Ultrasound of the brain cannot detect cerebral infarction. Ultrasound of the brain mainly examines blood vessels to see whether there are plaques and stenoses in the blood vessels and to assess the risk of cerebral infarction, and it mainly examines the blood vessels in the neck. If cerebral infarction needs to be examined, cranial CT or cranial MRI is mainly performed, among which cranial CT can detect part of the infarction and bleeding lesions, but the best examination is to perform cranial MRI after 24 hours of onset, because the lesions are generally clearer after 24 hours of onset. MRI can not only detect cerebral infarction, but also clearly identify old cerebral infarction and acute new infarction lesions, and can also detect lesions that are not detected by cranial CT. Therefore, if you want to examine cerebral infarction, the best examination method is generally cranial magnetic resonance examination, and cranial ultrasound has no way to detect cerebral infarction.