Radiologic importance of a high-resistive vertebral artery doppler waveform on carotid duplex ultrasonography

Objective. The appearance of the vertebral artery (VA) waveform on a pulsed Doppler examination performed during standard carotid duplex ultrasonography (CDU) may suggest vertebrobasilar disease. We sought to determine the radiographic importance of high-resistive (HR) pulsed Doppler VA waveforms seen on CDU. Methods. The Noninvasive Vascular Laboratory database was queried for CDU studies noting the HR VA Doppler signal. Studies with unilateral or bilateral HR and antegrade VA waveforms with correlative neuroimaging studies within 60 days were included. Imaging reports were reviewed to determine the following: (1) a normal VA; (2) at least moderate distal VA or basilar artery (BA) stenosis, occlusion, or dissection; (3) a congenitally diminutive VA; or (4) other abnormalities. Results. Of 1338 studies with 1 or more HR VA waveforms, 79 studies met all inclusion criteria (n = 157 arteries) and had adequate correlative neuroimaging. There were 90 HR VAs, and HR waveforms were equally distributed between right and left sides. The mean peak systolic velocity of HR versus lowresistive (LR) VAs was 51.7 versus 63.6 cm/s (P = .04); the mean end-diastolic velocity of HR versus LR VAs was 4.6 versus 17.3 cm/s (P < .001); and the resistive index of HR versus LR VAs was 0.92 versus 0.73 (P < .001). Of all HR VAs, 18.9% were normal; 38.9% had distal vertebrobasilar stenosis or occlusion; 35.6% were congenitally diminutive; and 6.7% had other abnormalities (proximal stenosis, excessive tortuosity, fibromuscular dysplasia, and BA hypoplasia). Conclusions. The finding of an HR spectral Doppler signal in the VA was associated with major vertebrobasilar disease (46% of cases) and should prompt additional neuroimaging in the appropriate clinical situation.