Congenital Absence of Right Internal Carotid Artery: Demonstration of Collateral Circulation by Computed Tomography Angiography

Congenital Absence of Right Internal Carotid Artery: Demonstration of Collateral Circulation by Computed Tomography Angiography In this paper we demonstrated a case with right internal carotid artery absence and collateral circulation via anterior communicating artery. A 58-year-old female with vertigo was referred to our department for computed tomography angiography. On arterial phase images, there was no internal carotid artery on the right. At the level of circle of Willis, right anterior and middle cerebral arteries were supplied by the contralateral internal carotid artery by means of anterior communicating artery. On bone window right carotid canal is also absent. Volume rendering technique revealed the absence of right internal carotid artery and collateral circulation via anterior communicating artery clearly. Absence of internal carotid artery is generally asymptomatic. Computed tomography angiography can visualize pathologies of carotid arteries and circle of Willis.