Duplex scanning of normal vertebral arteries.

Vertebral arteries were studied by Duplex scanning in 50 normal subjects. Pretransverse and C6-C5, C5-C4 intertransverse segments were visualized in all cases on both sides; segment C4-C3 was visualized in 100% of the cases on the right side and in 90% on the left; ostium was obtained in 94% of the cases on the right and in 60% on the left. The left vertebral artery was dominant in 48% of the cases while the right vertebral artery was dominant in 14%. Three vertebral arteries were hypoplasic. Duplex scanning was thus found to be an easily performed noninvasive method to study morphological and hemodynamic characteristics of vertebral arteries from their origin to the C4-C3 level.