The value of duplex and continuous wave Doppler sonography for evaluation of the extracranial vertebral arteries: a prospective comparison with angiography.

BACKGROUND. The role of duplex sonography in the detection of the extracranial vertebral arteries is not well established. The purpose of this study was to determine the practical possibilities of vascular sonography for non-invasive investigation of the vertebral arteries. METHODS. The extracranial vertebral artery was divided into the pretransverse segment, the intertransverse segment C6-C2, and the atlas loop. The first two segments were examined by duplex probe and the third segment, by continuous-wave probe. Sixty vertebral arteries were studied for detecting vessel diameter, peak systolic as well as diastolic frequency shifts, flow direction and Doppler flow characteristics. A blind angiographic comparison was also performed for the sake of confirming morphological findings and flow direction. RESULTS. Duplex imaging could detect more than 90% of the vertebral arteries. The mean value of vessel diameter was 3.3 +/- 0.6 mm for the right vertebral artery and 3.5 +/- 0.5 mm for the left. Peak systolic as well as diastolic frequency shifts expressed in KHz was 1.4 +/- 0.4 versus 1.6 +/- 0.5 and 0.5 +/- 0.2 versus 0.5 +/- 0.2 in the right and the left vertebral arteries respectively. A 74% agreement in vessel size was obtained by both duplex scanning and angiography. A 100% accuracy was obtained for blood flow direction through means of a Doppler signal. Abnormal findings included stenosis or occlusion (four arteries), hypoplasia or aplasia (two arteries), and subclavian steal phenomenon (two arteries); Six of these eight were correctly predicted by confirmation of the angiographic findings. CONCLUSIONS. A combination of duplex and continuous wave Doppler sonography was affirmed in this study as a relatively accurate screening technique for detection of vertebral artery abnormalities.