Biometry of the fetal corpus callosum by three-dimensional ultrasound

Fetal indusium griseum is a possible biomarker of the regularity of brain midline development in 3T MR imaging: A retrospective observational study

INTRODUCTION

This study aimed to assess the visibility of the indusium griseum (IG) in magnetic resonance (MR) scans of the human fetal brain and to evaluate its reliability as an imaging biomarker of the normality of brain midline development.

MATERIAL AND METHODS

The retrospective observational study encompassed T2-w 3T MR images from 90 post-mortem fetal brains and immunohistochemical sections from 41 fetal brains (16-40 gestational weeks) without cerebral pathology. Three raters independently inspected and evaluated the visibility of IG in post-mortem and in vivo MR scans. Weighted kappa statistics and regression analysis were used to determine inter- and intra-rater agreement and the type and strength of the association of IG visibility with gestational age.

RESULTS

The visibility of the IG was the highest between the 25 and 30 gestational week period, with a very good inter-rater variability (kappa 0.623-0.709) and excellent intra-rater variability (kappa 0.81-0.93). The immunochemical analysis of the histoarchitecture of IG discloses the expression of highly hydrated extracellular molecules in IG as the substrate of higher signal intensity and best visibility of IG during the mid-fetal period.

CONCLUSIONS

The knowledge of developmental brain histology and fetal age allows us to predict the IG-visibility in magnetic resonance imaging (MRI) and use it as a biomarker to evaluate the morphogenesis of the brain midline. As a biomarker, IG is significant for post-mortem pathological examination by MRI. Therefore, in the clinical in vivo imaging examination, IG should be anticipated when an assessment of the brain midline structures is needed in mid-gestation, including corpus callosum thickness measurements.

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.

Assessment of fetal corpus callosum biometry by 3D super-resolution reconstructed T2-weighted magnetic resonance imaging

Objective

To assess the accuracy of corpus callosum (CC) biometry, including sub-segments, using 3D super-resolution fetal brain MRI (SR) compared to 2D or 3D ultrasound (US) and clinical low-resolution T2-weighted MRI (T2WS).

Method

Fetal brain biometry was conducted by two observers on 57 subjects [21-35 weeks of gestational age (GA)], including 11 cases of partial CC agenesis. Measures were performed by a junior observer (obs1) on US, T2WS and SR and by a senior neuroradiologist (obs2) on T2WS and SR. CC biometric regression with GA was established. Statistical analysis assessed agreement within and between modalities and observers.

Results

This study shows robust SR to US concordance across gestation, surpassing T2WS. In obs1, SR aligns with US, except for genu and CC length (CCL), enhancing splenium visibility. In obs2, SR closely corresponds to US, differing in rostrum and CCL. The anterior CC (rostrum and genu) exhibits higher variability. SR's regression aligns better with literature (US) for CCL, splenium and body than T2WS. SR is the method with the least missing values.

Conclusion

SR yields CC biometry akin to US (excluding anterior CC). Thanks to superior 3D visualization and better through plane spatial resolution, SR allows to perform CC biometry more frequently than T2WS.

Corpus Callosum Length and Cerebellar Vermian Height in Fetal Growth Restriction

INTRODUCTION

Growth-restricted fetuses may have changes in their neuroanatomical structures that can be detected in prenatal imaging. We aim to compare corpus callosal length (CCL) and cerebellar vermian height (CVH) measurements between fetal growth restriction (FGR) and control fetuses and to correlate them with cerebral Doppler velocimetry in growth-restricted fetuses.

METHODS

This was a prospective cohort of FGR after 20 weeks of gestation with ultrasound measurements of CCL and CVH. Control cohort was assembled from fetuses without FGR who had growth ultrasound after 20 weeks of gestation. We compared differences of CCL or CVH between FGR and controls. We also tested for the correlations of CCL and CVH with middle cerebral artery (MCA) pulsatility index (PI) and vertebral artery (VA) PI in the FGR group. CCL and CVH measurements were adjusted by head circumference (HC).

RESULTS

CCL and CVH were obtained in 68 and 55 fetuses, respectively. CCL/HC was smaller in FGR fetuses when compared to control fetuses (difference = 0.03, 95% CI: [0.02, 0.04], p < 0.001). CVH/HC was larger in FGR fetuses compared to NG fetuses (difference = 0.1, 95% CI: [-0.01, 0.02], p = < 0.001). VA PI multiples of the median were inversely correlated with CVH/HC (rho = -0.53, p = 0.007), while CCL/HC was not correlated with VA PI. Neither CCL/HC nor CVH/HC was correlated with MCA PI.

CONCLUSIONS

CCL/HC and CVH/HC measurements show differences in growth-restricted fetuses compared to a control cohort. We also found an inverse relationship between VA PI and CVH/HC. The potential use of neurosonography assessment in FGR assessment requires continued explorations.

A de novo pathogenic variant in DHX30 gene in a fetus with isolated dysgenesis of the corpus callosum

A 36 years old woman in her first pregnancy was referred at 24w3d for a dedicated neurosonographic examination due to a suspected short corpus callosum (CC). The examination depicted a dysgenetic CC with asymmetric thickness at the level of the body in coronal views, very thin in the midline and thicker in both sides, suggesting bilateral formation of Probst bundles. The BPD, HC, and transverse cerebellar diameters were in the normal low range without associated growth restriction. Associated anomalies were not detected in the brain or other organs. Following genetic consultation and a normal CMA, trio exome sequencing was performed and a de novo missense pathogenic mutation c.2353 C > T in the DHX30 gene was detected. This variant has been previously reported in children and adults, mostly with a severe phenotype including neurodevelopmental disorder with variable motor and language impairment, but also mild phenotypes have been reported. MRI describes delayed myelination, ventriculomegaly, and cortical and cerebellar atrophy as imaging features in affected patients. This is the first prenatal report of a DHX30-associated neurodevelopmental disorder in which the fetus presents with isolated callosal dysgenesis, stressing the importance of exome sequencing in fetuses with this condition, as far as it is phenotypic presentation of numerous syndromes with different outcomes.

Corpus callosum in children with neurodevelopmental delay: MRI standard qualitative assessment versus automatic quantitative analysis

BACKGROUND

The corpus callosum (CC) is a key brain structure. In children with neurodevelopmental delay, we compared standard qualitative radiological assessments with an automatic quantitative tool.

METHODS

We prospectively enrolled 73 children (46 males, 63.0%) with neurodevelopmental delay at single university hospital between September 2020 and September 2022. All of them underwent 1.5-T brain magnetic resonance imaging (MRI) including a magnetization-prepared 2 rapid acquisition gradient echoes - MP2RAGE sequence. Two radiologists blindly reviewed the images to classify qualitatively the CC into normal, hypoplasic, hyperplasic, and/or dysgenetic classes. An automatic tool (QuantiFIRE) was used to provide brain volumetry and T1 relaxometry automatically as well as deviations of those parameters compared with a healthy age-matched cohort. The MRI reference standard for CC volumetry was based on the Garel et al. study. Cohen κ statistics was used for interrater agreement. The radiologists and QuantiFIRE's diagnostic accuracy were compared with the reference standard using the Delong test.

RESULTS

The CC was normal in 42 cases (57.5%), hypoplastic in 20 cases (27.4%), and hypertrophic in 11 cases (15.1%). T1 relaxometry values were abnormal in 26 children (35.6%); either abnormally high (18 cases, 24.6%) or low (8 cases, 11.0%). The interrater Cohen κ coefficient was 0.91. The diagnostic accuracy of the QuantiFIRE prototype was higher than that of the radiologists for hypoplastic and normal CC (p = 0.003 for both subgroups, Delong test).

CONCLUSIONS

An automated volumetric and relaxometric assessment can assist the evaluation of brain structure such as the CC, particularly in the case of subtle abnormalities.

RELEVANCE STATEMENT

Automated brain MRI segmentation combined with statistical comparison to normal volume and T1 relaxometry values can be a useful diagnostic support tool for radiologists.

KEY POINTS

• Corpus callosum abnormality detection is challenging but clinically relevant. • Automated quantitative volumetric analysis had a higher diagnostic accuracy than that of visual appreciation of radiologists. • Quantitative T1 relaxometric analysis might help characterizing corpus callosum better.

Evaluation of the height of the corpus callosum body region in fetal meningomyelocele malformation

PURPOSE

To investigate height of the corpus callosum (CC) in order to describe the corpus callosum anomalies in fetuses with meningomyelocele (MMC) and compare these findings with the corpus callosum of healthy fetuses.

METHODS

In this study, fetal MRI examinations were performed on 44 fetal MMC malformation cases. As the control group, 34 fetal MRI examinations, which were anatomically normal, were evaluated retrospectively. In the study group, lateral ventricle diameter, the level and diameter of the MMC defect, and CC height were measured. In the control group, CC height and lateral ventricular diameter were measured.

RESULTS

The mean CC body height was 1.36 mm in the study group, and 2.48 mm in the control group. The height of the CC body region of the study population was inclined to be thinner compared with the control population (p<0.001).

CONCLUSIONS

The fact that the height of the CC body region was found to be thinner in fetal MRI in cases of MMC compared with normal fetuses suggests that various callosal anomalies are uncertain, investigation of additional callosal anomalies may be beneficial in the decision for the continuation of pregnancy, and termination or intrauterine surgery in cases with MMC. Further large case group studies are needed.

Corpus callosum-fastigium and tectal lengths in late-onset small fetuses

OBJECTIVE

To investigate measurements on neurosonography of midbrain morphology, including corpus callosum-fastigium length and tectal length, in late-onset small fetuses subclassified as small-for-gestational-age (SGA) or growth-restricted (FGR).

METHODS

This was a case-control study of consecutive singleton pregnancies delivered at term at a single center between January 2019 and July 2021, including those with late-onset smallness (estimated fetal weight (EFW) < 10th centile) and appropriate-for-gestational-age controls matched by age at neurosonography. Small fetuses were further subdivided into SGA (EFW between 3rd and 9th centile and normal fetoplacental Doppler) and FGR (EFW < 3rd centile or EFW < 10th centile with abnormal cerebroplacental ratio and/or uterine artery Doppler). Transvaginal neurosonography was performed at a mean ± SD gestational age of 33 ± 1 weeks in all fetuses to evaluate corpus callosum-fastigium length and tectal length in the midsagittal plane. Intra- and interobserver agreement was evaluated using the intraclass correlation coefficient and Bland-Altman plots.

RESULTS

A total of 70 fetuses with late-onset smallness (29 with SGA and 41 with FGR) and 70 controls were included. Compared with controls, small fetuses showed significantly shorter corpus callosum-fastigium length (median (interquartile range), 44.7 (43.3-46.8) mm vs 43.7 (42.4-45.5) mm, P < 0.001) and tectal length (mean ± SD, 10.5 ± 0.9 vs 9.6 ± 1.0 mm, P < 0.001). These changes were more prominent in FGR fetuses, with a linear trend across groups according to severity of smallness. Corpus callosum-fastigium length and tectal length measurements showed excellent intra- and interobserver reliability.

CONCLUSIONS

Small fetuses exhibited shorter corpus callosum-fastigium length and tectal length compared with controls, and these differences were more pronounced in fetuses with more severe smallness. These findings illustrate the potential value of midbrain measurements assessed on neurosonography as biomarkers for brain development in a high-risk population. However, further studies correlating these parameters with postnatal functional tests and follow-up are needed. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Corpus callosal reference ranges: systematic review of methodology of biometric chart construction and measurements obtained

OBJECTIVE

Adequate reference ranges of size of the corpus callosum (CC) are necessary to improve characterization of CC abnormalities and parental counseling. The objective of this study was to evaluate the methodology used in studies developing references charts for CC biometry.

METHODS

We conducted a systematic review of studies on fetal CC biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods. We included observational studies whose primary aim was to create ultrasound or magnetic resonance imaging charts for CC size in a normal population of fetuses. Studies were scored against a predefined set of independently agreed methodological criteria, and an overall quality score was given for each study.

RESULTS

Twelve studies met the inclusion criteria. Quality scores ranged between 17.4% and 95.7%. The greatest potential for bias was noted for the following items: sample selection and sample-size calculation, as only 17% of the studies were population-based and had consecutive or random recruitment of patients and with a justification of the sample size; number of measurements obtained for CC biometry, as only 17% of the studies performed more than one measurement per fetus and per scan; and description of characteristics of the study population, as only 8% of the studies clearly reported a minimum dataset of demographic characteristics.

CONCLUSIONS

Our review demonstrates substantial heterogeneity in methods and final biometric values of the fetal CC across the evaluated studies. The use of uniform methodology of the highest quality is essential in order to define a 'short' CC and provide appropriate parental counseling. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Early Fetal Corpus Callosum: Demonstrating Normal Growth and Detecting Pathologies in Early Pregnancy

BACKGROUND AND PURPOSE

A malformed corpus callosum carries a risk for abnormal neurodevelopment. The advent of high-frequency transducers offers the opportunity to assess corpus callosum development in early pregnancy. The aim of the study was to construct a reference chart of the fetal corpus callosum length on ultrasound between 13 and 19 weeks of gestation and to prospectively examine growth patterns in pathologic cases.

MATERIALS AND METHODS

We performed a prospective cross-sectional study between 2020 and 2022 in well-dated, low-risk, singleton pregnancies between 13 and 19 weeks of gestation. A standardized image was obtained in the midsagittal plane. Imaging criteria were used as a confirmation of the early corpus callosum. Measurements were taken by 4 trained sonographers. Intra- and interobserver variability was assessed. Corpus callosum length in centiles were calculated for each gestational week.

RESULTS

One hundred eighty-seven fetuses were included in the study. All cases met inclusion criteria. At 13 weeks of gestation, the margins of the early corpus callosum were sufficiently clear to be measured in 80% (20/25) of fetuses. A cubic polynomial regression model best described the correlation between corpus length and gestational age. The correlation coefficient (r 2) was 0.929 (P < .001). Intra- and interobserver variability had high interclass correlation coefficients (>0.99). Presented is the earliest published case of agenesis of corpus callosum and a case of dysgenetic corpus callosum in Rubinstein-Taybi syndrome.

CONCLUSIONS

Provided is a nomogram of the early fetal corpus callosum. Applying imaging criteria helped to identify a case of complete agenesis of the corpus callosum as early as 14 weeks.

Visualization of the Third Ventricle, the Future Cavum Septi Pellucidi, and the Cavum Veli Interpositi at 11+3 to 13+6 Gestational Weeks on 3D Transvaginal Ultrasound Including Normative Data

OBJECTIVES

To show the development of the third ventricle, commissural plate, future cavum septi pellucidi, and cavum veli interpositi in weeks 12-14 by transvaginal 3D ultrasound.

METHODS

This is a prospective transvaginal 3D study carried out to define the third ventricle and the diencephalic midline structures surrounding it. 93 of 387 fetuses in which the commissural plate with the future cavum septi pellucidi, cavum veli interpositi, and the roof of the third ventricle could be well visualized, were selected with the choroid plexus of the third ventricle and the pituitary gland serving as leading structures. In a small number of fetuses, the optic chiasm could also be displayed. In addition, the following measurements were performed: third ventricle craniocaudal and anteroposterior, roof of the third ventricle/cavum veli interpositi, and fcsp.

RESULTS

The sonomorphologic characteristics of the commissural plate, the future cavum septi pellucidi, and the cavum veli interpositi are described IN 9% OF THE FETUSES examined. Measurements of the third ventricle, cavum veli interpositi, and the roof of the third ventricle show the following results: 3rd V cc = 3.895 + 0.091*CRL mm; 3rd V ap = 4.175 + 0.036*CRL mm; CVI ap = 2.223 + 0.029*CRL mm; CVI cc = 0.139 + 0.02*CRL mm.

CONCLUSION

Transvaginal neurosonography enables visualization and measurement of the normal fetal third ventricle at 12-14 weeks of gestation including visualization of the future cavum septi pellucidi and the cavum veli interpositi. BEFORE USE IN PATIENTS CAN BE CONSIDERED, FURTHER SCIENTIFIC WORK IS REQUIRED.

Reference Ranges for Corpus Callosum and Cavum Septi Pellucidi Biometry on Prenatal Ultrasound: Systematic Review and Meta-Analysis

We conducted a systematic review and meta-analysis of published nomograms for fetal corpus callosum and cavum septi pellucid biometry. A structured literature search was conducted to identify studies that reported normal measurements of the fetal corpus callosum and cavum septi pellucidi. Random effects metaanalysis was used to calculate normal ranges, and reference curves are provided. The quality assessment demonstrated that there was generally poor reporting regarding maternal characteristics and neonatal outcomes. Our findings emphasize that standardization of research protocols and publishing criteria for normal biometric ranges is needed.

Fetal corpus callosum abnormalities: Ultrasound and magnetic resonance imaging role

The corpus callosum (CC) is the major interhemispheric commissure and its abnormalities include agenesis, hypoplasia, and hyperplasia. The CC anomalies are typically related to other central nervous system (CNS) or extra-CNS malformations. The antenatal diagnosis of complete CC agenesis is easy after mid-trimester by ultrasound (US) even in the axial plane. The non-visualization of cavum septum pellucidum and colpocephaly are critical signs in the axial view. More subtle findings (i.e., hypoplasia and partial agenesis) might also be recognized antenatally. In this review, the focus was given on the prenatal diagnosis of CC abnormalities in US and magnetic resonance imaging.

Standard values for MRI brain biometry throughout the first year of life

BACKGROUND

Brain structures in the infant brain are investigated reliably using cranial magnetic resonance imaging. However, the lack of quantitative standard values for various brain regions results in data interpretation that is often subjective or based on small patient cohorts. The aim of this study was to create simple linear measurements to assess brain structures in infancy.

METHODS

We assessed cranial magnetic resonance imaging sessions of 131 children without intracerebral pathology retrospectively for size of various brain structures throughout the first year of life.

RESULTS

Standard values for the size and the growth rate of 14 brain structures including lateral ventricles, frontal subarachnoid space, pons, medulla oblongata, cerebellar vermis, pituitary gland, optical nerve, corpus callosum and the tegmentovermian angle were defined.

CONCLUSION

Our study offers reference values for the biometric assessment of the infant brain. Especially in children with multiple brain malformations, it is essential to know the normal absolute and relative size of brain structures.

Methodological quality of fetal brain structure charts for screening examination and targeted neurosonography: a systematic review

Introduction: The methodological quality of fetal brain charts has not been critically appraised yet. Material and methods: MEDLINE, EMBASE, CINAHL and the Web of Science databases were searched electronically up to December 31, 2020. The primary outcome was to evaluate the methodology of the studies assessing the growth of fetal brain structures throughout gestation. A list of 28 methodological quality criteria divided into three domains according to “study design”, “statistical and reporting methods”, and “specific relevant neurosonography aspects” was developed in order to assess the methodological appropriateness of the included studies. The overall quality score was defined as the sum of low risk of bias marks, with the range of possible scores being 0–28. This quality assessment was applied to each individual study reporting reference ranges for fetal brain structures. Results: Sixty studies were included in the systematic review. The overall mean quality score of the studies included in this review was 51.3%. When focusing on each of the assessed domains, the mean quality score was 53.7% for “study design”, 54.2% for “statistical and reporting methods” and 38.6% for “specific relevant neurosonography aspects”. The sample size calculation, the correlation with a postnatal imaging evaluation and the whole fetal brain assessment were the items at the highest risk of bias for each domain assessed, respectively. The subgroup analysis according to different anatomical location showed the lowest quality score for ventricular and periventricular structures and the highest for cortical structures. Conclusions: Most previously published studies reporting fetal brain charts suffers from poor methodology and are at high risk of biases, mostly when focusing on neurosonography issues. Further prospective longitudinal studies aiming at constructing specific growth charts for fetal brain structures should follow rigorous methodology to minimize the risk of biases, guarantee higher levels of reproducibility and improve the standard of care.

Corpus callosum size by neurosonography in fetuses with congenital heart defect and relationship with expected pattern of brain oxygen supply

OBJECTIVE

To evaluate corpus callosum (CC) size by neurosonography (NSG) in fetuses with an isolated major congenital heart defect (CHD) and explore the association of CC size with the expected pattern of in-utero oxygen supply to the brain.

METHODS

A total of 56 fetuses with postnatally confirmed isolated major CHD and 56 gestational-age-matched controls were included. Fetuses with CHD were stratified into two categories according to the main expected pattern of cerebral arterial oxygen supply: Class A, moderately to severely reduced oxygen supply (left outflow tract obstruction and transposition of the great arteries) and Class B, near normal or mildly impaired oxygenated blood supply to the brain (other CHD). Transvaginal NSG was performed at 32-36 weeks in all fetuses to evaluate CC length, CC total area and areas of CC subdivisions in the midsagittal plane.

RESULTS

CHD fetuses had a significantly smaller CC area as compared to controls (7.91 ± 1.30 vs 9.01 ± 1.44 mm² ; P < 0.001), which was more pronounced in the most posterior part of the CC. There was a significant linear trend for reduced CC total area across the three clinical groups, with CHD Class-A cases showing more prominent changes (controls, 9.01 ± 1.44 vs CHD Class B, 8.18 ± 1.21 vs CHD Class A, 7.53 ± 1.33 mm² ; P < 0.05).

CONCLUSIONS

Fetuses with major CHD had a smaller CC compared with controls, and the difference was more marked in the CHD subgroup with expected poorer brain oxygenation. Sonographic CC size could be a clinically feasible marker of abnormal white matter development in CHD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal diagnosis of a likely pathogenic variant in ZBTB18: Natural evolution of fetal phenotype including the long bones and corpus callosum

Pathogenic variants in ZBTB18 gene have been described only postnatally with a variable phenotypic spectrum that includes intellectual disability, microcephaly, hypotonia, poor growth, corpus callosum abnormalities, seizures, and dysmorphic facial features. These features overlap with the phenotype of 1q43-q44 deletion syndrome (OMIM #612337). There are several genes within the 1q43-q44 deletion region, and ZBTB18 is of particular interest due to its known involvement in neuronal differentiation and migration. We describe here a fetus presenting with an intrauterine growth restriction, diminished long bones growth, single umbilical artery, and a short corpus callosum. On mid pregnancy ultrasound, all biometric parameters including the corpus callosum were relatively small but still within the normal range. Only a targeted follow-up during the third trimester, including neurosonographic and MRI exams, revealed the full extent of the malformation, leading to amniocentesis and a genetic workup that led to the identification of a de novo likely pathogenic variant in ZBTB18 gene. This is the first description of the evolving phenotype of a ZBTB18-related disorder in a fetus, which emphasizes the challenging diagnosis of subtle findings, that mandates a high level of clinical suspicion and a targeted follow-up throughout pregnancy.

Hypoplasia of the Corpus Callosum: A Single Center Experience and a Concise Literature Review

AimCorpus callosum hypoplasia is described as a fully formed corpus callosum with reduced thickness. Our purpose is to evaluate the current knowledge about this anomaly including it's effect on the neurodevelopmental outcome and to report our single center experience. Methods: PubMed, Medline and reference lists were searched using combinations of these terms: "Hypoplasia of corpus callosum and prenatal diagnosis" and "neurodevelopmental outcome". Results: Eleven studies were included, with a final population of 48 patients (45 cases from literature plus 3 of our own cases). Hypoplasia of the corpus callosum was detected by ultrasound scan alone in 77% of cases: magnetic resonance confirmed the ultrasound suspicion in the remaining 23% of cases. Isolated form was detected in 31% cases. Adverse fetal outcomes occurred in 62% of cases, while 38% of cases were born alive. The neurodevelopmental outcome was found to be normal in 33% of cases. Conclusion: Antenatal detection of corpus callosum hypoplasia remains challenging. Counseling is difficult because neurodevelopmental outcomes are variable.

A novel family illustrating the mild phenotypic spectrum of TUBB2B variants

TUBB2B codes for one of the isotypes of β-tubulin and dominant negative variants in this gene result in distinctive malformations of cortical development (MCD), including dysgyria, dysmorphic basal ganglia and cerebellar anomalies. We present a novel family with a heterozygous missense variant in TUBB2B and an unusually mild phenotype. First, at 21 37 weeks of gestation ultrasonography revealed a fetus with a relatively small head, enlarged lateral ventricles, borderline hypoplastic cerebellum and a thin corpus callosum. The couple opted for pregnancy termination. Exome sequencing on fetal material afterwards identified a heterozygous maternally inherited variant in TUBB2B (NM_178012.4 (TUBB2B):c.530A > T, p.(Asp177Val)), not present in GnomAD and predicted as damaging. The healthy mother had only a language delay in childhood. This inherited TUBB2B variant prompted re-evaluation of the older son of the couple, who presented with a mild delay in motor skills and speech. His MRI revealed mildly enlarged lateral ventricles, a thin corpus callosum, mild cortical dysgyria, and dysmorphic vermis and basal ganglia, a pattern typical of tubulinopathies. This son finally showed the same TUBB2B variant, supporting pathogenicity of the TUBB2B variant. These observations illustrate the wide phenotypic heterogeneity of tubulinopathies, including reduced penetrance and mild expressivity, that require careful evaluation in pre- and postnatal counseling.

Incidence and patterns of abnormal corpus callosum in fetuses with isolated spina bifida aperta

OBJECTIVE

To determine the incidence and characterise corpus callosum (CC) abnormalities in fetuses with spina bifida aperta (SBA) between 18 and 26 weeks of gestation.

METHODS

This was a retrospective study on fetuses with isolated SBA and who were assessed for fetal surgery. Digitally stored ultrasound images of the brain were reviewed for the presence/absence of the CC, and the length and diameter of its constituent parts (rostrum, genu, body and splenium). We used regression analysis to determine the relationship between CC abnormalities and gestational age, head circumference, ventricle size, lesion level and lesion type.

RESULTS

Nearly three-quarters of fetuses with isolated SBA had an abnormal CC (71.7%, 76/106). Partial agenesis was most common in the splenium (18.9%, 20/106) and the rostrum (13.2%, 14/106). The most common abnormal pattern was of a short CC with normal diameter throughout. Of note, 20.8% (22/106) had a hypoplastic genu and 28.3% (30/106) had a thick body part. Larger lateral ventricle size was associated with partial agenesis of the CC (odds ratio [OR]: 0.14, p < 0.001) and inversely associated with a shorter CC (OR: 2.60, p < 0.01).

CONCLUSION

An abnormal CC is common in fetuses with isolated SBA who are referred for fetal surgery.

Normal cavum veli interpositi at 14-17 gestational weeks: three-dimensional and Doppler transvaginal neurosonographic study

OBJECTIVES

To provide evidence to support the hypothesis that the midline cyst-like fluid collection that is frequently observed on fetal brain ultrasound (US) imaging during the early second trimester represents a normal transient cavum veli interpositi (CVI).

METHODS

This was a retrospective analysis of 89 three-dimensional normal fetal brain volumes, acquired by transvaginal US imaging in 87 pregnant women between 14 and 17 gestational weeks. The midsagittal view was studied using multiplanar imaging, and the maximum length of the fluid collection located over (dorsal to) the tela choroidea of the third ventricle was measured. We calculated the correlation of the transverse cerebellar diameter (TCD) and of the maximum length of the fluid collection with gestational age according to last menstrual period. Color Doppler images were analyzed to determine the location of the internal cerebral veins with respect to the location of the fluid collection. Reports of the second-trimester anatomy scan at 22-24 weeks were also reviewed.

RESULTS

Interhemispheric fluid collections of various sizes were found in 55% (49/89) of the volumes (mean length, 5 (range, 3.0-7.8) mm). There was a strong correlation between TCD and gestational age (Pearson's correlation, 0.862; P < 0.001). There was no correlation between maximum fluid length and gestational age (Pearson's correlation, -0.442; P = 0.773). Color Doppler images were retrieved in 32 of the 49 fetuses; in 100% of these, the internal cerebral veins coursed within the echogenic roof of the third ventricle. The midline structures were normal at the 22-24-week scan in all cases.

CONCLUSIONS

In approximately half of normal fetuses, during the evolution of the midline structures of the brain, various degrees of fluid accumulate transiently in the velum interpositum, giving rise to a physiologic CVI. Patients should be reassured that this is a normal phenomenon in the early second trimester that, if an isolated finding, has no influence on fetal brain development. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

3-Dimensional Ultrasound: How can the Fetal Corpus Callosum Be Demonstrated Correctly?

The aim of this article is to outline the correct demonstration of the fetal corpus callosum with 3D ultrasound between 18 and 40 weeks of gestation. An abdominal or transvaginal 3D transducer can be used for acquisition of the fetal brain depending on the position of the fetus. The best demonstration of the corpus callosum can be achieved, when the volume with the corpus callosum is acquired from a sagittal or parasagittal sectional plane of the brain. Once the volume is stored in the memory, the multiplanar mode allows manipulation in all three dimensions until the exact median plane is seen, showing the corpus callosum as a hypo- or anechoic curved structure. Volume acquisition of the brain from an axial plane of the fetal head - typically used for biometrical measurements of the head diameters - is not recommended for clinical evaluation of the corpus callosum because the reconstructed median plane does not reveal the margins and the structure of the corpus callosum precisely. Other display modes such as volume contrast imaging (VCI), OmniView-VCI, and tomographic display may also be used for demonstration of the corpus callosum. However, these display modes only provide the operator with good image quality of the corpus callosum if the fetal brain was acquired from a sagittal and not from an axial plane. CONCLUSION:  3D ultrasound is an excellent clinical tool for the exact presentation of the fetal corpus callosum because it allows volume manipulation of the fetal head in all three dimensions with precise demonstration of the median plane of the brain.

Comparison between Two-Dimensional and Three-Dimensional Assessments of the Fetal Corpus Callosum: Reproducibility of Measurements and Acquisition Time

The objective of this article was to study the reproducibility and reliability of the fetal corpus callosum measurements between two-dimensional (2D) and three-dimensional (3D) acquisitions. This prospective study enrolled 475 fetuses, monitored between 18 and 38 weeks of gestation by two operators. Starting from a transcerebellar axial plane, 3D and 2D mid-sagittal views of the corpus callosum were obtained. Measurements of length and thickness were performed and underwent quality control by independent reviewers. The acquisition time of the two methods was measured. Means, differences, and linear correlations were analyzed using t-test, regression and Pearson's correlation coefficients, and Bland–Altman's plots. This analysis was performed for each operator to test the interobserver reproducibility. Among the 432 cases measured using both methods, 380 (88%) were validated by quality control. The mean corpus callosum length and thickness were essentially the same using 2D and 3D measurements (2D: 33.8 ± 8.7 vs. 3D: 33.7 ± 8.7 mm, 2D: 2.2 ± 0.4 vs. 3D: 2.2 ± 0.4 mm, respectively; mean ± standard deviation [SD]). Linear regression coefficients and Pearson's coefficients were similar for length (2D: 0.8283 and 0.9191 vs. 3D: 0.8271 and 0.9095), but slightly different regarding thickness (2D: 0.6775 and 0.8231 vs. 3D: 0.5831 and 0.7636). Differences between 2D and 3D measurements, considering Bland–Altman's plots and correlated with gestational age, were acceptable (2D: 0.097 ± 0.559 mm, 3D: 0.004 ± 0.111 mm). The acquisition time required was significantly lower for 3D acquisitions (3D: 25.2 ± 14.5 seconds vs. 2D: 35.1 ± 19.4 seconds, p < 0.01). Linear regression and Pearson's coefficients for the measurements of corpus callosum length and thickness using 2D or 3D acquisitions did not differ between the operators. This study confirmed good reproducibility of corpus callosum assessment by transabdominal 3D acquisitions. The good feasibility in routine scans may lead to better screening for callosal dysgenesis.

Magnetic Resonance Imaging Findings in Fetal Corpus Callosal Developmental Abnormalities: A Pictorial Essay

The corpus callosum is the principal supratentorial cerebral commissure, which connects the two cerebral hemispheres in the midline. It is divided into rostrum, genu, body, and splenium. Affected patients may develop mental retardation, dysmorphic features, spasticity, ataxia, or epilepsy. Corpus callosal abnormalities may be isolated or be associated with other anomalies such as sulcal abnormality, ventriculomegaly, cerebellar hypoplasia or cerebellar vermian hypoplasia. Magnetic resonance imaging (MRI) plays a major role in the diagnosis of fetal corpus callosal developmental abnormalities when they are suspected on sonography. This pictorial essay shows the MRI findings in fetal corpus callosal developmental abnormalities in a very systematic manner.

Ultrasound and Magnetic Resonance Imaging of Agenesis of the Corpus Callosum in Fetuses: Frontal Horns and Cavum Septi Pellucidi Are Clues to Earlier Diagnosis

OBJECTIVES

We hypothesized that: (1) fetal frontal horn (FH) morphology and their proximity to the cavum septi pellucidi (CSP) can assist in suspecting complete agenesis of the corpus callosum (cACC) and partial agenesis of the corpus callosum (pACC) earlier than known indirect ultrasound (US) findings; (2) FHs assist in differentiating a true CSP from a pseudocavum; and (3) magnetic resonance imaging (MRI) is useful in learning FH morphology and pseudocavum etiology.

METHODS

Thirty-two patients with cACC and 9 with pACC were identified on an Institutional Review Board-approved retrospective review. Of the 41 cases, 40 had prenatal US, and 21 had prenatal MRI; 17 had follow-up neonatal US, and 14 had follow-up neonatal MRI. Variables evaluated retrospectively were the presence of a CSP or a pseudocavum, ventricle size and shape, and FH shape (comma, trident, parallel, golf club, enlarged, or fused). Displacement between the inferior edge of the FH and the midline or cavum/pseudocavum was measured.

RESULTS

Fetal FHs had an abnormal shape in 77% ≤20 weeks' gestation, 86% ≤24 weeks, and 90% >24 weeks. Frontal horns were laterally displaced greater than 2 mm in 85% ≤20 weeks, 91% ≤24 weeks, and 95% >24 weeks. The CSP was absent in 100% of cACC cases and 78% of pACC cases, and a pseudocavum was present in 88% of cACC cases and 78% of pACC cases across gestation. Magnetic resonance imaging confirmed US pseudocavums to be focal interhemispheric fluid or an elevated/dilated third ventricle.

CONCLUSIONS

Frontal horns assist in assessing ACC ≤24 weeks and throughout gestation. Pseudocavums, often simulating CSPs, are common in ACC. Frontal horn lateral displacement and abnormal morphology, recognized by MRI correlations, are helpful in differentiating a pseudocavum from a true CSP. A normal CSP should not be cleared on screening US unless normally shaped FHs are seen directly adjacent to it.

Fetal magnetic resonance imaging: supratentorial brain malformations

Fetal MRI is the modality of choice to study supratentorial brain malformations. To accurately interpret the MRI, the radiologist needs to understand the normal sequence of events that occurs during prenatal brain development; this includes familiarity with the processes of hemispheric cleavage, formation of interhemispheric commissures, neuro-glial proliferation and migration, and cortical folding. Disruption of these processes results in malformations observed on fetal MRI including holoprosencephaly, callosal agenesis, heterotopic gray matter, lissencephaly and other malformations of cortical development (focal cortical dysplasia, polymicrogyria). The radiologist should also be familiar with findings that have high association with specific conditions affecting the central nervous system or other organ systems. This review summarizes and illustrates common patterns of supratentorial brain malformations and emphasizes aspects that are important to patient care.

Scoping Review of the Prenatal Diagnosis of Agenesis of the Corpus Callosum

OBJECTIVE

To map and summarize the literature related to the prenatal diagnosis of agenesis of the corpus callosum (ACC) to inform nursing practice.

DATA SOURCES

We searched MEDLINE, CINAHL, PyscINFO, and Academic Search Complete with the use of strings of curated terms to cover the broad ACC nomenclature. Documents were published in English between 2009 and June 1, 2020. We also hand searched the reference lists of included documents.

STUDY SELECTION

We screened 582 abstracts and retrieved the full texts of primary research articles, reviews, discussion papers, and peer-reviewed book chapters if the abstracts specifically mentioned ACC and the prenatal period. We excluded case reports, conference and poster abstracts, papers on broader anomalies, and animal studies. We reviewed 84 full-text documents and identified 61 for inclusion.

DATA EXTRACTION

We charted the data through an iterative process under headings for location, article type, study design, participant age, ACC type, recruitment, method, tools/assessments, results, key recommendations, gestational age at diagnosis, termination of pregnancy rate, the definition of isolated ACC, and our notes of critique of the document.

DATA SYNTHESIS

We constructed a narrative synthesis from thematically arranged data. In the included documents, ACC was diagnosed between 17 and 38 weeks gestation and was frequently described as heterogeneous because of different causes, presentations, and outcomes. Whether the ACC was isolated as the only anomaly or present with other anomalies was considered the key factor for prenatal counseling. However, the definition of isolated ACC was inconsistent.

CONCLUSION

The inconsistent nomenclature and definitions of an isolated presentation of ACC increase the ambiguity in the prenatal diagnosis and must be considered when the outcome and diagnostic efficacy studies are interpreted. There is an absence of research on parents' experiences of prenatal diagnoses of ACC to inform holistic nursing interventions and the provision of psychosocial support.

The early pattern of human corpus callosum development: A transvaginal 3D neurosonographic study

OBJECTIVE

To provide an in-vivo description of early corpus callosum (CC) development.

METHODS

We reviewed 3D US volumes acquired transvaginally (TVUS) through the anterior fontanelle, between 14 to 17 weeks. The following landmarks were recognized: tela-choroidea (TC), foramina of Moro, early CC and the evolving cavum septi pellucidi. The following measurements were taken: total, anterior and posterior sections, and height of the CC (referenced to the anterior TC border). All measurements were correlated to both the gestational age and the transverse cerebellar diameter (TCD).

RESULTS

Eighty nine volumes were included in the study (mean 15.1 weeks ± 0.84, TCD range, 13.1-18.4 mm) with high inter and intra observer correlation of the measurements. We found high correlation between CC length and height, and TCD. The anterior segment of the CC appear earlier than the posterior one, and growth continues bi-directionally. Initially, the posterior elongation is significantly larger than the anterior one. Association of all CC measurements with TCD remained significant when co-varying for maternal age and fetal sex.

CONCLUSIONS

imaging the fetal CC is feasible from 14 weeks by TVUS, by following the suggested insonation approach. The early CC develops bi-directionally, and the posterior elongation is more significant than the anterior one.

A methodological review of fetal neurosonographic studies: New directions in assessment of neurodevelopmental risk for mental health problems

Most mental disorders are now considered to have neurodevelopmental origins, with a growing body of research pointing to neural alterations that predate birth. However, lack of established methods for reliable investigation of fetal brain development has limited research into early neural vulnerability. Using a systematic approach and quantitative evaluation of study methodology, we review neurosonographic studies of fetal brain structure with objective quality measures. A total of 81 studies were identified. High quality studies were identified for measurement of the corpus callosum, cerebellum, vermis, ventricles and frontal cortex, with reference ranges provided to facilitate future clinical research. Fewer and lower quality studies were available for subcortical structures, prompting a need for further research to create reliable reference ranges. Development and adoption of reference ranges for fetal brain structures should facilitate future research in neurosonographic evaluation of fetal brain development and lead to a better understanding of neurodevelopmental risk and resilience processes for mental disorders.

A new method for evaluating short fetal corpus callosum

OBJECTIVE

Sonographic diagnosis of short corpus callosum (SCC) is based on measurement of a short for gestational age antero-posterior length of the corpus callosum (CC) in the midsagittal plane. We suggest a new method for evaluating SCC without referring to biometry tables.

METHODS

We measured the ratio between the CC length and the internal cranial occipitofrontal dimension (ICOFD) in the midsagittal plane in 399 normal fetuses at 20 + 6 to 35 + 3 weeks of gestation and in 31 fetuses with a diagnosis of a SCC and compared the mean ratio between two groups. The impact of cephalic biometric parameters, fetal presentation, and gender was assessed.

RESULTS

The ICOFD/CC length for normal pregnancies was constant throughout the pregnancy (2.35 ± 0.11). There was no correlation between the ICOFD/CC length and cephalic index, Biparietal Diameter (BPD), head circumference, fetal sex, or fetal presentation. The ratio of pregnancies with SCC was significantly higher: 3.20 ± 0.84 (P < .0001).

CONCLUSION

The ICOFD/CC length practically does not change throughout a normal pregnancy. The ratio was significantly higher in pregnancies with SCC. Measuring this ratio during fetal anatomical scan may enable rapid evaluation of the CC without the need to refer to biometry tables.

Ultrasound and MR Imaging of the Normal Fetal Brain

Prenatal imaging of the central nervous system has proven to be essential in the detection of anomalies to guide counseling and intrauterine and postnatal therapies. However, understanding the appearance of normal is important because the fetal brain changes dramatically during the pregnancy. In this review, normal imaging of the brain with ultrasound and MR imaging is discussed. The initial section stresses techniques for both modalities. The second section describes ultrasound and MR landmarks in a normal fetal brain.

Fetal midline anomalies: Diagnosis and counselling Part 1: Corpus callosum anomalies

Midline anomalies encompasses a heterogeneous group of conditions caused by an abnormal process of ventral induction after the end of primary neurulation. Advances in prenatal imaging techniques have led to an increase in the detection rate of such anomalies since the first trimester of pregnancy although a significant proportion of them remain undiagnosed until birth. Ultrasound is the primary technique in detecting such anomalies while fetal magnetic resonance imaging (MRI) is commonly performed to confirm the diagnosis and detect additional anomalies, especially those involving the cortical surface of the brain, which may potentially impact post-natal outcome. Neurodevelopmental outcome of cerebral anomalies involving the midline is directly related to the type of anomaly, cause and presence of associated anomalies. However, even in case of isolated anomalies prenatal counselling is challenging. The aim of this review is to provide an up to date on the diagnosis, counselling and management of the most common supra-tentorial anomalies involving the midline and diagnosed on prenatal ultrasound.

Personalized charts for the fetal corpus callosum length

Objective: To personally customize the antenatal ultrasound charts for the fetal corpus callosum (CC) length. Methods: A retrospective analysis of fetal neuro-sonography scans. Cases were grouped as normal neuro-sonographic evaluation (normal) or as high risk and suspected brain anomaly (abnormal). The normal group was subcategorized according to Cignini's CC length charts. Data of fetuses with a CC length between the 5th-95th percentile served for creating new charts, describing the ratio of the CC length to the major biometric parameters as a function of gestational age (GA). Results: A total of 410 measurements were included. Of them 255 were normal and 155 abnormal. The CC length/estimated fetal weight (EFW) ratio had the strongest linear association with GA (R² = 0.929). Applying charts using this ratio to the normal group, significantly increased the percent of CC length measurements defined as normal from 84.7 to 94.5% (p < .001). Conversely, applying these charts to the abnormal group nonsignificantly decreased the number of measurement defined as normal from 89 to 83.2% (p = .137) Conclusions: The CC length/EFW ratio is strongly and linearly associated with GA. Using this personalized ratio may improve the diagnostic accuracy of CC evaluation by adjusting the CC length to the fetus natural proportions.

Biometry reference range of the corpus callosum in neonates: An observational study

This study aims to present the reference range of corpus callosum by ultrasound imaging in neonates and to develop a clinically feasible screening method for congenital abnormalities of corpus callosum.An observational study was conducted between January 2015 and July 2016; 2D and 3D ultrasound evaluations were conducted and virtural organ computer-aided analysis was applied in the volume calculation of corpus callosum. The following parameters were measured: thickness of the rostum, thickness of the genu, thickness of the body, thickness of the splenium, anterior-posterior distance, true length of the corpus callosum and the volume of the corpus callosum. Inter- and intraobserver agreement was also evaluated. The corrected gestational age was between 38+0 and 47+2 weeks. The least-mean-square method was used to create the growth curve for each parameter.Complete data sets were available in 317 neonates, ranging from 0 to 28 days of age. Reference values from the 1st to 99th percentiles were provided. All parameters showed a nonlinear growth trend with age. Inter- and intraobserver agreement was excellent for 2D and 3D parameters.Our results suggested that computer techniques can assist in the volume assessment of corpus callosum. The 2D and 3D ultrasound data of 7 morphologic parameters may facilitate the identification of corpus callosum anomalies based on a large population.

How accurate are prenatal tractography results? A postnatal in vivo follow-up study using diffusion tensor imaging

Prenatal detection of abnormal white matter tracts might serve as a structural marker for altered neurodevelopment. As a result of many technical and patient-related challenges, the accuracy of prenatal tractography remains unknown. We hypothesized that characteristics of prenatal tractography of the corpus callosum and corticospinal tracts derived from fetal diffusion tensor imaging (DTI) data are accurate and predictive of the integrity of these tracts postnatally. We compared callosal and corticospinal tracts of 12 subjects with paired prenatal (age: 23-35 gestational weeks) and postnatal (age: 1 day to 2 years) DTI examinations (b values of 0 s/mm² and 700 s/mm², 16 gradient encoding directions) using deterministic tractography. Evaluation for the presence of callosal segments and corticospinal tracts showed moderate degrees of accuracy (67-75%) for the four segments of the corpus callosum and moderate to high degrees of accuracy (75-92%) for the corticospinal tracts. Positive predictive values for segments of the corpus callosum ranged from 50% to 100% and for the corticospinal tracts, 89% to 100%. Negative predictive values for segments of the corpus callosum ranged from 25% to 80% and for the corticospinal tracts, 33% to 50%. The results suggest that when the tracts are not well characterized on the fetal MR, predictions about the postnatal tracts are difficult to make. However, accounting for brain maturation, prenatal visualization of the main projection and commissural tracts can be clinically used as an important predictive tool in the context of image interpretation for the assessment of fetal brain malformations.

Cavum septi pellucidi (CSP) ratio: a marker for partial agenesis of the fetal corpus callosum

OBJECTIVE

While complete agenesis of the corpus callosum is often suspected on fetal ultrasound due to absence of the cavum septi pellucidi (CSP), suspicion of partial agenesis of the corpus callosum (pACC) is a challenge since the CSP is almost always present. The aim of this study was to measure the length and width of the CSP and calculate the length-to-width ratio (CSP ratio), and compare these between fetuses with pACC and normal fetuses.

METHODS

In this retrospective case-control study, the length and width of the CSP were measured in the axial plane of the fetal head, and the CSP length-to-width ratio calculated, in 323 normal fetuses and in 20 fetuses with pACC between 20 and 34 weeks' gestation. From the normal population we constructed reference ranges in relation to biparietal diameter (BPD). For all fetuses we calculated Z-scores for the CSP ratio.

RESULTS

In the normal population, the length and width of the CSP increased with increasing BPD, while the CSP ratio decreased. The CSP was short (< 5^th centile) in 85% (17/20) of fetuses with pACC and wide (> 95^th centile) in 65% (13/20). The CSP ratio was small (< 5^th centile) in 95% (19/20) of pACC fetuses, with 16/20 (80%) having a ratio below an empirical cut-off of 1.5. Analysis of Z-scores showed that fetuses with pACC had a significantly smaller CSP ratio (P < 0.0001) compared with the normal population.

CONCLUSIONS

Fetuses with a normal-sized corpus callosum have a rectangular-shaped CSP, with a CSP ratio > 1.5 in the second half of gestation. Most fetuses with pACC have an abnormally shaped, wide and short CSP, with a decreased CSP ratio. This simple ratio has the potential to identify fetuses at high risk for pACC. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Biometry of the corpus callosum assessed by 3D ultrasound and its correlation to neurodevelopmental outcome in very low birth weight infants

OBJECTIVE

Several studies have shown a relation between the size of corpus callosum (CC) and outcome in preterm infants. Three-dimensional ultrasound (3D-US) offers new perspectives in cerebral imaging. To establish reference values for biometry of the CC in very low birth weight infants and to correlate these measurements to neurodevelopmental outcome at 5 years of age.

STUDY DESIGN

Forty-three preterm infants with a gestational age <32 weeks were included. Transfontanellar 3D-US measurements were obtained at nine different timepoints.

RESULTS

3D-US-based reference values for size, length, circumference and surface area of the CC could be established. Measurements at term-equivalent age showed a correlation to neurodevelopment outcome.

CONCLUSION

Reliable biometric data of the CC can be established in preterm infants by 3D-US and correlate with neurodevelopmental outcome.

Thick Corpus Callosum in Children

BACKGROUND AND PURPOSE

A thick corpus callosum (TCC) can be associated with a very grave outcome in fetuses, but its clinical presentation in older children seems to be markedly different.

METHODS

The corpus callosum (CC) was defined as thick based on observations and impressions. We reviewed cases of children who were diagnosed as TCC based on brain magnetic resonance imaging (MRI) studies. The pertinent clinical data of these children were collected, and their CCs were measured.

RESULTS

Out of 2,552 brain MRI images, those of 37 children were initially considered as showing a TCC. Those initial imaging were reviewed by an experienced neuroradiologist, who confirmed the diagnosis in 34 children (1.3%): 13 had neurofibromatosis-1 (NF-1), 9 had epilepsy, 3 had macrocephaly capillary malformation (MCM) syndrome, 3 had autistic spectrum disorder, 1 had a Chiari-1 malformation, and 1 had increased head circumference. No specific neurologic disorder could be defined in seven children. The measured thickness of the CC in these children was comparable to those published in the literature for adults.

CONCLUSIONS

A TCC is a rare brain malformation that can be found in neuropathologies with apparently diverse pathognomonic mechanisms, such as NF-1 and MCM. It is not necessarily associated with life-threatening conditions, instead being a relatively benign finding, different in nature from that reported in fetuses.

The feasibility of using 5D CNS software in obtaining standard fetal head measurements from volumes acquired by three-dimensional ultrasonography: comparison with two-dimensional ultrasound

OBJECTIVE

To evaluate the performance of a new software (5D CNS) developed to automatically recognize the axial planes of the fetal brain from three-dimensional volumes and to obtain the basic standard biometric measurements. The accuracy, reproducibility, and time required for analysis of 5D CNS were compared with that of two-dimensional (2D) ultrasound.

METHODS

This was a prospective study of 120 uncomplicated singleton pregnancies undergoing routine second trimester examination. For every pregnancy standard biometric measurements including biparietal diameter, head circumference, distal lateral ventricle width, transverse cerebellar diameter and cisterna magna width were obtained using 2D ultrasound and three-dimensional (3D) ultrasound with 5D CNS software. Reliability and agreement of the two techniques were evaluated using intraclass correlation coefficients (ICCs) and proportionate Bland-Altman plots were constructed. The time necessary to complete the measurements with either technique was compared and intraobserver and interobserver agreements of measurements calculated.

RESULTS

In 118/120 (98.3%), 5D CNS successfully reconstructed the axial diagnostic planes and calculated all the basic biometric head and brain measurements. The agreement between the two techniques was high for all the measurements considered (all ICCS > 0.920). The time necessary to measure the biometric variables considered was significantly shorter with 5D CNS (54 versus 115 s, p < 0.0001) than with 2D ultrasonography. No significant differences were found in 5D CNS repeated measurements obtained either by the same observer or by two independent observers.

CONCLUSION

5D CNS software allows us to obtain reliable biometric measurements of the fetal brain and to reduce the examination time. Its application may improve work-flow efficiency in ultrasonographic practices.

Neurosonographic assessment of the corpus callosum as imaging biomarker of abnormal neurodevelopment in late-onset fetal growth restriction

OBJECTIVE

To explore corpus callosum (CC) developmental differences by ultrasound in late-onset small fetuses compared with adequate for gestational age (AGA) controls.

STUDY DESIGN

Ninety four small (estimated fetal weight <10th centile) and 71 AGA fetuses were included. Small fetuses were further subdivided into fetal growth restriction (IUGR, n = 64) and small for gestational age (SGA, n = 30) based on poor perinatal outcome factors, that is, birth weight <3rd centile and/or abnormal cerebroplacental ratio and/or uterine artery Doppler. The entire cohort was scanned to assess CC by transvaginal neurosonography obtaining axial, coronal and midsagittal images. CC length, thickness, total area and the areas after a subdivision in 7 portions were evaluated by semiautomatic software. Furthermore, the weekly average growth of the CC in each study group was calculated and compared.

RESULTS

Small fetuses showed significantly shorter (small fetuses: 0.49 vs. AGA: 0.52; p < 0.01) and smaller CC (1.83 vs. 2.03; p < 0.01) with smaller splenium (0.47 vs. 0.55; p < 0.01) compared to controls. The CC growth rate was also reduced when compared to controls. Changes were more prominent in small fetuses with abnormal cerebroplacental Doppler suggesting fetal growth restriction.

CONCLUSIONS

Neurosonographic assessment of CC showed significantly altered callosal development, suggesting in-utero brain reorganization in small fetuses. This data support the potential value of CC assessment by US to monitor brain development in fetuses at risk.

Current Role of 3D/4D Sonography in Obstetrics and Gynecology

Modern 3D/4D sonography provides a routine method not only for storing single image planes as in 2D ultrasound but also for storing complete sets of volume data in the computer memory. Once acquisition is completed, all volumes can be accessed from the memory and normal and abnormal findings in both obstetrics and gynecology can be demonstrated in different display modes. Furthermore digital storage of volumes permits virtual examinations by reloading of volumes and navigating through them in the absence of the patient.

This review article would like to give an illustration of the latest technologies in 3D/4D ultrasound in obstetrics and gynecology.

How to cite this article

Merz E, Pashaj S. Current Role of 3D/ 4D Sonography in Obstetrics and Gynecology. Donald School J Ultrasound Obstet Gynecol 2013;7(4):400-408.