Duplex ultrasonography of vertebral arteries: examination, technique, normal values, and clinical applications.

A technique for the imaging of vertebral arteries at their origins and along the longitudinal extracranial course is described. The results of the examination of 108 normal vertebral arteries are shown. The vertebral artery could be distinguished in the pretransverse and intertransverse segment C5-C6 in 100%. The average diameter of the vessel was 3.81 +/- 0.46 mm on the right and 3.88 +/- 0.47 on the left side. The average maximal systolic velocity was 43.0 +/- 8.9 cm/s on the right and 43.3 +/- 9.6 on the left side. In 81% of the cases the vertebral origin could be located on the right and in 65% of the cases on the left side. The technical quality of visualization, especially of the vertebral origin, was greatly influenced by the depth of the examined structure. Examples of pathologic findings, such as hypoplasia, stenosis, and occlusion, demonstrate the practical possibilities of this noninvasive method.