Case #1a
AP left subclavian injection
The left internal carotid is occluded and the left vertebral artery is irregular. The anterior spinal artery is opacified in this injection, as a branch of the thyrocervical trunk.
Case #1b
Lateral posterior fossa, left subclavian injection, early
The anterior spinal artery is again seen and partially opacifies the basilar artery. The left vertebral artery ends in an isolated PICA.
Case #1c
Lateral posterior fossa, left subclavian injection, late
A late view confirms that the left vertebral ends as an isolated posterior inferior cerebellar artery and that there is no contribution to the basilar artery.