1.What is cerebral angiography? Cerebral angiography is a new X-ray examination technique that has been widely used in clinical practice since the 1990s. It is performed by selecting an access artery, usually the right femoral artery (radial artery is also used). DSA can not only clearly display the internal carotid artery, vertebral basilar artery, intracranial vessels and cerebral hemispheres, but also measure the blood flow of the artery, so it has been widely used in cerebrovascular disease examination and treatment. Therefore, it has been widely used in the examination and treatment of cerebrovascular diseases. 2.Why do we need cerebral angiography? In case of cerebral artery thrombosis, cerebral angiography can pinpoint the location of the blockage. Some vascular malformations such as aneurysm or arteriovenous malformation can only be diagnosed by cerebral angiography. After decades of improvement, it is now possible to do not only an angiogram, but also a whole brain angiogram; not only arteries, but also veins and capillaries can be seen. 3.What diseases need cerebral angiography? (1) intracranial hemorrhage, need to find the cause of hemorrhage; (2) intracranial vascular lesions: such as cerebral artery atherosclerosis, embolism, stenosis, occlusive disease, aneurysm, arteriovenous malformation, arteriovenous fistula, etc.; (3) intracranial tumor, need to understand the source of blood supply, the richness of blood supply and the relationship between the lesion and the important blood vessels; (4) to understand the blood supply of certain extracranial lesions, such as carotid body aneurysm, scalp hemangioma, etc. scalp hemangioma, etc. (5) If a patient with brain tumor has a stroke and cannot be distinguished from cerebral hemorrhage or cerebral infarction, cerebral angiography can be considered to help the differential diagnosis. (6) To observe the cerebrovascular circulation status after surgery. 4.Is cerebral angiography safe? Cerebral angiography is relatively safe, but in a few patients, local hematoma may form at the puncture site, which will gradually disappear after a few days. However, some accidents may occur, such as local hemorrhage at the puncture site and intracranial artery spasm, etc. The chance is about one in a thousand. 5.What are the preparations for cerebral angiography and what precautions should be taken after the procedure? During the imaging process, patients should keep quiet and do not turn their heads at will; after returning to the ward after the imaging, patients should lie down and keep the lower limb of the punctured artery braked for at least 8 hours; patients with transradial artery puncture can walk back to the ward by themselves after the operation.