Carotid Doppler generally refers to carotid Doppler ultrasound, which can check for carotid atherosclerosis, carotid stenosis and occlusion. In addition, there is another test called transcranial Doppler also done as a primary screening test for intracranial blood vessels. The two can be used in combination. Carotid Doppler ultrasound is an ultrasound imaging technique that evaluates lesions in the walls of the carotid arteries. It can clearly show the presence or absence of intima-media thickening and atherosclerotic plaque formation in the vessels. It can show the location and size of plaque formation, and whether it has led to stenosis or occlusion of the vessel. At the same time, it can check whether there is vertebral artery blood theft and whether there is any abnormality in the vessel morphology. In the clinic, it is often used to check carotid atherosclerosis, carotid artery stenosis and occlusion and other diseases, which provides the basis for the early prevention and treatment of these diseases, and has a greater significance in guidance. Another test, called transcranial Doppler ultrasound, also uses the Doppler principle to measure the blood flow velocity and frequency spectrum of the middle cerebral artery, ophthalmic artery, and vertebral artery through the ophthalmic, temporal, and posterior occipital windows, and is used for initial screening and indirectly determining the presence or absence of stenosis or occlusion of the middle cerebral artery. Patients with related symptoms can consult a professional doctor for examination to determine whether there is any lesion of the carotid artery.