胎儿脊柱神经弓中心软骨联合形态学研究

Morphological study of neurocentral synchondrosis in fetal spines

目的本研究通过脊柱MRI与全脊柱CT＋三维重建技术来观察分析胎儿脊柱神经弓中心软骨联合（neurocentral synchondrosis，NCS）的形态特点及结构规律，以推断其对胎儿脊柱椎体及椎弓根生长的作用。方法收集2012年10月至2013年12月于我院因非脊柱畸形原因流产胎儿15例，胎龄23-33周，男8例，女7例，平均胎龄28^＋6周。胎儿分为两组，第1组为28周前引产胎儿7例，平均胎龄24周；第2组为28周后引产胎儿8例，平均胎龄32周，检查前均签订知情同意书。两组胎儿均接受脊柱（T1-L5）MRI，全脊柱螺旋CT＋三维重建观察比较NCS的三维形态结构，并采用Dicom软件测量两组胎儿T1～L5各个椎体MRI图像，测量相关参数分别计算均值，并利用Origin软件对各组参数作图分析，利用SPSS17．0软件分别对相关参数进行配对t检验。结果脊柱MRI横断面T2加权像显示胎儿NCS为外宽内窄指向椎体的三角形结构，其两侧沿椎体边缘向前后延伸，两部分于椎体前端相接，后端不连接。全脊柱螺旋CT三维重建显示胎儿NCS矢状面是位于椎体两侧面的线状低密度结构。Origin软件绘图比较，两组左右侧α角变化趋势基本一致，总体趋势都是先变大后变小。对两组左右两侧NCS的长宽比比较，第2组明显大于第1组，两侧的变化趋势基本一致。第1组胎儿左右侧α角为60．827°±2．794°和60．882°±2．840°，第2组相应角度58．878°±4．194°和58．749°±4．334°.第1组胎儿左右侧NCS长宽比1．452±0．096和1．435±0．124，第2组相应比值1．680±0．147和1．678±0．142。各组数据分别进行配对t检验结果提示尚不能认为两组胎儿左右α角及左右两侧NCS长宽比存在差异（P〉0．05）。结论胎儿神经弓中心软骨联合（NCS）是位于椎体及椎弓根之间的双侧对称的三维结构软骨板，于椎体前缘相连，后缘不连接，其在椎体中的位置以一定的规律变化。NCS于胎儿期在椎体中所占体积较大，其对脊柱生长所起的作用远胜过婴幼儿时期。

Objective To apply imaging examinations for surveying the morphological characteristics of neurocentral synchondrosis （NCS） in fetal spine so as to deduce the function of NCS in the growth of vertebra and vertebral pedicle in normal spines. Methods A total of 15 fetal samples （23 w-33 w） without congenital spinal deformity were collected from October 2012 to December 2013. There were 8 males and 7 females with an average gestational age of 28 ＋ 6 weeks. And informed consent form was signed. Based upon fetal age, the fetuses were divided into two groups of 7 samples （24 w） and 8 samples with an average gestational age of 32 w. All fetuses were visualized by magnetic resonance imaging （MRI） （T1-L5 vertebra） and full-spine spiral computed tomography （CT） ＋ three-dimensional （3D） reconstruction. The above methods could observe the 3D morphology of NCS. Then the relevant parameters were measured by dicom image processing software. And the mean value of each group was calculated and line plotted by Origin software. All parameters of both sides were analyzed by paired t-test. And the test standard was set at P = 0. 05. Results As a pair of triangular structure with a wide exterior and a narrow interior in sagittal plane on T2 MRI image, NCS surrounds both vertebral body and posterior arch and interconnected in anterior aspects. And it is reconstructed by two parallel lines perpendicular to vertebrae in sagittal plane on full-spine spiral CT ＋ 3D reconstruction images. The mean parameters of two groups were calculated and the corresponding lines plotted. It showed that a angle increased faster than that of the second one. The others parameters of the second fetal group were bigger than those of the first one. The mean a angles of left and right sides were 60. 827° ± 2. 794° and 60. 882° ± 2. 840° for the first group and 58. 878° ± 4. 194 and 58. 749 ±4. 334 for the second group respectively. And the bilateral length-width ratios were 1. 452 ± 0. 096 and 1. 435 ± 0. 124 for the first group and 1. 680 ±0. 147 and 1. 678 ± 0. 142 for the second group. The parameters of two groups were compared by paired t-test and the differences of two sides of two group were significant （P〈0. 05）. No statistical differences existed in left and right sides for the same group （P〉0.05）. Conelusior, s The position of NCS shifts constantly. It accounts for a bigger volume of vertebral body in fetal spines. And its role for the growth of spine is larger than that in infants and young children.