Three-dimensional CT angiography study on the relations between the vertebral artery and atlantoaxial joint

Background The vertebral artery(VA)and atlantoaxial joint(AAJ),with complicated structures,are located in thedepths of the head-neck boundary area,the regional anatomy of which cannot be shown globally and directly.This studyaims to evaluate three-dimensional CT angiography(3DCTA)in displaying the AAJ,atlantoaxial segment of the vertebralartery(ASVA)and the identification of their interrelations.Methods Sixty-eight subjects without pathology of the ASVA and AAJ were selected from head-neck CTA examination.All the 3D images were formed with volume rendering(VR)together with techniques of separating,fusing,opacifying andfalse-coloring(SFOF).On the 3D images,the ASVA and AAJ were observed,and their interrelations were measured.Results All the 3DCTA images were of high quality and up to our requirements.They could clearly and directly showthe ASVA,ascending along the AAJ.There were 5 curves in the course of the ASVA,of which 2 curves were away fromthe atlantoaxial joint,one in the 2nd curve of 0.0mm-5.4mm,the other in the 4th of 2.6 mm-9.2mm.There was nosignificant difference in the measurements between left and right(P>0.05).The curved parts of the ASVA slightlyexpanded,with the biggest diameter of 5.6 mm in the 4th curve.Statistical comparison shows that the left ASVA is largerthan the right(P<0.05).Variations of the ASVA were found in 8 cases and of the AAJ in 12.Conclusions 3DCTA can globally and directly demonstrate the structures of the AAJ,ASVA and their interrelations.The 3D imaging data make up and enrich the research contents of regional anatomy and lay the foundation for relatedstudy and applications.