Fetal Cerebellar Vermis Circumference Measured by 2-Dimensional Ultrasound Scan: Reference Range, Feasibility and Reproducibility

Feasibility of Cerebellar Measurements with Phased Array Sonography through the Anterior Fontanelle in Comparison to MRI

OBJECTIVE

Cerebral sonography (CS) through the anterior fontanelle is a neonatal brain imaging method that has become an integral part of modern neonatal bedside care for both screening and diagnostic purposes. Premature infants with cognitive delay have a reduction in cerebellar size at term corrected age on magnetic resonance imaging (MRI). We aimed to determine the level of agreement between postnatal MRI and CS for cerebellar biometry and to determine the level of agreement within one and between different examiners.

STUDY DESIGN

Cerebellar sonography and MRI measurements of the cerebellum from 30 term infants was assessed by Bland-Altman plots. Measurements between both modalities were compared using Wilcoxon's signed rank test. A p-value < 0.01 was considered statistically significant. Intraclass correlation coefficients (ICC) for intra- and interrater reliabilities of CS measurements were calculated.

RESULTS

There was no statistically significant difference between CS and MRI for linear measurements, but the measurements of perimeter and surface area differed significantly between the two techniques. There was a systematic bias between both modalities for most measurements except for anterior-posterior (AP) width and vermis height (VH). For measurements that were not statistically different from MRI, we found excellent intrarater ICC for the AP width, VH, and cerebellar width. The interrater ICC was excellent for the AP width and VH, but poor for the transverse cerebellar width.

CONCLUSION

With a strict imaging protocol, cerebellar measurements of the AP width and the VH can be used as an alternative to MRI for diagnostic-screening purposes in a neonatal department where multiple clinicians perform bedside CS.

KEY POINTS

· Abnormal cerebellar growth and injuries affect neurodevelopmental outcome.. · Cerebral sonography through the anterior fontanelle is used for bedside imaging.. · Postnatal sonographic cerebellar measurements are not validated against MRI.. · Measuring vermis height and anterior-posterior width are reliable.. · Measuring transverse cerebellar width through anterior fontanelle is unreliable..

Fetal Cerebellar Area: Ultrasound Reference Ranges at 13-39 Weeks of Gestation

BACKGROUND AND OBJECTIVES

The present study aims to provide prenatal 2-dimensional ultrasonographic (2D-US) nomograms of the normal cerebellar area.

MATERIALS AND METHODS

This is a prospective cross-sectional analysis of 252 normal singleton pregnancies, ranging from 13 to 39 weeks of gestation. The operator performed measurements of the fetal cerebellar area in the transverse plane using 2D-US. The relationship between cerebellar area and gestational age (GA) was determined through regression equations.

RESULTS

A significant, strong positive correlation was investigated between the cerebellar area with GA (r-value = 0.89), and a positive correlation indicates that with increasing GA, the cerebellar area increased in all the participants of the study. Several 2D-US nomograms of the normal cerebellar area were provided, and an increase of 0.4% in the cerebellar area each week of GA was reported.

CONCLUSIONS

We presented information on the typical dimensions of the fetal cerebellar area throughout gestation. In future studies, it could be evaluated how the cerebellar area changes with cerebellar abnormalities. It should be established if calculating the cerebellar area in addition to the routine transverse cerebellar diameter may help in discriminating posterior fossa anomalies or even help to identify anomalies that would otherwise remain undetected.

Reference Ranges for Vermis Biometry on Prenatal Ultrasound: Systematic Review and Meta-Analysis

PURPOSE

 To conduct a systematic review and meta-analysis of published nomograms for fetal vermis biometry.

MATERIALS AND METHODS

 A structured literature search was conducted to identify studies that reported normal measurements of the fetal vermis. A customized quality assessment tool was used to review the selected articles. Random effects meta-analysis was used to calculate normal ranges for vermian craniocaudal diameter, anteroposterior diameter, and surface area.

RESULTS

 A total of 21 studies were included for qualitative review and 3 studies were included for quantitative synthesis. The 3 included articles comprised a total of 10 910 measurements from gestational ages 17-35 weeks. The quality assessment demonstrated that there was generally poor reporting regarding maternal characteristics and neonatal outcomes. Except for one article with a large sample size, the mean number of fetuses per week of gestational age was 15.9, with the lowest number being 5. There was significant statistical heterogeneity. Non-visualization rates ranged from 0-35.4 %. The craniocaudal diameter (reported in 3 articles) increased from a mean of 7.90 mm (95 % confidence interval [CI] 7.42, 8.38) at 17 weeks to 21.90 mm (95 % CI 20.63, 23.16) at 35 weeks gestation. The anteroposterior diameter (reported in 2 articles) increased from 6.30 mm (95 % CI 5.42, 7.18) at 17 weeks to 15.85 (95 %CI 15.49, 16.21) at 32 weeks.

CONCLUSION

 Reference ranges for vermis biometry across gestation based on meta-analysis of existing references are provided. However, because many of the underlying studies suffered from significant methodological issues, the ranges should be used with caution.

Early alterations in cortical and cerebellar regional brain growth in Down Syndrome: An in vivo fetal and neonatal MRI assessment

Down Syndrome (DS) is the most frequent genetic cause of intellectual disability with a wide spectrum of neurodevelopmental outcomes. At present, the relationship between structural brain morphology and the spectrum of cognitive phenotypes in DS, is not well understood. This study aimed to quantify the development of the fetal and neonatal brain in DS participants, with and without a congenital cardiac defect compared with a control population using dedicated, optimised and motion-corrected in vivo magnetic resonance imaging (MRI). We detected deviations in development and altered regional brain growth in the fetus with DS from 21 weeks' gestation, when compared to age-matched controls. Reduced cerebellar volume was apparent in the second trimester with significant alteration in cortical growth becoming evident during the third trimester. Developmental abnormalities in the cortex and cerebellum are likely substrates for later neurocognitive impairment, and ongoing studies will allow us to confirm the role of antenatal MRI as an early biomarker for subsequent cognitive ability in DS. In the era of rapidly developing technologies, we believe that the results of this study will assist counselling for prospective parents.

Early alterations in cortical and cerebellar regional brain growth in Down Syndrome: An in vivo fetal and neonatal MRI assessment

Down Syndrome (DS) is the most frequent genetic cause of intellectual disability with a wide spectrum of neurodevelopmental outcomes. At present, the relationship between structural brain morphology and the spectrum of cognitive phenotypes in DS, is not well understood. This study aimed to quantify the development of the fetal and neonatal brain in DS participants, with and without a congenital cardiac defect compared with a control population using dedicated, optimised and motion-corrected in vivo magnetic resonance imaging (MRI). We detected deviations in development and altered regional brain growth in the fetus with DS from 21 weeks' gestation, when compared to age-matched controls. Reduced cerebellar volume was apparent in the second trimester with significant alteration in cortical growth becoming evident during the third trimester. Developmental abnormalities in the cortex and cerebellum are likely substrates for later neurocognitive impairment, and ongoing studies will allow us to confirm the role of antenatal MRI as an early biomarker for subsequent cognitive ability in DS. In the era of rapidly developing technologies, we believe that the results of this study will assist counselling for prospective parents.

The "vermian-crest angle": does it allow accurate categorisation of fetal upward rotation of cerebellar vermis on intrauterine MRI? A pilot study

AIM

To test a new parameter to assess the position of the fetal cerebellar vermis in the posterior fossa (PF) using intrauterine magnetic resonance imaging (MRI).

MATERIALS AND METHODS

The angle between the cerebellar vermis and the internal occipital crest (vermian-crest angle, VCA) was assessed retrospectively using MRI in fetuses with and without PF anomalies. Spearman's rank test was used to investigate correlation of the VCA with gestational age (GA). Groups were compared using Student's t-test and the one-way analysis of variance (ANOVA) with the Bonferroni adjustment. Box-and-whisker plots were also used.

RESULTS

One hundred and two normal cases were identified. Mean±SD GA at MRI was 26.5±2.8 weeks (range: 22-32 weeks). The VCA was 64.49±11.5° independently of GA (r=0.19; p=0.12). In addition, 30 fetuses at 19-28 weeks were identified with Blake's pouch cyst (BPC; n=5), Dandy-Walker malformation (DWM; n=12), mega cisterna magna (MCM; n=10), and vermian hypoplasia (VH; n=3). The VCA was significantly different in the DWM (p<0.001) and BPC (p<0.001) subgroups, but was not significantly different in cases of VH (p=0.84) and MCM (p=0.95) in comparison with controls.

CONCLUSIONS

A new method to assess vermian position within the PF using intrauterine MRI was assessed. In combination with the other existing parameters, it may be helpful for addressing the categorisation of upward rotation of the fetal cerebellar vermis; however, further studies are necessary to strengthen the present findings.

The Vermian-Crest Angle: A New Method to Assess Fetal Vermis Position within the Posterior Fossa Using 3-Dimensional Multiplanar Sonography

BACKGROUND

Normal morphometry of the vermis and its relation to the posterior fossa (PF) rule out most major anomalies of the cerebellum. However, accurate categorization of the position and size of the fetal vermis remains a challenge.

OBJECTIVE

Our aim was to test a new method to assess the position and size of fetal vermis on 3-dimensional ultrasound (3D-US).

METHODS

We measured the vermian-crest angle (VCA) in normal fetuses using multiplanar 3D-US. We also assessed the diameters (superoinferior, anteroposterior, and horizontal) and volume of the vermis. The Spearman rank test and linear and polynomial regression analyses were used for statistical purposes.

RESULTS

We included 126 fetuses. Mean ± SD gestational age (GA) was 26.3 ± 4.6 (range 17-35.5) weeks. Mean ± SD superoinferior, anteroposterior, and horizontal diameters were 16.2 ± 4.9, 11.2 ± 3.6, and 5.6 ± 1.6 mm, respectively. Median (range) vermian volume was 0.50 (0.05-2.9) cm3. The VCA was 64.49° ± 11.45. We found no correlation between GA and VCA (r = 0.15; p = 0.13), a linear correlation between GA and vermian diameters, and a quadratic correlation between GA and vermian volume.

CONCLUSIONS

We provide a new method to assess vermian position and size within the PF using 3D-US. The combined information may be of value for screening purposes, particularly to differentiate between the various pathological situations encountered within the PF.

Three-dimensional sonographic minute structure analysis of fetal cerebellar vermis development and malformations: utilizing volume contrast imaging

PURPOSE

To obtain three-dimensional ultrasonic (3D US) structural details and biometrics of the fetal cerebellar vermis and evaluate the value of developmental and malformation identification.

METHODS

The 3D US minute structure of the fetal cerebellar vermis in mid-sagittal view was detected in normal fetuses (n = 438; 16-41 weeks). Biometric sizes were measured to establish the stage-specific norms and reproducibility analysis. Additionally, 28 fetuses with suspected abnormal posterior fossa contents were assessed to analyze the clinical value.

RESULTS

The minute structure of normal fetuses, including cerebellar vermis contours and the fastigial recess of the fourth ventricle, were visible around Week 19. The main lobules and fissures were apparent around Week 22, and all nine lobules, fissures, and the fourth ventricle were clearly displayed by Week 28. Cerebellar vermis biometric sizes (anterior-posterior length, cranio-caudal length, circumference, and surface area (SA)) grew in a linear fashion with high reliability, especially SA measurements (for intraclass, ICC 0.989, 95% CI (0.980-0.994); for interclass, ICC 0.992, 95% CI (0.984-0.996)). On the middle sagittal section of 3D US, the SA reduced at least 50% in the Dandy-Walker group with no recognizable cerebellar vermis structures showing. The SA in vermian hypoplasia malformation reduced during [Formula: see text] to 50% with the primary/secondary fissures absent or partly absent and arborization of the lobules reduced. That would be an important diagnosis and antidiastole clue. Combined with minute structural observation, sonographic diagnoses were accurate in 88% of cases.

CONCLUSION

Minute structures obtained by 3D US were clinically useful in the evaluation of cerebellar vermis development and cerebellar vermis malformations.