胎儿磁共振成像MRImagingoftheFetus•超声－Ultrasound--母体肥胖--羊水过少--妊娠中晚期胎头增大--胎儿颅骨骨化•MRI－UltrafastMRI--单次激发快速序列--大FOV--安全性？MRI仅适用于当产前超声不足以解决临床问题时MRI检查技术•1.5T及以下MR机•体部相共振线圈•序列：单次激发FSE(0.5NEX）FIASTA序列•常规轴、冠、矢扫描胎儿头颅MRI检查•胎儿头颅MR检查主要观察--脑室扩大--可疑后颅窝异常--胼胝体发育不良LimperopoulosC,etal.AJRAmJRoentgenol2008;190:1637–1643.TotalfetusesMRIabnormal9060(67%)ComparisonofantenatalandpostnatalMRfindingsin39of42liveborninfantsCompleteagreement23(59%)Disagreement16(41%)ExcludedfetalMRI6(15%)Revealedadditionalabnormalities10(26%)•枕大池(cisternamagna)正常值2－11mm•侧脑室体部<10mm•异常表现：Dandy-Walker畸形，小脑蚓部发育不良，大枕大池，蛛网膜囊肿小脑蚓部的发育•11－12W，小脑及原始蚓部从第四脑室嘴侧发生•13－14W，原始顶点可见（第四脑室顶部裂缝）•14－16W，小脑蚓部原裂出现•16W，小脑蚓部向尾侧发育，于顶点处“折叠”覆盖四脑室顶，第四脑室“闭合”•16－17W，锥前裂、顶前裂等可见•18－19W，蚓部颅尾方向长度与小脑半球相等11－12W13－14W16W18W17.5w21w22w24w27wAssessmentofVermianMaturity•小脑原裂primaryfissure•顶点fastigialpoint•顶－蚓角tengmento-vermianangle，TVA•颅尾径craniocaudaldiameter，CCDNormalAbnormalTengmento-vermianangle22－weekfetusA.axialsonographyshowedalargecysticposteriorfossawithsmallcerebellarhemispheres.B.thetegmento-vermianangleisincreasedwiththefourthventricleuncovered.Thevermisisverysmall;thereisnoprimaryfissureorfastigialpoint.C.DiagrammaticrepresentationofDWC.D.thecerebellarhemispheresaresmall.Theventricularsystemisdilated,resultinginlargetemporalhorns22－weekfetusSonographyandMRIfindingsaresimilartothepreviouscaseexceptthatthecerebellarhemispheresseemslargerandvermiantissecanbeseeninthemidline.CraniocaudaldiameterCraniocaudaldiameter(perpendiculartofastigialpoint-decliveline)28-weekfetusThecraniocaudaldiameterofvermismeasures10.9mm(equivalentof22weeks).Theexpectedmeasurementis14.8mm.Thetranscerebellardiameterisalsosmall.孕28＋3周，B超提示胎儿脑室扩张14.9mm12.3mm9.8mm上下蚓比•小脑蚓部胚胎期呈线性协调发育•以顶点为分界上下蚓比例为47％和53％，不随生长发育变化23-weekfetus36-weekfetus大枕大池枕大池蛛网膜囊肿29-weekfetus5-month孕32周，外院超声提示左脑室扩张、枕大池积水孕31周，超声提示：可疑侧脑室增宽
