.,胎兒磁共振成像,MRImagingoftheFetus,.,超聲Ultrasound-母體肥胖-羊水過少-妊娠中晚期胎頭增大-胎兒顱骨骨化MRIUltrafastMRI-單次激發快速序列-大FOV-安全性？MRI僅適用于當產前超聲不足以解決臨床問題時,.,MRI檢查技術,1.5T及以下MR機體部相共振線圈序列：單次激發FSE(0.5NEX）FIASTA序列常規軸、冠、矢掃描,.,胎兒頭顱MRI檢查,.,胎兒頭顱MR檢查主要觀察-腦室擴大-可疑后顱窩異常-胼胝體發育不良,.,LimperopoulosC,etal.AJRAmJRoentgenol2008;190:16371643.,TotalfetusesMRIabnormal,9060(67%),ComparisonofantenatalandpostnatalMRfindingsin39of42liveborninfants,Completeagreement23(59%)Disagreement16(41%)ExcludedfetalMRI6(15%)Revealedadditionalabnormalities10(26%),.,枕大池(cisternamagna)正常值211mm側腦室體部10mm異常表現：Dandy-Walker畸形，小腦蚓部發育不良，大枕大池，蛛網膜囊腫,.,小腦蚓部的發育,1112W，小腦及原始蚓部從第四腦室嘴側發生1314W，原始頂點可見（第四腦室頂部裂縫）1416W，小腦蚓部原裂出現16W，小腦蚓部向尾側發育，于頂點處“折疊”覆蓋四腦室頂，第四腦室“閉合”1617W，錐前裂、頂前裂等可見1819W，蚓部顱尾方向長度與小腦半球相等,.,1112W1314W16W18W,.,17.5w21w22w24w27w,.,AssessmentofVermianMaturity,小腦原裂primaryfissure頂點fastigialpoint頂蚓角tengmento-vermianangle，TVA顱尾徑craniocaudaldiameter，CCD,.,NormalAbnormal,Tengmento-vermianangle,.,22weekfetus,A.axialsonographyshowedalargecysticposteriorfossawithsmallcerebellarhemispheres.B.thetegmento-vermianangleisincreasedwiththefourthventricleuncovered.Thevermisisverysmall;thereisnoprimaryfissureorfastigialpoint.C.DiagrammaticrepresentationofDWC.D.thecerebellarhemispheresaresmall.Theventricularsystemisdilated,resultinginlargetemporalhorns,.,22weekfetus,SonographyandMRIfindingsaresimilartothepreviouscaseexceptthatthecerebellarhemispheresseemslargerandvermiantissecanbeseeninthemidline.,.,Craniocaudaldiameter,Craniocaudaldiameter(perpendiculartofastigialpoint-decliveline),.,.,28-weekfetus,Thecraniocaudaldiameterofvermismeasures10.9mm(equivalentof22weeks).Theexpectedmeasurementis14.8mm.Thetranscerebellardiameterisalsosmall.,.,孕283周，B超提示胎兒腦室擴張,14.9mm,12.3mm,9.8mm,.,上下蚓比,小腦蚓部胚胎期呈線性協調發育以頂點為分界上下蚓比例為47和53，不隨生長發育變化,.,23-weekfetus,.,36-weekfetus,大枕大池,.,枕