Ultrasonography of Large-Vessel Vasculitides

Vasculitis is an autoimmune disease that is characterized by vascular wall inflammation, resulting in an inflamed arterial wall that is swollen and a narrow lumen. Ultrasonography has been proposed as a valuable tool for the evaluation of vasculitic disorders, particularly large-vessel vasculitides. There are three typical ultrasonic findings related to inflamed arteries: 1) the intimal edema forms a hypoechoic ring at the periphery of the lumen, i.e., the “halo sign”; 2) lumen stenosis; and/or 3) occlusion. When lumen stenosis is present, the velocity of the systolic blood flow increases. Color Doppler ultrasonography can show the persistence of color signals during the diastolic phase, and the mixture of colors (i.e., aliasing phenomenon) at the post-stenotic site. When the lumen is totally occluded, no color signal can be detected. Temporal arteritis has been widely studied using ultrasonography in patients who present with both typical symptoms and ultrasonic findings such as the halo sign, and a diagnosis of temporal arteritis can be made with a specificity of 99.5%. Ultrasonography can also be used to detect articular and periarticular involvement in various forms of vasculitis. In this report, we review the role of ultrasonography for the assessment of large-vessel vasculitides.