Ultrasound of the carotid arteries is, as the name implies, an ultrasound examination of the bilateral carotid arteries. It includes the unnamed, bilateral subclavian, common, internal, and external carotid arteries as well as the bilateral vertebral arteries. The examination of the carotid arteries involves determining the origin and course of the arteries and their relationship to the surrounding tissues. It is important to determine whether there are some congenital abnormalities or secondary changes in the vessels. It is also necessary to observe the condition of the vessel wall, such as whether the inner intima is continuous and smooth, whether there are structural abnormalities such as arterial entrapment and abnormal channels, and the location, echogenicity, and size of plaques in the arterial wall. It is also important to note whether the lumen is narrowed or dilated, and to measure the percentage of the diameter and area of the narrowed lumen. Color Doppler can observe and analyze parameters such as the direction of blood flow, the filling of the blood flow signal and the flow velocity. Carotid ultrasound is mainly used to assist in the clinical diagnosis of carotid artery diseases, such as those causing abnormal blood supply to the brain and stroke, and to accurately determine the degree and extent of stenosis of carotid arteries, as well as the morphology and nature of plaques, thus providing a diagnostic basis for clinical treatment plans.