Fig 2.

Arteriograms.

A–C, Frontal (A), lateral (B), and right anterior oblique (C) views from a conventional right common carotid arteriographic study demonstrate a low origin of the right ACA (black arrow), proximal to the ophthalmic artery. A small infundibulum (white arrow in A) demarcates the origin of the ophthalmic artery. The A1 segment of the ACA has a characteristic horizontal-medial course (as it passes under the ipsilateral optic nerve) before ascending to join a normally positioned AcomA. Reflux of contrast material across the patent AcomA illustrates the normal appearance of the contralateral A1 segment (arrowhead in C). The left middle cerebral artery bifurcation aneurysm (white arrow in C) is demonstrated.