真实稳态进动快速成像T2^＊加权序列在胎儿MRI中的应用

目的:探讨真实稳态进动快速成像T2*加权序列在胎儿MRI中的临床应用价值.材料和方法:6例中、晚期孕程的孕妇行真实稳态进动快速成像(true FISP)T2*加权序列扫描,评价图像质量、模糊程度、正常胎儿器官显示、胎儿和母体异常的显示以及胎儿信噪比(SNR)及胎儿-孕妇腰椎椎体对比噪声比(F-L CNR)等,并与TSE序列T2WI进行比较.结果:与TSE序列T2WI相比,true FISP序列T2*WI可清楚显示胎头、胎儿肢体、胎儿脊柱、胎儿的脏器解剖结构以及母体子宫、胎盘、脐带等附属结构,胎儿和母体异常显示也较清晰,并能清晰显示灰、白质分界、脑回、脑髓鞘等结构.true FISP序列获得的图像其SNR以及F-L CNR均优于TSE序列.结论:真实稳态进动快速成像T2*加权序列能够清晰显示胎儿及母体的解剖结构,获得的图像具有较高的T2对比,可作为胎儿MR成像的常用序列.     

产前超声诊断胎儿单侧手残缺畸形1例

孕妇 27岁,孕1产0,孕26周.夫妻双方身体健康,无先天性畸形及遗传性疾病.常规来我院行产前超声检查.超声所见:单胎,头位,双顶径6.7cm,头围24.8cm,腹围19.2cm,股骨长径4.6cm,胎儿颅内结构未见明显异常,脊柱排列整齐,胸腹腔脏器及颜面部器官未见明显异常.胎儿四肢扫查,右手掌未见显示,右上肢末端仅见3节长短不一残缺手指;实时三维显示胎儿右手残缺不全.胎盘位于后壁,成熟度Ⅰ级,羊水指数16.6cm.超声提示:①单胎中期妊娠;②胎儿右手残缺畸形.引产一死男婴,可见右上肢末端仅3节手指,长短不一,较大的手指可触及手指骨.     

胎儿、孕妇的磁共振成像

磁共振因多方位成像、图像清晰、对胎儿无辐射等优点而被应用于产科。虽然胎动等因素使磁共振图像质量不稳定,但抑制胎动药物的应用,便胎儿磁共振图像质量明显改善。尤其是妊娠中、晚期,胎儿各脏器细微结构及母体的子宫、胎盘等附属结构能够很好地不同程度地展现,从而较好地揭示胎儿的生长发育状况、先天畸形等。     

胎儿肝脏MRI信号强度的意义

目的：探讨宫内胎儿肝脏的生长发育状况。材料和方法：采用超导0．35T磁共振成像仪，对44例中、晚孕程孕妇进行MR成像，观察、分析其中42例正常胎儿肝脏的形态结构、信号变化。结果：胎肝的形态、大小以及肝内的门静脉、肝静脉等被良好显示。在T1WI上，孕32周前，胎儿肝脏的信号呈不均匀的高信号；在孕32周后，胎儿肝脏的信号呈均匀的一致的中等信号。在PDWI及T2WI上，胎儿肝脏的信号在不同的孕周均呈等信号。结论：MRI对胎肝的生长发育状态的研究有重要价值，胎肝在T1WI上均匀一致和中等信号（约孕32周后）代表着胎肝的发育成熟；而PDWI及T2WI对揭示胎肝的发育成熟不敏感。     

胎儿胸部发育异常的MRI应用

目的 探讨MRI在诊断胎儿胸部发育异常的临床应用价值.方法 对11例产前超声发现胎儿胸部发育异常者行MRI检查,分析胎儿胸部发育异常的MRI表现.结果 11例中肺发育不良1例,先天性膈疝3例,先天性肺囊腺瘤样畸形5例,肺隔离症2例.产前MRI检查对于得到随访结果的9例胎儿均诊断正确.结论 MRI具有良好的软组织分辨率和多方位成像及大视野的优点,且不受羊水量多少的影响,对于胎儿胸部发育异常的诊断具有较高的应用价值,可以作为产科胎儿超声检查的一种重要补充方式.     

MSCT容积再现在并腿畸形尸检中的应用

目的：探讨胎儿并腿畸形的骨骼异常及尸检胎儿 MSCT容积再现对产前B超的提示作用。方法：对8例疑似并腿畸形胎儿行 MRI检查,引产后行 MSCT检查。结果：8例并腿畸形胎儿中,7例为单胎,1例为臀部联体双胎之一。8例中,1例表现为单个下肢,7例为形式各异的下肢融合畸形。8例均有髂骨异常、尾椎部分或全部缺失。7例伴有各种各样的胸腰椎和肋骨畸形,2例并左上肢畸形融合。结论：MSCT容积再现可以提供胎儿详细立体的影像学资料,提高对并腿畸形骨骼异常的认识及产前诊断水平。     

MRI在胎儿中枢神经系统中的临床应用

目的探讨MRI在胎儿中枢神经系统发育异常中的应用价值。方法24例孕妇，年龄25～34岁，平均28岁；孕龄20～39周，平均30周。产前例行超声检查后24h内行MR检查，T2WI采用半傅立叶单激励快速自旋回波(HASTE)快速扫描序列，T1WI采用二维快速小角度激励(FLASH)序列。将超声、MRI结果与出生后或引产后随访结果对照。结果24例孕妇共检出胎儿24个。MR T2WI可清楚、直观地显示出大脑实质、脑回、脑沟裂、胼胝体、丘脑、小脑、脑干及脊髓等解剖结构，T1WI质量差于T2WI。超声共显示病灶27个，MRI显示31个。MRI证实超声怀疑的诊断2例，进一步完善诊断10例，与超声诊断一致12例。结论MRI对胎儿中枢神经系统解剖结构的显示优于超声，而且不受孕妇体型、羊水量多少、胎儿颅骨及母体骨盆骨骼影响。在超声检查基础上进行胎儿MR检查，有助于弥补超声的不足，甚至更正超声诊断，可作为产前胎儿检查的辅助措施。     

胎儿泄殖腔畸形谱系的MRI表现

目的:探讨胎儿泄殖腔畸形谱系的MRI表现及应用价值。方法:回顾性分析2017年1月至2021年2月在广州医科大学附属广州市妇女儿童医疗中心6例泄殖腔畸形谱系胎儿的临床、MRI及超声资料,分析各亚型的MRI特征。结果:6例泄殖腔畸形谱系胎儿5例经生后影像及手术证实,1例经引产尸检证实,包含3例永存泄殖腔、1例后泄殖腔畸形...     

胎儿后颅窝积液产前超声影像监测的临床意义

目的:探讨胎儿后颅窝积液的诊断标准、临床意义及Dandy-Walker综合症的超声特征。方法:产前超声检查胎儿后颅窝池增宽者71例,仔细对胎儿全身部位进行检查,特别观察后颅窝,尤其是小脑结构,每2~3周对后颅窝池及其它情况进行观察直至分娩,其中21例行MRI检查。结果:后颅窝池宽10~14mm 40例,平均12.6±1.8mm,38例胎儿生后均未见异常改变,围产儿不良发生率5%。后颅窝池宽15~37mm 31例,平均21.7±2.7mm,围产儿不良发生率68%,9例羊水过多,其中2例合并室间隔缺损约10mm,4例合并神经系统畸形,3例产后未见异常:12例为神经系统发育异常:4例肾脏发育不良;2例四肢发育短小,其中1例合并心脏畸形、左肾上腺肿块,1例合并双腕内翻畸形;1例胎儿宫内生长迟缓。结论:产前超声可清晰显示胎儿后颅窝情况,后颅窝池10~14mm可为异常,定期随访,15mm时应密切观察,胎儿异常发生率增高。MRI可明确的显示小脑结构以排除合并小脑发育异常的Dandy-Walker综合症。     

胎儿期大脑皮质发育异常MRI征象分析

目的探讨MRI对胎儿期大脑皮质发育异常(malformations of cortical development,MCDs)的诊断价值。方法选取54例胎儿期MCDs的MR图像,总结其MRI影像特征。结果54例MCDs患者中,小头畸形10例,半侧巨脑畸形5例,灰质异位5例,无脑回畸形9例,多小脑回畸形11例,脑裂畸形8例,局灶性皮层发育不良6例。MRI征象:外侧裂异常45例;皮层发育节点延迟28例;不成熟或异常脑沟33例;侧脑室形态异常44例;皮质厚度异常36例;脑沟、回异常39例;大脑半球形态异常42例;皮层结构简化26例;皮层信号不连续8例;皮层出现异常结节灶8例。结论在MCDs的产前诊断影像检查中,MRI较超声检查有一定的优势,可提高胎儿期MCDs诊断率。     

Maternal and fetal 11C-cocaine uptake and kinetics measured in vivo by combined PET and MRI in pregnant nonhuman primates.

Cocaine use during pregnancy has been shown to be deleterious to the infant. This may reflect reduction of flow to placenta or effects on the fetal brain. Methods to assess pharmacokinetics of drugs of abuse in vivo would be useful to investigate the mechanisms underlying the fetal adverse effects. We recently reported that combined MRI and PET technology allows the measurement of radioisotope distribution in maternal and fetal organs in pregnant Macaca radiata. Here, we evaluate the utility of PET to measure the uptake and distribution of (11)C-cocaine in the third-trimester fetus. METHODS: Six pregnant M. radiata weighing 3.8-9.0 kg were anesthetized and MR images were acquired on a 4-T MRI instrument. In all 6 animals, dynamic PET scans were subsequently acquired using 148-259 MBq of (11)C-cocaine. Time-activity curves for both maternal and fetal organs were obtained simultaneously with the pregnant animal positioned transverse in the PET scanner. Distribution volume ratios for maternal and fetal brain for (11)C-cocaine were calculated. RESULTS: Coregistration of PET and MR images allowed identification of fetal organs and brain regions and demonstrated that (11)C-cocaine or its labeled metabolites readily cross the placenta and accumulate mainly in fetal liver and to a lesser extent in the brain. Time to reach peak (11)C uptake in brain was shorter for the mother than for the fetus. The distribution volume ratios of the maternal striatum were higher than those of the fetus. Placenta was clearly visible on the early time frames and showed more rapid uptake and clearance than other fetal tissues. CONCLUSION: The pregnant M. radiata model allows the noninvasive measurement of radioisotope pharmacokinetics in maternal and fetal brain and other organs simultaneously. Although the uptake of radioactivity into the fetal brain after the injection of (11)C-cocaine is lower and slower than in the maternal brain, a measurable quantity of (11)C-cocaine (or its labeled metabolites) accumulates in the fetal brain at early times after injection. The highest accumulation of (11)C occurs in the fetal liver. Rapid radioisotope accumulation and clearance in the placenta offer potential as an input function for kinetic modeling for future studies of binding site availability.     

Maternal-fetal in vivo imaging: a combined PET and MRI study.

An understanding of how drugs are transferred between mother and fetus during the gestational period is an important medical issue of relevance to both therapeutic drugs and drugs of abuse. Though there are several in vitro and in vivo methods to examine this issue, all have limitations. Furthermore, ethical and safety considerations generally preclude such studies in pregnant humans. PET and appropriately labeled compounds have the ability to provide information on both maternal-fetal drug pharmacokinetics and pharmacodynamics. We present here a nonhuman primate animal model and the methodology for combining PET and MRI to identify fetal organs and to measure maternal and fetal isotope distribution using (18)F-FDG and a whole-body imaging protocol to demonstrate proof-of-principle. METHODS: One nonpregnant nonhuman primate was used for determination of the anesthesia protocol and MRI methods and 3 pregnant nonhuman primates (Macaques radiata) weighing 4.5-7 kg were used for the imaging study and anesthetized with propofol (160-300 micro g/kg/min). Anatomic T2-weighted MR images were acquired on a 4-T MR instrument. Subsequently, whole-body PET images were acquired 35 min after injection of (18)F-FDG, and standardized uptake values (SUVs) were calculated. Image processing and coregistration were performed using commercial software. RESULTS: All animals underwent uneventful general anesthesia for a period of up to 7 h. Coregistration of PET and MR images allowed identification of fetal organs and demonstrated that (18)F-FDG readily crosses the placenta and that (18)F accumulates in both maternal and fetal brain, heart, and bladder. Brain SUVs averaged 1.95 +/- 0.08 (mean +/- SD) and 1.58 +/- 0.11 for mothers and fetuses, respectively. Monkeys delivered healthy babies after a normal gestational term of 170 d following the PET/MRI study. CONCLUSION: The pregnant macaque in combination with PET and MRI technology allows the measurement of radioisotope distribution in maternal and fetal organs. This demonstrates the potential for noninvasively measuring the transfer of drugs across the placenta and for measuring the fetal drug distribution. It also opens up the possibility for studying binding and elimination as well as the effects of a drug on specific cellular elements and physiologic processes during the gestational period in a primate model.     

Sonographic findings in abdominal pregnancy

The sonograms of 20 proven cases of abdominal pregnancy were evaluated to determine the frequency of specific abnormalities associated with this condition. The most frequent and reliable finding was separation of the uterus from the fetus (90%). Extrauterine placenta (75%) and oligohydramnios (45%) were next in frequency. Other features such as fetal parts close to the maternal abdominal wall (25%), failure to visualize myometrium between the fetus or placenta and maternal bladder (15%), abnormal fetal lie (25%), poor visualization of the placenta (25%), and maternal bowel gas impeding fetal visualization (25%) were noted.     

Fetales MRT und Ultraschall der angeborenen ZNS-Fehlbildungen

In the last decade the newest technologies, fetal magnetic resonance imaging (MRI) and 3D ultrasound, have given an insight into the minute structures of the fetal brain. However, without knowledge of the basic developmental processes the imaging is futile. Knowledge of fetal neuroanatomy corresponding to the gestational week is necessary in order to recognize pathological structures. Furthermore, a modern neuroradiologist should be acquainted with the three steps in the formation of the cerebral cortex: proliferation, migration and differentiation of neurons in order to be in a position to suspect that there is a pathology and start recognizing and discovering the abnormalities. The fetal MRI has become an important complementary method to ultrasound especially in cortical malformations when confirmation of the prenatal diagnosis is needed and additional pathologies need to be diagnosed. In this manner these two methods help in parental counseling and treatment planning.     

Computer-assisted imaging of the fetus with magnetic resonance imaging

The purpose of this paper is to review the use of magnetic resonance imaging (MRI) of the fetus and to propose future techniques and applications. Institutional review board approved MR images of the fetus were acquired in 66 patients with sonographically suspected fetal abnormalities. Axial, coronal, and sagittal short TR, short TE images were obtained. In addition, 12 studies were performed with rapid scans requiring 700–1200 ms using either GRASS or Spoiled GRASS techniques. Sequential studies demonstrating fetal motion were also performed. Three studies with 3D IR prepped GRASS were performed. These allowed for orthogonal and non-orthogonal reformatted views and 3D display. Normal fetal structures were shown with MRI, including brain, heart, liver, stomach, intestines, and bladder. Gross fetal anomalies could generally be demonstrated with MRI. MRI may give additional information to that of sonography in fetal anomalies, particularly those involving the central nervous system, and in the detection of fat, blood, and meconium. MRI of the fetus can demonstrate normal and abnormal structures. Newer techniques with faster imaging will allow for greater possibility of computer assisted manipulation of data.     

产前MRI对先天性心脏病胎儿心血管异常和脑发育的量化评估

先天性心脏病（CHD）是影响胎儿生长发育的常见严重疾病,可以合并脑发育迟缓。MRI在胎儿发育定量评估中正逐渐成为超声以外的一种具有潜在价值的补充成像技术。就胎儿CHD与其脑发育的关系,以及产前MRI对CHD胎儿心血管和脑的结构、血流、氧合情况、脑成熟度及代谢情况量化评估的进展进行综述。     

胎儿主要器官的正常解剖及MR表现

目的了解胎儿主要器官的正常解剖及MR表现。方法对47例胎儿行快速MR成像检查，使用序列为单次激发快速自旋回波序列，观察主要正常器官的解剖和MR表现，包括脑、肺、心脏、肝、脾、胃肠道、肾脏、膀胱、骨骼、脊柱和皮下脂肪，并按不同的胎龄分组观察。结果47例胎儿MR检查结果表明：孕20周时，胎儿各主要器官均已发育。20周左右，大脑皮层光滑，无脑回、脑沟，之后脑回、脑沟逐渐缓慢形成；肺、气管、支气管均呈高信号，心脏、大血管及肝脾呈低信号，胃肠道、肾孟肾盏、膀胱呈高信号，肾实质为等信号，骨骼、肌肉呈低信号；脊柱20周已形成，皮下脂肪20周可见，随胎龄增长逐渐增多。结论快速MR成像能清楚显示胎儿各主要器官的正常解剖和发育变化，胎儿主要器官的解剖和MR表现与新生儿有较大的差别。     

MR在妊娠中晚期正常胎儿及胎盘检查中的应用价值

目的了解正常胎儿主要器官及胎盘的MRI表现。资料与方法对36例孕20周以上正常胎儿行MRI检查,采用单次激发快速自旋回波序列(SSFSE),从胎儿头颅、躯干轴位、冠状位、矢状位等多体位观察胎儿各系统主要器官,包括脑、肺、心脏、肝、脾、胃肠道等和胎盘的解剖和MRI表现。结果 36例胎儿MRI检查结果表明:中枢神经系统:孕20周以后大脑三层结构在SSFSE上已经可以辨别,皮质与脑室周围的生发层呈稍低信号,中间白质为高信号。双侧侧脑室在25周前呈生理性扩大状态,枕角明显,25周后逐渐缩小;孕20周时,两侧大脑皮层光滑,无明显沟回形成;孕23周时,仅见双侧侧裂池初具形态;23～30周,两侧大脑皮质主要沟回逐渐形成;30～37周,两侧脑皮质脑沟、回形成明显增多。呼吸循环系统:两肺呈高信号,纵隔内心脏、大血管及两肺纹理呈低信号。消化系统:胃泡、胆囊呈高信号,肠管不扩张时呈等低信号,部分肠管内见低信号胎粪影。肝脏、脾脏呈等低信号位于上腹部两侧。泌尿系统:双侧肾脏呈卵圆形等低信号,膀胱呈囊性高信号位于盆腔内。骨骼、肌肉系统:脊柱、四肢呈低信号,肌肉呈等信号。胎盘信号从均匀、稍高信号向不均匀、稍低信号过渡,胎盘边缘也从平滑向分叶状过渡。结论快速MRI能清楚显示胎儿各主要器官正常解剖和发育变化,同时可以对胎盘成熟度进行准确判断。