There are many items that can be examined by brain Doppler ultrasound, as follows: 1.Determination of blood vessel condition: It can examine the blood flow rate from the neck to the blood vessels in the skull, so as to determine the narrowing of blood vessels or whether there is atherosclerosis from the side. 2.Diagnose migraine or cerebrovascular spasm: Migraine can also be examined by cerebrovascular ultrasound, such as cerebrovascular spasm, which can also be judged by brain Doppler ultrasound. 3.Determine whether there is an unclosed foramen ovale: TCD can also do foam test. Foam test can indirectly determine whether there is an unclosed foramen ovale on the other hand. If there is an unclosed foramen ovale, further transesophageal ultrasound is needed to determine whether there is really an unclosed foramen ovale, and if there is, sealing surgery is needed.