artery, equivalent to CT examination, but also to inject contrast, and then through rapid scanning after the three-dimensional reconstruction, the whole pulmonary artery is shown, mainly for the diagnosis of pulmonary embolism. The disadvantage is that it can only diagnose but not treat. The advantage is that it is non-invasive, fast and low risk, and it has gradually become the gold standard for the diagnosis of pulmonary embolism.