FIG 1. Regions of interest at the internal carotid artery (ICA), in the cavernous sinus, and the sigmoid sinus (SS) are set on the axial image. The peak times for the ICA and SS, and the peak-to-peak time are analyzed on time-attenuation curves. ICA indicates internal carotid artery; SS, sigmoid sinus; A, arterial-phase scan for 3D-CT arteriography; V, venous-phase scan for 3D-CT venography