胎儿后颅窝池畸形的磁共振诊断价值

Application value of MRI in the diagnosis of fetal posterior fossa cistern malformation

目的探讨1.5T磁共振常规序列对胎儿后颅窝池畸形的诊断价值。方法回顾性分析自贡市第一人民医院及四川大学华西第二医院2017年1月至2020年12月期间产前超声检查异常并行胎儿颅脑MRI平扫检查,经临床综合诊断为后颅窝池畸形的17例胎儿的临床影像资料。采用快速稳态进动序列(Balance-FFE)和三维快速扰相梯度回波序列(FFE)进行胎儿颅脑横断、矢状和冠状面快速扫描,选择T2WI冠状位测量小脑横径(TCD),选择胎儿小脑蚓部的正中矢状面观察后颅窝结构及相邻结构间的毗邻关系,测量小脑蚓部上下径、小脑蚓部前后径、BV角、BT角。结果17例胎儿后颅窝畸形中Dandy-Walker综合征2例,小脑蚓部发育不良3例,后颅窝蛛网膜囊肿8例,胎儿后颅窝池增宽3例,小脑发育异常1例;所有患者小脑蚓部上下径、小脑蚓部前后径、BV角、BT角及小脑横径均小于正常值,且符合超声测值标准。结论1.5T磁共振对胎儿后颅窝池畸形的产前诊断具有重要临床价值。

Objective To investigate the diagnostic value of 1.5T MRI in fetal posterior fossa cistern malformation.Methods The retrospective analysis was performed on the imaging data of 17 fetuses diagnosed as posterior fossa cisternal malformation by prenatal ultrasound examination and fetal brain MRI scan from January 2017 to December2020 in the First People’s Hospital of Zigong City and West China Second Hospital of Sichuan University.Fast steady-state precession sequence(Balance FFE)and three-dimensional fast spoiled gradient-recalled echo sequence(FFE)were used to scan the transverse,sagittal,and coronal planes of fetal brain.The transverse diameter(TCD)of cerebellum was measured on coronal plane of T2WI.The midline sagittal plane of fetal cerebellum vermis was selected to observe the structure of posterior fossa and the adjacent relationship between adjacent structures posterior diameter,BV angle,BT angle and transverse diameter of cerebellar vermis.Results Among 17 cases of fetal posterior fossa malformation,there were 2 cases of Dandy-Walker syndrome,3 cases of cerebellar vermis dysplasia,8 cases of posterior fossa arachnoid cyst,3 cases of posterior fossa cistern widening,and 1 case of cerebellar dysplasia.In all the cases,the upper and lower diameter of cerebellar vermis,anterior and posterior diameter of cerebellar vermis,BV angle,BT angle,and transverse diameter of cerebellar vermis were less than normal values,which met the standard of ultrasonic measurement.Conclusion The 1.5T MRI has important clinical value in prenatal diagnosis of fetal posterior fossa cistern malformation.