Angiotomographic study of the normal cerebral circulation. II. The vertebrobasilar system.

Simultaneous tomography applied to normal vertebral angiography has, by the dissociation of the vascular planes, made a selective and spatial study of the vertebrobasilar circulation possible, and therefore, the identification of the vessels which are partly or totally hidden by other vascular structures. This technique has also led to a better delimitation and sometimes a direct observation and spatial localization of some anatomical structures above and below the tentorium.