Three-dimensional CT study on the anatomy of vertebral artery at atlantoaxial and intracranial segment

The atlantoaxial and intracranial segments of vertebral artery (V3-4) are winding around their peripheral structures. Their panorama is not easy to be observed in surgery. CT angiography (CTA) shows some advantages in this aspect. So, the aim of this study is to reveal the three-dimensional (3D) anatomy related to V3-4 and prepare ground for clinical diagnosis and treatment. Ninety-eight cases without the pathologies of V3-4 were selected from the head-neck CTA examination. All the 3D images were formed with multiplanar reconstruction, volume rendering and volume rendering together with separating, fusing, opacifying and false-coloring. On the 3D images, the courses and branch of V3-4 were observed and measured, as well as their peripheral venous vascular plexus (VVP). V3-4 with typical five curves was found in 85 cases and with variations in 13. The left V3-4 is larger than right (P < 0.05). The branch shown on the 3D image is the posterior inferior cerebellar artery at V-4, at most two on either side. VVP are at the back of the atlantoaxial joints and around the V-3, each on either side. There is no significant difference in size and shape between left and right (P > 0.05). The anatomy and variations of V3-4 can be clearly and directly shown by 3DCTA. The understanding of vertebral artery and bony structures around there can provide anatomic basis for surgery and radiological diagnosis.