目的　应用胎儿标本MR图像测量小脑的径线和体积，获得小脑发育指标的正常范围。 方法    87例无中枢神经系统疾病的胎儿标本，胎龄为14～40周，行3.0TMR扫描，使用Amira软件分别测量小脑径线：横径（TCD），前后径(A-PD)、上下径（小脑蚓长度）及小脑体积（CV），并分析它们与胎龄的关系。 结果　小脑横径、前后径、上下径均随胎龄呈直线增长趋势，TCD=0.165FA－1.410(r2=0.929, P＜0.05); A-PD=0.091FA－0.717(r2=0.833, P＜0.05); （vermis length）=0.108FA－0.832(r2=0.859, P＜0.05)；小脑体积随胎龄增加呈指数曲线增长，CV=0.034 exp (FA/5.918)(r2=0.915，P<0.05)，小脑体积的倍增时间为4.1周。 结论　胎儿标本MR图像可以清晰并准确的显示胎儿小脑大小的发育变化，所得测量结果可为临床宫内胎儿小脑发育状况的诊断与评估提供解剖和影像学依据。

Objective　To measure the volume and main dimensions of fetal cerebellum with MRI, and obtain the ranges of their normal values.  Methods　87 fetal specimens without CNS diseases aged from 14-40 gestational weeks were scanned under 3.0T MRI. The cerebellar transverse diameter (TCD), anteroposterior diameter (A-PD), vermis length and cerebellar volume were then calculated by Amira software. Lastly the relationship between these values with fetal age(FA) was analyzed statistically.   Results　The TCD, A-PD and vermis length increased linearitily following the growth of the fetuses [TCD=0.165FA－1.410; A-PD=0.091FA－0.717; vermis length=0.108FA－0.832]. The relationship between cerebellar volume (in cubic centimeters) and FA (in weeks) was well described by a single exponential function [CV=0.034 exp (FA/5.918)]. The doubling time of CV was about 4.1 weeks.   Conclusions　The development of fetal cerebellum could be displayed and quantified by 3.0T MRI, which is valuable for clinical diagnosis and evaluation of fetal development in vivo.