Clinical Aspects of the Venous System in Cerebral Angiography, especially for treating Vascular Lesions and Tumors at the Skull Base(<SPECIAL ISSUES>Veins of the Skull Base (2): Petroclival Region)

Recently, Magnetic Resonance Angiography and three-dimensional CT angiography have become important tools for neurosurgeons and neuroradiologists. In the daily clinical diagnosis, the number of diagnostic cerebral angiographies performed has actually been reduced, but its dominant position in the evaluation of detailed information for advanced treatment of skull base diseases, such as dural arteriovenous fistulas, arteriovenous malformations, or skull base tumors, still remains and is much required. Classical venous anatomy and landmarks are not described in this chapter. We illustrate how to obtain much clearer venous images and analyze venous hemodynamic conditions from the aspect of endovascular treatment or direct surgery. Practically important points of venous findings for treatments are also described here mainly from the standpoint of "venous cross roads".