MRI Study Of Growth And Development Of Fetal Posterior Fossa In The Second And Third Trimester Of Pregnancy And Its Relationship With Simple Posterior Fossa Pool Broadening

Part1 MRI STUDY ON THE DEVELOPMENT OF POSTERIOR FOSSA STRUCTURE OF NORMAL FETUS IN THE SECONDAND THIRD TRIMESTER OF PREGNANCYObjective:Quantitative analysis of biological measurements of posterior fossa structure of nor-mal fetus by MRI,to study its developmental rule with gestational age.Methods:This study was a prospective study,involving 139 fetuses with normal brains ranging in age from 24 to 38 gestational weeks,fetal brain was performed 1.5T MRI,then mea-surement cerebellar vermian anteroposterior diameter(AP diameter),craniocaudal diame-ter(CC diameter),vermian cross-sectional area(VS),cerebellar transverse diameter(TCD),volume(CV)and brainstem-vermis angle(BV angle),brainstem-tentorium angle(BT angle)by a three-dimensional post-processing workstation(Osiri X software),and analysis its developmental rule with gestational age.Results:1.The fetal vermian AP diameter、CC diameter、VS、TCD is linearly positively corre-lated with gestational age,The linear equation is AP diameter=-0.495+0.055GA(R~2=0.925,P<0.05)、CC diameter=-0.396+0.068GA(R~2=0.922,P<0.05),VS=-2.955+0.161GA(R~2=0.898,P<0.05),TCD=-1.746+0.182GAR2=0.953(R~2=0.953,P<0.05),the fetal cere-bellar volume is exponential-dependent with gestational age,and the curve equation is CV=0.072exp(0.151GA)(R~2=0.957,P<0.05);2.In normal fetuses,the BV angle with an average of(4.65±1.29)°,and the BT angle with an average of(28.37±5.59)°.From the scatter plot,there is no correlation between BV angle and BT angle and gestational age.Conclusion:1.The cerebellar vermian anteroposterior diameter、craniocaudal diameter、vermian cross-sectional area、cerebellar transverse diametert increased linearly with the gestational age in the second and third trimester of pregnancy,the cerebellar volume of the normal fetal cerebellum increased exponentially with the gestational age in the second and third trimester of pregnancy.This result is more helpful in assessing the characteristics and extent of fetal posterior fossa structure development;2.There was no significant correlation between normal fetal BV angle and BT angle with gestational age,and provide quantitative indicators for the determination and class-ification of cerebellar dysplasia.Part2 MRI STUDY ON THE CORRELATION BETWEEN THE POSTERIOR FOSSA POOL BROADENING AND NORMAL CEREBELLUM DEVELOPMENT IN THE THIRD TRIMESTER OF PREGNANCYObjective: Quantitative analysis of the correlation between cerebellar development in the posterior cranial fossa pool broadening and the normal fetus by MRI,so as to explore its clinical value.Methods: 45 cases of prenatal ultrasound and magnetic resonance diagnosis were included in the study,at the same time according to the gestational age and the number of cases matched 45 normal fetus as a control group,quantitative analysis of the growth and development of the posterior fossa structure of the fetus after the posterior cranial fossa pool was widened.Results: There were no significant differences in the AP diameter,CC diameter,VS and cerebellar TCD and CV between the study group and the control group(P>0.05).Conclusion: The fetus posterior cranial fossa pool widened will not affect the growth of the anterior and posterior diameter of the cerebellum,the diameter of the cerebellum,the area of the cerebellum and the diameter of the cerebellum,and the cerebellar volume.Quantitative analysis was obtained and revise for its clinical significance.