Early arterial phase of the right vertebral artery injection, delineating the configuration of a fusiform aneurysm at the basilar end of the right posterior communicating artery. It appears that the origin of the right P1 segment of the posterior cerebral artery is incorporated in the aneurysm segment and the posterior communicating artery distal to the aneurysm is obtuse. The ipsilateral supraclinoidal artery is also perfused by this injection.