There are many items that can be examined by brain Doppler ultrasound, as follows: 1.Judging the vascular condition: It can check the blood flow rate from the neck to the intracranial vessels, thus judging the narrowing of the vessels or whether there is atherosclerosis from the side. 2.Diagnosing 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.