A normal MRI of the head can rule out cerebral infarction in most cases because the lesion can already be seen on MRI after half an hour to an hour after the cerebral infarction, and thereafter the imaging of the lesion can be seen as a cerebral infarction change, although it is changing. After the occurrence of cerebral infarction, generally half an hour to one hour later, it can be seen on the magnetic resonance imaging of localized foci of cerebral infarction changes, a very small number of patients may be able to see the changes only after 2 hours, if the magnetic resonance examination is performed within this period of time, may not be able to find cerebral infarction, and the duration of this period of time varies from person to person. However, clinically, when family members find abnormalities in patients and send them to the hospital, it is often more than 2 hours from the onset of the disease, so if it is a cerebral infarction, basically it can be detected by MRI, and after that, the patient’s performance of MRI will go through several stages of changes in the hyper-acute, acute, sub-acute, and chronic phases. If patients have symptoms related to cerebral infarction, please follow the doctor’s instructions for examination and treatment.