Magnetic resonance imaging examination of the fetal brain

Machine learning in prenatal MRI predicts postnatal ventricular abnormalities in fetuses with isolated ventriculomegaly

OBJECTIVES

To evaluate the intracranial structures and brain parenchyma radiomics surrounding the occipital horn of the lateral ventricle in normal fetuses (NFs) and fetuses with ventriculomegaly (FVs), as well as to predict postnatally enlarged lateral ventricle alterations in FVs.

METHODS

Between January 2014 and August 2023, 141 NFs and 101 FVs underwent 1.5 T balanced steady-state free precession (BSSFP), including 68 FVs with resolved lateral ventricles (FVM-resolved) and 33 FVs with stable lateral ventricles (FVM-stable). Demographic data and intracranial structures were analyzed. To predict the enlarged ventricle alterations of FVs postnatally, logistic regression models with 5-fold cross-validation were developed based on lateral ventricle morphology, blended-cortical or/and subcortical radiomics characteristics. Validation of the models' performance was conducted using the receiver operating characteristic curve (ROC), calibration curve, and decision curve analysis (DCA).

RESULTS

Significant alterations in cerebral structures were observed between NFs and FVs (p < 0.05), excluding the maximum frontal horn diameter (FD). However, there was no notable distinction between the FVM-resolved and FVM-stable groups (all p > 0.05). Based on subcortical-radiomics on the aberrant sides of FVs, this approach exhibited high efficacy in distinguishing NFs from FVs in the training/validation set, yielding an impressive AUC of 1/0.992. With an AUC value of 0.822/0.743 in the training/validation set, the Subcortical-radiomics model demonstrated its ability to predict lateral ventricle alterations in FVs, which had the greatest predictive advantages indicated by DCA.

CONCLUSIONS

Microstructural alterations in subcortical parenchyma associated with ventriculomegaly can serve as predictive indicators for postnatal lateral ventricle variations in FVs.

CLINICAL RELEVANCE STATEMENT

It is critical to gain pertinent information from a solitary fetal MRI to anticipate postnatal lateral ventricle alterations in fetuses with ventriculomegaly. This approach holds the potential to diminish the necessity for recurrent prenatal ultrasound or MRI examinations.

KEY POINTS

Fetal ventriculomegaly is a dynamic condition that affects postnatal neurodevelopment. Machine learning and subcortical-radiomics can predict postnatal alterations in the lateral ventricle. Machine learning, applied to single-fetal MRI, might reduce required antenatal testing.

PDFF-CNN: An attention-guided dynamic multi-orientation feature fusion method for gestational age prediction on imbalanced fetal brain MRI dataset

BACKGROUND

Fetal brain magnetic resonance imaging (MRI)-based gestational age prediction has been widely used to characterize normal fetal brain development and diagnose congenital brain malformations.

PURPOSE

The uncertainty of fetal position and external interference leads to variable localization and direction of the fetal brain. In addition, pregnant women typically concentrate on receiving MRI scans during the fetal anomaly scanning week, leading to an imbalanced distribution of fetal brain MRI data. The above-mentioned problems pose great challenges for deep learning-based fetal brain MRI gestational age prediction.

METHODS

In this study, a pyramid squeeze attention (PSA)-guided dynamic feature fusion CNN (PDFF-CNN) is proposed to robustly predict gestational ages from fetal brain MRI images on an imbalanced dataset. PDFF-CNN contains four components: transformation module, feature extraction module, dynamic feature fusion module, and balanced mean square error (MSE) loss. The transformation and feature extraction modules are employed by using the PSA to learn multiscale and multi-orientation feature representations in a parallel weight-sharing Siamese network. The dynamic feature fusion module automatically learns the weights of feature vectors generated in the feature extraction module to dynamically fuse multiscale and multi-orientation brain sulci and gyri features. Considering the fact of the imbalanced dataset, the balanced MSE loss is used to mitigate the negative impact of imbalanced data distribution on gestational age prediction performance.

RESULTS

Evaluated on an imbalanced fetal brain MRI dataset of 1327 routine clinical T2-weighted MRI images from 157 subjects, PDFF-CNN achieved promising gestational age prediction performance with an overall mean absolute error of 0.848 weeks and anR 2 $R^2$ of 0.904. Furthermore, the attention activation maps of PDFF-CNN were derived, which revealed regional features that contributed to gestational age prediction at each gestational stage.

CONCLUSIONS

These results suggest that the proposed PDFF-CNN might have broad clinical applicability in guiding treatment interventions and delivery planning, which has the potential to be helpful with prenatal diagnosis.

Perceptions of Magnetic Resonance Imaging During Pregnancy: A Newfoundland and Labrador Perspective

OBJECTIVES

This study aimed to identify enablers and barriers to participation in MRI for clinical indications and scientific research, and to determine the perceptions of MRI performed during pregnancy.

METHODS

We conducted a survey of 156 pregnant people in Newfoundland and Labrador including sociodemographic information, obstetrical history, MRI history, and willingness to participate in an MRI. Categorical variables were analyzed using a Fisher exact test and open-ended questions were analyzed using thematic analysis.

RESULTS

In total, 80% of participants reported willingness to receive an MRI while pregnant for clinical indications compared to 24% for research. Only 10% reported prior knowledge about MRI during pregnancy and most participants (94%) wanted additional information from their physician before feeling comfortable with the procedure. Participants who knew someone with complications during pregnancy were more likely to be willing to participate in an MRI for research (uncorrected P < 0.05). Participants' positive perceptions towards MRI during pregnancy for clinical indications were that it was a necessary and useful procedure, while the negative perceptions identified MRI as unsafe. For research MRI, participants' positive perceptions included that it would add to the advancement of knowledge and the negative perceptions were that it was an unnecessary and risky procedure.

CONCLUSIONS

Strategies are needed to improve patient knowledge about the benefits and safety of MRI during pregnancy. The present study suggests recruitment for research should incorporate education on safety concerns and relative risk, personal stories about the benefits of MRI in diagnosing pregnancy complications and should highlight the contribution to advancing scientific knowledge.

Agreement between Fetal Brain Ultrasonography and Magnetic Resonance Imaging in the Measurements of the Corpus Callosum and Transverse Cerebellar Diameter

As the use of magnetic resonance imaging of the fetal brain has evolved, the need to understand its efficiency in the biometry of the fetal brain has broadened. This study aimed to assess the level of agreement and correlation between the two cardinal imaging methods of fetal neuroimaging, ultrasonography (US) and magnetic resonance imaging (MRI), by measuring the corpus callosum (CC) and transverse cerebellar diameter (TCD) in terms of length and percentile. Measurements of CC and TCD length and percentile were documented over a 7-year span in a tertiary referral medical center. All US and MRI examinations were performed in the customary planes and subcategorized by valid reference charts. Exclusion and inclusion criteria were set before the collection and processing of the data. A total of 156 fetuses out of 483 were included in the study. A positive, strong correlation and agreement were found (r = 0.78; ICC = 0.76) between US and MRI in TCD measurements. For CC length measurement, a moderate correlation and moderate agreement (r = 0.51; ICC = 0.49) between US and MRI was observed. TCD and CC percentiles had lower levels of correlation and agreement compared with the length variables. Our study indicates good agreement between MRI and US in the assessment of TCD measurement as a part of antenatal neuroimaging. Furthermore, while the two techniques are not always compatible, they are complementary methods.

Navigating paediatric virology through the COVID‑19 era (Review)

The present review article presents the key messages of the 8th Workshop on Paediatric Virology organised virtually by the Institute of Paediatric Virology based on the island of Euboea in Greece. The major topics covered during the workshop were the following: i) New advances in antiviral agents and vaccines against cytomegalovirus; ii) hantavirus nephropathy in children; iii) human rhinovirus infections in children requiring paediatric intensive care; iv) complications and management of human adenovirus infections; v) challenges of post‑coronavirus disease 2019 (COVID‑19) syndrome in children and adolescents; and vi) foetal magnetic resonance imaging in viral infections involving the central nervous system. The COVID‑19 era requires a more intensive, strategic, global scientific effort in the clinic and in the laboratory, focusing on the diagnosis, management and prevention of viral infections in neonates and children.

European recommendations on practices in pediatric neuroradiology: consensus document from the European Society of Neuroradiology (ESNR), European Society of Paediatric Radiology (ESPR) and European Union of Medical Specialists Division of Neuroradiology (UEMS)

Pediatric neuroradiology is a subspecialty within radiology, with possible pathways to train within the discipline from neuroradiology or pediatric radiology. Formalized pediatric neuroradiology training programs are not available in most European countries. We aimed to construct a European consensus document providing recommendations for the safe practice of pediatric neuroradiology. We particularly emphasize imaging techniques that should be available, optimal site conditions and facilities, recommended team requirements and specific indications and protocol modifications for each imaging modality employed for pediatric neuroradiology studies. The present document serves as guidance to the optimal setup and organization for carrying out pediatric neuroradiology diagnostic and interventional procedures. Clinical activities should always be carried out in full agreement with national provisions and regulations. Continued education of all parties involved is a requisite for preserving pediatric neuroradiology practice at a high level.

Epigenetic regulation of fetal brain development in pig

How fetal brain development is regulated at the molecular level is not well understood. Due to ethical challenges associated with research on the human fetus, large animals particularly pigs are increasingly used to study development and disorders of fetal brain. The pig fetal brain grows rapidly during the last ∼ 50 days before birth which is around day 60 (d60) of pig gestation. But what regulates the onset of accelerated growth of the brain is unknown. The current study tests the hypothesis that epigenetic alteration around d60 is involved in the onset of rapid growth of fetal brain of pig. To test this hypothesis, DNA methylation changes of fetal brain was assessed in a genome-wide manner by Enzymatic Methyl-seq (EM-seq) during two gestational periods (GP): d45 vs. d60 (GP1) and d60 vs. d90 (GP2). The cytosine-guanine (CpG) methylation data was analyzed in an integrative manner with the RNA-seq data generated from the same brain samples from our earlier study. A neural network based modeling approach was implemented to learn changes in methylation patterns of the differentially expressed genes, and then predict methylations of the brain in a genome-wide manner during rapid growth. This approach identified specific methylations that changed in a mutually informative manner during rapid growth of the fetal brain. These methylations were significantly overrepresented in specific genic as well as intergenic features including CpG islands, introns, and untranslated regions. In addition, sex-bias methylations of known single nucleotide polymorphic sites were also identified in the fetal brain ide during rapid growth.

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.

Attention-guided deep learning for gestational age prediction using fetal brain MRI

Magnetic resonance imaging offers unrivaled visualization of the fetal brain, forming the basis for establishing age-specific morphologic milestones. However, gauging age-appropriate neural development remains a difficult task due to the constantly changing appearance of the fetal brain, variable image quality, and frequent motion artifacts. Here we present an end-to-end, attention-guided deep learning model that predicts gestational age with R² score of 0.945, mean absolute error of 6.7 days, and concordance correlation coefficient of 0.970. The convolutional neural network was trained on a heterogeneous dataset of 741 developmentally normal fetal brain images ranging from 19 to 39 weeks in gestational age. We also demonstrate model performance and generalizability using independent datasets from four academic institutions across the U.S. and Turkey with R² scores of 0.81–0.90 after minimal fine-tuning. The proposed regression algorithm provides an automated machine-enabled tool with the potential to better characterize in utero neurodevelopment and guide real-time gestational age estimation after the first trimester.

Indications for magnetic resonance imaging of the fetal central nervous system: recommendations from the European Society of Paediatric Radiology Fetal Task Force

Fetal central nervous system MRI is a well-established method to complement a high-quality fetal ultrasound and to clarify sonographically detected abnormalities in complex pregnancies. However, there is still worldwide heterogeneity and confusion regarding the indications of fetal central nervous system MRI, which has roots in differences among countries regarding the performance of ultrasound examinations and legislation on pregnancy termination. The purpose of this article is to clarify the indications for fetal central nervous system MRI by focusing on the ultrasound findings that guide further investigation with MRI and highlight the strengths and the weaknesses of each modality on imaging the fetal central nervous system.

What does the normal fetal face look like? MR imaging of the developing mandible and nasal cavity

PURPOSE

Analyze fetal facial structures using MR imaging scans in an aim to establish normal biometrical measures of fetal nasal and mandibular structures for multiple gestational weeks, comprise nomograms and compare female and male fetuses.

METHODS

A Historic cohort study of 255 fetal facial MR imaging scans was performed at a tertiary medical center during a 4-year period. Clinical data was collected from electronic medical charts. Length of septal height (SH), septal length (SL), Interocular Distance(IOD), maximal nasal length(MNL), mandibular vertebral length(MVL), antero-posterior diameter(APD), inferior facial angle(IFA) and biparietal diameter(BPD) were measured and compared with gender and gestational age (GA). Interrater and intrarater reliability was investigated.

RESULTS

Normal measures were established for each gestational age. We found that all parameters but IFA correlated with GA. Males had a longer SL, BPD and MNL while females had a wider IFA.

CONCLUSIONS

Novel facial biometric parameters that correlate with GA hold cardinal information for the prenatal evaluation of facial development and thus surface the need for additional research in order to asses these findings as radiologic markers for facial structural pathologies.

Prenatal diagnosis of congenital head, face, and neck malformations-Is complementary fetal MRI of value?

OBJECTIVES

The aim of this study was to evaluate the role of fetal magnetic resonance imaging (MRI) as a complement to ultrasound (US) in the prenatal diagnosis of craniofacial anomalies.

METHODS

A historical cohort study including all pregnant women who were referred for fetal MRI because of antenatal diagnosis of craniofacial anomalies on screening US. Prenatal diagnostic US, MRI, and postnatal diagnosis were compared for consistencies and discrepancies.

RESULTS

Forty-five pregnant women with 73 suspected fetal craniofacial anomalies diagnosed by US underwent MRI. In 40 out of 73 anomalies (54.8%), US and MRI findings were in complete agreement with postnatal diagnoses. MRI correctly ruled out the diagnosis of 24 anomalies suspected on US and diagnosed four additional pathologies that were not demonstrated by US. Out of the 85 anomalies (suspected by imaging or confirmed postnatally), confident diagnosis could be made by MRI in 68 anomalies (80%), not diagnosed in 10 (11.8%), and over-diagnosed in seven (8.2%). By US, confident diagnosis could be made in 44 anomalies (51.8%), not diagnosed in 11 (12.9%), and over-diagnosed in 30 (35.3%).

CONCLUSION

MRI is valuable in the antenatal evaluation of fetal craniofacial anomalies and may be useful as an adjunct to US in the prenatal work-up of craniofacial anomalies.

The use of image fusion in prenatal medicine

Fusion imaging (FI), the simultaneous display of the same anatomical region using two imaging modalities, has been used in other areas of medicine for both diagnosis and guiding interventions. Examples include positron emission tomography-computed tomography (PET-CT) imaging in oncology and ultrasound-magnetic resonance imaging (US-MRI) fusion in biopsies of the prostate gland. The underlying principle is to take advantage of the complementary information in each modality to improve accuracy, be it diagnostic accuracy or targeting accuracy in biopsies. For example, PET-CT overlays the metabolic activity of lesions on the superb spatial and anatomical detail of CT. While the historical mainstay of fetal imaging has been ultrasound, advances in ultrafast MR imaging together with advances in fetal MRI over the past two decades, have resulted in the opportunity to explore fusion imaging in fetal medicine. We present an overview of the principles of US-MRI fusion imaging in prenatal medicine, report our local experience, and review the literature in this emerging area. We share our perspective on how FI can improve diagnostic confidence, be used as an educational tool, and potentially enhance guidance in certain fetal procedures.

Prenatal diagnosis of arachnoid cysts: MRI features and neurodevelopmental outcome

OBJECTIVE

Arachnoid cysts (AC) are congenital lesions comprising 1% of all intracranial mass lesions. The aim of this study was to characterize arachnoid cysts and their neurodevelopmental outcome and to compare it with the outcome of children without AC.

METHODS

This is a retrospective cohort study of arachnoid cysts detected prenatally by fetal MRI in 29 fetuses compared to a control group of 59 fetuses without arachnoid cyst who were examined by MRI. The cohort was investigated from two different angles: anatomical and developmental. Anatomical analyzation, the cohort was divided into 2 groups by the arachnoid cyst anatomical location: group A (n = 9), which included cases with supratentorial cyst, and group B (n = 20), which included cases with infratentorial cyst. Developmental analyzation, the cohort was divided into 2 groups by the neurodevelopmental outcome: group γ (n = 5) which included cases that were affected by arachnoid cyst presence, and group δ (n = 17) which included cases that had neurodevelopmental outcome within the normal range. Data collected included prenatal history, MRI features, sonographic follow up, and neurodevelopmental outcome.

RESULTS

In 22/29 cases we achieved a long-term follow up, by evaluation of children development in a range of ages from 6 months to 6 years. In group A (n = 9), 4 infants had normal outcome, 2 had abnormal outcome, 1 pregnancy was terminated, and 2 cases were not cooperative with the study. In group B (n = 20), 13 infants had normal outcome, 3 had abnormal outcome, and 4 cases were not cooperative with the study.

CONCLUSIONS

From all cases with AC detected by fetal MRI, 77.3% had normal neurodevelopmental outcome and 22.7% had abnormal neurodevelopment.

MR Imaging of Fetal Musculoskeletal Disorders

This article outlines the main findings in prenatal musculoskeletal disorders. Three main technologies are generally used to obtain images within the uterus during pregnancy: ultrasound (US), MR imaging, and computed tomography (CT). Currently, the primary imaging method used for fetal assessment during pregnancy is US because it is patient friendly, useful, cost-effective, and (considered) safe. MR imaging is generally performed when US yields equivocal results because it offers additional information about fetal abnormalities and conditions in situations in which US is unable to provide high-quality images.

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.

The role of a novel magnetic resonance imaging sequence in the evaluation of the fetal skeleton: a pilot study

Objective

We aimed to study the role of magnetic resonance imaging (MRI), including a novel MRI sequence-the modified volumetric interpolated breath-hold examination (VIBE)-in the characterization of the fetal skeleton. This novel sequence was useful for reconstructing three-dimensional images of the skeleton.

Materials and Methods

We enrolled 22 pregnant women whose fetuses had shown congenital abnormalities on ultrasound examinations. The women underwent prenatal fetal MRI in a 1.5-T scanner with a T2-weighted modified VIBE sequence. Three-dimensional reconstructions of the fetal skeleton were performed manually on the instrument itself or via an interactive pen-tablet workstation.

Results

Three-dimensional reconstructions of the fetal skeleton were performed after the acquisition of modified VIBE MRI sequences, and it was possible to characterize the fetal skeleton in all MRI examinations.

Conclusion

A detailed evaluation of the three-dimensional reconstructions of fetal skeleton performed after acquisition of a modified VIBE MRI sequence allowed a full characterization of the skeleton. However, improvements to the proposed sequence should be addressed in future studies.

A metabolomics-based approach for non-invasive screening of fetal central nervous system anomalies

BACKGROUND

Central nervous system anomalies represent a wide range of congenital birth defects, with an incidence of approximately 1% of all births. They are currently diagnosed using ultrasound evaluation. However, there is strong need for a more accurate and less operator-dependent screening method.

OBJECTIVES

To perform a characterization of maternal serum in order to build a metabolomic fingerprint resulting from congenital anomalies of the central nervous system.

METHODS

This is a case-control pilot study. Metabolomic profiles were obtained from serum of 168 mothers (98 controls and 70 cases), using gas chromatography coupled to mass spectrometry. Nine machine learning and classification models were built and optimized. An ensemble model was built based on results from the individual models. All samples were randomly divided into two groups. One was used as training set, the other one for diagnostic performance assessment.

RESULTS

Ensemble machine learning model correctly classified all cases and controls. Propanoic, lactic, gluconic, benzoic, oxalic, 2-hydroxy-3-methylbutyric, acetic, lauric, myristic and stearic acid and myo-inositol and mannose were selected as the most relevant metabolites in class separation.

CONCLUSION

The metabolomic signature of second trimester maternal serum from pregnancies affected by a fetal central nervous system anomaly is quantifiably different from that of a normal pregnancy. Maternal serum metabolomics is therefore a promising tool for the accurate and sensitive screening of such congenital defects. Moreover, the details of the most relevant metabolites and their respective biochemical pathways allow better understanding of the overall pathophysiology of affected pregnancies.

Prenatal Evaluation, Imaging Features, and Neurodevelopmental Outcome of Prenatally Diagnosed Periventricular Pseudocysts

BACKGROUND AND PURPOSE

Periventricular pseudocysts are cystic cavities that lack the ependymal cell lining found in true cysts. The aim of this study was to characterize periventricular pseudocysts and related findings and their neurodevelopmental outcome.

MATERIALS AND METHODS

This was a retrospective study of periventricular pseudocysts detected prenatally on fetal MR imaging in 26 fetuses. The fetuses were divided into group A (n = 8), which included cases with isolated periventricular pseudocysts, and group B (n = 18), which included cases of periventricular pseudocysts with additional findings. Cases were further subdivided into connatal cysts and subependymal pseudocysts. Data collected included prenatal history, MR imaging features, sonographic follow-up, and neurodevelopmental outcome.

RESULTS

All cases in group A (n = 8) had a normal outcome. In group B (n = 18), 6 pregnancies were terminated and 2 had an abnormal outcome. Both cases with an abnormal outcome involved patients with subependymal pseudocysts. No significant association was found between the morphologic features on MR imaging and the neurodevelopmental outcome.

CONCLUSIONS

Neurodevelopmental outcome in cases of isolated periventricular pseudocysts detected prenatally appears to be normal. A detailed evaluation should be performed to rule out additional brain findings, chromosomal aberration, and fetal malformation. This evaluation should include the following: maternal TORCH status, detailed fetal sonographic anatomic evaluation, fetal echocardiogram, fetal brain MR imaging, amniocentesis and karyotyping/comparative genomic hybridization, and genetic counseling. Additional findings on MR imaging, including mild-to-moderate dilated ventricles, asymmetric ventricles, or T2 hyperintense signal in the white matter without other findings or major fetal abnormality, appear to be benign. Connatal cysts appear to be benign.

Evaluation of Fetal Central Nervous System Anomalies by Ultrasound and Its Anatomical Co-relation

INTRODUCTION

Central nervous system anomalies are often severe and are the most common indications for therapeutic abortions. Ultrasound examination helps to identify and evaluate them well before birth.

OBJECTIVES

Present study was undertaken to evaluate the incidence of central nervous system anomalies in utero by ultrasound and to confirm them by autopsy or postnatal examination.

METHOD

Ultrasound screening of 7485 pregnant women was performed. Pregnancy with ultrasound findings of central nervous system anomalies were followed up. Prenatal ultrasound findings were confirmed by autopsy in cases of therapeutic abortions and fetal losses. In case of live birth postnatal findings were noted.

RESULTS

Ultrasound detected central nervous system malformations in 24 fetuses. Ultrasound findings were matching in 83% on autopsy. Autopsy and postnatal findings together were matching with ultrasound in 85.7%. Two cases had additional minor findings on autopsy.

CONCLUSION

The incidence of central nervous system malformations on ultrasound was 0.31%. Autopsy and postnatal examination showed high degree of correlation with ultrasound findings.

MRI and ultrasound fusion imaging for prenatal diagnosis

OBJECTIVE

A combination of magnetic resonance imaging (MRI) images with real time high-resolution ultrasound known as fusion imaging may improve prenatal examination. This study was undertaken to evaluate the feasibility of using fusion of MRI and ultrasound (US) in prenatal imaging.

STUDY DESIGN

This study was conducted in a tertiary referral center. All patients referred for prenatal MRI were offered to undergo fusion of MRI and US examination. All cases underwent 1.5 Tesla MRI protocol including at least 3 T2-weighted planes. The Digital Imaging and Communications in Medicine volume dataset was then loaded into the US system for manual registration of the live US image and fusion imaging examination.

RESULTS

Over the study period, 24 patients underwent fusion imaging at a median gestational age of 31 (range, 24-35) weeks. Data registration, matching and then volume navigation was feasible in all cases. Fusion imaging allowed superimposing MRI and US images therefore providing with real time imaging capabilities and high tissue contrast. It also allowed adding a real time Doppler signal on MRI images. Significant fetal movement required repeat-registration in 15 (60%) cases. The average duration of the overall additional scan with fusion imaging was 10 ± 5 minutes.

CONCLUSION

The combination of fetal real time MRI and US image fusion and navigation is feasible. Multimodality fusion imaging may enable easier and more extensive prenatal diagnosis.

Postnatal outcome of isolated, nonprogressive, mild borderline fetal ventriculomegaly

BACKGROUND

This study aimed to evaluate postnatal outcome of fetuses affected by nonprogressive, isolated, mild (≥10 and ≤12 mm) borderline ventriculomegaly (BVM).

METHODS

We studied 25 consecutive fetuses with BMV and evaluated patients' characteristic, ultrasonographic findings, and the neurodevelopmental outcome at age ≥24 months.

RESULTS

The mean gestational age at diagnosis was 23.84 ± 5.02 weeks (min-max; 17-34 weeks). In 16 cases, BVM was bilateral (16/25, 64 %), 4 left sided (4/25, 16 %), and 5 right sided (5/25, 20 %). Fourteen cases were males (14/25, 56 %), and 11 cases were females (11/25, 44 %). In two cases, ventriculomegaly was regressed 4 weeks after the initial diagnosis (2/25, 8 %), and in the remaining cases, ventriculomegaly persisted between initial measurement and 12 mm. The mean age of the infant at the time of the neurodevelopmental evaluation was 45.9 months (24-77 months). The neurodevelopmental outcome at the mean age of 45.9 months was completely normal in 16 infants (16/25, 64 %). The remaining nine infants (9/25, 36 %) had mild degree of neuromotor developmental delay.

CONCLUSION

Prenatal counseling for isolated, nonprogressive, mild BVM should be mainly reassurance since it is not associated with severe neurodevelopmental delay. However, parents should be educated about the developmental milestone of children to observe and detect mild neurodevelopmental delay which can be associated with mild BVM.

Management of pregnancies with confirmed cytomegalovirus fetal infection

Systematic screening for cytomegalovirus (CMV) maternal infection is not recommended in most countries. Nevertheless, primary CMV infection will occur in around 1% of women. The vertical transmission rate is estimated to be around 30-50%. Newborns with congenital CMV infection remain asymptomatic in the majority of cases and around 10% will present with a wide range of abnormalities. Fetal infection can be diagnosed by amniocentesis with amplification of the viral genome in the amniotic fluid by polymerase chain reaction. This prenatal diagnosis is mainly performed when ultrasound abnormalities are observed. The purpose of this mini-review is to describe the management options when a fetus is known to be infected.

Advancing fetal brain MRI: targets for the future

Fetal MRI is becoming an increasingly powerful imaging tool for studying brain development in vivo. Until recently, the application of advanced magnetic resonance imaging techniques was limited by motion in the nonsedated fetus. Extensive research efforts currently underway are focusing on the development of dedicated magnetic resonance imaging sequences and sophisticated postprocessing techniques that are revolutionizing our ability to study the healthy and compromised fetus. The ongoing refinement of these magnetic resonance imaging techniques will undoubtedly lead to the development of cornerstone biomarkers that will provide healthcare caregivers with vital, and currently lacking, information upon which to counsel parents effectively, and base rational decisions regarding the timing and type of novel medical and surgical interventions currently on the horizon.

Counseling in isolated mild fetal ventriculomegaly

In this Review we aim to provide up-to-date and evidence-based answers to the common questions regarding the diagnosis of isolated mild fetal ventriculomegaly (VM). A literature search was performed to identify all reports of antenatal VM in the English language literature. In addition, reference lists of articles identified using the search were scrutinized to further identify relevant articles. Fetal mild VM is commonly defined as a ventricular atrial width of 10.0-15.0 mm, and it is considered isolated if there are no associated ultrasound abnormalities. There is no good evidence to suggest that the width of the ventricular atria contributes to the risk of neurodevelopmental outcome in fetuses with mild VM. The most important prognostic factors are the association with other abnormalities that escape early detection and the progression of ventricular dilatation, which are reported to occur in about 13% and 16% of cases, respectively. Most infants with a prenatal diagnosis of isolated mild VM have normal neurological development at least in infancy. The rate of abnormal or delayed neurodevelopment in infancy is about 11%, and it is unclear whether this is higher than in the general population. Furthermore, the number of infants that develop a real handicap is unknown. There are limitations of existing studies of mild VM. Although they address many of the relevant questions regarding the prognosis and management of fetal isolated mild VM, there is a lack of good-quality postnatal follow-up studies. The resulting uncertainties make antenatal counseling for this abnormality difficult.

The neurocognitive outcome of mild isolated fetal ventriculomegaly verified by prenatal magnetic resonance imaging

OBJECTIVE

Neurocognitive outcome of preschool children, prenatal diagnosis of isolated mild ventriculomegaly compared with 2 control groups.

STUDY DESIGN

Case-controlled study at the University Hospital of Tel Aviv between October 1999 and December 2002. Study groups consisted of 12 children with bilateral isolated mild ventriculomegaly, and 16 children with unilateral isolated mild ventriculomegaly, mean age 4.4 years, prenatally diagnosed by both ultrasound and fetal magnetic resonanace imaging. Control groups consisted of 16 children with normal prenatal magnetic resonance imaging and 16 regular kindergarten children. A neurodevelopmental examination and the Kaufman Assessment Battery for Children were performed.

RESULTS

The neurodevelopmental and Kaufman scores were within normal range in the study groups. No significant differences between the study and control groups for most measures; however, Kaufman achievement score was significantly lower for the bilateral isolated mild ventriculomegaly group (P < .05) compared with the kindergarten children.

CONCLUSION

Preschool children with isolated mild ventriculomegaly performed within normal range compared with the controls. Nevertheless, a significant percentage of the children demonstrated developmental difficulties, lower achievement scores, justifying early school years follow-up.

Abnormalities of the foetal cerebral cortex

Prenatal ultrasound has concentrated on readily visible cerebral structures including head size, shape, ventricles, CSP (cavum septi pellucidi), cerebellar size/vermian presence and cisterna magna. However, apart from these easily visible structures it is important to evaluate the brain itself. Patients who initially appear to have mild isolated findings such as borderline ventriculomegaly in fact can have many more subtle findings that significantly alter prognosis and management that can be detected on detailed examination of the brain. There has been rapid evolution in imaging these foetuses, especially with neurosonography and MRI, and a revolution in understanding the underlying genetic and biochemical mechanisms. There is increasing emphasis to detect cortical abnormalities as early as possible. This article reviews development of the cerebral cortex, the classification, aetiologies and clinical manifestations of cortical disorders, normal and abnormal appearances at ultrasound and MRI, and approaches to investigation.

Disorders of prosencephalic development

Abnormal ventral induction may result in disorders of formation, cleavage, and midline development of prosencephalic structures. Holoprosencephaly is a developmental field defect of impaired cleavage of prosencephalon. The most widely accepted classification of holoprosencephaly recognizes three major varieties: the alobar, semilobar and lobar types, according to the severity of the malformation. The brain malformations, characterized by the fusion of the cerebral hemisphere along the midline are commonly associated with facial anomalies. Corpus callosum agenesis and septo-optic dysplasia are disorders of prosencephalic midline development, and usually have less severe presentations but still, affected subjects may suffer from neurodevelopmental retardation, and/or endocrinologic and visual disorders. In this article we report an up-to-date of pathogenesis, prenatal sonographic findings, differential diagnosis and prognosis of the aforementioned anomalies.

Contribution of fetal cerebral MRI for diagnosis of structural anomalies

More than 20 years after its introduction, magnetic resonance imaging (MRI) is now considered a useful complementary tool in the imaging work-up of fetal brain structural anomalies, but its real contribution in neuro-fetal imaging is still controversial. Our purpose is to present an overview of the most valuable indications of fetal cerebral MRI in current practice as guided by dedicated ultrasound analysis. On the basis of a review of the literature and our personal experience, we underline herein the real complementarities between these two techniques in different clinical or imaging settings and show how MRI adds significant information compared with ultrasound, especially in the late second and third trimesters. We assess the interest of using MRI from a technical point of view (complete and extensive anatomical analysis, analysis of developmental and pathological processes) and from a practical point of view in different imaging and clinical settings.

Cytomegalovirus-related fetal brain lesions: comparison between targeted ultrasound examination and magnetic resonance imaging

OBJECTIVE

To evaluate the relative contributions to the diagnosis of fetal brain abnormalities of targeted ultrasound examination and magnetic resonance imaging (MRI) in fetuses infected with cytomegalovirus (CMV).

METHODS

This was a retrospective analysis of targeted brain ultrasound examination and fetal brain MRI performed in fetuses diagnosed with CMV infection following proven maternal primary infection. The prenatal findings were compared with findings from postnatal transfontanellar ultrasound examination during the first week following delivery or from postmortem when the pregnancy was terminated.

RESULTS

Both targeted prenatal ultrasound and MRI were performed on 49 fetuses. Brain abnormalities were present in 15/49 (30.6%) cases at postnatal/post-mortem follow-up. Fetal cerebral abnormalities were observed in 19/49 (38.8%) cases by ultrasound and/or MRI. The most frequent cerebral lesions induced by CMV and seen on ultrasound and MRI, respectively, included ventricular dilatation in nine and five cases, subependymal cysts in two cases each, microcephaly in five and three cases and periventricular calcifications in five cases on ultrasound only. Termination of pregnancy was performed in 10/49 cases. Sensitivity, specificity and positive and negative predictive values for the presence of cerebral lesions were 88.9%, 93.3%, 88.9% and 93.3%, respectively, when both prenatal ultrasound and MRI findings were abnormal, 85.7%, 85.3%, 70.6% and 93.5%, respectively, for ultrasound alone, and 42.9%, 91.2%, 66.7% and 79.5%, respectively, for MRI alone. Prenatal ultrasound, MRI and postnatal or postmortem examinations were concordant with the presence of brain abnormalities in six cases; however, their conclusions were exactly concordant in only two (33.3%) of these cases. In cases without cerebral abnormality, the results of prenatal and postnatal/postmortem examinations were concordant in 28/34 cases.

CONCLUSIONS

The addition of MRI to ultrasound increases the positive predictive value for the diagnosis of fetal brain abnormalities in fetuses with CMV. The two techniques appear to be complementary and should not be mutually exclusive in high-risk fetuses. Their high predictive value for the presence or absence of cerebral lesions provides a useful tool for appropriate counseling since current evaluation of the prognosis is based mainly on the presence of fetal brain lesions. The lack of concordance between ultrasound and MRI should stimulate standardization of the interpretation of both ultrasound and MRI prospectively.