Carotid ultrasound. 
Carotid duplex ultrasonography is a noninvasive technique for hemodynamically significant stenosis detection and cardiovascular risk estimation.  Anatomic information of carotid arteries is provided by B-mode scanning.  Hemodynamic features are displayed color-flow and pulsed Doppler imaging.  Examination technique, normal carotid anatomy and flow pattern, and potential limitations are presented.