Volume development changes in the occipital lobe gyrus assessed by MRI in fetuses with isolated ventriculomegaly correlate with neurological development in infancy and early childhood

OBJECTIVE

This study was to systematically assess the occipital lobe gray and white matter volume of isolated ventriculomegaly (IVM) fetuses with MRI and to follow up the neurodevelopment of participants.

METHOD

MRI was used to evaluate 37 IVM fetuses and 37 control fetuses. The volume of gray and white matter in each fetal occipital gyrus was manually segmented and compared, and neurodevelopment was followed up and assessed in infancy and early childhood.

RESULT

Compared with the control group, the volume of gray matter in occipital lobe increased in the IVM group, and the incidence of neurodevelopmental delay increased.

CONCLUSION

We tested the hypothesis that prenatal diagnosis IVM represents a biological marker for development in fetal occipital lobe. Compared with the control group, the IVM group showed differences in occipital gray matter development and had a higher risk of neurodevelopmental delay.

Prenatal diagnosis and pregnancy outcomes in fetuses with ventriculomegaly

Objective

Genetic etiology plays a critical role in fetal ventriculomegaly (VM). However, the studies on chromosomal copy number variants (CNVs) in fetal VM are limited. This study aimed to investigate the chromosomal CNVs in fetuses with mild to moderate VM, and explore its genotype-phenotype correlation.

Methods

A total of 242 fetuses with mild to moderate VM detected by prenatal ultrasound were enrolled in our study from October 2018 to October 2022. All cases underwent chromosomal microarray analysis (CMA) and G-banding simultaneously. All VM cases were classified different subgroups according to the maternal age, severity, VM distribution and presence/absence of other ultrasound abnormalities. The pregnancy outcomes and health conditions after birth were followed up. We also performed a pooled analysis regarding likely pathogenic and pathogenic CNVs (LP/P CNVs) for VM.

Results

The detection rate of chromosomal abnormalities by karyotyping was 9.1% (22/242), whereas it was 16.5% (40/242) when CMA was conducted (P < 0.05). The total detection rate of chromosomal abnormalities by karyotyping and CMA was 21.1% (51/242). A 12.0% incremental yield of CMA over karyotyping was observed. The detection rate of total genetic variants in fetuses with bilateral VM was significantly higher than in fetuses with unilateral VM (30.0% vs. 16.7%, P = 0.017). No significant differences were discovered between isolated VM and non-isolated VM, or between mild and moderate VM, or between advanced maternal age (AMA) and non-AMA (all P > 0.05). 28 fetuses with VM were terminated and 214 fetuses were delivered: one presented developmental delay and one presented congenital heart disease. The VM cases with both positive CMA and karyotypic results had a higher rate of termination of pregnancy than those with either a positive CMA or karyotypic result, or both negative testing results (P < 0.001).

Conclusion

The combination of CMA and karyotyping should be adopted to improve the positive detection rate of chromosomal abnormalities for VM. The total genetic abnormalities detected using both techniques would affect the final pregnancy outcomes. LP/P CNVs at 16p11.2, 17p13, and 22q11.21 were identified as the top three chromosomal hotspots associated with VM, which would enable genetic counselors to provide more precise genetic counseling for VM pregnancies.

Fetal neuroimaging applications for diagnosis and counseling of brain anomalies: Current practice and future diagnostic strategies

Advances in fetal brain neuroimaging, especially fetal neurosonography and brain magnetic resonance imaging (MRI), allow safe and accurate anatomical assessments of fetal brain structures that serve as a foundation for prenatal diagnosis and counseling regarding fetal brain anomalies. Fetal neurosonography strategically assesses fetal brain anomalies suspected by screening ultrasound. Fetal brain MRI has unique technological features that overcome the anatomical limits of smaller fetal brain size and the unpredictable variable of intrauterine motion artifact. Recent studies of fetal brain MRI provide evidence of improved diagnostic and prognostic accuracy, beginning with prenatal diagnosis. Despite technological advances over the last several decades, the combined use of different qualitative structural biomarkers has limitations in providing an accurate prognosis. Quantitative analyses of fetal brain MRIs offer measurable imaging biomarkers that will more accurately associate with clinical outcomes. First-trimester ultrasound opens new opportunities for risk assessment and fetal brain anomaly diagnosis at the earliest time in pregnancy. This review includes a case vignette to illustrate how fetal brain MRI results interpreted by the fetal neurologist can improve diagnostic perspectives. The strength and limitations of conventional ultrasound and fetal brain MRI will be compared with recent research advances in quantitative methods to better correlate fetal neuroimaging biomarkers of neuropathology to predict functional childhood deficits. Discussion of these fetal sonogram and brain MRI advances will highlight the need for further interdisciplinary collaboration using complementary skills to continue improving clinical decision-making following precision medicine principles.

Atypical fetal brain development in fetuses with non-syndromic isolated musculoskeletal birth defects (niMSBDs)

Non-syndromic, isolated musculoskeletal birth defects (niMSBDs) are among the leading causes of pediatric hospitalization. However, little is known about brain development in niMSBDs. Our study aimed to characterize prenatal brain development in fetuses with niMSBDs and identify altered brain regions compared to controls. We retrospectively analyzed in vivo structural T2-weighted MRIs of 99 fetuses (48 controls and 51 niMSBDs cases). For each group (19-31 and >31 gestational weeks (GW)), we conducted repeated-measures regression analysis with relative regional volume (% brain hemisphere) as a dependent variable (adjusted for age, side, and interactions). Between 19 and 31GW, fetuses with niMSBDs had a significantly (P < 0.001) smaller relative volume of the intermediate zone (-22.9 ± 3.2%) and cerebellum (-16.1 ± 3.5%,) and a larger relative volume of proliferative zones (38.3 ± 7.2%), the ganglionic eminence (34.8 ± 7.3%), and the ventricles (35.8 ± 8.0%). Between 32 and 37 GW, compared to the controls, niMSBDs showed significantly smaller volumes of central regions (-9.1 ± 2.1%) and larger volumes of the cortical plate. Our results suggest there is altered brain development in fetuses with niMSBDs compared to controls (13.1 ± 4.2%). Further basic and translational neuroscience research is needed to better visualize these differences and to characterize the altered development in fetuses with specific niMSBDs.

White matter changes in fetal brains with ventriculomegaly

Introduction

Ventriculomegaly (VM) is a fetal brain malformation which may present independently (isolated form) or in association with different cerebral malformations, genetic syndromes or other pathologies (non-isolated form).

Methods

This paper aims to study the effect of ventriculomegaly on the internal tridimensional architecture of fetal brains by way of Klingler's dissection. Ventriculomegaly was diagnosed using fetal ultrasonography during pregnancy and subsequently confirmed by necropsy. Taking into consideration the diameter of the lateral ventricle (measured at the level of the atrium), the brains were divided into two groups: moderate ventriculomegaly (with atrial diameter between 13 and 15 mm) and severe ventriculomegaly (with atrial diameter above 15 mm).

Results and discussion

The results of each dissection were described and illustrated, then compared with age-matched reference brains. In the pathological brains, fascicles in direct contact with the enlarged ventricles were found to be thinner and displaced inferiorly, the opening of the uncinate fasciculus was wider, the fornix was no longer in contact with the corpus callosum and the convexity of the corpus callosum was inverted. We have studied the prevalence of neurodevelopmental delay in children born with ventriculomegaly in the literature and discovered that a normal developmental outcome was found in over 90% of the mild VM cases, approximately 75% of the moderate and 60% in severe VM, with the correlated neurological impairments ranging from attention deficits to psychiatric disorders.

BOUNTI: Brain vOlumetry and aUtomated parcellatioN for 3D feTal MRI

Fetal MRI is widely used for quantitative brain volumetry studies. However, currently, there is a lack of universally accepted protocols for fetal brain parcellation and segmentation. Published clinical studies tend to use different segmentation approaches that also reportedly require significant amounts of time-consuming manual refinement. In this work, we propose to address this challenge by developing a new robust deep learning-based fetal brain segmentation pipeline for 3D T2w motion corrected brain images. At first, we defined a new refined brain tissue parcellation protocol with 19 regions-of-interest using the new fetal brain MRI atlas from the Developing Human Connectome Project. This protocol design was based on evidence from histological brain atlases, clear visibility of the structures in individual subject 3D T2w images and the clinical relevance to quantitative studies. It was then used as a basis for developing an automated deep learning brain tissue parcellation pipeline trained on 360 fetal MRI datasets with different acquisition parameters using semi-supervised approach with manually refined labels propagated from the atlas. The pipeline demonstrated robust performance for different acquisition protocols and GA ranges. Analysis of tissue volumetry for 390 normal participants (21-38 weeks gestational age range), scanned with three different acquisition protocols, did not reveal significant differences for major structures in the growth charts. Only minor errors were present in < 15% of cases thus significantly reducing the need for manual refinement. In addition, quantitative comparison between 65 fetuses with ventriculomegaly and 60 normal control cases were in agreement with the findings reported in our earlier work based on manual segmentations. These preliminary results support the feasibility of the proposed atlas-based deep learning approach for large-scale volumetric analysis. The created fetal brain volumetry centiles and a docker with the proposed pipeline are publicly available online at https://hub.docker.com/r/fetalsvrtk/segmentation (tag brain_bounti_tissue).

Abnormal prenatal brain development in Chiari II malformation

Introduction

The Chiari II is a relatively common birth defect that is associated with open spinal abnormalities and is characterized by caudal migration of the posterior fossa contents through the foramen magnum. The pathophysiology of Chiari II is not entirely known, and the neurobiological substrate beyond posterior fossa findings remains unexplored. We aimed to identify brain regions altered in Chiari II fetuses between 17 and 26 GW.

Methods

We used in vivo structural T2-weighted MRIs of 31 fetuses (6 controls and 25 cases with Chiari II).

Results

The results of our study indicated altered development of diencephalon and proliferative zones (ventricular and subventricular zones) in fetuses with a Chiari II malformation compared to controls. Specifically, fetuses with Chiari II showed significantly smaller volumes of the diencephalon and significantly larger volumes of lateral ventricles and proliferative zones.

Discussion

We conclude that regional brain development should be taken into consideration when evaluating prenatal brain development in fetuses with Chiari II.

Characterisation of ASD traits among a cohort of children with isolated fetal ventriculomegaly

Fetal ventriculomegaly is the most common antenatally-diagnosed brain abnormality. Imaging studies in antenatal isolated ventriculomegaly demonstrate enlarged ventricles and cortical overgrowth which are also present in children with autism-spectrum disorder/condition (ASD). We investigate the presence of ASD traits in a cohort of children (n = 24 [20 males/4 females]) with isolated fetal ventriculomegaly, compared with 10 controls (n = 10 [6 males/4 females]). Neurodevelopmental outcome at school age included IQ, ASD traits (ADOS-2), sustained attention, neurological functioning, behaviour, executive function, sensory processing, co-ordination, and adaptive behaviours. Pre-school language development was assessed at 2 years. 37.5% of children, all male, in the ventriculomegaly cohort scored above threshold for autism/ASD classification. Pre-school language delay predicted an ADOS-2 autism/ASD classification with 73.3% specificity/66.7% sensitivity. Greater pre-school language delay was associated with more ASD symptoms. In this study, the neurodevelopment of children with isolated fetal ventriculomegaly, associated with altered cortical development, includes ASD traits, difficulties in sustained attention, working memory and sensation-seeking behaviours.

Concordance between US and MRI Two-Dimensional Measurement and Volumetric Segmentation in Fetal Ventriculomegaly

We provide a study comparison between two-dimensional measurement and volumetric (3D) segmentation of the lateral ventricles and brain structures in fetuses with isolated and non-isolated ventriculomegaly with 3D virtual organ computer-aided analysis (VOCAL) ultrasonography vs. magnetic resonance imaging (MRI) analyzed with 3D-Slicer software. In this cross-sectional study, 40 fetuses between 20 and 38 gestational weeks with various degrees of ventriculomegaly were included. A total of 71 ventricles were measured with ultrasound (US) and with MRI. A total of 64 sonographic ventricular volumes, 80 ventricular and 40 fetal brain MR volumes were segmented and analyzed using both imaging modalities by three observers. Sizes and volumes of the ventricles and brain parenchyma were independently analyzed by two radiologists, and interobserver correlation of the results with 3D fetal ultrasound data was performed. The semiautomated rotational multiplanar 3D VOCAL technique was performed for ultrasound volumetric measurements. Results were compared to manually extracted ventricular and total brain volumes in 3D-Slicer. Segmentation of fetal brain structures (cerebral and cerebellar hemispheres, brainstem, ventricles) performed independently by two radiologists showed high interobserver agreement. An excellent agreement between VOCAL and MRI volumetric and two-dimensional measurements was established, taking into account the intraclass correlation coefficients (ICC), and a Bland-Altman plot was established. US and MRI are valuable tools for performing fetal brain and ventricular volumetry for clinical prognosis and patient counseling. Our datasets could provide the backbone for further construction of quantitative normative trajectories of fetal intracranial structures and support earlier detection of abnormal brain development and ventriculomegaly, its timing and progression during gestation.

Comprehensive quantitative analyses of fetal magnetic resonance imaging in isolated cerebral ventriculomegaly

Isolated cerebral ventriculomegaly (IVM) is the most common prenatally diagnosed brain anomaly occurs in 0.2-1 % of pregnancies. However, knowledge of fetal brain development in IVM is limited. There is no prenatal predictor for IVM to estimate individual risk of neurodevelopmental disability occurs in 10 % of children. To characterize brain development in fetuses with IVM and delineate their individual neuroanatomical variances, we performed comprehensive post-acquisition quantitative analysis of fetal magnetic resonance imaging (MRI). In volumetric analysis, brain MRI of fetuses with IVM (n = 20, 27.0 ± 4.6 weeks of gestation, mean ± SD) had revealed significantly increased volume in the whole brain, cortical plate, subcortical parenchyma, and cerebrum compared to the typically developing fetuses (controls, n = 28, 26.3 ± 5.0). In the cerebral sulcal developmental pattern analysis, fetuses with IVM had altered sulcal positional (both hemispheres) development and combined features of sulcal positional, depth, basin area, in both hemispheres compared to the controls. When comparing distribution of similarity index of individual fetuses, IVM group had shifted toward to lower values compared to the control. About 30 % of fetuses with IVM had no overlap with the distribution of control fetuses. This proof-of-concept study shows that quantitative analysis of fetal MRI can detect emerging subtle neuroanatomical abnormalities in fetuses with IVM and their individual variations.

Abnormal development of transient fetal zones in mild isolated fetal ventriculomegaly

Mild isolated fetal ventriculomegaly (iFVM) is the most common abnormality of the fetal central nervous system. It is characterized by enlargement of one or both of the lateral ventricles (defined as ventricular width greater than 10 mm, but less than 12 mm). Despite its high prevalence, the pathophysiology of iFVM during fetal brain development and the neurobiological substrate beyond ventricular enlargement remain unexplored. In this work, we aimed to establish the relationships between the structural development of transient fetal brain zones/compartments and increased cerebrospinal fluid volume. For this purpose, we used in vivo structural T2-weighted magnetic resonance imaging of 89 fetuses (48 controls and 41 cases with iFVM). Our results indicate abnormal development of transient zones/compartments belonging to both hemispheres (i.e. on the side with and also on the contralateral side without a dilated ventricle) in fetuses with iFVM. Specifically, compared to controls, we observed enlargement of proliferative zones and overgrowth of the cortical plate in iFVM with associated reduction of volumes of central structures, subplate, and fetal white matter. These results indicate that enlarged lateral ventricles might be linked to the development of transient fetal zones and that global brain development should be taken into consideration when evaluating iFVM.

Short-Term and Long-Term Outcomes of Fetal Ventriculomegaly beyond Gestational 37 Weeks: A Retrospective Cohort Study

Birth defects have brought about major public health problems, and studying the clinical outcomes of the most common prenatal central nervous system abnormality, namely, fetal ventriculomegaly (VM), is helpful for improving reproductive health and fertility quality. This is a retrospective cohort study from 2011 to 2020 in the West China Second University Hospital, Sichuan University, aiming to evaluate the short-term and long-term outcomes of VM over 37 weeks' gestation to exclude the influence of preterm birth. The study analyzed data from 401 term pregnancies, with 179 VM and 222 controls. From the short-term outcomes, the rate of the neonatal intensive care unit (NICU) admission under the VM group (10.06%) was comparatively higher than the control (0.45%), but Apgar scores between both groups at 1 min, 5 min and 10 min were not significantly different. From the long-term outcomes, there were more infants with abnormal neurodevelopment under the VM group than control (14.53% vs. 2.25%, p < 0.001). In addition, NICU admission (p = 0.006), peak width of lateral ventricles (p = 0.030) and postnatal cranial ultrasound suggestive with VM (p = 0.002) were related to infants' long-term outcomes. NICU admission during the perinatal period was an independent risk factor for the adverse long-term outcomes (OR = 3.561, 95% CI 1.029-12.320, p = 0.045). In conclusion, VM impairs short-term and long-term outcomes of term infants. Short-term outcome, especially NICU admission, could predict their adverse long-term outcomes.

Retrospective motion correction in foetal MRI for clinical applications: existing methods, applications and integration into clinical practice

Foetal MRI is a complementary imaging method to antenatal ultrasound. It provides advanced information for detection and characterisation of foetal brain and body anomalies. Even though modern single shot sequences allow fast acquisition of 2D slices with high in-plane image quality, foetal MRI is intrinsically corrupted by motion. Foetal motion leads to loss of structural continuity and corrupted 3D volumetric information in stacks of slices. Furthermore, the arbitrary and constantly changing position of the foetus requires dynamic readjustment of acquisition planes during scanning.

Regional brain development in fetuses with Dandy-Walker malformation: A volumetric fetal brain magnetic resonance imaging study

Dandy-Walker malformation (DWM) is a common prenatally diagnosed cerebellar malformation, characterized by cystic dilatation of the fourth ventricle, upward rotation of the hypoplastic vermis, and posterior fossa enlargement with torcular elevation. DWM is associated with a broad spectrum of neurodevelopmental abnormalities such as cognitive, motor, and behavioral impairments, which cannot be explained solely by cerebellar malformations. Notably, the pathogenesis of these symptoms remains poorly understood. This study investigated whether fetal structural developmental abnormalities in DWM extended beyond the posterior fossa to the cerebrum even in fetuses without apparent cerebral anomalies. Post-acquisition volumetric fetal magnetic resonance imaging (MRI) analysis was performed in 12 fetuses with DWM and 14 control fetuses. Growth trajectories of the volumes of the cortical plate, subcortical parenchyma, cerebellar hemispheres, and vermis between 18 and 33 weeks of gestation were compared. The median (interquartile range) gestational ages at the time of MRI were 22.4 (19.4–24.0) and 23.9 (20.6–29.2) weeks in the DWM and control groups, respectively (p = 0.269). Eight of the 12 fetuses with DWM presented with associated cerebral anomalies, including hydrocephalus (n = 3), cerebral ventriculomegaly (n = 3), and complete (n = 2) and partial (n = 2) agenesis of the corpus callosum (ACC); 7 presented with extracerebral abnormalities. Chromosomal abnormalities were detected by microarray analysis in 4 of 11 fetuses with DWM, using amniocentesis. Volumetric analysis revealed that the cortical plate was significantly larger in fetuses with DWM than in controls (p = 0.040). Even without ACC, the subcortical parenchyma, whole cerebrum, cerebellar hemispheres, and whole brain were significantly larger in fetuses with DWM (n = 8) than in controls (p = 0.004, 0.025, 0.033, and 0.026, respectively). In conclusion, volumetric fetal MRI analysis demonstrated that the development of DWM extends throughout the brain during the fetal period, even without apparent cerebral anomalies.

Optimal Method for Fetal Brain Age Prediction Using Multiplanar Slices From Structural Magnetic Resonance Imaging

The accurate prediction of fetal brain age using magnetic resonance imaging (MRI) may contribute to the identification of brain abnormalities and the risk of adverse developmental outcomes. This study aimed to propose a method for predicting fetal brain age using MRIs from 220 healthy fetuses between 15.9 and 38.7 weeks of gestational age (GA). We built a 2D single-channel convolutional neural network (CNN) with multiplanar MRI slices in different orthogonal planes without correction for interslice motion. In each fetus, multiple age predictions from different slices were generated, and the brain age was obtained using the mode that determined the most frequent value among the multiple predictions from the 2D single-channel CNN. We obtained a mean absolute error (MAE) of 0.125 weeks (0.875 days) between the GA and brain age across the fetuses. The use of multiplanar slices achieved significantly lower prediction error and its variance than the use of a single slice and a single MRI stack. Our 2D single-channel CNN with multiplanar slices yielded a significantly lower stack-wise MAE (0.304 weeks) than the 2D multi-channel (MAE = 0.979, p < 0.001) and 3D (MAE = 1.114, p < 0.001) CNNs. The saliency maps from our method indicated that the anatomical information describing the cortex and ventricles was the primary contributor to brain age prediction. With the application of the proposed method to external MRIs from 21 healthy fetuses, we obtained an MAE of 0.508 weeks. Based on the external MRIs, we found that the stack-wise MAE of the 2D single-channel CNN (0.743 weeks) was significantly lower than those of the 2D multi-channel (1.466 weeks, p < 0.001) and 3D (1.241 weeks, p < 0.001) CNNs. These results demonstrate that our method with multiplanar slices accurately predicts fetal brain age without the need for increased dimensionality or complex MRI preprocessing steps.

Is fetal MRI ready for neuroimaging prime time? An examination of progress and remaining areas for development

A major challenge in designing large-scale, multi-site studies is developing a core, scalable protocol that retains the innovation of scientific advances while also lending itself to the variability in experience and resources across sites. In the development of a common Healthy Brain and Child Development (HBCD) protocol, one of the chief questions is "is fetal MRI ready for prime-time?" While there is agreement about the value of prenatal data obtained non-invasively through MRI, questions about practicality abound. There has been rapid progress over the past years in fetal and placental MRI methodology but there is uncertainty about whether the gains afforded outweigh the challenges in supporting fetal MRI protocols at scale. Here, we will define challenges inherent in building a common protocol across sites with variable expertise and will propose a tentative framework for evaluation of design decisions. We will compare and contrast various design considerations for both normative and high-risk populations, in the setting of the post-COVID era. We will conclude with articulation of the benefits of overcoming these challenges and would lend to the primary questions articulated in the HBCD initiative.

Early magnetic resonance imaging biomarkers of schizophrenia spectrum disorders: Toward a fetal imaging perspective

There is mounting evidence to implicate the intrauterine environment as the initial pathogenic stage for neuropsychiatric disease. Recent developments in magnetic resonance imaging technology are making a multimodal analysis of the fetal central nervous system a reality, allowing analysis of structural and functional parameters. Exposures to a range of pertinent risk factors whether preconception or in utero can now be indexed using imaging techniques within the fetus' physiological environment. This approach may determine the first "hit" required for diseases that do not become clinically manifest until adulthood, and which only have subtle clinical markers during childhood and adolescence. A robust characterization of a "multi-hit" hypothesis may necessitate a longitudinal birth cohort; within this investigative paradigm, the full range of genetic and environmental risk factors can be assessed for their impact on the early developing brain. This will lay the foundation for the identification of novel biomarkers and the ability to devise methods for early risk stratification and disease prevention. However, these early markers must be followed over time: first, to account for neural plasticity, and second, to assess the effects of postnatal exposures that continue to drive the individual toward disease. We explore these issues using the schizophrenia spectrum disorders as an illustrative paradigm. However, given the potential richness of fetal magnetic resonance imaging, and the likely overlap of biomarkers, these concepts may extend to a range of neuropsychiatric conditions.

Estimating cerebral venous oxygenation in human fetuses with ventriculomegaly using quantitative susceptibility mapping

RATIONALE AND OBJECTIVES

The goal of this study was to estimate venous blood oxygen saturation (SvO2) in the superior sagittal sinus (SSS) in fetal brains with ventriculomegaly (VM) using quantitative susceptibility mapping (QSM).

MATERIALS AND METHODS

A radiofrequency spoiled gradient echo sequence was used to evaluate data on 19 fetuses with VM (gestational age(GA): median = 29.9 weeks (range 23 to 37.3 weeks)) and 20 healthy fetuses (GA: median = 30.9 (range 22.7 to 38.7 weeks)) at 1.5 T. Susceptibility weighted images encompassing the entire fetal brain were acquired within 1 min. An iterative, geometry constraint-based thresholded k-space division algorithm was used for generating QSM data of the fetal brain. The venous oxygen saturation was calculated using the magnetic susceptibility of the SSS obtained from the QSM data. Mixed-model analysis of variance and interobserver variability assessment were used to analyze the results.

RESULTS

The median SvO2 values in the entire VM cohort as well as for second and third trimester fetuses (with interquartile range) were: 67.8% (63.2%, 73.6%), 73.1% (69.1%, 77.3%) and 63.8% (59.4%, 68.1%), respectively. The corresponding median SvO2 value in the healthy control group was: 65.3% (58.3%, 68.2%), 67.5% (61.7%, 69.2%) and 60.8% (53.6%, 68.2%), respectively. However, the difference of SvO2 between VM and control groups was not significant at the p = 0.05 level (p = 0.076). The SvO2 was found decreasing significantly with GA in the healthy control group (p < 0.05).

CONCLUSIONS

We report for the first time the estimation of cerebral SvO2 in human fetuses with VM using QSM. This measure of oxygen saturation might be beneficial in assessing and monitoring the metabolic status of the fetus in various clinical conditions.

Detection of copy number variation associated with ventriculomegaly in fetuses using single nucleotide polymorphism arrays

Etiopathogenesis of fetal ventriculomegaly is poorly understood. Associations between fetal isolated ventriculomegaly and copy number variations (CNVs) have been previously described. We investigated the correlations between fetal ventriculomegaly-with or without other ultrasound anomalies-and chromosome abnormalities. 222 fetuses were divided into four groups: (I) 103 (46.4%) cases with isolated ventriculomegaly, (II) 41 (18.5%) cases accompanied by soft markers, (III) 33 (14.9%) cases complicated with central nervous system (CNS) anomalies, and (IV) 45 (20.3%) cases with accompanying anomalies. Karyotyping and single nucleotide polymorphism (SNP) array were used in parallel. Karyotype abnormalities were identified in 15/222 (6.8%) cases. Karyotype abnormalities in group I, II, III, and IV were 4/103 (3.9%), 2/41 (4.9%), 4/33 (12.1%), and 5/45 (11.1%), respectively. Concerning the SNP array analysis results, 31/222 (14.0%) were CNVs, CNVs in groups I, II, III, and IV were 11/103 (10.7%), 6/41 (14.6%), 9/33 (27.3%), and 5/45 fetuses (11.1%), respectively. Detections of clinical significant CNVs were higher in non-isolated ventriculomegaly than in isolated ventriculomegaly (16.81% vs 10.7%, P = 0.19). SNP arrays can effectively identify CNVs in fetuses with ventriculomegaly and increase the abnormal chromosomal detection rate by approximately 7.2%, especially ventriculomegaly accompanied by CNS anomalies.

Imaging of fetal ventriculomegaly

Fetal ventriculomegaly is the most common central nervous system abnormality detected by prenatal imaging. It has a high association with other anomalies. Etiologies and prognoses for fetal ventriculomegaly range from normal outcomes to significant neurodevelopmental sequelae. In this paper, we review the development, terminology, pathogenesis, imaging and prognosis of fetal ventriculomegaly.

Normative linear and volumetric biometric measurements of fetal brain development in magnetic resonance imaging

PURPOSE

To provide normative two-dimensional and three-dimensional measurements of brain development in normal fetuses during the second and third trimester by a new semi-automated method.

METHODS

In this retrospective study, we included 98 normal fetuses at our institution between 21 and 38 weeks of gestation. Two-dimensional measurements of the brain were including biparietal diameter, occipitofrontal diameter, head circumference, transverse cerebellar diameter, and atrial diameter. Volumetric parameters were obtained by using ITK-SNAP software, including left and right cerebral hemispheres, lateral ventricle, the cerebellum, and extracerebral cerebrospinal fluid.

RESULTS

All linear and volume measurements were positively correlated with gestational age except for cerebrospinal fluid. Each anatomical region of the fetal brain showed a different relative growth rate. There was some volume asymmetry between the left and right lateral ventricles, and the left side was larger. The inter-observer and intra-observer agreement was excellent for all measures.

CONCLUSION

We established the 5th, 50th, and 95th percentile values of fetal brain volume measurements in magnetic resonance, and this may be helpful to understand the damage of fetal brain development.

Lateral ventricular volume and calcarine sulcus depth: a fetal MRI analysis of mild ventriculomegaly: A STROBE compliant article

The aim of this study was to quantify changes in the lateral ventricular volume, the depth of the calcarine sulcus (CS), and apparent diffusion coefficient (ADC) values of occipital lobe in fetuses with isolated mild ventriculomegaly (IMVM) using MRI.Seventy-one fetuses with IMVM at 25 to 38 weeks gestational age (GA) and 58 fetuses with normal lateral ventricles at 25 to 38 weeks GA were enrolled. Volumes of the lateral ventricles were measured by 3D magnetic resonance hydrography. Depths of the CS and ADC values were also evaluated. All differences were tested by t test. Bivariate correlations were performed using Pearson method.Fetuses with IMVM had significantly larger lateral ventricular volumes and smaller CS depths than controls (volumes: 9.37 ± 2.20 mL vs 5.04 ± 1.33 mL, respectively, P < .001; depths: 8.27 ± 2.55 mm vs 10.30 ± 3.14 mm, respectively, P < .001). In IMVM cases, the CS depths were smaller on the side with the larger ventricle (8.10 ± 2.54 mm vs 9.59 ± 2.81 mm, P < .001). No differences were observed in occipital lobe ADC values between the2 groups (IMVM = 1.80 ± 0.24 μm/ms; controls = 1.78 ± 0.28 μm/ms, P > .05).Fetuses with IMVM had larger lateral ventricular volumes, shallower CS depths, but normal occipital lobe ADC values.

Global and Regional Changes in Cortical Development Assessed by MRI in Fetuses with Isolated Nonsevere Ventriculomegaly Correlate with Neonatal Neurobehavior

BACKGROUND AND PURPOSE

Fetuses with isolated nonsevere ventriculomegaly (INSVM) are at risk of presenting neurodevelopmental delay. However, the currently used clinical parameters are insufficient to select cases with high risk and determine whether subtle changes in brain development are present and might be a risk factor. The aim of this study was to perform a comprehensive evaluation of cortical development in INSVM by magnetic resonance (MR) imaging and assess its association with neonatal neurobehavior.

MATERIALS AND METHODS

Thirty-two INSVM fetuses and 29 healthy controls between 26-28 weeks of gestation were evaluated using MR imaging. We compared sulci and fissure depth, cortical maturation grading of specific areas and sulci and volumes of different brain regions obtained from 3D brain reconstruction of cases and controls. Neonatal outcome was assessed by using the Neonatal Behavioral Assessment Scale at a mean of 4 ± 2 weeks after birth.

RESULTS

Fetuses with INSVM showed less profound and underdeveloped sulcation, including the Sylvian fissure (mean depth: controls 16.8 ± 1.9 mm, versus INSVM 16.0 ± 1.6 mm; P = .01), and reduced global cortical grading (mean score: controls 42.9 ± 10.2 mm, versus INSVM: 37.8 ± 9.9 mm; P = .01). Fetuses with isolated nonsevere ventriculomegaly showed a mean global increase of gray matter volume (controls, 276.8 ± 46.0 ×10 mm³, versus INSVM 277.5 ± 49.3 ×10 mm³, P = .01), but decreased mean cortical volume in the frontal lobe (left: controls, 53.2 ± 8.8 ×10 mm³, versus INSVM 52.4 ± 5.4 ×10 mm³; P = < .01). Sulcal depth and brain volumes were significantly associated with the Neonatal Behavioral Assessment Scale severity (P = .005, Nagelkerke R² = 0.732).

CONCLUSIONS

INSVM fetuses showed differences in cortical development, including regions far from the lateral ventricles, that are associated with neonatal neurobehavior. These results suggest the possible use of these parameters to identify cases at higher risk of altered neurodevelopment.

A novel approach to multiple anatomical shape analysis: Application to fetal ventriculomegaly

Fetal ventriculomegaly (VM) is a condition in which one or both lateral ventricles are enlarged, and is diagnosed as an atrial diameter larger than 10 mm. Evidence of altered cortical folding associated with VM has been shown in the literature. However, existing works use a single scalar value such as diagnosis or lateral ventricular volume to characterize VM and study its relationship with alterations in cortical folding, thus failing to reveal the spatially-heterogeneous associations. In this work, we propose a novel approach to identify fine-grained associations between cortical folding and ventricular enlargement by leveraging the vertex-wise correlations between their growth patterns in terms of area expansion and curvature. Our approach comprises three steps. In the first step, we define a joint graph Laplacian matrix using cortex-to-ventricle correlations. The joint Laplacian is built based on multiple cortical features. Next, we propose a spectral embedding of the cortex-to-ventricle graph into a common underlying space where its nodes are projected according to the joint ventricle-cortex growth patterns. In this low-dimensional joint ventricle-cortex space, associated growth patterns lie close to each other. In the final step, we perform hierarchical clustering in the joint embedded space to identify associated sub-regions between cortex and ventricle. Using a dataset of 25 healthy fetuses and 23 fetuses with isolated non-severe VM within the age range of 26-29 gestational weeks, our approach reveals clinically relevant and heterogeneous regional associations. Cortical regions forming these associations are further validated using statistical analysis, revealing regions with altered folding that are significantly associated with ventricular dilation.

Altered local cerebellar and brainstem development in preterm infants

BACKGROUND

Premature birth is associated with high prevalence of neurodevelopmental impairments in surviving infants. The putative role of cerebellar and brainstem dysfunction remains poorly understood, particularly in the absence of overt structural injury.

METHOD

We compared in-utero versus ex-utero global, regional and local cerebellar and brainstem development in healthy fetuses (n ​= ​38) and prematurely born infants without evidence of structural brain injury on conventional MRI studies (n ​= ​74) that were performed at two time points: the first corresponding to the third trimester, either in utero or ex utero in the early postnatal period following preterm birth (30-40 weeks of gestation; 38 control fetuses; 52 premature infants) and the second at term equivalent age (37-46 weeks; 38 control infants; 58 premature infants). We compared 1) volumetric growth of 7 regions in the cerebellum (left and right hemispheres, left and right dentate nuclei, and the anterior, neo, and posterior vermis); 2) volumetric growth of 3 brainstem regions (midbrain, pons, and medulla); and 3) shape development in the cerebellum and brainstem using spherical harmonic description between the two groups.

RESULTS

Both premature and control groups showed regional cerebellar differences in growth rates, with the left and right cerebellar hemispheres showing faster growth compared to the vermis. In the brainstem, the pons grew faster than the midbrain and medulla in both prematurely born infants and controls. Using shape analyses, premature infants had smaller left and right cerebellar hemispheres but larger regional vermis and paravermis compared to in-utero control fetuses. For the brainstem, premature infants showed impaired growth of the superior surface of the midbrain, anterior surface of the pons, and inferior aspects of the medulla compared to the control fetuses. At term-equivalent age, premature infants had smaller cerebellar hemispheres bilaterally, extending to the superior aspect of the left cerebellar hemisphere, and larger anterior vermis and posteroinferior cerebellar lobes than healthy newborns. For the brainstem, large differences between premature infants and healthy newborns were found in the anterior surface of the pons.

CONCLUSION

This study analyzed both volumetric growth and shape development of the cerebellum and brainstem in premature infants compared to healthy fetuses using longitudinal MRI measurements. The findings in the present study suggested that preterm birth may alter global, regional and local development of the cerebellum and brainstem even in the absence of structural brain injury evident on conventional MRI.

Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly

OBJECTIVES

To systematically investigate chromosomal abnormalities and copy number variants (CNVs) in fetuses with different types of ventriculomegaly (VM) by karyotyping and/or chromosomal microarray analysis (CMA).

METHODS

This retrospective study included 312 fetuses diagnosed with VM. Amniotic fluid and umbilical blood samples were collected by amniocentesis and cordocentesis, respectively, and subjected to karyotyping and/or CMA. Subgroup analysis by VM type, including mild VM (MVM) and severe VM (SVM), unilateral and bilateral VM, isolated VM (IVM), and non-isolated VM (NIVM), was performed.

RESULTS

The detection rate of chromosomal abnormalities was 12.1% (34/281) by karyotyping and 20.6% when CMA was additionally performed (P < 0.05). Abnormalities were identified by CMA in 17.4% (38/218) of fetuses and pathogenic CNVs in 5.0% (11/218). Notably, CMA detected CNVs in 10.6% (23/218) of fetuses with normal karyotypes. The incidence of chromosomal abnormalities by karyotyping was higher in bilateral than in unilateral VM (20.5% versus 6.5%), whereas the incidence detected by CMA was higher in NIVM than in IVM (21.4% versus 10.3%; both P < 0.05). In NIVM, CMA provided an additional detection rate of 11.4% (16/140) and a detection rate of 10.0% for pathogenic CNVs and aneuploidies. Central nervous system (CNS) abnormalities were the most common other ultrasonic abnormalities.

CONCLUSIONS

CMA is highly recommended for prenatal diagnosis of fetal VM together with karyotyping, especially in fetuses with bilateral VM and NIVM with abnormal CNS findings. Further study is necessary to explore the relationships between genotypes and phenotypes to facilitate prenatal diagnosis of fetal VM.

Prognosis of fetuses with ventriculomegaly: An observational retrospective study

OBJECTIVE

To investigate the prognosis of fetuses with ventriculomegaly (VM).

METHODS

Clinical data were collected from 234 cases of fetal VM diagnosed by ultrasound between March 2010 and July 2016. VM progression was monitored, and karyotyping and infection screening performed. Magnetic resonance imaging (MRI) was performed where increasing ventricular diameter was noted. Neonatal behavioral neurological assessment (NBNA) was carried out after birth, and Bayley Scales of Infant Development assessment at 6 months.

RESULTS

The in utero outcomes of Group A were better than Group B in 173 pregnancies. Isolated VM (IVM) was associated with better prognosis than nonisolated VM (NIVM); the regression rates were 74.6% (59/79) and 52.1% (49/94), respectively (χ² = 10.222, .006). The NBNA scores were significantly higher in Group A than Group B (χ² = 4.231, .004), but not significantly different between IVM and NIVM. The composition ratios of both the psychomotor and mental developmental index (PDI and MDI) scores were not significantly different between Groups A and B (Z = 1.869, .062 and Z = 0.826, .409, respectively). Significant differences in in utero outcomes were observed between IVM and NIVM cases in Groups A and B.

CONCLUSIONS

Fetal VM prognosis is affected by the width of ventricle, chromosome abnormalities, coexisted abnormalities, and in utero progression.

Volume growth trend and correlation of atrial diameter with lateral ventricular volume in normal fetus and fetus with ventriculomegaly: A STROBE compliant article

To explore the growth trend of fetal lateral ventricular volume, for understanding the relationship between atrial diameter (AD) and volume in normal fetus and fetus with ventriculomegaly.Overall, 97 sequential fetal head magnetic resonance imaging scans were performed; these pertained to 50 fetuses with normal lateral ventricles [normal group; gestational age (GA): 24-38 weeks] and 47 fetuses with ventriculomegaly (VM) (VM group; GA: 24-37 weeks). The left, right, and total lateral ventricular volume were measured using 3-dimensional magnetic resonance hydrography (MRH). Correlation coefficient (r) was calculated to assess the relationships of measurements. Lineal regression analysis was used to assess correlation of AD and GA with volume. Between-group differences in terms of AD and volume were assessed using t test.Significant linear growth was observed in the total lateral ventricular volume compared with GA in the normal group with a relative growth rate of 2.87% per week (P <.001). Significant linear relationship between AD and volume was observed, and a significant equation was acquired in the normal group and VM groups, respectively, using the simple linear regression model: left volume = 0.438 * normal left diameter (NLD) + 1.359; right volume = 0.493 * normal right diameter (NRD) + 1.012; left volume = 0.959 * left diameter in VM (VLD) - 2.074; right volume = 0.799 * right diameter in VM (VRD) - 0.443. A significant equation was obtained in the normal group and the VM group, using the multiple linear regression model: Total volume (mL) = 0.396 * NLD + 0.410 * NRD + 3.101; and total volume = 0.989 * VLD + 0.834 * VRD - 3.141, respectively. In terms of AD and volume, the left lateral ventricle was significantly larger than the right side in both groups. The volume of lateral ventricle in AD ≥10 mm group was larger than that in the AD <10 mm group. The total volume in the VM group was significantly larger than that in the normal group.The total lateral ventricular volume increased with GA. AD can be used to evaluate the fetal ventricular volume.

Morphologic Evolution and Coordinated Development of the Fetal Lateral Ventricles in the Second and Third Trimesters

BACKGROUND AND PURPOSE

Few investigators have studied the lateral ventricle formation related to the development of the calcarine sulcus. Our purpose was to establish the relationship between the lateral ventricles and the calcarine sulcus in the second and third trimesters.

MATERIALS AND METHODS

Fetal brain MR imaging (3T and 7T) was performed in 84 fetuses at 14-35 gestational weeks. The lateral ventricles and calcarine sulcus were 3D-reconstructed, and quantitative measurements were obtained.

RESULTS

The lateral ventricle volume decreases slowly at 14-23 gestational weeks and then increases rapidly at 24-35 gestational weeks. The depth and length of the calcarine sulcus develop with the increase in gestational weeks, leading to be squeezed in the lateral ventricle posterior horn. A linear correlation occurs between the calcarine sulcus length and posterior horn length: Right-length = 2.4204 (L_PH) - 27.5706, Left-length = 2.0939 (L_PH) - 23.4099.

CONCLUSIONS

The variation of lateral ventricle volume evolved from a slow to rapid increase at 14-35 gestational weeks. The shrinkage in the lateral ventricle posterior horn is accompanied by the development of the calcarine sulcus, resulting in a better linear correlation between the calcarine sulcus length and the posterior horn length. The present results are valuable in elucidating the evolution of lateral ventricle development and provide clues for the diagnosis of lateral ventricle abnormalities in the prenatal examination.

Altered cortical development in fetuses with isolated nonsevere ventriculomegaly assessed by neurosonography

OBJECTIVES

To perform a comprehensive assessment of cortical development in fetuses with isolated nonsevere ventriculomegaly (INSVM) by neurosonography.

METHODS

We prospectively included 40 fetuses with INSVM and 40 controls. INSVM was defined as atrial width between 10.0 and 14.9 mm without associated malformation, infection, or chromosomal abnormality. Cortical development was assessed by neurosonography at 26 and 30 weeks of gestation measuring depth of selected sulci and applying a maturation scale from 0 (no appearance) to 5 (maximally developed) of main sulci and areas.

RESULTS

INSVM showed underdeveloped calcarine and parieto-occipital sulci. In addition, significant delayed maturation pattern was also observed in regions distant to ventricular system including Insula depth (controls 30.8 mm [SD 1.7] vs INSVM 31.7 mm [1.8]; P = .04), Sylvian fissure grading (>2 at 26 weeks: controls 87.5% vs INSVM 50%, P = .01), mesial area grading (>2 at 30 weeks: controls 95% vs INSVM 62.5%; P = .03), and cingulate sulcus grading (>2 at 30 weeks: controls 100% vs INSVM 80.5%; P = .01).

CONCLUSIONS

Fetuses with INSVM showed underdeveloped cortical maturation including also regions, where effect of ventricular dilatation is unlikely. These results suggest that in a proportion of fetuses with INSVM, ventricular dilation might be related with altered cortical architecture.

Fetal and neonatal neuroimaging

Magnetic resonance imaging (MRI) can provide detail of the soft tissues of the fetal and neonatal brain that cannot be obtained by any other imaging modality. Conventional T1 and T2 weighted sequences provide anatomic detail of the normally developing brain and can demonstrate lesions, including those associated with preterm birth, hypoxic ischemic encephalopathy, perinatal arterial stroke, infections, and congenital malformations. Specialized imaging techniques can be used to assess cerebral vasculature (magnetic resonance angiography and venography), cerebral metabolism (magnetic resonance spectroscopy), cerebral perfusion (arterial spin labeling), and function (functional MRI). A wealth of quantitative tools, most of which were originally developed for the adult brain, can be applied to study the developing brain in utero and postnatally including measures of tissue microstructure obtained from diffusion MRI, morphometric studies to measure whole brain and regional tissue volumes, and automated approaches to study cortical folding. In this chapter, we aim to describe different imaging approaches for the fetal and neonatal brain, and to discuss their use in a range of clinical applications.

Early extra-uterine exposure alters regional cerebellar growth in infants born preterm

Objectives

To compare third trimester global and regional cerebellar volumetric growth at two time-points between very preterm (PT) infants and healthy gestational age-matched fetuses in the PT period and at term equivalent age (TEA).

Study design

Using a prospective study design, high resolution anatomic magnetic resonance images (MRI) were acquired in PT infants (gestational age at birth < 32 weeks; birthweight < 1500 g) without cerebellar injury and healthy full-term controls. PT infants completed two MRIs, one as soon as medically stable and the other around TEA. Controls also completed two MRIs, one in utero (i.e. fetal MRI) and a postnatal MRI shortly after birth. The cerebellum of each participant was parcellated into 5 regions: left and right hemispheres, the anterior, neo and posterior vermis. Evidence of differences in regional volumes between term and pre-term infants matched for gestational age (GA) at the time of the first MRI were assessed using multiple linear regression.

Results: we studied 76 subjects

38 PT infants were matched to 38 healthy fetuses. At MRI-1, PT infants demonstrated decreased cerebellar hemispheric volumes and increased anterior, neo- and posterior vermian regional volumes when compared to healthy fetuses. At TEA, PT infants demonstrated a persistent increase in anterior, neo- and posterior vermian regional volumes but no longer showed reductions in cerebellar hemispheric volume. Only the neovermis volume demonstrated a significant negative association with birthweight, male gender and supratentorial injury.

Conclusions

In the absence of demonstrable cerebellar parenchymal injury evident on conventional MRI, PT birth is associated with cerebellar growth alterations that are regionally- and temporally-specific.

•

Regional cerebellar growth is altered in preterm infants versus control fetuses.

•

Cerebellar hemispheric volume in preterm infants is similar to term controls.

•

Vermis volume is larger in preterm infants in the third trimester versus controls.

Mild ventriculomegaly from fetal consultation to neurodevelopmental assessment: A single center experience and review of the literature

OBJECTIVE

The aim of our study was to determine the outcome of fetuses with isolated mild ventriculomegaly, with prenatal imaging work-up, prenatal consultation, delivery and clinical follow-up performed in a single tertiary referring center.

METHODS

Fetuses with isolated and non-progressive mild ventriculomegaly (10-15 mm) were included in the study. Inclusion criteria were as follows: singleton pregnancies, normal chromosomal analysis, normal serological evaluation of TORCH, fetal ultrasound and MRI excluding additional CNS or extra-CNS malformations. The prenatal consultation consisted in discussing the prognosis of ventriculomegaly, according to the literature. The postnatal follow-up protocol included a neuroradiological investigation (cranial ultrasound or MRI), neurological and pediatric examinations. The Griffiths Scales were used to assess the neurodevelopmental outcome.

RESULTS

Thirty newborns were included in follow-up. The postnatal neuroradiological investigations confirmed the ventriculomegaly as an isolated finding in all cases except one. Nineteen children were available for formal neurodevelopmental testing. In our case series, 93.3% of the children had a favorable outcome or mild anomalies. Two children (6.6%) with mild ventriculomegaly were diagnosed as having rare genetic conditions. The Griffiths developmental quotients were normal (mean General Quotient 98.3) at the latest assessment (mean age 20.8 months) in all but one case.

DISCUSSION

Most children in our case series had a favorable outcome, as described in the literature. Even though a large quantity of data is now available on ventriculomegaly, fetal consultation remains challenging and requires caution. The diagnostic work-up of pregnancies diagnosed with mild ventriculomegaly must be very meticulous and include TORCH evaluation, microarray, serial ultrasounds to exclude progression, and a fetal MRI. However, despite accurate screening, there are more complex conditions in which ventriculomegaly can be the only non-specific finding in fetal life, making postnatal follow up mandatory.

Revealing Regional Associations of Cortical Folding Alterations with In Utero Ventricular Dilation Using Joint Spectral Embedding

Fetal ventriculomegaly (VM) is a condition with dilation of one or both lateral ventricles, and is diagnosed as an atrial diameter larger than 10 mm. Evidence of altered cortical folding associated with VM has been shown in the literature. However, existing studies use a holistic approach (i.e., ventricle as a whole) based on diagnosis or ventricular volume, thus failing to reveal the spatially-heterogeneous association patterns between cortex and ventricle. To address this issue, we develop a novel method to identify spatially fine-scaled association maps between cortical development and VM by leveraging vertex-wise correlations between the growth patterns of both ventricular and cortical surfaces in terms of area expansion and curvature information. Our approach comprises multiple steps. In the first step, we define a joint graph Laplacian matrix using cortex-to-ventricle correlations. Next, we propose a spectral embedding of the cortex-to-ventricle graph into a common underlying space where their joint growth patterns are projected. More importantly, in the joint ventricle-cortex space, the vertices of associated regions from both cortical and ventricular surfaces would lie close to each other. In the final step, we perform clustering in the joint embedded space to identify associated sub-regions between cortex and ventricle. Using a dataset of 25 healthy fetuses and 23 fetuses with isolated non-severe VM within the age range of 26-29 gestational weeks, our results show that the proposed approach is able to reveal clinically relevant and meaningful regional associations.

Learning to combine complementary segmentation methods for fetal and 6-month infant brain MRI segmentation

Segmentation of brain structures during the pre-natal and early post-natal periods is the first step for subsequent analysis of brain development. Segmentation techniques can be roughly divided into two families. The first, which we denote as registration-based techniques, rely on initial estimates derived by registration to one (or several) templates. The second family, denoted as learning-based techniques, relate imaging (and spatial) features to their corresponding anatomical labels. Each approach has its own qualities and both are complementary to each other. In this paper, we explore two ensembling strategies, namely, stacking and cascading to combine the strengths of both families. We present experiments on segmentation of 6-month infant brains and a cohort of fetuses with isolated non-severe ventriculomegaly (INSVM). INSVM is diagnosed when ventricles are mildly enlarged and no other anomalies are apparent. Prognosis is difficult based solely on the degree of ventricular enlargement. In order to find markers for a more reliable prognosis, we use the resulting segmentations to find abnormalities in the cortical folding of INSVM fetuses. Segmentation results show that either combination strategy outperform all of the individual methods, thus demonstrating the capability of learning systematic combinations that lead to an overall improvement. In particular, the cascading strategy outperforms the ensembling one, the former one obtaining top 5, 7 and 13 results (out of 21 teams) in the segmentation of white matter, gray matter and cerebro-spinal fluid in the iSeg2017 MICCAI Segmentation Challenge. The resulting segmentations reveal that INSVM fetuses have a less convoluted cortex. This points to cortical folding abnormalities as potential markers of later neurodevelopmental outcomes.

Annual Research Review: Not just a small adult brain: understanding later neurodevelopment through imaging the neonatal brain

BACKGROUND

There has been a recent proliferation in neuroimaging research focusing on brain development in the prenatal, neonatal and very early childhood brain. Early brain injury and preterm birth are associated with increased risk of neurodevelopmental disorders, indicating the importance of this early period for later outcome.

SCOPE AND METHODOLOGY

Although using a wide range of different methodologies and investigating diverse samples, the common aim of many of these studies has been to both track normative development and investigate deviations in this development to predict behavioural, cognitive and neurological function in childhood. Here we review structural and functional neuroimaging studies investigating the developing brain. We focus on practical and technical complexities of studying this early age range and discuss how neuroimaging techniques have been successfully applied to investigate later neurodevelopmental outcome.

CONCLUSIONS

Neuroimaging markers of later outcome still have surprisingly low predictive power and their specificity to individual neurodevelopmental disorders is still under question. However, the field is still young, and substantial challenges to both acquiring and modeling neonatal data are being met.

[Clinical value of genome-wide chromosome microarray technique in diagnosis of fetal cerebral ventriculomegaly]

OBJECTIVE

To investigate the clinical value of gnome-wide chromosome microarray (CMA) technique in genetic etiological diagnosis of fetal cerebral ventriculomegaly.

METHODS

A retrospective analysis was conducted in 109 women with singleton pregnancy, who were admitted in Nanfang Hospital with the diagnosis of cerebral ventriculomegaly in the fetuses by ultrasound between January, 2014 and December, 2016. Routine karyotype analysis and chromosome microarray analysis were performed to identify the chromosomal abnormalities in the fetuses.

RESULTS

Karyotype analysis detected chromosomal abnormalities at a rate of 12.84% in these fetuses, significantly lower than the rate of 26.60% with CMA technique (P=0.004); the combined detection rate of the two techniques was 28.44%. In 17 cases, karyotype analysis yielded normal results while CMA microarray showed abnormalities with an extra abnormal detection rate of 15.60%. Among the 17 fetuses with chromosomal abnormalities, 6 had micro-deletion, 9 had micro-duplication, 1 had both micro-deletion and micro-duplication, and 1 had heterozygous loss of single parent diploid.

CONCLUSION

CMA technique can be used to detect abnormal chromosomal copy numbers in fetuses with cerebral ventriculomegaly to increase the detection rate of chromosomal abnormalities and facilitate prenatal consultation and prognostic evaluation.

Cortical folding alterations in fetuses with isolated non-severe ventriculomegaly

Neuroimaging of brain diseases plays a crucial role in understanding brain abnormalities and early diagnosis. Of great importance is the study of brain abnormalities in utero and the assessment of deviations in case of maldevelopment. In this work, brain magnetic resonance images from 23 isolated non-severe ventriculomegaly (INSVM) fetuses and 25 healthy controls between 26 and 29 gestational weeks were used to identify INSVM-related cortical folding deviations from normative development. Since these alterations may reflect abnormal neurodevelopment, our working hypothesis is that markers of cortical folding can provide cues to improve the prediction of later neurodevelopmental problems in INSVM subjects. We analyzed the relationship of ventricular enlargement with cortical folding alterations in a regional basis using several curvature-based measures describing the folding of each cortical region. Statistical analysis (global and hemispheric) and sparse linear regression approaches were then used to find the cortical regions whose folding is associated with ventricular dilation. Results from both approaches were in great accordance, showing a significant cortical folding decrease in the insula, posterior part of the temporal lobe and occipital lobe. Moreover, compared to the global analysis, stronger ipsilateral associations of ventricular enlargement with reduced cortical folding were encountered by the hemispheric analysis. Our findings confirm and extend previous studies by identifying various cortical regions and emphasizing ipsilateral effects of ventricular enlargement in altered folding. This suggests that INSVM is an indicator of altered cortical development, and moreover, cortical regions with reduced folding constitute potential prognostic biomarkers to be used in follow-up studies to decipher the outcome of INSVM fetuses.

Lateral ventricular volume measurement by 3D MR hydrography in fetal ventriculomegaly and normal lateral ventricles

BACKGROUND

In fetuses with prenatal ventriculomegaly (VM), ventricular volume on MRI has been shown to correlate with poor postnatal outcomes and in utero death. 3D magnetic resonance hydrography (MRH) has been widely used for MR cholangiopancreatography.

PURPOSE

To investigate the reliability of 3D MRH for lateral ventricular volume measurement in fetuses with VM and normal lateral ventricles, using manual multisection planimetry (MSP) as a reference standard.

STUDY TYPE

Prospective study.

POPULATION

Thirty-five fetuses with VM at 24-37 gestational weeks (GA) and 35 fetuses with normal lateral ventricles at 24-38 GA.

FIELD STRENGTH/SEQUENCE

1.5T MRI with 3D MRH and T₂ -weighted single-shot fast-spin echo sequence.

ASSESSMENT

Left, right, and total lateral ventricle volumes in fetuses were acquired from 3D MRH and manual MSP. All image analysis was performed by a radiologist twice and another radiologist once, blindly.

STATISTICAL TESTS

Analysis of linear regression analysis, Pearson's correlation coefficient, Bland-Altman plots, intraclass correlation coefficient (ICC), and independent samples t-test were used for statistical analyses.

RESULTS

There were highly significant relationships between all 3D MRH and manual MSP measurements of lateral ventricular volumes (r_VM  = 0.92-0.98; r_N  = 0.95-0.98; all P < 0.0001; VM: VM group, N: normal group), although left, right, and total lateral ventricular volumes measured by 3D MRH tended to be slightly larger than MSP (bias_VM 0.1 ± 0.95, 0.26 ± 0.63, and 0.3 ± 0.68 mL, respectively; bias_N 0.1 ± 0.95, 0.26 ± 0.63, and 0.3 ± 0.68 mL, respectively). Interrater agreement and intrarater repeatability were also excellent for 3D MRH (ICC_VM  = 0.994-0.99, ICC_N  = 0.989-0.992; ICC_VM  = 0.975-0.987, ICC_N  = 0.958-0.971, respectively). 3D MRH showed significantly reduced measurement time (VM: 3.55 ± 0.42 vs. 11.81 ± 0.13 min; N: 3.08 ± 0.39 vs. 12.12 ± 0.11 min; all P < 0.0001).

DATA CONCLUSION

Lateral ventricular volume measurement by 3D MRH was comparable to manual MSP.

LEVEL OF EVIDENCE

1 Technical Efficacy Stage 1 J. Magn. Reson. Imaging 2017.

Altered Cerebellar Biochemical Profiles in Infants Born Prematurely

This study aims to compare the cerebellar biochemical profiles in preterm (PT) infants evaluated at term equivalent age (TEA) and healthy full-term newborns using proton magnetic resonance spectroscopy (¹H-MRS). We explore the associations between altered cerebellar metabolite profiles and brain injury topography, severity of injury, and prematurity-related clinical complications. We prospectively collected high quality ¹H-MRS in 59 premature infants born ≤32 weeks and 61 healthy full term controls. ¹H-MRS data were processed using LCModel software to calculate absolute metabolite concentration for N-acetyl-aspartate (NAA), choline (Cho) and creatine (Cr). PT infants had significantly lower cerebellar NAA (p < 0.025) and higher Cho (p < 0.001) at TEA when compared to healthy controls. Creatine was not different between the two groups. The presence of cerebellar injury was consistently associated with reduced concentrations for NAA, Cho, and Cr. Postnatal infection was negatively associated with NAA and Cr (p < 005), while cerebral cortical brain injury severity was inversely associated with both Cho and Cr (p < 0.01). We report for the first time that premature birth is associated with altered cerebellar metabolite profiles when compared to term born controls. Infection, cerebellar injury and supratentorial injury are important risk factors for impaired preterm cerebellar biochemistry.

Normative biometry of the fetal brain using magnetic resonance imaging

The fetal brain shows accelerated growth in the latter half of gestation, and these changes can be captured by 2D and 3D biometry measurements. The aim of this study was to quantify brain growth in normal fetuses using Magnetic Resonance Imaging (MRI) and to produce reference biometry data and a freely available centile calculator ( https://www.developingbrain.co.uk/fetalcentiles/ ). A total of 127 MRI examinations (1.5 T) of fetuses with a normal brain appearance (21-38 gestational weeks) were included in this study. 2D and 3D biometric parameters were measured from slice-to-volume reconstructed images, including 3D measurements of supratentorial brain tissue, lateral ventricles, cortex, cerebellum and extra-cerebral CSF and 2D measurements of brain biparietal diameter and fronto-occipital length, skull biparietal diameter and occipitofrontal diameter, head circumference, transverse cerebellar diameter, extra-cerebral CSF, ventricular atrial diameter, and vermis height, width, and area. Centiles were constructed for each measurement. All participants were invited for developmental follow-up. All 2D and 3D measurements, except for atrial diameter, showed a significant positive correlation with gestational age. There was a sex effect on left and total lateral ventricular volumes and the degree of ventricular asymmetry. The 5th, 50th, and 95th centiles and a centile calculator were produced. Developmental follow-up was available for 73.1% of cases [mean chronological age 27.4 (±10.2) months]. We present normative reference charts for fetal brain MRI biometry at 21-38 gestational weeks. Developing growth trajectories will aid in the better understanding of normal fetal brain growth and subsequently of deviations from typical development in high-risk pregnancies or following premature delivery.

Formation of the calcarine sulcus: a potential marker to predict the progression in utero of isolated mild fetal ventriculomegaly

Our previous study confirmed the negative association between the development of calcarine sulcus and the width of lateral ventricles. The purpose of current study was to evaluate the reliability of calcarine sulcus depth in the 2nd trimester to predict the prenatal enlargement of lateral ventricle in fetuses with isolated mild fetal ventriculomegaly (IMVM).This study used a retrospective cohort study design. A total of 97 pregnant women with IMVM diagnosed between 20 and 26 weeks' gestation returned for a 2nd examination at 30 to 32 weeks. Lateral ventricular size and calcarine sulcus depth were acquired from ultrasonography and magnetic resonance imaging (MRI) scans, respectively. Progression was defined as the process of developing from a lower group toward a higher (<10 mm, 10-12 mm, 13-15 mm, and ≥16 mm).Significant correlation was observed between calcarine sulcus depth and ventricular measurements at the 2nd scan (r = -0.71, P < .0001). Receiver-operating characteristic curves showed that calcarine sulcus depth (area under curve [AUC] = 0.83, 95% confidence interval [CI] = 0.74-0.92) had the best diagnostic performance in predicting the prenatal progression, as compared with lateral ventricle width (AUC = 0.69, 95%CI = 0.54-0.84) and gestational age (AUC = 0.70, 95%CI = 0.57-0.83) at the initial scan. The cutoff value for calcarine sulcus depth was 3.3 mm, with the corresponding sensitivity and specificity were 75.0% and 81.3%, respectively. Multivariate analyses showed that calcarine sulcus depth ≥3.3 mm (odds ratio = 0.09, 95%CI = 0.02-0.38, P = .001) was an independent predictor of the prenatal progression.For IMVM, calcarine sulcus depth might be a powerful marker to identify subjects at higher risk for worse prenatal progression.

Toward the automatic quantification of in utero brain development in 3D structural MRI: A review

Investigating the human brain in utero is important for researchers and clinicians seeking to understand early neurodevelopmental processes. With the advent of fast magnetic resonance imaging (MRI) techniques and the development of motion correction algorithms to obtain high-quality 3D images of the fetal brain, it is now possible to gain more insight into the ongoing maturational processes in the brain. In this article, we present a review of the major building blocks of the pipeline toward performing quantitative analysis of in vivo MRI of the developing brain and its potential applications in clinical settings. The review focuses on T1- and T2-weighted modalities, and covers state of the art methodologies involved in each step of the pipeline, in particular, 3D volume reconstruction, spatio-temporal modeling of the developing brain, segmentation, quantification techniques, and clinical applications. Hum Brain Mapp 38:2772-2787, 2017. © 2017 Wiley Periodicals, Inc.

Brain Volumes at Term-Equivalent Age in Preterm Infants: Imaging Biomarkers for Neurodevelopmental Outcome through Early School Age

OBJECTIVE

To evaluate the relationship between brain volumes at term and neurodevelopmental outcome through early school age in preterm infants.

STUDY DESIGN

One hundred twelve preterm infants (born mean gestational age 28.6 ± 1.7 weeks) were studied prospectively with magnetic resonance imaging (imaged at mean 41.6 ± 1.0 weeks). T2- and T1-weighted images were automatically segmented, and volumes of 6 tissue types were related to neurodevelopmental outcome assessed using the Bayley Scales of Infant and Toddler Development, Third Edition (cognitive, fine, and gross motor scores) at 24 months corrected age (n = 112), Griffiths Mental Development Scales (developmental quotient) at age 3.5 years (n = 98), Movement Assessment Battery for Children, Second Edition (n = 85), and Wechsler Preschool and Primary Scale of Intelligence, Third Edition at age 5.5 years (n = 44). Corrections were made for intracranial volume, maternal education, and severe brain lesions.

RESULTS

Ventricular volumes were negatively related to neurodevelopmental outcome at age 24 months and 3.5 years, as well as processing speed at age 5.5 years. Unmyelinated white matter (UWM) volume was positively associated with motor outcome at 24 months and with processing speed at age 5.5 years. Cortical gray matter (CGM) volume demonstrated a negative association with motor performance and cognition at 24 months and with developmental quotient at age 3.5 years. Cerebellar volume was positively related to cognition at these time points. Adjustment for brain lesions attenuated the relations between cerebellar and CGM volumes and cognition.

CONCLUSIONS

Brain volumes of ventricles, UWM, CGM, and cerebellum may serve as biomarkers for neurodevelopmental outcome in preterm infants. The relationship between larger CGM volumes and adverse neurodevelopment may reflect disturbances in neuronal and/or axonal migration at the UWM-CGM boundary and warrants further investigation.

Altered white matter and cortical structure in neonates with antenatally diagnosed isolated ventriculomegaly

Ventriculomegaly (VM) is the most common central nervous system abnormality diagnosed antenatally, and is associated with developmental delay in childhood. We tested the hypothesis that antenatally diagnosed isolated VM represents a biological marker for altered white matter (WM) and cortical grey matter (GM) development in neonates.

25 controls and 21 neonates with antenatally diagnosed isolated VM had magnetic resonance imaging at 41.97(± 2.94) and 45.34(± 2.14) weeks respectively. T₂-weighted scans were segmented for volumetric analyses of the lateral ventricles, WM and cortical GM. Diffusion tensor imaging (DTI) measures were assessed using voxel-wise methods in WM and cortical GM; comparisons were made between cohorts.

Ventricular and cortical GM volumes were increased, and WM relative volume was reduced in the VM group. Regional decreases in fractional anisotropy (FA) and increases in mean diffusivity (MD) were demonstrated in WM of the VM group compared to controls. No differences in cortical DTI metrics were observed. At 2 years, neurodevelopmental delays, especially in language, were observed in 6/12 cases in the VM cohort.

WM alterations in isolated VM cases may be consistent with abnormal development of WM tracts involved in language and cognition. Alterations in WM FA and MD may represent neural correlates for later neurodevelopmental deficits.

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This study compared brain development in neonates with isolated VM to controls.

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Neonates with isolated VM have enlarged cortical volumes compared to controls.

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FA was reduced and MD was increased in the WM of the VM cohort.

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Children with antenatal isolated VM are at increased risk for language delay.

Developmental neurotoxicity of inhaled ambient ultrafine particle air pollution: Parallels with neuropathological and behavioral features of autism and other neurodevelopmental disorders

Accumulating evidence from both human and animal studies show that brain is a target of air pollution. Multiple epidemiological studies have now linked components of air pollution to diagnosis of autism spectrum disorder (ASD), a linkage with plausibility based on the shared mechanisms of inflammation. Additional plausibility appears to be provided by findings from our studies in mice of exposures from postnatal day (PND) 4-7 and 10-13 (human 3rd trimester equivalent), to concentrated ambient ultrafine (UFP) particles, considered the most reactive component of air pollution, at levels consistent with high traffic areas of major U.S. cities and thus highly relevant to human exposures. These exposures, occurring during a period of marked neuro- and gliogenesis, unexpectedly produced a pattern of developmental neurotoxicity notably similar to multiple hypothesized mechanistic underpinnings of ASD, including its greater impact in males. UFP exposures induced inflammation/microglial activation, reductions in size of the corpus callosum (CC) and associated hypomyelination, aberrant white matter development and/or structural integrity with ventriculomegaly (VM), elevated glutamate and excitatory/inhibitory imbalance, increased amygdala astrocytic activation, and repetitive and impulsive behaviors. Collectively, these findings suggest the human 3rd trimester equivalent as a period of potential vulnerability to neurodevelopmental toxicity to UFP, particularly in males, and point to the possibility that UFP air pollution exposure during periods of rapid neuro- and gliogenesis may be a risk factor not only for ASD, but also for other neurodevelopmental disorders that share features with ASD, such as schizophrenia, attention deficit disorder, and periventricular leukomalacia.

Region-specific changes in brain diffusivity in fetal isolated mild ventriculomegaly

OBJECTIVES

To evaluate the impact of symmetric and asymmetric isolated mild ventriculomegaly (IMVM, atrial width 10-15 mm) on apparent diffusion coefficient (ADC) values in fetal brain areas.

METHODS

Sixty-seven sequential fetal head magnetic resonance imaging scans (feMRI) of VM cases performed between 2009 and 2014 were compared to 38 normal feMRI scans matched for gestational age (controls). Ultrasound- and MRI-proven IMVM cases were divided into asymmetrical (AVM, ≥2 mm difference in atrial width), symmetrical (SVM, <2 mm difference in atrial width), and asymmetrical IMVM with one normal-sized ventricle (AV1norm).

RESULTS

ADC values were significantly elevated in the basal ganglia (BG) of the SVM and AV1norm groups compared to controls (p < 0.004 and p < 0.013, respectively). High diffusivity was constantly detected in the BG ipsilateral to the enlarged atria relative to the normal-sized atria in the AV1norm group (p < 0.03). Frontal lobe ADC values were significantly reduced in the AVM and SVM groups (p < 0.003 and p < 0.003 vs. controls). Temporal lobe ADC values were significantly reduced in the AVM group (p < 0.001 vs. controls).

CONCLUSION

Isolated mild ventriculomegaly is associated with distinct ADC value changes in different brain regions. This phenomenon could reflect the pathophysiology associated with different IMVM patterns.

KEY POINTS

Various ventriculomegaly patterns are associated with distinct diffusional changes. Frontal and temporal lobe ADC values are altered bilaterally, even in asymmetric ventriculomegaly. Basal ganglia ADC values are elevated ipsilateral to the enlarged ventricle.

Construction of a fetal spatio-temporal cortical surface atlas from in utero MRI: Application of spectral surface matching

In this study, we construct a spatio-temporal surface atlas of the developing cerebral cortex, which is an important tool for analysing and understanding normal and abnormal cortical development. In utero Magnetic Resonance Imaging (MRI) of 80 healthy fetuses was performed, with a gestational age range of 21.7 to 38.9 weeks. Topologically correct cortical surface models were extracted from reconstructed 3D MRI volumes. Accurate correspondences were obtained by applying a joint spectral analysis to cortices for sets of subjects close to a specific age. Sulcal alignment was found to be accurate in comparison to spherical demons, a state of the art registration technique for aligning 2D cortical representations (average Fréchet distance≈0.4 mm at 30 weeks). We construct consistent, unbiased average cortical surface templates, for each week of gestation, from age-matched groups of surfaces by applying kernel regression in the spectral domain. These were found to accurately capture the average cortical shape of individuals within the cohort, suggesting a good alignment of cortical geometry. Each spectral embedding and its corresponding cortical surface template provide a dual reference space where cortical geometry is aligned and a vertex-wise morphometric analysis can be undertaken.