不同影像学方法测量斜坡椎管角的一致性分析

目的：测量斜坡椎管角在不同骨科患者群的数值范围，分析X线及CT矢状位重建法测量斜坡椎管角的一致性，并探讨斜坡椎管角的测量对枕颈融合术的临床意义。方法纳入189例无上颈髓压迫症患者和37例枕颈部序列异常合并上颈髓压迫症患者，测量颈椎中立位和过屈、过伸位侧位X线片上斜坡椎管角的数值。随机选取有或无上颈髓压迫症患者各10例的颈椎中立位X线和CT正中矢状重建图像，由2位测量者重复测量斜坡椎管角并计算组内相关系数。结果无上颈髓压迫症状者过屈位、中立位和过伸位的斜坡椎管角均显著大于枕颈部序列异常合并上颈髓压迫症患者（P＜0．01）；前者斜坡椎管角数值的变化范围为23．87°±10．23°，后者为19．10°±7．96°（P＜0．01）；说明后者的枕颈复合体较前者僵硬并处于异常屈曲位。 X线法测量斜坡椎管角的观察者之间组内相关系数为0．619，低于CT重建法的相应值0．897；X线法的观察者组内相关系数在观察者1和观察者2分别为0．635和0．657，也低于CT重建法的相应值0．937和0．924；CT重建法较X线法具有更好的一致性。结论本研究得出了不同骨科患者群斜坡椎管角的数值范围，为枕颈融合术患者的体位摆放和枕颈部固定融合角度的选择提供了理论依据，并为术中准确测量斜坡椎管角提供了具体方法。

Reliability analysis of different imaging modalities for measuring clivus-canal angle

Objective To compare the intra-observer and inter-observer reliability of X-ray film and CT saggital reconstruction imaging modalities for measuring clivus-canal angle in different patients, and to discuss its clinical relevance for occipitocervical fusion. Methods A totle of 189 orthopedic patients without symptoms related to upper cervical spinal cord compression (NC group) and 37 patients with malalignment of occipito-atlanto-axial complex and symptoms related to upper cervical spinal cord compression (MC group) were included in the study. The clivus-canal angle was measured on lateral cervical radiographs of neutral and extension-flexion position. Two observers independently measured clivus-canal angle of 10 patients from NC group and 10 patients from MC group using X-ray film and CT saggital reconstruction methods on 2 separate occasions, and the intra-observer and inter-observer reliability of the 2 imaging modalities were analyzed. Results The values of clivus-canal angle measured on flexion, neutral and extension position in NC group were significantly higher than that in MC group (P<0.01) respectively. The range of the value change of clivus-canal angle in NC group was 23.87°±10.23°, also significantly higher than that in MC group, which was 19.10°±7.96°(P<0.01). The occipito-atlanto-axial complex of the patients in MC group was more rigid and flexed than in NC group. The inter-observer correlation coefficient for X-ray films and CT saggital reconstruction were 0.619 and 0.897, respectively. The intra-observer correlation coefficient among observer 1 and observer 2 for X-ray films were 0.635 and 0.657, while that for CT saggital reconstruction were 0.937 and 0.924. CT saggital reconstruction could improve the reliability of measuring clivus-canal angle in comparison to X-ray method. Conclusion The current study gave the value range of clivus-canal angle in different patient populations, and provided practical evidence for patient positioning and determination of fixed angle of occipito-atlanto-axial complex during occipitocervical fusion procedure.