Carotid artery stenosis assessed by duplex ultrasonography

Carotid duplex ultrasonography of the right internal carotid artery.
(Left) The high peak systolic flow velocity indicates the presence of 80 to 90 percent stenosis in the right internal carotid artery proximal to the measurement.
(Right) Ultrasonic image of the right internal carotid artery distal to the stenosis; the foot pad (arrow) represents the site at which the flow velocity is measured. These findings were confirmed by MR angiography.