下颈椎椎弓根螺旋CT扫描的三维重建及测量

Multiplanar spinal CT 3D reconstruction and measurement of the lower cervical pedicle

目的评价应用多层螺旋CT扫描三维重建技术测量下颈椎椎弓根相关参数的可行性。方法8具成年男性颈椎标本经螺旋CT扫描后，把信息传送至随机工作站（Silicon Graphics O2），结合下颈椎椎弓根置钉的参数需求，进行三维重建[容积成像（VR）和多平面重组（MPR）]后测量椎弓根各个相关数据，然后对这些数据进行分析。结果本组下颈椎椎弓根的外展角平均为42．02°±7．55°，C7最小（35．63°±6．34°），C4最大（46．94°±5．69°）；头倾角平均为76．30°±12．01°，C3最小（72．93°±6．57°），C7最大（81．27°±13．34°）；入点至下关节缘距离平均为（11．23±1．78）mm，C3最小[（10．54±1．25）mm]，C6最大[（12．05±1．40）mm]；入点至侧块外缘距离各椎体相差较大，平均为（2．65±1．21）mm，C4最小[（1．69±0．81）mm]，C7最大[（3．74±0．99）mm]；入点至椎体前缘距离各椎体差异较小，平均为（31．42±2．13）mm；椎弓根皮质骨高度平均为（8．43±1．30）mm，宽度平均为（5．54±1．26）mm；椎弓根松质骨高度平均为（3．69±1．19）mm，宽度平均为（2．67±1．15）mm；椎弓根皮质高度一般大于宽度，C4内径最小，C7内径最大。结论VR、MPR重建图像可满足椎弓根参数测量要求，其所测量的下颈椎椎弓根参数可满足经椎弓根手术的术前评估需求；下颈椎椎弓根变异较大。

Objective To evaluate the clinical significance of measuring the lower cervical pedicle using multiplanar spinal CT （MSCT） 3D reconstruction. Methods Eight specimens of adult male vertebrae were examined by MSCT. The data were sent to Silicon Graphics O2 for 3D reconstruction according to the parameter requirements for lower cervical pedicle fixation, using reconstruction images of volume rendering （VR） and muhiplanar reformation （MPR）. Results Statistically significant differences were found between vertebrae in the following lower cervical data, including the pedicle angle relative to transverse plane = 42.02° ± 7.55°, with the largest at C4 and the smallest at C7; the pedicle angle relative to sagittal plane = 76. 30°± 12.01°, with the largest at C7 and the smallest at C3; the distance from the entry-point to the margin of lower joint = 11.23 mm ± 1.78 mm, with the longest at C6 and the shortest at C3; the distance from the entry-point to the outermost margin of lateral mass = 2.65 mm ± 1.21 mm, with the longest at C7 and the shortest at C4. The distance from the entry-point to the vertebral anterior border = 31.42 mm ± 2. 13 mm, with little difference between C3 and C7; the height of pedicle cancellous bone = 3.69 mm ± 1.19 mm and the width = 2.67 mm ± 1. 15 mm; the height of pedicle cortical bone - 8.43 mm ± 1.30 mm and the width = 5.54 mm ± 1.26 mm. The longest inside diameter of pedicle was seen at C7 and the shortest at C4. Generally the height of pedicle was larger than the width of pedicle. Conclusion Since 3D reconstruction images by VR and MPR techniques can be used to measure various data related to the pedicles, they can help the preoperative planning for transpedicular screw fixation of the lower cervical spine.