Increased Sylvian fissure angle as early sonographic sign of malformation of cortical development

Disproportion of Corpus Callosum in Fetuses With Malformations of Cortical Development

OBJECTIVE

To evaluate corpus callosum (CC) size in fetuses with malformations of cortical development (MCD) and to explore the diagnostic value of three CC length (CCL) ratios in identifying cortical abnormalities.

METHODS

This is a single-center retrospective study in singleton fetuses at 20-37 weeks of gestation between April 2017 and August 2022. The midsagittal plane of the fetal brain was obtained and evaluated for the following variables: length, height, area of the corpus callosum, and relevant markers, including the ratios of corpus callosum length to internal cranial occipitofrontal dimension (CCL/ICOFD), corpus callosum length to femur length (CCL/FL), and corpus callosum length to cerebellar vermian diameter (CCL/VD). Intra-class correlation coefficient (ICC) was used to evaluate measurement consistency. The accuracy of biometric measurements in prediction of MCD was assessed using the area under the receiver-operating-characteristics curves (AUC).

RESULTS

Fetuses with MCD had a significantly decreased CCL, height (genu and splenium), and area as compared with those of normal fetuses (P < .05), but there was no significant difference in body height (P = .326). The CCL/ICOFD, CCL/FL, and CCL/VD ratios were significantly decreased in fetuses with MCD when compared with controls (P < .05). The CCL/ICOFD ratio offered the highest predictive accuracy for MCD, yielding an AUC of 0.856 (95% CI: 0.774-0.938, P < .001), followed by CCL/FL ratio (AUC, 0.780 (95% CI: 0.657-0.904), P < .001), CCL/VD ratio (AUC, 0.677 (95% CI: 0.559-0.795), P < .01).

CONCLUSION

The corpus callosum biometric parameters in fetuses with MCD are reduced. The CCL/ICOFD ratio derived from sonographic measurements is considered a promising tool for the prenatal detection of cortical malformations. External validation of these findings and prospective studies are warranted.

Developmental Process and Symmetry of Fetal Sulci in the Mesial Area Assessed by Ultrasound: A Cohort Study in Chinese Population

OBJECTIVE

We aimed to investigate the progression of cortical development in Chinese population and to determine the rate of isolated asymmetric cortical development. We also explored the outcomes of these fetuses and determined whether cortical asymmetry represents normal individual physiological variation.

METHODS

Our observational cohort study included 456 healthy singleton pregnant women who visited Peking University First Hospital between September 2020 and December 2021. We evaluated the progression and symmetry of the parieto-occipital sulcus, calcarine sulcus, and cingulate sulcus using a scoring system during routine fetal ultrasound examinations. The outcomes of the included fetuses after birth were assessed using the Ages and Stages Questionnaire, Third Edition (ASQ-3).

RESULTS

The median gestational ages at which the parieto-occipital, calcarine, and cingulate sulci reached grade 1 were 22, 22, and 26 weeks, respectively. Among 456 included fetuses, 426 showed symmetric cortical development and 30 showed asymmetric cortical development during ultrasound examination. Fetuses with asymmetric cortical development underwent 'catch-up growth' and developed to the same grade in 2-6 weeks. All fetuses with symmetric or asymmetric cortical development had normal neurodevelopment after birth according to ASQ-3 assessment.

CONCLUSION

The gestational age at which the parieto-occipital, calcarine, and cingulate sulci can be detected using ultrasound varies in different studies. Racial differences may be present in cortical development. Normal fetuses may physiologically have mildly asymmetric cortical development in the mesial area.

Sonographic demonstration of the sulci and gyri on the convex surface in normal fetuses using 3D-ICRV rendering technology

PURPOSE

To demonstrate morphological alteration of the sulci and gyri on the convex surface in normal fetuses using innovative three-dimensional inversion and Crystalvue and Realisticvue (3D-ICRV) rendering technology.

MATERIALS AND METHODS

3D fetal brain volumes were collected from low-risk singleton pregnancies between 15+0 and 35+6 gestational weeks. Volumes were acquired from the transthalamic axial plane by transabdominal ultrasonography and were then post-processed with Crystalvue, Realisticvue rendering software and inversion mode. Volume quality was assessed. The anatomic definition of the sulci and gyri was determined according to location and orientation. The morphology alteration and sulcus display rates were recorded in sequential order of gestational weeks. Follow-up data were collected in all cases.

RESULTS

294 of 300 fetuses (294 brain volumes) (98%) with qualified fetal brain volumes were included (n=294, median 27 gestational weeks). 6 fetuses with unsatisfactory 3D-ICRV image quality were excluded. The morphology of the sulci and gyri on the brain convex surface could be demonstrated clearly on 3D-ICRV images. The Sylvian fissure was the first structure to be recognized. From 25 to 30 weeks, other sulci and gyri became visible. An ascending trend in the display rate of the sulci was found in this period. Follow-up showed no detectable anomalies.

CONCLUSION

3D-ICRV rendering technology is different from traditional 3D ultrasound. It can provide vivid and intuitive prenatal visualization of the sulci and gyri on the brain surface. Moreover, it may offer new ideas for neurodevelopment exploration.

A Clinical Approach to Semiautomated Three-Dimensional Fetal Brain Biometry-Comparing the Strengths and Weaknesses of Two Diagnostic Tools: 5DCNS+TM and SonoCNSTM

(1) Objective: We aimed to evaluate the accuracy and efficacy of AI-assisted biometric measurements of the fetal central nervous system (CNS) by comparing two semiautomatic postprocessing tools. We further aimed to discuss the additional value of semiautomatically generated sagittal and coronal planes of the CNS. (2) Methods: Three-dimensional (3D) volumes were analyzed with two semiautomatic software tools, 5DCNS+™ and SonoCNS™. The application of 5DCNS+™ results in nine planes (axial, coronal and sagittal) displayed in a single template; SonoCNS™ depicts three axial cutting sections. The tools were compared regarding automatic biometric measurement accuracy. (3) Results: A total of 129 fetuses were included for final analysis. Our data indicate that, in terms of the biometric quantification of head circumference (HC), biparietal diameter (BPD), transcerebellar diameter (TCD) and cisterna magna (CM), the accuracy of SonoCNS™ was higher with respect to the manual measurement of an experienced examiner compared to 5DCNS+™, whereas it was the other way around regarding the diameter of the posterior horn of the lateral ventricle (Vp). The inclusion of four orthogonal coronal views in 5DCNS+™ gives valuable information regarding spatial arrangements, particularly of midline structures. (4) Conclusions: Both tools were able to ease assessment of the intracranial anatomy, highlighting the additional value of automated algorithms in clinical use. SonoCNS™ showed a superior accuracy of plane reconstruction and biometry, but volume reconstruction using 5DCNS+™ provided more detailed information, which is needed for an entire neurosonogram as suggested by international guidelines.

Cat-Ear-Line: A Sonographic Sign of Cortical Development?

OBJECTIVES

Diagonal echogenic lines outside the lateral ventricle have often been observed in the anterior coronal planes of the normal fetal brain by neurosonography. We have observed abnormal shapes of these echogenic lines in cases of malformation of cortical development (MCD). We named the ultrasound finding "cat-ear-line" (CEL). This study aimed to examine how and when CEL develops in normal cases compared with MCD cases.

METHODS

We retrospectively examined the fetal brain volume dataset acquired through transvaginal 3D neurosonography of 575 control cases and 39 MCD cases from 2014 to 2020. We defined CEL as the hyperechogenic continuous lines through subplate (SP) and intermediate zone (IZ), pre-CEL as the lines that existed only within the SP, and abnormal CEL as a mass-like or mosaic shadow-like structure that existed across the SP and IZ. All fetuses in the MCD group had some neurosonographic abnormalities and were ultimately diagnosed with MCD.

RESULTS

The CEL was detected in 97.9% (369/377) of the control group from 19 to 30 weeks. The CEL visualization rate of the MCD group in the same period was 40.0% (14/35) which was significantly lower than that of the control group (P < .001).

CONCLUSIONS

From this study, it appears that the CEL is an ultrasound finding observed at and beyond 19 weeks in a normally developing fetus. In some MCD cases, pre-CEL at and beyond 19 weeks or abnormal CEL was observed. Maldeveloped CEL at mid-trimester may help identify cases at-risk of subsequent MCD.

Brain cortical maturation assessed by magnetic resonance imaging in unaffected or mildly affected fetuses with cytomegalovirus infection

OBJECTIVES

To assess by magnetic resonance imaging (MRI) the cortical maturation pattern in fetuses with cytomegalovirus (CMV) infection with mild or no abnormalities on ultrasound (US) and MRI, and to establish possible differences compared with healthy controls.

METHODS

This was a retrospective case-control study of consecutive pregnancies with a CMV-infected fetus undergoing prenatal MRI as a complementary diagnostic tool in two centers, and a control group of singleton low-risk pregnancies without fetal structural abnormalities, with normal fetal growth and with healthy newborns. CMV infection was confirmed by extraction of CMV-DNA from fetal and neonatal samples. Only fetuses with mild (mildly affected) or no (unaffected) neuroimaging abnormalities on US and MRI were included. MRI measurements of fetal parieto-occipital sulcus, cingulate sulcus and calcarine sulcus depth, Sylvian fissure depth and Sylvian fissure angles were performed and cortical development grading of specific cortical areas and sulci were assessed by one operator who was blinded to CMV infection status. Data were compared between controls and fetuses with CMV infection, using linear regression and non-parametric trend analysis.

RESULTS

Twenty-four CMV-infected fetuses (seven unaffected and 17 mildly affected) and 24 healthy controls that underwent fetal MRI between 27 and 36 weeks' gestation were included. Compared with controls, CMV-infected fetuses showed significantly larger median lateral ventricular width (right side, 7.8 (interquartile range (IQR), 5.9-9.9) mm vs 3.9 (IQR, 2.6-5.3) mm; left side, 7.5 (IQR, 6.0-10.9) mm vs 4.2 (IQR, 3.2-5.3) mm), significantly decreased parieto-occipital sulcus depth (right side, 12.6 (IQR, 11.3-13.5) mm vs 15.9 (IQR, 13.5-17.3) mm; left side, 12.3 (IQR, 10.6-13.5) mm vs 16.0 (IQR, 13.3-17.5) mm) and calcarine sulcus depth (right side, 15.4 (IQR, 14.4-16.3) mm vs 17.5 (IQR, 16.1-18.7) mm; left side, 14.6 (IQR, 14.1-15.6) mm vs 16.7 (IQR, 15.6-18.9) mm) (P < 0.001 for all). Compared with controls, CMV-infected fetuses also had significantly smaller upper (right side, 42.8° (IQR, 35.8-45.8°) vs 48.9° (IQR, 38.4-64.7°); left side, 40.9° (IQR, 34.2-45.8°) vs 48.2° (IQR, 41.9-60.7°)) and lower (right side, 41.6° (IQR, 34.4-49.2°) vs 48.9° (IQR, 40.6-60.9°); left side, 42.2° (IQR, 38.8-46.9°) vs 48.9° (IQR, 39.5-57.5°)) Sylvian fissure angles (P < 0.05 for all). In addition, the mildly affected CMV-infected fetuses had a significantly lower cortical development grading in the temporal and parietal areas, and the parieto-occipital and calcarine sulci compared with healthy fetuses (P < 0.05). These differences persisted when adjusting for gestational age, ipsilateral atrium width, fetal gender and when considering small-for-gestational age as a confounding factor.

CONCLUSIONS

Unaffected and mildly affected CMV-infected fetuses showed delayed cortical maturation compared with healthy controls. These results suggest that congenital CMV infection, even in non-severely affected fetuses that are typically considered of good prognosis, could be associated with altered brain cortical structure. Further research is warranted to better elucidate the correlation of these findings with neurodevelopmental outcomes. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Malformation of cortical development with abnormal cortex: early ultrasound diagnosis between 14 and 24 weeks of gestation

OBJECTIVE

To describe neurosonographic findings diagnostic or highly suggestive of the presence of malformations of cortical development involving the cortex that may be identified before 24 weeks of gestation.

METHODS

This was a retrospective single-center study of fetuses referred for neurosonography, during 2012-2019, with an abnormal cortical or sulcation pattern diagnosed early in the mid trimester. Stored files were analyzed for demographic data, abnormal brain findings, non-central nervous system abnormalities, final diagnosis and postnatal outcome.

RESULTS

The study cohort included 20 fetuses, with a mean gestational age at diagnosis of 18.7 (range, 14.4-23.6) weeks, in 11 of which the diagnosis was made before 20 weeks of gestation. Reasons for referral were: midline anomaly (n = 7), ventriculomegaly (n = 4), infratentorial findings (n = 3), suspected malformation of cortical development (n = 3), 'abnormal brain' (n = 2) and skeletal dysplasia (n = 1). On neurosonography, both the sulcation pattern and the cortical layer were abnormal in four cases, only the sulcation pattern was considered abnormal in seven and only the cortical layer was abnormal in nine. Nineteen fetuses presented with associated central nervous system anomalies and six also had non-central nervous system malformations. One case was recurrent. Eighteen parents opted for termination of pregnancy, including one selective termination in a twin pregnancy, and two fetuses were liveborn.

CONCLUSIONS

Familiarity with fetal brain anatomy and its early sonographic landmarks allowed early diagnosis of malformations involving cortical development. These patients are likely to represent the most severe cases and all had associated malformations. The presence of an abnormal cortical layer and/or abnormal overdeveloped sulci appear to be early signs of malformation of cortical development. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Feasibility of extended ultrasound examination of the fetal brain between 24 and 37 weeks' gestation in low-risk pregnancies

OBJECTIVES

To assess the feasibility of identifying fetal brain structures and anatomic landmarks included in the anterior complex (AC) and posterior complex (PC), as well as the proximal hemisphere (PH).

METHODS

This was a prospective observational multicenter study of healthy pregnant women evaluated by ultrasound screening at 24 to 36 + 6 weeks' gestation. Six physicians performed transabdominal ultrasound, to obtain the planes required to visualize the AC, PC, and PH. Blind analysis by an expert and non-expert operator in fetal neurosonography was used to assess the structures included in each plane view.

RESULTS

In the population studied (n=366), structure detection rates for AC were over 95 %, with an agreement of 96 % when comparing expert and non-expert examiners. Visualization of the corpus callosum crossing the midline was detected in over 97 and 96 % of cases for the AC and PC, respectively, with an agreement of over 96 %. The PH plane, particularly through the posterior access via the mastoid fontanelle, enabled visualization of the proximal anatomical structures in almost 95 % of cases. Detection of the corpus callosum through the AC and PC, both proximal/distal germinal matrix (AC) and proximal Sylvian fissure through the anterior access (PH) in the 24-25 + 6, 26-31 + 6 and 32-36 + 6 weeks' gestation groups were successful in over 96 % of cases with high level of agreement.

CONCLUSIONS

Inclusion of AC, PC, and PH later in pregnancy proves feasible with a high level of agreement between both expert and non-expert operators.

Three-Dimensional Crystal Vue Imaging technology assessment of Sylvian fissures at 20-32+6 weeks' normal gestation

OBJECTIVE

Assess developmental pattern of Sylvian fissures (SF) with Three-Dimensional Crystal Vue Imaging (3D-CVI) at 20-32⁺⁶ weeks of gestation.

METHODS

This was a prospective cross-sectional study. Assess 20-32⁺⁶ weeks' gestation normal development of fetal brain SF with 3D-CVI imaging. Measure the uncovered area and perimeter of the insula on the Three-Dimensional (3D) image and establish reference ranges for the uncovered area and perimeters of the insula during normal pregnancy 20-32⁺⁶ weeks' gestation. Examine intra- and interobserver repeatability of measurements of the uncovered area and perimeter of the insula.

RESULTS

A total of 286 normal fetuses from 20 to 32⁺⁶ weeks of gestation were studied. The SF first was trapezoidal in the 25 weeks of gestation, gradually becoming triangular as gestational age (GA) increased, and then closing from posterior up to anterior down. The uncovered area and dimension of the insula showed a parabolic curve that first increased and then decreased as GA and head circumference (HC) increased. Reference ranges for measurements of the uncovered area and perimeters of the insula during normal pregnancy 20-32⁺⁶ weeks' gestation were established. The intra- and interobserver agreements were reproducible (all ICC > 0.850); there were more than 95% dots in the Bland-Altman plots (95 limits of agreement (LOA)) scale in every figure.

CONCLUSIONS

3D-CVI can be used to observe the morphological changes of SF during middle and late pregnancy, which is an intuitive supplementary means for prenatal evaluation of cerebral cortex development, guiding subsequent follow-up and referral for assessment by expert neurosonologists.

KEY POINTS

• A new imaging technique was found to visualize the SF of fetal brain surface. • This technique has the advantages of good consistency and repeatability, simple operation, short time-consuming, and low cost. • Its 3D visualization images can be used to the development and changes of the sulci on the brain surface, it provides a new method to evaluate the development of cerebral cortex.

Applicability of a semiautomated volumetric approach (5D CNS+™) for detailed antenatal reconstruction of abnormal fetal CNS anatomy

BACKGROUND

The aim of this study was to evaluate the accuracy and reliability of a semiautomated volumetric approach (5D CNS+™) when examining fetuses with an apparent abnormal anatomy of the central nervous system (CNS).

METHODS

Stored 3D volumes extracted from a cohort of > 1.400 consecutive 2nd and 3rd trimester pregnancies (range 15-36 gestational weeks) were analyzed using the semiautomatic software tool 5D CNS+™, enabling detailed reconstruction of nine diagnostic planes of the fetal brain. All 3D data sets were examined and judged for plane accuracy, the need for manual adjustment, and fetal CNS anomalies affecting successful plane reconstruction.

RESULTS

Based on our data of 91 fetuses with structural cerebral anomalies, we were able to reveal details of a wide range of CNS anomalies with application of the 5D CNS+™ technique. The corresponding anatomical features and consecutive changes of neighboring structures could be clearly demonstrated. Thus, a profound assessment of the entire altered CNS anatomy could be achieved in nearly all cases. The comparison with matched controls showed a significant difference in volume acquisition (p < 0.001) and in need for manual adjustment (p < 0.001) but not in the drop-out rates (p = 0.677) of both groups.

CONCLUSION

5D CNS+™ is applicable in the majority of cases with brain lesions and constitutes a reliable tool even if the integrity of the fetal CNS is compromised by structural anomalies. Using volume data that were acquired in identical cutting sections needed for conventional biometry allows for detailed anatomic surveys grossly independent of the examiner's experience.

WAPM-World Association of Perinatal Medicine Practice Guidelines: Fetal central nervous system examination

These practice guidelines follow the mission of the World Association of Perinatal Medicine in collaboration with the Perinatal Medicine Foundation, bringing together groups and individuals throughout the world, with the goal of improving the ultrasound assessment of the fetal Central Nervous System (CNS) anatomy. In fact, this document provides further guidance for healthcare practitioners for the evaluation of the fetal CNS during the mid-trimester ultrasound scan with the aim to increase the ability in evaluating normal fetal anatomy. Therefore, it is not intended to establish a legal standard of care. This document is based on consensus among perinatal experts throughout the world, and serves as a guideline for use in clinical practice.

Fetal cerebellar growth and Sylvian fissure maturation: international standards from Fetal Growth Longitudinal Study of INTERGROWTH-21st Project

OBJECTIVE

To construct international ultrasound-based standards for fetal cerebellar growth and Sylvian fissure maturation.

METHODS

Healthy, well nourished pregnant women, enrolled at < 14 weeks' gestation in the Fetal Growth Longitudinal Study (FGLS) of INTERGROWTH-21^st , an international multicenter, population-based project, underwent serial three-dimensional (3D) fetal ultrasound scans every 5 ± 1 weeks until delivery in study sites located in Brazil, India, Italy, Kenya and the UK. In the present analysis, only those fetuses that underwent developmental assessment at 2 years of age were included. We measured the transcerebellar diameter and assessed Sylvian fissure maturation using two-dimensional ultrasound images extracted from available 3D fetal head volumes. The appropriateness of pooling data from the five sites was assessed using variance component analysis and standardized site differences. For each Sylvian fissure maturation score (left or right side), mean gestational age and 95% CI were calculated. Transcerebellar diameter was modeled using fractional polynomial regression, and goodness of fit was assessed.

RESULTS

Of those children in the original FGLS cohort who had developmental assessment at 2 years of age, 1130 also had an available 3D ultrasound fetal head volume. The sociodemographic characteristics and pregnancy/perinatal outcomes of the study sample confirmed the health and low-risk status of the population studied. In addition, the fetuses had low morbidity and adequate growth and development at 2 years of age. In total, 3016 and 2359 individual volumes were available for transcerebellar-diameter and Sylvian-fissure analysis, respectively. Variance component analysis and standardized site differences showed that the five study populations were sufficiently similar on the basis of predefined criteria for the data to be pooled to produce international standards. A second-degree fractional polynomial provided the best fit for modeling transcerebellar diameter; we then estimated gestational-age-specific 3^rd , 50^th and 97^th smoothed centiles. Goodness-of-fit analysis comparing empirical centiles with smoothed centile curves showed good agreement. The Sylvian fissure increased in maturation with advancing gestation, with complete overlap of the mean gestational age and 95% CIs between the sexes for each development score. No differences in Sylvian fissure maturation between the right and left hemispheres were observed.

CONCLUSION

We present, for the first time, international standards for fetal cerebellar growth and Sylvian fissure maturation throughout pregnancy based on a healthy fetal population that exhibited adequate growth and development at 2 years of age. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Sylvian fossa sonographic measurements in 18 to 23 weeks fetuses with and without cerebral malformations

BACKGROUND

Abnormal sulcation of the brain is frequently associated with severe malformations, but the prenatal diagnosis is challenging, especially in early pregnancy.

OBJECTIVE

Our study aimed to investigate the value of Sylvian fossa sonographic biometry in the diagnosis of cerebral malformation in the second trimester of gestation.

STUDY DESIGN

We prospectively established the normal values of the Sylvian fossa depth in a cohort of nonconsecutive patients, with singleton pregnancies and normal fetuses between 18+0 and 23+0 weeks' gestation. For each patient, a coronal view of the fetal brain, with a clear visualization of the anterior complex and the Sylvian fissure, was acquired by 1 sonologist, who also measured the depth of the fossa. Reproducibility for each parameter was assessed by a second sonologist using stored images. We also retrospectively acquired the same measurements in second trimester fetuses with central nervous system anomalies.

RESULTS

In 103 fetuses with a normal sonogram, the mean depth of the Sylvian fossa was 3.9±0.8 mm Interobserver reproducibility analysis demonstrated good results. Notably, 11 of 31 fetuses with cerebral malformations had a Sylvian fossa depth of <-2 z-scores, and these were found to have malformations of cortical development, lissencephaly in particular, or microcephaly.

CONCLUSION

Sonographic measurement of the Sylvian fossa during second trimester is feasible and reproducible. A shallow Sylvian fossa is associated with malformations of cortical development, microcephaly, or both.

Superficial anatomy of the neonatal cerebrum - an ultrasonographic roadmap

Neurosonography is an essential imaging modality for assessing the neonatal brain, particularly as a screening tool to evaluate intracranial hemorrhage, hydrocephalus and periventricular leukomalacia. The primary advantages of neurosonography include portability, accessibility and lack of ionizing radiation. Its main limitations are intrinsic operator dependence and the need for an open fontanelle. Neurosonographic imaging acquisition is typically performed by placing a sector transducer over the anterior fontanelle and following sagittal and coronal sweeps. The sensitivity of neurosonography has markedly improved thanks to the adoption of modern imaging equipment, the use of dedicated head probes, and the employment of advanced diagnostic US techniques. These developments have facilitated more descriptive identification of specific cerebral anatomical details, improving understanding of the cerebral anatomy by conventional US. Such knowledge is fundamental for enhanced diagnostic sensitivity and is a key to understanding pathological states. Furthermore, familiarity with normal anatomy is crucial for understanding pathological states. Our primary goal in this review was to supplement these technological developments with a roadmap to the cerebral landscape. We accomplish this by presenting a systematic approach to using routine US for consistent identification of the most crucial cerebral landmarks, reviewing their relationship with adjacent structures, and briefly describing their primary function.

Brain views that benefit from three-dimensional ultrasound

PURPOSE OF REVIEW

Fetal central nervous system malformations are among the most common congenital anomalies. Whereas simple axial views are sufficient for basic fetal brain examination, other important views are essential for a more detailed examination, which are sometimes challenging to obtain. Three-dimensional ultrasound can be helpful in obtaining standardized and reproducible images of many difficult fetal brain views. The aim of the present review is to explore the most recent evidence on the utility and technique of three-dimensional ultrasound in the examination of the fetal brain, with particular emphasis on the brain views that benefit from three-dimensional ultrasound.

RECENT FINDINGS

The article describes the various techniques of acquisition and analyses of three-dimensional ultrasound volumes of the fetal brain and their usefulness in the assessment of normal and abnormal fetal brain anatomy. Three-dimensional ultrasound has also permitted the application of many new technologies, such as artificial intelligence and deep machine learning. Recently, thanks to high-quality three-dimensional ultrasound, fetal cortical development can be assessed quantitatively and reliably.

SUMMARY

Three dimensional ultrasound can help as a complementary tool to two-dimensional ultrasound in the assessment of the fetal brain development and malformations. In addition, it paves the way for the application of promising technologies in the evaluation of fetal brain.

VIDEO ABSTRACT

A video summarizing the findings of the article. The video illustrates the various approaches and techniques applied for the examination of the fetal brain using three-dimensional ultrasound. Furthermore, the advantages and future perspectives of the application of three-dimensional ultrasound in the examination of the fetal brain are discussed, http://links.lww.com/COOG/A74.

Validation of a semiautomated volumetric approach for fetal neurosonography using 5DCNS+ in clinical data from > 1100 consecutive pregnancies

OBJECTIVE

The aim of this study was to evaluate the validity of a semiautomated volumetric approach (5DCNS+) for the detailed assessment of the fetal brain in a clinical setting.

METHODS

Stored 3D volumes of > 1100 consecutive 2nd and 3rd trimester pregnancies (range 15-36 gestational weeks) were analyzed using a workflow-based volumetric approach 5DCNS+, enabling semiautomated reconstruction of diagnostic planes of the fetal central nervous system (CNS). All 3D data sets were examined for plane accuracy, the need for manual adjustment, and fetal-maternal characteristics affecting successful plane reconstruction. We also examined the potential of these standardized views to give additional information on proper gyration and sulci formation with advancing gestation.

RESULTS

Based on our data, we were able to show that gestational age with an OR of 1.085 (95% CI 1.041-1.132) and maternal BMI with an OR of 1.022 (95% CI 1.041-1.054) only had a slight impact on the number of manual adjustments needed to reconstruct the complete volume, while maternal age and fetal position during acquisition (p = 0.260) did not have a significant effect. For the vast majority (958/1019; 94%) of volumes, using 5DCNS+ resulted in proper reconstruction of all nine diagnostic planes. In less than 1% (89/9171 planes) of volumes, the program failed to give sufficient information. 5DCNS+ was able to show the onset and changing appearance of CNS folding in a detailed and timely manner (lateral/parietooccipital sulcus formation seen in < 65% at 16-17 gestational weeks vs. 94.6% at 19 weeks).

CONCLUSIONS

The 5DCNS+ method provides a reliable algorithm to produce detailed, 3D volume-based assessments of fetal CNS integrity through a standardized reconstruction of the orthogonal diagnostic planes. The method further gives valid and reproducible information regarding ongoing cortical development retrieved from these volume sets that might aid in earlier in utero recognition of subtle structural CNS anomalies.