Fig. 2

Duplex sonography of the right common carotid artery. Note the dissection membrane (dashed line) separating two distinct lumina, each with different flow profiles. The false lumen (1) exhibits systolic and diastolic orthograde flow (arrow). The true lumen (2) also displays orthograde flow, but is narrowed to a luminal stenosis of 50% (peak systolic velocity 271 cm/s, reference range 29–178 cm/s [2])