MRI在胎儿中枢神经系统畸形的应用价值

目的 评价MRI在胎儿中枢神经系统畸形中的应用价值.资料与方法 22例孕妇,年龄23～40岁,年龄平均28岁;孕龄23～40周,平均30周.产前超声(US)检查后48 h内行MRI检查,T2WI采用半傅里叶单激发快速自旋回波序列(HASTE)、真稳态进动快速成像序列(True FISP),T1WI采用超快速小角度激发序列(FLASH)(Turbo FLASH)扫描,将产前MRI、US表现与产后诊断或尸检结果对照.结果 产前MRI与US诊断一致并正确者9例,产前MRI正确并证实US可疑病变2例,产前MRI正确并完善产前US诊断1例,产前MRI正确并改变产前US诊断7例,产前US正确MRI不正确1例,产前US正确且完善MRI诊断2例.结论 MRI对胎儿神经系统畸形的诊断具有一定的优势,与US相比,MRI可提供更全面、更准确的信息,甚至更正US诊断,可作为胎儿中枢神经系统畸形的一种重要检查方法和补充手段.     

MRI对胎儿结节性硬化症的诊断价值

【摘要】目的：评价MRI对胎儿结节性硬化症的诊断价值。方法：25例孕妇,24～39岁,平均26.4岁;孕龄22.3～35.0周,平均24.6周,产前超声发现胎儿心脏横纹肌瘤或其他畸形行MRI检查,将产前MRI诊断与出生后随访或引产后尸检结果对照,评估MRI对胎儿结节性硬化症的诊断价值。结果：25例孕妇,超声筛查发现心脏横纹肌瘤24例,腹裂1例,行MRI检查,产前MRI发现室管膜下结节6例,脑皮质结节3例,室管膜下结节伴皮质结节1例,室管膜下结节伴心脏横纹肌瘤8例,心脏横纹肌瘤2例,5例未发现阳性征象,18例产前诊断为结节性硬化症,均由出生后随访或引产后尸检证实,1例产前MRI诊断为心脏横纹肌瘤,产后诊断为TSC。结论：MRI对超声难以检出的胎儿脑内室管膜下及皮质下结节敏感,对结节性硬化病的产前诊断具有重要价值。     

羊水过少胎儿结构和相关畸形的MRI诊断价值

目的:评价磁共振成像(MRI)对羊水过少胎儿结构及相关畸形的诊断价值.方法:34例孕妇,孕龄20～35周.产前常规行超声(US)检查后24～48h内行MR检查,采用二维快速平衡稳态采集(2D FIESTA)序列、单次激发快速自旋回波(SSFSE)序列,行胎儿颅脑胸腹部常规及双肺、双肾重点冠状面、矢状面及横断面扫描,将产前MRI、US表现与出生后影像或引产后尸解对照.通过MRI采用感兴趣区工具(ROI)测量胎儿肺肝信号强度比(LLSIR).结果:34例羊水过少胎儿MRI均能清晰显示其结构,20例存在泌尿系统畸形(其中12例合并肺发育不良),3例只合并双肺发育不良,特发性羊水过少11例.合并肺发育不良共计15例.18例出生,16例引产.除4例引产未尸检外,其余均由出生影像学或引产后尸解证实.结论:MRI是显示羊水过少胎儿结构及相关异常最有效的诊断方法,它能不受羊水过少的影响,清晰显示胎儿结构及相关异常.     

胎儿羊膜带综合征所致四肢畸形的MRI诊断

目的:探讨快速MRI对胎儿羊膜带综合征所致四肢先天畸形的诊断价值。方法:搜集本院行产前超声检查(US)和MRI检查的68例孕妇中发现并经引产后胎儿尸检证实的胎儿四肢畸形病例资料12例。这12例孕妇年龄22~34岁,平均27.3岁;其12例胎儿,胎龄20~38周,平均26.8周。US检查后3天内行胎儿肢体轴面、冠状面、矢状面MRI扫描。MRI扫描采用单次激发快速自旋回波(SSFSE)序列。观察胎儿四肢骨骼及软组织的形态、结构,并与US及尸检结果进行比较。结果:快速MRI视野大,运动伪影少,组织分辨力高,能清楚显示四肢骨骼、软组织等解剖结构。引产后尸检发现12例四肢畸形(左前臂缺失3例,右前臂残端畸形4例,左侧手指缺失1例,下肢狭窄环2例,马蹄内翻足畸形2例);US诊断10例,误诊、漏诊各1例;MRI诊断11例,漏诊1例。比较两者正确诊断数及误漏诊数,采用四格表的确切概率法检验,P>0.05,差异无统计学意义。结论:MRI对胎儿四肢先天畸形具有较高的诊断价值,是胎儿肢体先天畸形影像学诊断的重要手段之一。     

胎儿胼胝体发育不全的MRI诊断

【摘要】目的：探讨产前MRI在胎儿胼胝体发育不全（ACC）中的应用价值。方法：回顾性分析64例行头部MRI并诊断为ACC的胎儿,孕周23+1~38+1周,中位数孕周29周,采用三维容积内插快速T1WI序列、单次激发快速自旋回波序列和平衡式稳态自由进动序列扫描,分析MRI表现。结果：64例ACC胎儿中,胼胝体完全缺如者有49例,胼胝体部分缺如者15例。所有的ACC均伴有侧脑室形态异常或扩大。伴颅内其它畸形的胎儿28例。结论：胎儿MRI可以明确诊断ACC及其类型,是否伴发颅内其他畸形,对于胎儿胼胝体发育不全产前诊断及预后评价具有重要价值。     

MRI在诊断胎儿肾发育异常中的价值

目的 探讨MRI在诊断胎儿肾发育异常(FRDA)中的价值.方法 采用MR扩散加权成像(DWI)和快速成像序列对11例超声(US)提示FRDA的胎儿进行盆腹部横断面、矢状面及冠状面扫描,将MRI表现与产前和产后超声结果对照.结果 MRI诊断结果与产后US一致,MRI和产后US诊断一侧异位肾4例(左侧2例、右侧2例,其中1例产前US诊断为右肾缺如),一侧肾缺如5例(左侧2例、右侧3例,其中1例产前US诊断为左肾发育不全),1例左肾发育不全,1例双肾发育不全(产前US诊断为右肾缺如伴左肾发育不全).结论 MRI可以清晰显示胎儿肾的形态和位置,是产前US诊断FRDA的重要补充.     

快速MRI对胎儿胼胝体发育不全的诊断价值及与超声对照研究

目的:探讨快速MRI对胎儿胼胝体发育不全(ACC)的诊断价值,并与超声对比。方法:回顾性分析16例经引产证实ACC的胎儿,孕20-36周,平均30周,产前常规超声检查后1～3天内行胎儿颅脑快速MRI检查,采用单次激发快速自旋回波序列(SSTSE)和平衡式稳态自由进动序列(balance-FFE)行T2WI扫描,回顾性分析超声及产前MRI表现,并与引产后尸体MRI检查或尸体解剖结果对照。结果:16例ACC胎儿中,产前MRI明确诊断16例,诊断合并其他中枢系统畸形5例,与产后检查结果相符。超声明确诊断9例,可疑6例,误诊1例;合并畸形确诊4例,漏诊1例。结论:快速MRI对胎儿ACC的诊断优于超声,有助于明确诊断并判断其分型及合并畸形,可作为超声的补充诊断方法。     

高场MRI在超声疑诊胼胝体发育不全胎儿中的应用价值

目的 探讨MRI对超声疑诊胎儿胼胝体发育不全的诊断价值.方法 产前例行超声检查后疑诊有胎儿胼胝体发育不全的19例孕妇,年龄20～37岁(平均28岁),孕龄22～38周(平均29周),24 h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结果与尸体解剖或随访结果对照.结果 19例孕妇共检出胎儿19个,MRI证实超声疑诊的胎儿胼胝体发育不全14例,3例为单纯侧脑室轻度扩张,2例考虑脑白质发育不良,合并Dandy-Walker综合征1例,胼胝体脂肪瘤1例,检出超声漏诊合并Dandy-Walker综合征1例及脑小畸形1例.结论 MRI对胎儿胼胝体发育不全的显示明显优于超声,有助于明确胎儿胼胝体发育不全、分型及合并畸形的诊断.     

快速MRI对胎儿中枢神经系统先天畸形的诊断价值与超声对照研究

目的 探讨快速MRI对胎儿中枢神经系统先天畸形的诊断价值并与超声（US）对照。方法 对48例孕妇产前行US和MRI检查，胎儿尸检及出生后随访检查证实中枢神经系统畸形22例，共26处。于US检查后3d内行胎儿颅脑脊柱及胸腹部MR扫描，并与US诊断结果和尸检及随访结果进行比较。结果 引产后尸检发现17处畸形，出生后随访检查证实9处畸形，共26处（无脑畸形6处、脊柱裂2处、脑膜脑膨出3处、先天性脑积水7处、前脑无裂畸形1处、脑穿通畸形3处、蛛网膜囊肿2处、脉络丛囊肿2处），US诊断24处，准确率92．3％（24／26），误、漏诊各1处，假阳性率3．8％（1／26），漏诊率为3．8％（1／26），MRI诊断23处，准确率88．5％，误诊1处，假阳性率3．8％（1／26），漏诊2处，漏诊率为7．7％（2／26）。比较2种方法差异无统计学意义（X^2=0．22，P〉0．05）。但快速MRI视野大，运动伪影少，组织分辨率高，能清楚显示脑灰白质、脑室系统、脑沟裂、蛛网膜下腔、脊柱等中枢神经系统解剖结构。结论 MRI对胎儿中枢神经系统先天畸形具有较高的诊断价值，可作为胎儿中枢神经系统先天畸形的一种重要的影像学诊断手段。     

MRI在胎儿泌尿系统畸形诊断中的价值

目的评估MRI在胎儿泌尿系统畸形诊断中的价值。方法对34例泌尿系统畸形的胎儿MRI结果，结合超声诊断以及部分产后或术后结果进行分析。结果胎儿肾脏积水12例，包括7例随访积水消失；2例失访；产前MRI诊断的1例梗阻性右肾发育不良正在随访中，1例右双肾盂输尿管畸形在产后MRI随访中证实，1例肾盂输尿管连接处异常产后超声随访证实。双侧性泌尿系统畸形胎儿7例，显示羊水量减少，肺信号减低，其中双侧性多囊性肾发育不良3例（均引产），双肾发育不良2例（1例失访，1例尸检），双侧肾不发育1例（引产后尸检证实），右肾缺如伴左肾发育不良1例（失访），1例尸检胎儿产前MRI诊断正确，1例MRI上清晰显示双侧下肢合并成团块状。单侧性泌尿系统畸形胎儿15例，包括单侧肾发育不良9例（3例随访中，2例引产，1例失访，3例产后超声或MRI证实），单侧肾脏不发育4例（2例引产，2例产后超声或MRI证实），异位肾1例产后经超声证实，脐尿管囊肿1例引产，产前MRI对于得到随访结果的6例胎儿均诊断正确。结论MRI可以不受羊水量的影响，多方位清晰显示各类泌尿系统畸形及其伴发的其他系统畸形，并作出准确诊断，作为产前超声的重要补充检查手段具有很高的临床应用价值。     

Truncus arteriosus communis in a midtrimester fetus: comparison of prenatal ultrasound and MRI with postmortem MRI and autopsy

Different techniques are used in fetal cardiology, and their accuracy has been demonstrated on several occasions. Color Doppler US has proved to be a reliable and valuable tool in the diagnosis of fetal cardiac abnormalities. Magnetic resonance imaging (MRI) of the fetal heart has, so far, played no role in prenatal diagnostics. We report on a truncus arteriosus communis diagnosed prenatally during a screening ultrasound at 22 weeks of gestation. In addition to real-time ultrasound and color Doppler echocardiography, fetal MRI was performed. Fetal echocardiography arose suspicion of a type I common trunk. Fetal MR showed solely a widened vessel coursing retrocardially and additionally an inhomogeneous fluid distribution of the lung not shown on prenatal US. After termination of pregnancy at 23 weeks of gestation, MR fetography and autopsy were performed, and both found a type II common trunk. MR autopsy of the heart was very reliable in this case and could be an alternative when fetal pathology is not available for different reasons. Postmortem MRI was also able to demonstrate the inhomogeneous fluid distribution in the lung, which was confirmed by autopsy. Fetal and postmortem MR was reliable in the detection of an inhomogeneous fluid distribution in the lung not shown on prenatal US, providing a relevant additional finding to US. Therefore, MRI should be used more often in fetal cardiology, although it still must be further developed.     

Agenesis of the corpus callosum in fetuses with mild ventriculomegaly: role of MR imaging

Purpose

We evaluated the role of magnetic resonance (MR) imaging in the diagnosis of corpus callosum agenesis — isolated or associated with other anomalies — in fetuses with mild cerebral ventriculomegaly, as depicted at prenatal sonography.

Material and methods

Between January 2005 and March 2007, 33 fetuses with a mean gestational age of 28.9 weeks (range 17–37) and mild ventriculomegaly diagnosed at prenatal sonography were included in this prospective study. All fetuses underwent MR imaging according to the following protocol: half-Fourier T2-weighted images along the three orthogonal plane according to the longitudinal axis of the mother, and subsequently three orthogonal planes were acquired according to the fetal brain. Quantitative image analysis included the size of the transverse diameter of the lateral ventricles, in the axial plane, and the thickness of the adjacent cerebral cortex. Qualitative image analysis included morphology of the lateral ventricles (normal, parallel pattern colpocephaly), signal intensity changes of the fetal brain, interruption of the germinative matrix, agenesis of the corpus callosum (complete/partial) and associated malformations. Postnatal physical examination and diagnostic imaging, as well as surgery, were the standard of diagnosis.

Results

Mean axial diameter of the lateral ventricle was 11.6 mm (range 10–15 mm), and mean thickness of the adjacent cerebral cortex was 2.1 mm (range 1.8–3 mm); 23/33 fetuses (70%) showed normal morphology of the lateral ventricles, and 8/33 (24%) showed abnormal morphology (parallel pattern, colpocephaly). The entire corpus callosum was visualised in 20/33 fetuses (60%). In 8/33 fetuses (25%), partial agenesis was diagnosed, whereas in 5/33 (15%), there was hypogenesis. In 6/13 fetuses (46%), isolated corpus callosum agenesis was detected, and two cases of hypogenesis of the corpus callosum were misinterpreted — overestimated in one case and underestimated in another.

Conclusions

MR imaging may prove to be a useful second-line imaging modality in the prenatal diagnosis of corpus callosum agenesis in fetuses with mild ventriculomegaly.     

Anomalies of the corpus callosum: correlation with further anomalies of the brain

The MR imaging studies of 68 patients who had brain anomalies were reviewed retrospectively to evaluate specific anatomic abnormalities of the corpus callosum. The corpus callosum was abnormal in 32 (47%) of the 68 patients. Excluding patients with the Chiari I malformation, callosal anomalies were present in 30 (68%) of 44 patients. Callosal dysgenesis was most common, followed by callosal atrophy or hypoplasia and complete agenesis. The anterior commissure was present in all patients. On the basis of the known temporal sequence of brain and callosal embryogenesis, we deduced the following regarding the pathogenesis of developmental anomalies: (1) callosal dysgenesis occurs as a result of insults during the formation of its precursors, not during formation of the corpus callosum itself; (2) the Dandy-Walker malformation sometimes occurs as a result of an insult in the eighth week of gestation, several weeks later than has been generally accepted; (3) sphenoidal encephaloceles probably occur as a result of faulty disjunction of neuroectoderm and cutaneous ectoderm at the anterior neuropore; and (4) a complete but atrophic corpus callosum results from an insult to the cortex or white matter after formation of the corpus callosum is complete (18-20 weeks). Callosal anomalies, easily identified on MR, are an important indicator of additional brain anomalies. Analysis of the corpus callosum provides important information about the embryogenesis of brain anomalies and may assist in distinguishing between in utero and perinatal brain insults.     

Variability of Forebrain Commissures in Callosal Agenesis: A Prenatal MR Imaging Study

BACKGROUND AND PURPOSE:Agenesis of the corpus callosum, even when isolated, may be characterized by anatomic variability. The aim of this study was to describe the types of other forebrain commissures in a large cohort of randomly enrolled fetuses with apparently isolated agenesis of the corpus callosum at prenatal MR imaging.MATERIALS AND METHODS:All fetuses with apparent isolated agenesis of the corpus callosum undergoing prenatal MR imaging from 2004 to 2014, were evaluated for the presence of the anterior or a vestigial hippocampal commissure assessed in consensus by 2 pediatric neuroradiologists.RESULTS:Overall, 62 cases of agenesis of the corpus callosum were retrieved from our data base. In 3/62 fetuses (4.8%), no forebrain commissure was visible at prenatal MR imaging, 23/62 fetuses (37.1%) presented with only the anterior commissure, and 20/62 fetuses (32.3%) showed both the anterior commissure and a residual vestigial hippocampal commissure, whereas in the remaining 16/62 fetuses (25.8%), a hybrid structure merging a residual vestigial hippocampal commissure and a rudiment of the corpus callosum body was detectable. Postnatal MR imaging, when available, confirmed prenatal forebrain commissure findings.CONCLUSIONS:Most fetuses with apparent isolated agenesis of the corpus callosum showed at least 1 forebrain commissure at prenatal MR imaging, and approximately half of fetuses also had a second commissure: a vestigial hippocampal commissure or a hybrid made of a hippocampal commissure and a rudimentary corpus callosum body. Whether such variability is the result of different genotypes and whether it may have any impact on the long-term neurodevelopmental outcome remains to be assessed.

The corpus callosum (CC) is the major white matter forebrain commissure. Agenesis of the corpus callosum (ACC) is among the most common congenital brain anomalies, often coexisting with chromosomal or genetic syndromes and other malformations of the central nervous system or extra-CNS location,^1–4 which may negatively impact the neurodevelopmental outcome.^5–7 MR imaging^8,9 has been introduced in prenatal assessment of suspected ACC as a complementary investigation to sonography, due to its high performance in evaluating the fetal brain structures and detecting associated anomalies that may be overlooked at sonography but may impact the final outcome.Both prenatal and postnatal MR imaging may accurately depict the brain features accompanying ACC. For example, the presence or absence of Probst bundles has been extensively addressed in the literature.^10–12 On the contrary, the involvement in ACC of the other forebrain commissures, namely the anterior commissure (AC) and the hippocampal commissure (HC), has been poorly investigated and mainly as sporadic imaging reports in the postnatal setting.^8,13 These postnatal reports did not provide consistent data about how the other forebrain commissures are involved in ACC. These reports are not the result of a random case screening; rather, they are a collection of clinical cases.Consistent visualization of the other forebrain commissures seems feasible at prenatal MR imaging, albeit very poor data are available regarding the forebrain commissures in fetuses with ACC.The aim of this study was to describe the types of other forebrain commissures and to assess their frequency in a large cohort of fetuses with apparent isolated ACC on prenatal MR imaging.     

Contribution of MRI to ultrasound in the diagnosis of fetal anomalies

Purpose:

To evaluate the contribution of MRI to ultrasound (US) in the diagnosis of fetal anomalies.

Materials and Methods:

After informed consent and institutional review board approval, concomitant US and MR imaging were performed for 184 fetuses with suspected anomalies in university hospital. Postnatal final diagnoses were obtained for 183 anomalies in 151 fetuses either by radiological examination, surgery, autopsy, or inspection. The prenatal US and MR diagnoses were compared with respect to postnatal diagnoses. Sign test was used to determine the statistical significance.

Results:

Both ultrasound and MR imaging correctly diagnosed 93 (50%) cases and failed in 12 (7%) cases. Ultrasound was superior in 7 (4%) cases. MR imaging was superior in 71 (39%) cases (P < 0.001). MR contributed to the prenatal diagnosis by the confirmation of the suspected US diagnosis in 13%, by demonstration of additional findings in 31% and by changing the diagnosis in 56% of the cases. The contribution rates were 55% for the central nervous system (CNS) (P < 0.001), 44% for thorax (P = 0.016), 38% for gastrointestinal system (GIS) (P = 0.031) and 29% for genitourinary system (GUS) (P = 0.003) anomalies. In facial, cardiac and extremity‐skeletal system anomalies, there was not a significant contribution of MR imaging over US.

Conclusion:

MR imaging can be used as an adjunct to US in the prenatal diagnosis of fetal anomalies of not only the CNS but also the non‐CNS origin especially those involving the GIS, GUS and thorax. J. Magn. Reson. Imaging 2012;35:882–890. © 2011 Wiley Periodicals, Inc.     

MRI在显示胎儿中枢神经系统发育畸形中优势的初步探讨

目的:探讨MRI在检出胎儿中枢神经系统发育异常中的优势。方法:对42例超声检查发现胎儿异常的孕妇进行胎儿MRI检查(超声检查48h内完成),孕妇年龄22~35岁,胎龄16~35周。MRI检查采用半傅立叶单激励快速自旋回波(HASTE)序列获得T2WI,其中8例还行快速小角度激励(fastlowangleshot,FLASH)T1WI成像,4例行扩散加权成像。将超声结果、MRI与尸体解剖、手术或/和出生后随访MRI比较。结果:产前超声漏诊的病例共20例,MRI的T2WI仅漏诊1例。超声漏诊病例多数为脑实质及脊髓病变,且多种中枢神经系统发育畸形的声像图可表现相同,缺乏特异性。结论:MRI可直接显示脑实质、脊髓以及病变与脑脊髓的关系,在超声检查基础上进行胎儿磁共振成像,有助于弥补超声之不足,进一步完善、验证、甚至更正超声诊断。     

产前超声及磁共振成像在胎儿肺隔离症诊断中的价值探讨

目的 探讨超声及MRI诊断胎儿肺隔离症的临床应用价值.方法 对12例产前超声怀疑胎儿肺隔离症者,24h内进行MRI检查,诊断结果均经尸检病理及产后随访证实.对12例胎儿的超声和MRI图像资料进行分析,并与随访结果对照.结果 产前超声诊断的12例胎儿肺隔离症,超声诊断符合率83.3％,误诊2例,（1例为隔疝,1例为肺囊腺瘤）;产前MRI检查诊断准确率为91.7％,误诊1例（隔离肺误诊为腹腔肿瘤）.结论 产前超声检查是诊断胎儿肺隔离症主要筛选方法,MRI可以作为胎儿超声检查的重要补充,二者联合应用,可进一步提高该病的诊断率.     

Fetal Pericallosal Lipoma: US and MR Findings

We report a case of fetal pericallosal lipoma occurring at the anterior interhemispheric fissure and associated with agenesis of the corpus callosum. During targeted prenatal ultrasonography at 26 weeks'' gestation, the lesion was seen as a highly echogenic mass. MR imaging performed at 35 weeks'' gestation and during the postnatal period revealed a pericallosal fatty mass and agenesis of the corpus callosum.