MRA is magnetic resonance angiography, a state-of-the-art test to examine the blood vessels in the brain. Magnetic resonance angiography is a non-invasive examination method without ionizing radiation, which is most suitable for the diagnosis of vascular diseases in the brain. It can quickly analyze and diagnose cerebrovascular malformations, aneurysms, stenosis and dilatation of blood vessels in the brain, and is more suitable for the diagnosis of cerebrovascular diseases in the elderly. At the same time, MRA has the feature of non-invasive compared with CTA. In clinical diagnosis of cerebrovascular diseases, the most effective method is cerebral angiography, but it is invasive, and cerebral angiography is generally used only when other methods cannot clearly diagnose or require surgical treatment.