Inclusion Criteria:  It meets the diagnostic criteria of acute ST segment elevation myocardial infarction: ① ischemic chest pain lasts for more than 30 minutes and can not be relieved by taking nitroglycerin; ② ST segment elevation of ECG with two or more adjacent leads, limb lead ≥ 1mm, chest lead ≥ 2mm; Or new left bundle branch block; ③ The serum markers of myocardial necrosis increased at least twice the normal value Acute myocardial infarction was confirmed by coronary angiography The clinical and angiographic data were complete Direct PCI was performed within 12 hours after onset  Exclusion Criteria:  Those who do not cooperate in the inspection, have poor compliance and cannot guarantee the completion of the test Conscious disorder, obvious intellectual disorder and mental disorder With metal foreign bodies, such as metal prosthesis, intraocular metal foreign bodies, intracranial aneurysm clamp, etc People with claustrophobia Had a history of myocardial infarction, PCI and coronary artery bypass grafting Factors affecting ST segment changes of ECG: complete left bundle branch block, preexcitation syndrome, pacemaker ECG, etc