3.0T磁共振对正常成人环枕关节轴向旋转角度测定的探讨

Normative data on axial rotation of the atlanto-occipital joint on 3.0T MR imaging using a simple and reliable method of calculation

目的应用高场强MRI,探索正常成人不同体位下环枕关节轴向旋转角度范围的一种简单、准确的测量方法。方法应用高场强3. 0T MR扫描仪,对100名健康志愿者进行以环枕关节为扫描中心的七个不同体位的上颈椎MR扫描。环枕关节的轴位旋转角度是指颅骨中线与环椎前后结节连线之间的夹角,以颅骨中线为参考线,当上述两线成角于参考线的右侧时,设定所成角度为正值,成角于左侧时,所成角度为负值。轴面内不同体位下的实际旋转角度是指对同一个志愿者而言,其它六个体位下所测得的夹角与中立位时所测得的夹角的差值。并对所得数值进行进一步统计学分析。结果七个不同体位下环枕关节轴面内旋转角度的范围介于-4. 8°～+5. 0°之间,实际的环枕关节仰卧位轴面内最大侧屈范围介于-1. 0°～+1. 0°之间,实际的环枕关节仰卧位轴面内最大旋转范围介于-3°～+3. 2°之间,实际的环枕关节俯卧位轴面内最大旋转范围介于-4. 0°～+3. 8°之间。实际仰卧位右侧屈、仰卧右侧旋转、俯卧位右旋转平均值分别是0. 1°、1. 7°、0. 8°;实际仰卧位左侧屈、仰卧左侧旋转、俯卧位左旋转平均值分别是-0. 1°、-1. 7°、-0. 8°。结论正常人不同体位下环枕关节轴向旋转角度能够应用3. 0T MR进行测量,并在理论上和数据上证实了此方法的准确性,对环枕关节轴位内的旋转脱位提供了一种新的简单、可靠的影像学诊断方法。

Objective To generate normative ranges for AOJ rotation in various ‘in vivo’ positions and to investigate the reliability of a simple imaging method for measurement using routine high-field magnetic resonance （MR） imaging. Methods 100 healthy volunteers were imaged on 3 T MR imaging with the AOJ in the center of the field of view. The scans were uniformly performed in seven different positions. The range of axial rotation was calculated by the angle between the craniofacial midline and the line linking the anterior and posterior tubercles of the atlas. Based on the reference line of craniofacial midline, the angle was defined as positive when it was angled right, and negative when it was angled left. The actual normative range of axial rotation was the difference between the angle in the supine neutral position and in the other positions for the same volunteer. All the data of measuring angle were analyzed further. Results The normative axial rotation range of the AOJ in different positions was between -4.8° and ＋5.0°. The mean values of the actual rotation angles in the right supine position with maximum bending, the right supine position maximum rotation, and the right prostrate position maximum rotation were 0.1°, 1.70°, and 0.8°, respectively. The mean values of actual rotation angles in the left supine position with maximum bending, the left supine position with maximum rotation, and the left prostrate positive with maximum rotation were -0.1°, -1.7°, and -1.1°, respectively. Conclusion A simple and reliable method of measurement on 3.0 T MRI demonstrated the normative axial rotation range of the AOJ in different positions. This method could be practically used to precisely diagnose AOJ rotary subluxation or dislocation.