Brain color ultrasound transcranial Doppler ultrasound examination is to detect the blood flow velocity of cerebral arterial ring at the base of the skull through the temporal window, occipital window, and ocular window of the head, and to determine the functional condition of the cerebral arteries, which can diagnose cerebral vascular stenosis, atherosclerosis, hypertension, and cerebral infarction. The head needs to be cleaned the day before the examination, and normal food and water should be taken in the morning to avoid the increase of blood viscosity, which will lead to the decrease of cerebral blood flow velocity and affect the accuracy of the results, and no communication equipment should be used in the examination room to avoid the interference of electromagnetic signals to the cerebral blood flow instrument.