CT can detect cerebral infarction. 1. 24 hours after the occurrence of cerebral infarction, low-density lesions may appear in all CT examinations. 2. Some patients with onset within 24 hours show negative CT examinations, but infarct foci may appear in nuclear magnetic examinations. Cerebral infarction is an acute ischemic cerebrovascular disease with rapid onset and high mortality and disability rates. Cranial CT should be examined promptly after the onset to make a clear diagnosis.3. If the onset is within 4.5 hours and there is no clear lesion on brain CT examination, but cerebral hemorrhage is excluded when the physical symptoms and signs are heavy, there are indications for thrombolysis and thrombolytic therapy can be performed when there are no contraindications. This treatment method can rapidly restore cerebral blood flow and improve brain tissue metabolism, which can reduce the disability and mortality rate of patients and improve the cure rate.