Three-dimensional imaging of the postmortem fetus by MRI: early experience.

OBJECTIVE: The feasibility and significance of three-dimensional (3D) visualization of the postmortem fetus using magnetic resonance imaging (MRI) was investigated. METHODS: 3D reconstruction of sectional MRI data sets from 8 postmortem fetuses was performed. RESULTS: Fetal configurations and internal structures, both normal and pathological, were clearly demonstrated by 3D display. CONCLUSION: This new technique provides high quality fetal 3D images for postmortem morphological diagnosis and interactive visual teaching. It may eventually have applications in prenatal diagnosis and the preoperative simulation of fetal surgery.     

Magnetic resonance imaging and the detection of fetal brain anomalies, injury, and physiologic adaptations

PURPOSE OF REVIEW: Magnetic resonance imaging is playing an increasingly prominent role in depicting brain maturation, especially gyral formation that follows a temporospatial pattern, and in detecting developmental abnormalities of the cortex and other brain sectors. Knowledge of the technical advantages and limitations of in-utero magnetic resonance imaging techniques, relative to those of the postnatal period, is essential to optimize magnetic resonance sequences for early diagnosis. This includes an understanding of the changes in both brain anatomy and magnetic resonance signals that occur with an increase in gestational age. RECENT FINDINGS: Magnetic resonance imaging has evolved has an important adjunct in the diagnosis of brain malformations, particularly in the late-second or third trimester. Noxious conditions elicit more of a chronic rather than acute response in the fetal brain, which differs from that observed postnatally. Clinical applications of proton magnetic resonance spectroscopy may help elucidate fetal brain maturation and its abnormalities from a metabolic point of view. SUMMARY: Indications for fetal brain magnetic resonance imaging have increased because of improvements in magnetic resonance techniques and the ability to detect subtle changes within the cerebral parenchyma, especially in fetuses at increased risk of brain damage.     

Prenatal diagnosis of neurofibromatosis type 1: sonographic and MRI findings

Prenatal ultrasound and magnetic resonance imaging (MRI) demonstrated a large oropharyngeal tumor, and cardiac and cranial abnormalities consistent with neurofibromatosis type 1 (NF1) in a third-trimester fetus, which were confirmed on postmortem examination. Sonographic features of NF1 are generally nonspecific; MR examination provided significant additional information, facilitating prenatal diagnosis.     

Prenatal magnetic resonance imaging of optic nerve head coloboma

OBJECTIVE: Congenital optic nerve head coloboma represents an important cause of childhood visual impairment and blindness; it can be isolated or, more often, it can be associated with several syndromes. Ultrasound has limitations in depicting the posterior aspect of the fetal eye globe, so prenatal information about ocular coloboma are very scarce. The purpose of this paper was to report prenatal magnetic resonance (MR) imaging features of optic nerve head coloboma. METHODS: MR imaging at 1.5 Tesla was based on multiplanar single-shot fast spin-echo T2-weighted 3-4 mm thick contiguous sections. RESULTS: Three fetal cases with optic nerve head coloboma and one with microphthalmos and colobomatous cyst are reported. Coloboma appeared as a focal bulging of ocular globe profile at the insertion of optic nerve. CONCLUSION: Prenatal MR imaging allowed an accurate diagnosis to be obtained.     

Ultrafast scan magnetic resonance in prenatal diagnosis

OBJECTIVE: To determine whether magnetic resonance (MR) can give additional information in prenatal diagnosis of congenital anomalies, when the ultrasound (US) analysis is not conclusive. METHODS: Ultrafast MR scanning examined 39 pregnant women with 41 fetuses in whom US was suspicious of fetal congenital abnormalities. Two techniques were used namely (1) HASTE inversion recovery sequence and (2) FISP 2D. RESULTS: Thirty-nine patients with 41 fetuses were referred for MR because of an equivocal US with regard to brain, spine, skeletal and miscellaneous anomalies. In 1 twin pregnancy, 1 co-twin has not been examined with MRI because of its demise. In 22 of them, additional information was obtained by MR. In 9 the MR was confirmative with the US examination. Four were false negative, comparing with the postnatal diagnosis. Three failed because of maternal claustrophobia and in 2 a diagnosis could not be made. From the 40 fetuses in this study, 38 were examined postnatally by MR, US, plain X-ray or autopsy was performed to confirm the prenatal diagnosis. CONCLUSION: The use of MRI in obstetrics has been limited, until recently. With fast MRI sequences it is not necessary to sedate the fetus. It is advisable in cases where US is equivocal concerning congenital anomalies of the fetus to use MR with fast or ultrafast scan technique, especially when the central nervous system is concerned.     

Prenatal imaging of congenital cerebral primitive neuroectodermal tumor

A case of fetal brain tumor, which appeared after 32 weeks' gestation, is presented. Prenatal ultrasonography and magnetic resonance imaging demonstrated a large heterogeneous mass in the right supratentorial region and left enlarged ventricle. A male fetus weighing 2,616 g was delivered at 34 weeks' gestation by cesarean section and died on the 37th day of life due to rapid growth of the tumor. Following autopsy, the pathohistological examination revealed primitive neuroectodermal tumor. Magnetic resonance imaging in the prenatal management of the congenital brain tumor is efficient in evaluating the expansion and margin of the tumor and intratumoral bleeding, which are not demonstrated by ultrasonography.     

Diagnosing fetal urinary tract abnormalities: benefits of MRI compared to ultrasonography

BACKGROUND: To compare antepartum ultrasonography with magnetic resonance imaging for prenatal diagnosis of malformations in the fetal urinary tract in high risk patients during the last trimester. MATERIALS AND METHODS: The study involved 22 women and 24 fetuses with either severe oligohydramnios or ultrasonographically or clinically suspected abnormality of urinary tract. Ultrasound examination was carried out with 5 MHz abdominal convex probe and magnetic resonance imaging with superconductive 1.5 T equipment. Postnatal findings were used as reference. RESULTS: Correct diagnosis of urinary tract anomaly was done in 15 fetuses on ultrasound and in 20 fetuses on magnetic resonance imaging. Both methods enabled correct diagnosis in 12, only ultrasound in three and only magnetic resonance imaging in eight fetuses. Both methods imaged equivocally in one case. The additional information by magnetic resonance imaging was gained from five fetuses out of 12 pregnancies with oligohydramnios and from three fetuses out of ten pregnancies with normal amount of amniotic fluid. CONCLUSIONS: MRI is a valuable additional method to ultrasonography of fetal urinary tract if resolution of ultrasound is impaired for reason of oligohydramnios or technical deterioration.     

Prenatal diagnosis of capillary telangiectasia of the cerebellum--ultrasound and MRI features

OBJECTIVE: To report three cases of capillary telangiectasia (CT) of the cerebellum revealed as focal cerebellar lesions. METHODS: Ultrasound and magnetic resonance imaging (MRI) were performed in all cases in the prenatal period. Prenatal imaging findings were compared with either post-mortem examination (case 1) or post-natal MRI (cases 2 & 3). RESULTS: A discrepancy between a hyperechoic lesion without any mass effect on sonogram and normal T1 and T2 spin-echo fetal magnetic resonance images was found in all cases. The diagnosis of CT was made on post-mortem examination in case 1. Prenatal ultrasound and magnetic resonance imaging findings were suggestive of the diagnosis in cases 2 and 3. In both cases, the pregnancy was managed conservatively and the diagnosis of CT was documented on post-natal MRI after gadolinium injection. CONCLUSION: The diagnosis of CT of the cerebellum was strongly suggested in these three cases in the prenatal period by the combination of ultrasound and fetal MRI findings. In the vast majority of cases, CT has a benign clinical course and complication with haemorrhage appears to be exceedingly rare. This fact should be taken into account in the prenatal counselling.     

Prenatal ultrasound detection of bilateral focal polymicrogyria

OBJECTIVES: Prenatal diagnosis by ultrasound of fetal polymicrogyria has been reported only once. METHODS: We describe an additional case of polymicrogyria in a fetus from a monozygotic twin pair, probably the consequence of twin-to-twin transfusion syndrome. RESULTS: On ultrasound, there were bilateral cortical hyperechogenic spots, and prenatal magnetic resonance imaging demonstrated the typical features of bilateral focal polymicrogyria. CONCLUSION: Polymicrogyria can be considered in the differential diagnosis of hyperechogenic brain lesions on fetal ultrasound. We also confirm the risk of brain damage in monochorionic twins pregnancies and the likely hypoxic-ischemic etiology of polymicrogyria.     

Effect of fetal magnetic resonance imaging on fetal heart rate patterns

OBJECTIVE: Our aim was to record the fetal heart rate before and during magnetic resonance imaging to observe the effects of the magnetic resonance imaging process on fetal heart rate parameters during imaging. STUDY DESIGN: Fetal heart rate recordings were obtained in 10 pregnant volunteers at the time of magnetic resonance imaging. All the pregnant women were at term (37-41 weeks) with singleton fetuses in the cephalic presentation. The scanning was performed on a 0.5-T purpose-built superconductive magnet by use of echo-planar imaging. The fetal heart recordings were obtained with a modified Sonicaid Meridian 800 (Oxford) Doppler ultrasound monitor. Recordings of the fetal heart were made for a period of at least 15 minutes outside the magnet and then for at least 15 minutes inside the magnet. RESULTS: There were no significant changes in any fetal heart rate parameters before and during the magnetic resonance imaging, as determined by the Wilcoxon matched-pairs signed-ranks test (P >.3). CONCLUSION: This is the first report of fetal heart rate recording during magnetic resonance imaging of the fetus. Magnetic resonance imaging does not produce demonstrable effects on fetal heart rate patterns.     

超声与MRI联合诊断14例单绒毛膜多胎畸形

目的 探讨超声和MRI联合诊断单绒毛膜多胎妊娠畸形的应用价值.方法 产前超声检出14例多胎妊娠畸形,均于超声检查后48 h内接受MRI检查,并于分娩或引产后证实.回顾性分析此14例的超声和MRI图象,并与随访结果比较.结果 14例多胎妊娠中无心畸胎7例、联体双胎5例、多胎之一消失2例.超声与MRI图像比较:(1)对于无心畸胎和多胎之一消失,超声可以明确诊断且是重要的随访手段;MRI能更清晰显示无心胎儿的器官与结构,并能检测供血胎儿和存活胎儿有无颅内继发改变.(2)对于联体儿,在心脏和血管结构的显示及心功能判断中超声明显优于MRI;在胃泡、肾脏、膀胱、肢体等结构的显示中超声与MRI较一致;在食管、肺、肝脏、肠管等器官的显示超声不如MRI,尤其是颅脑的显示;MRI具有较高软组织分辨力及视野大的特点,可显示较大病变及其与周围组织结构的关系,在联体双胎中可以同时显示两胎儿及两胎儿间的关系.结论 产前超声和MRI在诊断单绒毛膜多胎妊娠畸形中各有优劣,两者联合应用诊断价值更高.     

超声与MRI联合诊断14例单绒毛膜多胎畸形

目的 探讨超声和MRI联合诊断单绒毛膜多胎妊娠畸形的应用价值.方法 产前超声检出14例多胎妊娠畸形,均于超声检查后48 h内接受MRI检查,并于分娩或引产后证实.回顾性分析此14例的超声和MRI图象,并与随访结果比较.结果 14例多胎妊娠中无心畸胎7例、联体双胎5例、多胎之一消失2例.超声与MRI图像比较:(1)对于无心畸胎和多胎之一消失,超声可以明确诊断且是重要的随访手段;MRI能更清晰显示无心胎儿的器官与结构,并能检测供血胎儿和存活胎儿有无颅内继发改变.(2)对于联体儿,在心脏和血管结构的显示及心功能判断中超声明显优于MRI;在胃泡、肾脏、膀胱、肢体等结构的显示中超声与MRI较一致;在食管、肺、肝脏、肠管等器官的显示超声不如MRI,尤其是颅脑的显示;MRI具有较高软组织分辨力及视野大的特点,可显示较大病变及其与周围组织结构的关系,在联体双胎中可以同时显示两胎儿及两胎儿间的关系.结论 产前超声和MRI在诊断单绒毛膜多胎妊娠畸形中各有优劣,两者联合应用诊断价值更高.     

超声与MRI联合诊断14例单绒毛膜多胎畸形

目的 探讨超声和MRI联合诊断单绒毛膜多胎妊娠畸形的应用价值.方法 产前超声检出14例多胎妊娠畸形,均于超声检查后48 h内接受MRI检查,并于分娩或引产后证实.回顾性分析此14例的超声和MRI图象,并与随访结果比较.结果 14例多胎妊娠中无心畸胎7例、联体双胎5例、多胎之一消失2例.超声与MRI图像比较:(1)对于无心畸胎和多胎之一消失,超声可以明确诊断且是重要的随访手段;MRI能更清晰显示无心胎儿的器官与结构,并能检测供血胎儿和存活胎儿有无颅内继发改变.(2)对于联体儿,在心脏和血管结构的显示及心功能判断中超声明显优于MRI;在胃泡、肾脏、膀胱、肢体等结构的显示中超声与MRI较一致;在食管、肺、肝脏、肠管等器官的显示超声不如MRI,尤其是颅脑的显示;MRI具有较高软组织分辨力及视野大的特点,可显示较大病变及其与周围组织结构的关系,在联体双胎中可以同时显示两胎儿及两胎儿间的关系.结论 产前超声和MRI在诊断单绒毛膜多胎妊娠畸形中各有优劣,两者联合应用诊断价值更高.     

Second-trimester diagnosis of intracranial vascular anomalies in a fetus with subdural hemorrhage

OBJECTIVES: Risk factors for intracranial hemorrhage occurring in prenatal life are imperfectly known. A case of prenatal diagnosis of subdural hemorrhage associated with multiple intracranial vascular aneurysms is described. METHODS: Sonography and magnetic resonance imaging of the fetal head were obtained at 21 weeks' gestation and compared with pathologic findings. RESULTS: Sonography showed a large transonic mass displacing the normal intracranial structures. Magnetic resonance imaging demonstrated the hemorrhagic origin of the mass and showed multiple vascular anomalies. Postmortem examination confirmed the compression of the cerebral hemisphere by a blood collection, probably because of bleeding from one of the multiple vascular aneurysms into the subdural space. CONCLUSION: Magnetic resonance imaging with the use of single-shot ultrafast sequences may be useful not only in the differential diagnosis of fetal intracranial hemorrhage but also in identifying vascular risk factors.     

A new tool for prenatal diagnosis: ultrafast fetal MRI

The development of ultrafast magnetic resonance imaging scanners and sequences provides a new tool for the diagnosis of fetal anomalies. Magnetic resonance imaging is a valuable adjunct to prenatal ultrasound especially for the evaluation of suspected fetal brain anomalies, chest masses, abdominal masses, and renal diseases.     

Outcome following prenatal diagnosis of complete atrioventricular septal defect

OBJECTIVE: To identify in a case cohort study, overall outcome following prenatal diagnosis of complete AVSD (cAVSD) in a tertiary referral fetal cardiology center. METHOD: We retrospectively reviewed all pregnancies from 1997 to 2004 in which the fetus was identified on ultrasound examination as having a cAVSD. RESULTS: A prenatal diagnosis of cAVSD was made using fetal echocardiography in 99 fetuses. The median (range) gestational age at diagnosis was 23 weeks (17-37). In 41 cases, cAVSD was the sole cardiac lesion. The remaining 58 fetuses had associated additional intracardiac malformations. Prenatal karyotype was obtained in 43 fetuses and was abnormal in 23. Extracardiac anomalies were also identified in 25 fetuses. Following prenatal counseling, 35 couples chose termination. Of the 64 continuing pregnancies, 12 were stillbirths and 4 were lost to follow-up. Of the 48 live births, 16 were neonatal deaths without surgery while 32 babies underwent surgery and 19 have survived to date (follow-up between 2 years 10 months to 9 years 10 months). CONCLUSION: At the time of prenatal diagnosis at a regional fetal medicine center, the overall survival rate for fetuses with cAVSD is 32% (excluding termination and those lost to follow-up). This information has important implication for parents of fetuses with cAVSD and when undergoing prenatal counseling.     

Prenatal diagnosis of a trauma-related fetal epidural hematoma

BACKGROUND: Prenatal diagnosis of fetal intracranial hemorrhage has important etiologic, management, and prognostic implications. Ultrasonography and magnetic resonance imaging (MRI) have been used to identify and evaluate this condition. We present the first reported case of epidural hematoma diagnosed prenatally. CASE: A 25-year-old para 3 was referred for evaluation of a suspected fetal intracranial abnormality following an alleged assault. Ultrasonography and MRI were used to diagnose an epidural hematoma prenatally. The fetus subsequently died in utero. Autopsy confirmed the presence of an epidural hematoma. CONCLUSION: Ultrasonography and MRI were useful in diagnosing a fetal epidural hematoma. Unfortunately, no known effective in utero therapy exists for this rare problem.     

Prenatal diagnosis of purine nucleoside phosphorylase deficiency in the first and second trimesters of pregnancy

Prenatal diagnosis was performed in two successive pregnancies of a mother with a previous child with purine nucleoside phosphorylase (PNP) deficiency. In one pregnancy, an affected fetus was diagnosed in the 18th week of gestation after the demonstration of PNP deficiency in cultured amniotic fluid cells. Also an abnormal purine nucleoside profile was found in the amniotic fluid. The diagnosis of an affected fetus was confirmed by the analysis of cultured fetal skin fibroblasts and placental villi. The complete deficiency of PNP activity in placental villi confirms that the prenatal diagnosis of this disorder is possible by the direct investigation of chorionic villi. In the subsequent pregnancy, a heterozygous fetus was predicted in the tenth week of pregnancy by using chorionic villi.     

9例多胎妊娠合并胎儿染色体异常患者的产前诊断和治疗

目的探讨多胎妊娠合并胎儿染色体异常的产前诊断方法及选择性减胎术定位方法。 方法选取2012年1月至2013年12月就诊于广州医科大学附属第三医院9例多胎妊娠合并胎儿染色体异常患者的临床资料,采用回顾性研究方法对其产前诊断方法、染色体异常情况、选择性减胎术的方法及妊娠结局进行分析。 结果9例患者中3例为三胎妊娠,6例为双胎妊娠。(1)产前诊断：①超声检查：9例患者早孕期行超声检查,均提示存在胎儿颈项透明层(nuchal translucency, NT)增厚,孕中期超声检查提示有6例患者存在胎儿结构异常,包括颈部囊肿、心脏异常、外生殖器畸形、足内翻、全身水肿等;②染色体检查：5例胎儿21-三体综合征,1例Turner综合征,1例染色体微缺失,1例染色体重复,1例双胎染色体异常。(2)治疗及妊娠结局：9例患者中7例患者行选择性减胎术治疗,1例流产,3例早产(新生儿均存在并发症),3例足月分娩(新生儿均未见异常);2例患者拒绝减胎,1例于孕中期自然流产,1例于孕35^＋周剖宫产分娩(1胎儿为21-三体综合征,另一胎儿为健康儿)。 结论多胎妊娠应注重早孕期染色体筛查,确诊宫内胎儿染色体异常的患者可在超声引导下行选择性减胎术治疗。     

Prenatal diagnosis of congenital mesoblastic nephroma in mid-second trimester by sonography and magnetic resonance imaging

Although congenital mesoblastic nephroma (CMN) is a rare benign congenital renal tumor, it is the most common solid renal tumor in the newborn period. The most common presentation of congenital mesoblastic nephroma is polyhydramnios, and only one case with prenatal fetal hydrops has been previously reported. Prenatal diagnosis of CMN has previously been made on the basis of the findings of sonography in the third trimester, and magnetic resonance imaging (MRI)-based diagnosis has been reported recently. Here we report a case of prenatally diagnosed classical type CMN diagnosed at 22 + 3 weeks of gestation based on the findings of sonography and magnetic resonance imaging. The characteristic imaging findings in this case were fetal hydrops and polyhydramnios. To our knowledge, this is the youngest reported gestational age for prenatal diagnosis of CMN and it is the second case of CMN associated with fetal hydrops detected prenatally.