Periventricular nodular heterotopia on prenatal ultrasound and magnetic resonance imaging

Comparison of Intrauterine and Postnatal Brain Magnetic Resonance Imaging: Systematic Review

BACKGROUND

Fetal magnetic resonance imaging (MRI) identifies brain abnormalities better than transabdominal ultrasound. Most studies compare fetal MRI with postnatal cranial ultrasound or postmortem, so it is unclear how useful postnatal MRI is after fetal MRI. This work aimed to review the literature on postnatal MRI compared with fetal MRI to determine whether it provided useful clinical information.

METHODS

A literature search to April 2024 was performed to identify publications on fetal brain abnormalities examined using both fetal MRI and postnatal MRI. A systematic review was performed. The quality of research was evaluated using Joanna Briggs Institute checklists.

RESULTS

We identified 24 studies of 401 participants. All identified papers were retrospective or prospective case series at high risk of bias. Fourteen (58.3%) of the studies were high or moderate quality and 10 (41.7%) were low. Postnatal MRI confirmed the findings of fetal MRI in 296 (73.8%), refuted the diagnosis on fetal MRI in 24 (6.2%), and found additional abnormalities in 81 (20.2%). The suspected abnormalities on fetal MRI not confirmed on postnatal MRI were 12 isolated inferior cerebellar vermis hypoplasia, eight cerebellar vermis cysts, one mild ventriculomegaly, and one each of focal white matter abnormality, mega cisterna magna, and an unstated abnormality. Two papers including 17 participants reported that postnatal MRI changed the management or prognosis in nine (52.9%) participants.

CONCLUSIONS

The evidence on the value of postnatal MRI following a diagnosis of fetal brain abnormality is limited in size and quality, and further prospective research evidence is required.

Anatomic Approach to Fetal Hydrocephalus

Hydrocephalus is an imprecise term and refers to the imbalance of brain parenchyma and cerebral spinal fluid in the cranial vault. Ventriculomegaly, or enlargement of the ventricular system, is often the more precise term and is therefore preferred. Appropriate imaging and measurement techniques are critical to detect ventriculomegaly and grade its severity. There is a broad differential diagnosis with resultant highly variable clinical outcomes. Furthermore, some causes have a substantial recurrence risk in future pregnancies. Therefore, accurate diagnosis of the underlying cause is essential for pregnancy management and patient counseling. Understanding ventricular anatomy and correct measurement technique is needed for assessing and grading ventriculomegaly. This is achieved through an anatomically based approach to reach the differential diagnosis, with a focus on key decision points for delineating causes of ventriculomegaly. In particular, the posterior fossa is first assessed for structural or developmental abnormalities; then, midline brain development abnormalities and associated pathologic conditions are reviewed; and last, the cortical mantle is assessed for developmental or destructive processes. In each category, different entities are highlighted, with a particular focus on illustrating the US and MRI findings of the underlying condition and tips to differentiate similar-appearing entities. Ultimately, the informed fetal radiologist can use the proposed algorithmic approach to hydrocephalus to narrow the differential and thus provide vital diagnostic information for pregnancy counseling and management discussions. ©RSNA, 2025.

Overview of reproductive and pregnancy health principles and practice used by maternal-fetal medicine specialists for fetal-neonatal neurology consultants

Unique from other fetal anatomical systems, the central nervous system (CNS) starts development early in the embryonic period shortly after fertilization before most patients are even aware they are pregnant. Maturation throughout pregnancy involve complicated structural and functional changes, most likely below the resolution of testing to detect. During this time, the fetal CNS is susceptible to lesions that reflect trimester-specific adverse events. Neonatal neurological status with childhood sequelae can result from combinations of antenatal, peripartum and neonatal adverse events. Person-specific clinical management choices must consider the timing of multiple mechanisms that can alter neurodevelopment including genetic causes, aetiologies after conception as well as communicable and non-communicable conditions that result in anomalous or destructive brain lesions. The appearance of the fetal brain also changes significantly through gestation as different structures mature and the cerebral cortex in particular increases in size and complexity. Therefore, obstetrical imagers and maternal fetal medicine physicians need to be aware of the expected evolving appearances of the healthy fetal brain as the fetus advances in gestation. Often when fetal CNS pathology is detected or anticipated during pregnancy, there is understandably significant parental anxiety regarding the long-term implications of their child's neurodevelopmental prognosis. In these instances, Maternal Fetal Medicine specialists often collaborate with Pediatric Neurologists in the antenatal period regarding diagnoses that anticipate neonatal or later childhood neurologic sequelae. Potential adverse outcomes are discussed with prospective parents to be integrated into choices based on shared decisions.

A familial case of diffuse periventricular nodular heterotopia identified prenatally: Filamin A defect as the probable cause

Periventricular nodular heterotopia (PNH) is a neuronal migration defect characterized by the presence of ectopic grey matter nodules adjacent to the walls of the lateral ventricles. The main genetic etiology of PNH are variants in the Filamin A gene (FLNA, MIM #300049), located in the X chromosome. It affects mostly females (embryonic lethality in males), with about 50% of cases inherited from healthy mothers or with a mild phenotype. It is associated with epilepsy (75%-90%), cardiovascular (65%) and pulmonary pathologies (25%). A 28-year-old primigravida was referred for prenatal care in obstetrics department because of personal history of obliterative bronchiolitis. She has a family history of asthma (mother and sister) and adulthood-onset epilepsy (father). The pregnancy was uneventful up to 20 weeks and 3 days when bilateral periventricular irregularities and mega cisterna magna were identified on ultrasound in a female fetus. Neurosonography was performed, which led to the hypothesis of diffuse PNH, supported by MRI. The hypothesis of PNH associated to the FLNA gene was made. Brain MRI on the pregnant woman was requested, which confirmed a similar pattern of PNH. The arrayCGH (PerkinElmer, Prenatal filter 37K) was normal, and whole exome sequencing identified the likely pathogenic c.1554del p.(Val519fs*) variant in the FLNA gene. We present a case of X-linked hereditary PNH that highlights the value of fetal neurosonography in making a putative diagnosis. The diagnosis was supported by MRI in both fetus and mother. The investigation was supplemented by genetic studies, which confirmed the diagnosis.

The fetal brain: migration and gyration anomalies - pre- and postnatal correlations

The cerebral cortex represents a laminar structure of precisely spatially organized neurons in horizontal layers and vertical columns. Neurogenesis, neuronal migration and neuronal wiring are tightly regulated and coordinated procedures that result in the accurate formation of the human cerebral cortex. Abnormal fetal corticogenesis results in several types of migration and gyration anomalies, known as malformations of cortical development, which have long been a topic of investigation. According to the stage of cortical development that is affected, with diverse genetic and non-genetic etiologies, these malformations can cause abnormal head size, abnormal brain surface and abnormal cortical layering with various degrees of neurodevelopmental delay and epilepsy. The pathogenesis of these malformations is multifactorial and includes genetic mutations or environmental insults, acquired either in utero at varying stages of brain development or during the perinatal period after corticogenesis. In this article, we focus on cortical malformations detected on fetal MRI. We present the main antenatal findings that should raise suspicion for malformations of cortical development, together with findings that might be missed on prenatal imaging and describe the correlations between fetal and postnatal MRI.

The Role of Fetal Brain Magnetic Resonance Imaging in Current Fetal Medicine

In open spina bifida we studied the use of MRI for the assessment of the posterior fossa and prevalence of supratentorial anomalies before and after in utero repair. New postprocessing techniques were applied to evaluate fetal brain development in this population compared to controls. In fetuses with congenital diaphragmatic hernia, we evaluated the brain development in comparison to controls. Diffusion weighted imaging was applied to study difference between fetuses with proven first trimester cytomegalovirus infection and controls. Finally, we investigated the value of third trimester fetal brain MRI after treatment for complicated monochorionic diamniotic pregnancies.

Newborn Periventricular Nodular Heterotopia with Persistent Feeding Cyanosis and Apneic Spell: A Case Report

Periventricular nodular heterotopia (PNH) is a neuronal migration disorder that occurs during early brain development. Patients with PNH may be asymptomatic and have normal intelligence; however, PNH is also known to cause various symptoms such as seizures, dyslexia, and cardiovascular anomalies. PNH is not commonly diagnosed during early infancy because of the lack of clinical manifestations during this period. We present the case of a female infant diagnosed with PNH based on brain magnetic resonance imaging, who had symptomatic patent ductus arteriosus that had to be ligated surgically and had prolonged feeding cyanosis with frequent apneic spells.

Prevalence of supratentorial anomalies assessed by magnetic resonance imaging in fetuses with open spina bifida

OBJECTIVES

To determine the prevalence of brain anomalies at the time of preoperative magnetic resonance imaging (MRI) assessment in fetuses eligible for prenatal open spina bifida (OSB) repair, and to explore the relationship between brain abnormalities and features of the spinal defect.

METHODS

This was a retrospective cross-sectional study, conducted in three fetal medicine centers, of fetuses eligible for OSB fetal surgery repair between January 2009 and December 2019. MRI images obtained as part of the presurgical assessment were re-evaluated by two independent observers, blinded to perinatal results, to assess: (1) the type and area of the defect and its anatomical level; (2) the presence of any structural central nervous system (CNS) anomaly and abnormal ventricular wall; and (3) fetal head and brain biometry. Binary regression analyses were performed and data were adjusted for type of defect, upper level of the lesion (ULL), gestational age (GA) at MRI and fetal medicine center. Multiple logistic regression analysis was performed in order to identify lesion characteristics and brain anomalies associated with a higher risk of presence of abnormal corpus callosum (CC) and/or heterotopia.

RESULTS

Of 115 fetuses included, 91 had myelomeningocele and 24 had myeloschisis. Anatomical level of the lesion was thoracic in seven fetuses, L1-L2 in 13, L3-L5 in 68 and sacral in 27. Median GA at MRI was 24.7 (interquartile range, 23.0-25.7) weeks. Overall, 52.7% of cases had at least one additional brain anomaly. Specifically, abnormal CC was observed in 50.4% of cases and abnormality of the ventricular wall in 19.1%, of which 4.3% had nodular heterotopia. Factors associated independently with higher risk of abnormal CC and/or heterotopia were non-sacral ULL (odds ratio (OR), 0.51 (95% CI, 0.26-0.97); P = 0.043), larger ventricular width (per mm) (OR, 1.23 (95% CI, 1.07-1.43); P = 0.005) and presence of abnormal cavum septi pellucidi (OR, 3.76 (95% CI, 1.13-12.48); P = 0.031).

CONCLUSIONS

Half of the fetuses assessed for OSB repair had an abnormal CC and/or an abnormal ventricular wall prior to prenatal repair. The likelihood of brain abnormalities was increased in cases with a non-sacral lesion and wider lateral ventricles. These findings highlight the importance of a detailed preoperative CNS evaluation of fetuses with OSB. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Cranial ultrasonographic screening findings among healthy neonates and their association with neurodevelopmental outcomes

BACKGROUND

To analyze the findings of cranial ultrasonographic screening in asymptomatic neonates and to assess the association between abnormal results and neurodevelopment.

METHODS

We retrospectively reviewed the cranial ultrasonographic screening results of healthy neonates born between 35 and 42 weeks gestation at our hospital from October 2011 to October 2018.

RESULTS

In total, 11,681 neonates underwent cranial ultrasonographic screening during the study period, and 9666 (82.7%) had normal results. Of 2015 neonates with abnormal findings, 294 had more than two abnormalities. The most common minor findings were subependymal cysts (8.99%), choroid plexus cysts (2.43%), lenticulostriate vasculopathy (2.34%), frontal horn cysts (1.80%), and enlarged cisterna magna (1.04%). Then, 33 (0.28%) neonates had major abnormalities, including cerebral hemorrhage, periventricular heterotopia, focal cortical dysplasia, anomalies of the corpus callosum, and vascular malformation. Of 1334 neonates who underwent serial clinical evaluations, 76 (5.69%) had neurodevelopmental disorders, including developmental delay, attention-deficit/hyperactivity disorder, and autistic spectrum disorder.

CONCLUSION

The incidence rate of intracranial anomalies in healthy neonates was 17.3%, and about 5.69% had neurodevelopmental disorders. Cranial ultrasonographic screening has its own value in helping early detection of intracranial anomalies in healthy neonates, some of which have prognostic implications.

Role of prenatal magnetic resonance imaging in fetuses with isolated mild or moderate ventriculomegaly in the era of neurosonography: international multicenter study

OBJECTIVES

To assess the role of fetal magnetic resonance imaging (MRI) in detecting associated anomalies in fetuses presenting with mild or moderate isolated ventriculomegaly (VM) undergoing multiplanar ultrasound evaluation of the fetal brain.

METHODS

This was a multicenter, retrospective, cohort study involving 15 referral fetal medicine centers in Italy, the UK and Spain. Inclusion criteria were fetuses affected by isolated mild (ventricular atrial diameter, 10.0-11.9 mm) or moderate (ventricular atrial diameter, 12.0-14.9 mm) VM on ultrasound, defined as VM with normal karyotype and no other additional central nervous system (CNS) or extra-CNS anomalies on ultrasound, undergoing detailed assessment of the fetal brain using a multiplanar approach as suggested by the International Society of Ultrasound in Obstetrics and Gynecology guidelines for the fetal neurosonogram, followed by fetal MRI. The primary outcome of the study was to report the incidence of additional CNS anomalies detected exclusively on prenatal MRI and missed on ultrasound, while the secondary aim was to estimate the incidence of additional anomalies detected exclusively after birth and missed on prenatal imaging (ultrasound and MRI). Subgroup analysis according to gestational age at MRI (< 24 vs ≥ 24 weeks), laterality of VM (unilateral vs bilateral) and severity of dilatation (mild vs moderate VM) were also performed.

RESULTS

Five hundred and fifty-six fetuses with a prenatal diagnosis of isolated mild or moderate VM on ultrasound were included in the analysis. Additional structural anomalies were detected on prenatal MRI and missed on ultrasound in 5.4% (95% CI, 3.8-7.6%) of cases. When considering the type of anomaly, supratentorial intracranial hemorrhage was detected on MRI in 26.7% of fetuses, while polymicrogyria and lissencephaly were detected in 20.0% and 13.3% of cases, respectively. Hypoplasia of the corpus callosum was detected on MRI in 6.7% of cases, while dysgenesis was detected in 3.3%. Fetuses with an associated anomaly detected only on MRI were more likely to have moderate than mild VM (60.0% vs 17.7%; P < 0.001), while there was no significant difference in the proportion of cases with bilateral VM between the two groups (P = 0.2). Logistic regression analysis showed that lower maternal body mass index (adjusted odds ratio (aOR), 0.85 (95% CI, 0.7-0.99); P = 0.030), the presence of moderate VM (aOR, 5.8 (95% CI, 2.6-13.4); P < 0.001) and gestational age at MRI ≥ 24 weeks (aOR, 4.1 (95% CI, 1.1-15.3); P = 0.038) were associated independently with the probability of detecting an associated anomaly on MRI. Associated anomalies were detected exclusively at birth and missed on prenatal imaging in 3.8% of cases.

CONCLUSIONS

The incidence of an associated fetal anomaly missed on ultrasound and detected only on fetal MRI in fetuses with isolated mild or moderate VM undergoing neurosonography is lower than that reported previously. The large majority of these anomalies are difficult to detect on ultrasound. The findings from this study support the practice of MRI assessment in every fetus with a prenatal diagnosis of VM, although parents can be reassured of the low risk of an associated anomaly when VM is isolated on neurosonography. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Fetal Neuroimaging Update

OBJECTIVES

To review the current imaging techniques available for the evaluation of the fetal brain.

FINDINGS

Ultrasound remains the initial screening modality with routine scanning typically performed at 18-20 weeks gestation. When a central nervous system (CNS) abnormality is noted by ultrasound, MRI is increasingly being used to further clarify findings. Fetal MRI has the unique ability to provide high detailed anatomical information of the entire human fetus with high contrast resolution. This technique has grown due to the development of rapid single shot image acquisition sequences, improvement of motion correction strategies and optimizing shimming techniques.

CONCLUSIONS

The assessment of fetal CNS anomalies continues to improve. Advanced MRI techniques have allowed for further delineation of CNS anomalies and have become a cornerstone in the assessment of fetal brain well-being. Those interpreting fetal studies need to be familiar with the strengths and limitations of each exam and be sensitive to the impact discussing findings can have regarding perinatal care and delivery planning. Collaboration with neurologists, neurosurgeons, geneticists, counselors, and maternal fetal specialists are key in providing the best care to the families we treat.

New insights in cerebral findings associated with fetal myelomeningocele: a retrospective cohort study in a single tertiary centre

OBJECTIVE

To investigate cerebral anomalies other than Chiari type 2 malformation in fetuses with myelomeningocele (MMC).

DESIGN

A retrospective cohort study in a single tertiary centre.

SETTING

A review of associated cerebral anomalies in cases with prenatal diagnosis of myelomeningocele.

POPULATION

Seventy cases of fetal myelomeningocele.

METHODS

Ultrasound and MRI images were blindly reviewed. Postnatal imaging and results of the postmortem results were also reviewed. The association between cerebral anomalies and the following ultrasound findings was measured: level of the defect, ventriculomegaly, microcephaly and fetal talipes.

MAIN OUTCOME MEASURES

A microcephaly was observed in 32/70 cases (46%) and a ventriculomegaly was observed in 39/70 cases (56%). Other cerebral anomalies were diagnosed in 47/70 (67%).

RESULTS

Other cerebral anomalies were represented by 42/70 cases with abnormal CC (60%), 8/70 cases with perinodular heterotopia (PNH; 11%), 2/70 cases with abnormal gyration (3%). MRI performed only in fetal surgery cases confirmed the ulltrasound findings in all cases and provided additional findings in two cases (PNH). Risk ratios of fetal cerebral anomalies associated with MMC did not reach significance for microcephaly, ventriculomegaly, talipes or the level of the defect There was an overall good correlation between pre- and postnatal findings with a Kappa value of 0.79 [95% CI 0.57-1] and 82% agreement.

CONCLUSION

Fetal brain anomalies other than Chiari type 2 malformation are frequently observed in fetuses with myelomeningocele, predominantly represented by CC anomalies. Whether these associated cerebral anomalies have an impact on selecting cases eligible for fetal surgery needs further evaluation.

TWEETABLE ABSTRACT

Fetal cerebral anomalies other than Chiari type 2 malformation, microcephaly, and ventriculomegaly may be associated with MMC in up to 67% of the cases.

Ultrasound Measurements of Frontal Horns and the Cavum Septi Pellucidi in Healthy Fetuses in the Second and Third Trimesters of Pregnancy

OBJECTIVES

To assess the visualization rate and size of the frontal horns (FHs) and cavum septi pellucidi (CSP) in healthy fetuses throughout pregnancy.

METHODS

After Institutional Review Board approval, 522 consecutive uncomplicated singleton pregnancies between 15 and 39 gestational weeks were enrolled in the study. Ultrasound measurements of the anterior horn width (AHW), center from the horn distance (CFHD), distance from the FHs to the CSP, and CSP width were retrospectively performed using axial transventricular or transcerebellar planes. Available maternal body mass indices were recorded.

RESULTS

At least 1 FH was seen in 78% of the cases. The mean AHW decreased over the second trimester and plateaued in the third trimester. The CFHD plateaued in the second trimester and increased in the third trimester. Downside FHs were generally larger than upside FHs. More FHs were measured in transventricular (69%) than transcerebellar (31%) planes. Frontal horns were seen with high, low, and no confidence in 57%, 21%, and 22% of cases, respectively. No-confidence rates were 17% in the second trimester and 42% in the third trimester. The CSP was not visualized in 4% of cases; 15 of 19 cases of a nonvisualized CSP were scanned between 18 and 37 weeks. Mean body mass indices ± SDs were 27.6 ± 6.7 kg/m² for the patients in cases of a visualized CSP and 32.4 ± 9.1 kg/m² for the patients in cases of a nonvisualized CSP.

CONCLUSIONS

Normative data for the fetal FH and CSP width were established. Frontal horns are more frequently seen on transventricular views and are difficult to confidently assess in the late third trimester. This study challenges previously reported data that the CSP is seen in 100% of cases from 18 to 37 weeks.

Familial NEDD4L variant in periventricular nodular heterotopia and in a fetus with hypokinesia and flexion contractures

Background

Mutations in the HECT domain of NEDD4L have recently been identified in a cohort of eight patients with a syndromic form of bilateral periventricular nodular heterotopia (PVNH) in association with neurodevelopmental delay, cleft palate, and toe syndactyly (PVNH7).

Methods

Case report based on NGS sequencing.

Results

Here, we describe a girl with a novel heterozygous NEDD4L missense variant, p.Tyr679His, and characteristic clinical findings, including bilateral periventricular nodular heterotopia, cleft palate and mild toe syndactyly. Molecular testing from peripheral blood identified the healthy father to carry the NEDD4L variant in mosaic state. Notably, a previous pregnancy of the couple had been terminated due to a complex fetal developmental disorder, including hypokinesia and flexion contractures. Upon review, this affected fetus was also shown to carry the familial NEDD4L variant.

Conclusion

Our findings may suggest a broader spectrum of NEDD4L‐associated phenotypes, including severe prenatal neurodevelopmental manifestations, which might represent yet another genetic form of fetal hypokinesia with flexion contractures.

Prenatal imaging of posterior fossa disorders. A review

With advances in fetal imaging, prenatal diagnosis of posterior fossa anomalies has been greatly improved. Based on the anatomical approach proposed by Guibaud and Desportes in 2006, the main anomalies depicted according to the algorithm includes: (1) increased "fluid-filled" space of the posterior fossa, (2) abnormal biometry of the cerebellum, and (3) abnormal cerebellar anatomy. In this review, the spectrum of PF anomalies is covered in an attempt to update this approach in the light of both our experience, more than a decade since this algorithm was published, and the latest data in the literature.

Prenatally diagnosed periventricular nodular heterotopia: Further delineation of the imaging phenotype and outcome

OBJECTIVES

Periventricular nodular heterotopia (PNH) is a malformation of cortical development which presents with heterogeneous imaging, neurological phenotype and outcome. There is a paucity of comprehensive description detailing the prenatal diagnosis of PNH. The aim of this study is to report neuroimaging features and correlated outcomes in order to delineate the spectrum of prenatally diagnosed PNH.

METHODS

It was a retrospective study over 15 years in five tertiary centers. All fetuses with prenatally diagnosed PNH were collected. Fetal ultrasound and MRI were reviewed and genetic screening collected. Prenatal findings were analyzed in correlation to fetopathological analyses and post-natal follow up.

RESULTS

Thirty fetuses (22 females and 8 males) with PNH were identified. The two major ultrasound signs were ventriculomegaly associated with dysmorphic frontal horns (60%) and posterior fossa anomalies (73.3%). On MRI, two groups of PNH were identified: the contiguous and diffuse PNH (n = 15, 50%), often associated with megacisterna magna, and the non-diffuse, either anterior, posterior or unilateral PNH. FLNA mutations were found in 6/11 cases with diffuse PNH. Additional cortical malformations were exclusively observed in non diffuse PNH (9/15; 60%). Twenty-four pregnancies (80%) were terminated. Six children aged 6 months to 5 years are alive. Five have normal neurodevelopment (all had diffuse PNH) whereas one case with non diffuse PNH has developmental delay and epilepsy.

CONCLUSION

PNH is heterogeneous but patients with diffuse PNH are a common subgroup with specific findings on prenatal imaging and implications for prenatal counseling.

Complex Trajectories of Brain Development in the Healthy Human Fetus

This study characterizes global and hemispheric brain growth in healthy human fetuses during the second half of pregnancy using three-dimensional MRI techniques. We studied 166 healthy fetuses that underwent MRI between 18 and 39 completed weeks gestation. We created three-dimensional high-resolution reconstructions of the brain and calculated volumes for left and right cortical gray matter (CGM), fetal white matter (FWM), deep subcortical structures (DSS), and the cerebellum. We calculated the rate of growth for each tissue class according to gestational age and described patterns of hemispheric growth. Each brain region demonstrated major increases in volume during the second half of gestation, the most pronounced being the cerebellum (34-fold), followed by FWM (22-fold), CGM (21-fold), and DSS (10-fold). The left cerebellar hemisphere, CGM, and DSS had larger volumes early in gestation, but these equalized by term. It has been increasingly recognized that brain asymmetry evolves throughout the human life span. Advanced quantitative MRI provides noninvasive measurements of early structural asymmetry between the left and right fetal brain that may inform functional and behavioral laterality differences seen in children and young adulthood.

Fetal neuroimaging: an update on technical advances and clinical findings

This paper is based on a literature review from 2011 to 2016. The paper is divided into two main sections. The first section relates to technical advances in fetal imaging techniques, including fetal motion compensation, imaging at 3.0 T, 3-D T2-weighted MRI, susceptibility-weighted imaging, computed tomography, morphometric analysis, diffusion tensor imaging, spectroscopy and fetal behavioral assessment. The second section relates to clinical updates, including cerebral lamination, migrational anomalies, midline anomalies, neural tube defects, posterior fossa anomalies, sulcation/gyration and hypoxic-ischemic insults.

Prenatal diagnosis of periventricular nodular heterotopia in borderline ventriculomegaly using sonography and magnetic resonance imaging

Periventricular nodular heterotopia (PNH) is usually missed on prenatal sonographic examinations, even on targeted scans. Irregular ventricular walls on axial view and irregular square-shaped lateral ventricles on coronal view are suggestive of PNH in the early third trimester. To achieve an early prenatal diagnosis, it is important to keep in mind the possible coexistence of PNH with brain malformations such as ventriculomegaly, posterior fossa anomalies, or agenesis of corpus callosum. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:510-513, 2016.

Evaluation of Subependymal Gray Matter Heterotopias on Fetal MRI

BACKGROUND AND PURPOSE

Subependymal grey matter heterotopias are seen in a high proportion of children with Chiari II malformation and are potentially clinically relevant. However, despite its growing use, there is little in the literature describing its detection on fetal MRI. Our aim was to evaluate the accuracy in diagnosing subependymal gray matter heterotopias in fetuses with spinal dysraphism on fetal MR imaging.

MATERIALS AND METHODS

This study is a retrospective analysis of 203 fetal MRIs performed at a single institution for spinal dysraphism during a 10-year period. Corresponding obstetric sonography, postnatal imaging, and clinical/operative reports were reviewed.

RESULTS

Of the fetal MRIs reviewed, 95 fetuses were included in our analysis; 23.2% (22/95) were suspected of having subependymal gray matter heterotopias on fetal MR imaging prospectively. However, only 50% (11/22) of these cases were confirmed on postnatal brain MR imaging. On postnatal brain MR imaging, 28.4% (27/95) demonstrated imaging findings consistent with subependymal gray matter heterotopia. Only 40.7% (11/27) of these cases were prospectively diagnosed on fetal MR imaging.

CONCLUSIONS

Fetal MR imaging is limited in its ability to identify subependymal gray matter heterotopias in fetuses with spinal dysraphism. It is believed that this limitation relates to a combination of factors, including artifacts from fetal motion, the very small size of fetal neuroanatomy, differences in imaging techniques, and, possibly, irregularity related to denudation of the ependyma/subependyma in the presence of spinal dysraphism and/or stretching of the germinal matrix in ventriculomegaly.