The presence of high-density shadow on brain CT indicates the presence of hematoma, calcification and vascular-rich tumor in the brain. Common diseases include cerebral hemorrhage, calcification in the brain caused by abnormal parathyroid function or calcium and phosphorus metabolism disorders, and intracranial tumors, all of which can lead to high-density shadowing on brain CT. 1, hematoma: If trauma leads to depressed fractures in the skull, it can cause the volume in the cranial cavity to become smaller, causing an increase in intracranial blood pressure, resulting in local hematoma, or due to increased vascular flow in the brain, resulting in high-density shadowing on brain CT. 2 The calcification is mainly divided into physiological calcification and pathological calcification. Physiological calcification can be seen in part of the normal population, and the calcification foci are usually located in the choroid plexus, pineal gland, pallidum and other parts of the lateral ventricles, which do not require special treatment and do not cause clinical symptoms. Pathological calcification is mostly caused by calcification foci that are not fixed and can be located in the brain parenchyma, often causing dizziness, headache, cognitive impairment and seizures, both of which will show high density in brain CT images; 3. Vascular-rich tumors: There are many types of vascular-rich tumors, which are malignant tumors, most of which are secondary or metastatic tumors, which are relatively rare. This type of tumor can secrete a chemotactic factor by itself, which makes many small blood vessels grow toward itself and grow faster, mainly for the purpose of absorbing nutrition from the whole body. Even if the patient does not take in nutrition, the tumor can still break down various tissues in the patient’s body to supply its own growth, resulting in high-density brain CT images. It is recommended that patients with high-density brain CT images should undergo more detailed brain examination in time to facilitate the follow-up treatment.