Objective The study aimed to determine the influence of head neck position on imaging measurements used to assess the craniovertebral junction (CVJ) and to recommend the most appropriate position for the evaluation of the CVJ.

Study Design A cross-sectional sample of adult dogs' cadavers was subjected to a computed tomography scan of the cranium and the cranial cervical region in three standardized head positions. Imaging measurements often used to assess the CVJ were measured. The influence of the head neck position, breed, weight and gender on imaging measurements was tested using repeated measures analysis of variance.

Results Twenty-eight cadavers of small breed dogs were enrolled in the study. All cadavers examined had occipital dysplasia. All transarticular imaging measurements were dependent on the head neck position. In addition, the breed, weight and gender had an influence on several measurements.

Conclusion We recommend a standardized head neck position of 50 degrees flexion if quantitative imaging measurements of the CVJ are used to diagnose pathologies in this region. Future studies should focus on the definition of cut-off values for quantitative imaging measurements of the CVJ to differentiate between healthy and diseased small breed dogs. Regarding atlantoaxial instability, a combination of six parameters (C1-C2 angle, C1-C2 overlap, atlantoaxial distance, dens-to-axis length ratio, ventral compression index and clivus canal angle) is promising for its diagnosis.

目的 本研究旨在确定头颈部位置对用于评估颅椎交界处 (CVJ) 的成像测量的影响，并为评估 CVJ 推荐最合适的位置。

研究设计 对成年犬尸体的横截面样本在三个标准化头部位置进行颅骨和颅颈区域的计算机断层扫描。测量常用于评估 CVJ 的成像测量值。使用重复测量方差分析测试头颈部位置、品种、体重和性别对成像测量的影响。

结果 28 具小型犬的尸体被纳入研究。所有检查的尸体都有枕骨发育不良。所有经关节成像测量均取决于头颈部位置。此外，品种、体重和性别对多项测量有影响。

结论 如果 CVJ 的定量成像测量用于诊断该区域的病理，我们建议采用标准化的 50 度屈曲头颈部位置。未来的研究应侧重于 CVJ 定量成像测量临界值的定义，以区分健康和患病的小型犬。关于寰枢椎不稳，六个参数（C1-C2 角、C1-C2 重叠度、寰枢距、密度与轴长比、腹侧压缩指数和斜坡管角度）的组合有利于其诊断。