At present, there are four tests for cerebrovascular, which can be selected according to the situation: 1, Doppler ultrasound, non-invasive, the worst accuracy; 2, CTA, i.e. CT angiography, which requires contrast injection and is generally used for the examination of neck vessels; 3, MRA, i.e. magnetic resonance angiography, non-invasive, high cost; 4, DSA, i.e. cerebral angiography, the current gold standard for the diagnosis of cerebrovascular lesions, which requires hospitalization, is traumatic and has certain risks.