Carotid ultrasound examination is useful in evaluating the whole-body development of atherosclerosis, because the carotid arteries are susceptible to atherosclerosis and easy to examine. The first stage of evaluating carotid-artery atherosclerosis is based on the thickness of the intima-media complex. Development of arthrosclerosis creates plaque that forms local protruding lesions. Presence of this plaque produces narrowing of the arteries, adversely effecting blood flow. Although intima-media thickness (IMT) is a useful parameter, a resolution of 7-10 MHz proves only the presence of plaque with a thickness of at least 0.1 mm. Thin plaque, around 1.1 mm thick, does not always correspond pathologically to the identified atheroma. Echogenesity, heterogeneity, surface, and mobility should be evaluated when the plaque is large. It should be noted that the calculated number of carotid artery stesosis varies with method of calculation, and that stenosis is usually evaluated from peak systolic velocity in Europe and the United States.