Small patchy slightly hyperdense shadows in the left cerebellar hemisphere need to be considered for cerebellar hemorrhage, calcification and artifacts. 1. Cerebellar hemorrhage: patients presenting with cerebellar hyperdense shadow do not exclude cerebellar hemorrhage. In addition to the high-density shadow, there will be cerebral edema around the cerebral hemorrhage, which is manifested as a low-density edema band around the cerebral hemorrhage on cranial CT. At the same time, it should be combined with the clinical manifestations of the patient to make a comprehensive judgment, and the patient may have headache, dizziness, nausea, vomiting and optic papillae edema and other symptoms of increased intracranial pressure. 2. Calcification: High-density shadow is also shown on cranial CT, and punctate high-density shadow is more common, usually there is no special symptom, no need to deal with it. 3. Artifacts: When the patient performs cranial CT, due to restlessness and uncooperative examination, it can also show high-density artifacts, and it can be reviewed regularly at a later stage. If you find high density shadow in the brain, you need to go to the hospital and avoid carelessness, so as not to delay the treatment.