目的　研究正常胎儿标本椎体、椎管在不同孕周的发育表现及生长曲线。  方法　52例15～40孕周的胎儿标本接受3.0T磁共振T2WI腰椎横轴位和冠状位扫描；观察及测量内容： ①L1椎间盘信号及高度变化；②L2椎体、骨化中心高度和面积及其相应水平椎体、椎管前后径和面积。对上述测量结果和孕周间作回归分析。  结果　①L1椎间盘在小于或等于21周时为低信号，21周后逐渐为高信号，其高度随孕周呈线性增长(P<0.01)；②L2椎体及骨化中心的高度、面积随孕周呈线性增长(P<0.01)，骨化中心与椎体面积比值随孕周增大(P<0.01)；L2椎体前后径与相应水平椎管前后径比值范围为1:1.3到1:0.6。  结论　磁共振可明确显示胎儿椎体、椎间盘、椎管在不同孕周的发育表现及变化规律。

Objective　To describe MR imaging features of normal fetal spine at different gestational ages.　Methods　Postmortem MR imaging was performed on 52 fetuses ranging from 15 to 40 gestational weeks. T2-weighted MR imaging of the lumbar spine was performed in the coronal, sagittal and axial planed. The following parameters were measured: signal and height of L1 disk, height and area of the L2 vertebral body and ossification center, area of vertebral canal, the ratio of ossification center to the overall size of the vertebral body, and the range of A-P vertebral body to vertebral canal.　Results　The L1 disk space increased linearly with gestational age (P<0.01). It appeared as a linear low-signal-intensity area in fetuses less than 21 weeks gestation but increasingly developed high signal intensity in the disk after 21weeks. The height and area of the vertebral body, ossification center, vertebral canal increased linearly with gestational age (P<0.01) .The ratio of ossification center to the overall size of the vertebral body increased with gestational age (P<0.01). The range of A-P vertebral body to vertebral canal was 1:1.3 to 1:0.6.　Conclusions　The normal growth and signal-intensity characteristics of the vertebral body, vertebral canal and spinal cord can be well described on Postmortem MR imaging.