CT can detect cerebral infarction, but for acute cerebral infarction, it cannot be detected by early CT in clinical practice, and it is usually necessary to review the head CT after 6 h. At this time, the low-density foci in the infarcted area can be seen by CT, and for patients with normal early head CT but with limb dysfunction, such as hemiparesis of one limb, aphasia and sensory impairment, it is necessary to highly It should be highly suspected whether acute cerebral infarction has occurred. For this type of patients, an emergency assisted head MRI is needed to confirm the diagnosis of cerebral infarction as early as possible. The time window of cerebral infarction is more important, if the diagnosis of acute cerebral infarction can be confirmed early and then effective treatment can be carried out, the patient’s neurological function can be completely restored. Therefore, for patients with normal head CT examinations but neurological dysfunction in the early stage, it is necessary to be highly alert to the possibility of acute cerebral infarction. For such patients, MRI is recommended to be preferred.