Since the winter, the weather has been alternating between cold and warm, and the number of patients with cerebral hemorrhage or cerebral infarction has gradually increased. I rushed to the emergency room and found that the patient was not breathing and his cerebral nerve reflexes had disappeared. The patient was treated with tracheal intubation, ventilator-assisted breathing, and hemostasis to lower cranial pressure to prevent cerebral vasospasm. The family and their close friends said that the patient had a sudden headache 3 hours ago, and an emergency brain CT scan revealed a subarachnoid hemorrhage, and then the patient was already in a severe coma when he was transferred to our hospital, which was only 3 hours before and after. Everyone could not accept the reality that a person who was usually in good health could suddenly have such a serious brain hemorrhage. How could we know that there was a cerebrovascular lesion before the attack? Generally speaking, cerebrovascular lesions have a potential development process and some prognostic manifestations. Patients often have transient and sudden onset of symptoms such as weakness of arms and legs, unsteady walking, slurred speech, blurred vision or black haze before cerebral infarction, which can be relieved after a few minutes, and some patients may have recurrent attacks within a short period of time, which is a very dangerous sign that a permanent cerebral infarction is about to occur and should be seen by a hospital immediately. Other patients, who may have frequent headaches, may neglect to see a doctor because they think it is cervical spondylosis or poor rest, and then see a doctor when the headache is severe and unbearable and when they vomit, the examination will reveal that the brain hemorrhage has caused such severe headaches. People may ask, “How can we detect cerebrovascular lesions at an early stage when they are inside the body? Then, the following are some tests that can detect cerebrovascular lesions. 1, ultrasonography: vascular color ultrasound can detect lesions in the large blood vessels of the neck: such as carotid atherosclerosis in the elderly, stenosis and measure the degree of stenosis to determine whether further treatment is needed. The test is convenient and inexpensive, and can be the first choice when carotid artery and vein lesions are suspected. The disadvantage is that it is difficult to examine the blood vessels in the brain because of the influence of the skull. 2.CT: For patients with stroke, CT can quickly determine whether there is bleeding in the brain, the site of bleeding, and whether the intracerebral hematoma needs to be removed by surgery; if it is subarachnoid hemorrhage, CT scan (CT angiography, CTA) must be performed by intravenous injection of enhancer (contrast agent) to show the vascular structure through computer reconstruction processing, so as to initially determine the presence of vascular lesions and the type of lesions. CTA requires advanced equipment, usually 64-layer spiral CT or higher, to show small vascular lesions more clearly, and requires high scanning skills and is relatively expensive. This test is suitable for emergency patients and patients with suspected cerebrovascular lesions. 3.Magnetic resonance imaging (MRI): With the continuous improvement of MRI examination technology, the examination time is getting shorter and the clarity of images is getting higher. For intracerebral lesions (non-acute hemorrhage or traumatic brain injury) is the preferred method of examination. Because MRA requires patients to enter a strong magnetic field, patients with pacemakers and ferromagnetic metals in the body are prohibited from entering the magnetic field, and patients with claustrophobia and those who cannot stay still to cooperate with the examination also cannot undergo the examination. 4.Angiography (DSA): Angiography is a minimally invasive technique in which a very small catheter is inserted through a puncture in the femoral artery (root of the thigh) and sent into the carotid artery respectively, and then an enhancement agent is injected to show the blood vessels in the neck and brain, and to observe the blood circulation in the brain. The technique is highly demanding and is usually performed by a specialized interventional clinician. This test is the gold standard for identifying cerebrovascular lesions and can guide the development of treatment plans. The disadvantage is that patients often need to be hospitalized for the examination, which is invasive and has certain complications, although the chance of complications is extremely low, a few of them may lead to catastrophic consequences. In conclusion, for potential cerebrovascular lesions, CTA and MRA can initially determine the presence or absence of lesions and the type of lesions, such as arterial stenosis, aneurysm, vascular malformation, tumor, etc. DSA can clarify the extent of cerebrovascular lesions, cerebral blood circulation compensation and formulate treatment plans.