Brain metastases are tumors that metastasize to the brain through blood circulation and lymphatic system. in CT examination, if single or multiple lesions are found in the brain, consider the tumor. Typical CT manifestations of brain metastasis tumor are as follows: 1. CT plain scan: abnormal lesions are found; 2. CT enhanced scan: brain metastasis tumor is generally rich in blood supply, contrast agent enters the lesion through blood vessels, which shows different from the surrounding normal brain tissue and manifests as enhancement, generally ring-like enhancement, nodular enhancement, or both; 3. Obvious edematous band around the tumor: normal brain tissue cells around the metastases are changed and The oedema is manifested. Head MRI is more clear and accurate for the detection and diagnosis of brain metastases.