FIG 1. Patient with a left internal carotid artery aneurysm.

3D-CTA (superior view) shows drainage of well-developed SSVs (black arrow) into the SPS at the inner portion of the sphenoid wing (black arrowhead) on the left side. A well-developed DMCV (white arrow) connecting to the BVR (double black arrowheads) is also visualized on the left side. DMCV and BVR development (double black arrows) on the right side is poor compared with that on the left side.