Case Description: Infra-Optic Anterior Cerebral Artery in a Neonatal Doppler Ultrasound

There are few publications about the visualization of the circle of Willis and its variations using ultrasound. We hereby document the possibility of detecting a rare and clinically relevant variation of the circle of Willis, the infra-optic origin of the ACA, during routine cranial ultrasound in a preterm girl. Best visualization was with high resolution power doppler imaging, the diagnosis was MR confirmed near term. The importance of this diagnosis lies in the risk of aneurysm formation at an atypical location, information essential for proper management thereof. We suggest it is in a child's best interest to include a careful description of the circle of Willis when a sonographic or MR angio exam is performed for whatever reason.