There is a kind of examination called MRI, which shows the structure of the organs on the body through the magnetic field, and it is clearer than the previous CT examination. In addition to being able to find structural abnormalities, it can also check the narrowing of the cerebral blood vessels as well as whether or not they are blocked, and this kind of examination is the magnetic resonance angiography. There are two methods for this kind of examination, as follows: 1. Ordinary method, whose examination is almost the same as ordinary MRI, and the time may be shorter; 2. Playing the enhancer, the cerebral blood vessels are displayed more clearly, which belongs to the enhanced magnetic resonance angiography, and the cerebral blood vessels can be basically displayed through this examination. The display is mainly large blood vessels, giving valuable information to the clinic.