下颈椎椎弓根入口处皮质厚度的影像学测量

Imageology Measurement of Cortex Thickness on Pedicle Entry's Circumferential Structures of Subaxial Cervical Vertebrae

目的:对下颈椎椎弓根四壁及入口毗邻结构的皮质厚度行影像学测量,为临床椎弓根钉植入提供参考。方法:对8例新鲜颈椎进行DR摄片和螺旋CT扫描重建,在AutoCAD软件中测量CT图像显示的椎弓根四壁及入口处毗邻结构(包括上关节突前壁(ACS)、椎板前壁(ACL)、下关节突前壁(ACI)和横突孔后壁(PCT))的皮质厚度,并行统计学分析。结果:双斜位DR片示颈椎椎弓根内壁(MCP)、上壁(SCP)、下壁(ICP)皮质较厚,而外壁(LCP)菲薄。统计学分析发现同一颈椎的MCP、SCP、ICP、ACL、ACS和ACI之间的厚度无差别,LCP和PCT皮质菲薄,明显薄于前6项指标。MCP、SCP、ICP、ACS和PCT在C3～7间的厚度无差别,PCTc明显小于其它4项指标。结论:同一颈椎PCT和LCP明显薄于其它各项指标,提示PCT和LCP抵抗外力强度最小,MCP、SCP、ICP和ACS在C3～7间厚度无差别,提示其在不同颈椎间抵抗外力可能一致。颈椎椎弓根钉固定时应该避免靠近PCT和LCP。

Objective：Cortex thicknesses of subaxial cervical pedicle entry＇s circumferential structures were measured on planar CT images to provide quantitative data for cervical pedicle screw insertion. Methods： Eight subaxial cervical spine specimens were collected from fresh cadavers. Projectional Digital Radiography （DR） and multi - slice spiral CT volumetric scanning were done on each specimen from C3 to C7. Raw transaxial sectional CT images were then reconstructed by interpolation reconstruction method. The thickness of median, superior, lateral and inferior cortex of pedicle （MCP, SCP, LCP and ICP, respectively）, thickness of anterior cortex of lamina （ACL） adjacent to MCP, anterior cortex of superior articularis （ACS） adjacent to SCP, posterior cortex of transverse foramen （PCT） adjacent to LCP and anterior cortex of inferior articularis （ACI） adjacent to ICP were then measured in AutoCAD2000 Software as raster images. Results：Oblique DR images showed subaxial cervical pedicle＇ s sagittal and coronal projections clearly, which indicated qualitatively MCP, SCP and ICP were thicker than their corresponding LCP. Quantitative measurement on CT muhiplanar images found SCP, MCP, ICP, ACS, ACL and ACI were not significantly different, while LCP and PCT were not significantly different, but the former six indexes were significantly thicker than the latter two on the same vertebra. SCP, MCP, ICP, ACS and PCT were not significantly different among different cervical vertebrae and could be combined together, respectively. SCPc and ICPc were statistically thicker than ACSc, MCPc and ACSc were statistically thicker than PCTc. Conclusions： SCP, MCP, ICP, ACS and PCT were not significantly different among different cervical vertebrae, which might implicate they have similar resistance to exotic force, respectively. The results that SCPc and ICPc were statistically thicker than ACSc, MCPc and ACSc were statistically thicker than PCTc might implicate PCTc had the weakest resistance to exotic force. When penetrating pedicle screw, one should make alert the screw should avoid locating too close to posterior cortex of transverse foramen or lateral cortex of pedicle.