The significance of CT multi-planar reconstruction of vertebral artery CT angiography in C2 pedicle screw placement

English Keywords:Axis  Pedicle screw  Multi-planar recontruction  Vertebral artery  CT angiography

English Abstract:

  【Abstract】 Objectives: To investigate the significance of CT multi-planar reconstruction of vertebral artery CT angiography(CTA) in C2 pedicle screw placement. Methods: The vertebral artery CTA images of 77 patients were reviewed retrospectively by CT multi-planar reconstruction. The positions in three dimensions were adjusted according to the screw′s ideal direction, and the cross section of the screw passing through the pedicle was displayed based on CT multi-planar reconstruction. A circle was demarcated on the former plane to simulate the cross section of the screw. The diameter of the circle, the accommodation of screw in C2 pedicle, and the positions of the screw related to the vertebral artery were taken into account to assess the feasibility of pedicle screw placement. And meanwhile, the feasibility was assessed by measuring the inner diameters of pedicle complex. The results of the two methods were compared. Results: The simulation of placement of C2 pedicle screw basing on CT multi-planar reconstruction illustrated the accommodation of screw in C2 and its relationship with surrounding structures. According to this method, 10(13%) cases of left side and 19(25%) cases of right side could not accommodate the circle with the diameter of 4mm and could not be placed pedicle screw, while operation was unavailable for 12(16%) cases of left side and 20(26%) cases of right side by measurement of inner diameters. The P value of McNamara test was 0.5 in the left and 1 in the right. There was no significant differences between the results of two methods(P>0.05). The result of Kappa test was 0.770 in the left and 0.732 in the right, and the P value of the Kappa test in the both sides was 0, which showed good consistency. Conclusions: The simulation of placing pedicle screw in axis basing on CT multi-planar reconstruction can illustrate the screw accommodation in C2 and its relationship with surrounding structures, which can provide good reference for the operation.