Pulmonary embolism is also relatively common in clinical practice, primarily caused by an embolus blocking the pulmonary artery system, leading to a group of clinical syndromes. The clinical manifestations of pulmonary embolism mainly include the following points: The first is that patients may experience unexplained difficulty breathing and shortness of breath, especially after activity. The second is that patients experience significant chest pain. The third may be accompanied by hemoptysis, but usually, the amount of blood expectorated is not large. The fourth is that patients may experience restlessness, panic, and even a sense of impending doom. Clinically, there sometimes appears the so-called triad, which includes simultaneous occurrence of difficulty breathing, chest pain, and hemoptysis, etc. Pulmonary embolism is primarily diagnosed clinically through pulmonary artery CT.