Fetal cerebellum: US appearance with advancing gestational age

External validation of models to estimate gestational age in the second and third trimester using ultrasound: A prospective multicentre observational study

OBJECTIVES

Accurate assessment of gestational age (GA) is important at both individual and population levels. The most accurate way to estimate GA in women who book late in pregnancy is unknown. The aim of this study was to externally validate the accuracy of equations for GA estimation in late pregnancy and to identify the best equation for estimating GA in women who do not receive an ultrasound scan until the second or third trimester.

DESIGN

This was a prospective, observational cross-sectional study.

SETTING

57 prenatal care centres, France.

PARTICIPANTS

Women with a singleton pregnancy and a previous 11-14-week dating scan that gave the observed GA were recruited over an 8-week period. They underwent a standardised ultrasound examination at one time point during the pregnancy (15-43 weeks), measuring 12 foetal biometric parameters that have previously been identified as useful for GA estimation.

MAIN OUTCOME MEASURES

A total of 189 equations that estimate GA based on foetal biometry were examined and compared with GA estimation based on foetal CRL. Comparisons between the observed GA and the estimated GA were made using R2, calibration slope and intercept. RMSE, mean difference and 95% range of error were also calculated.

RESULTS

A total of 2741 pregnant women were examined. After exclusions, 2339 participants were included. In the 20 best performing equations, the intercept ranged from -0.22 to 0.30, the calibration slope from 0.96 to 1.03 and the RSME from 0.67 to 0.87. Overall, multiparameter models outperformed single-parameter models. Both the 95% range of error and mean difference increased with gestation. Commonly used models based on measurement of the head circumference alone were not amongst the best performing models and were associated with higher 95% error and mean difference.

CONCLUSIONS

We provide strong evidence that GA-specific equations based on multiparameter models should be used to estimate GA in late pregnancy. However, as all methods of GA assessment in late pregnancy are associated with large prediction intervals, efforts to improve access to early antenatal ultrasound must remain a priority.

TRIAL REGISTRATION

The proposal for this study and the corresponding methodological review was registered on PROSPERO international register of systematic reviews (registration number: CRD4201913776).

Role of Transcerebellar Diameter and Transcerebellar Diameter/Abdominal Circumference Ratio in Assessing Fetal Growth and Diagnosing Intrauterine Growth Restriction

Background In obstetrics, accurately determining gestational age (GA) is a critical aspect of managing pregnancy and evaluating fetal growth and development. Intrauterine growth restriction (IUGR) is characterized by the failure of the fetus to reach its potential growth. Early detection of IUGR is crucial for optimal obstetric care to reduce fetal complications and neonatal morbidity and mortality. The purpose of the current research is to determine the role of transcerebellar diameter (TCD) and the TCD/abdominal circumference (AC) ratio in assessing fetal growth and diagnosing IUGR. Methods In the sample, there were 600 expectant mothers with GA exceeding 28 weeks. We measured TCD and AC and then calculated the TCD/AC ratio. We used IBM SPSS Statistics for Windows, V. 22.0 (IBM Corp., Armonk, NY), for statistical analysis. The data was subjected to statistical tests, including Pearson's correlation coefficient, coefficient of determination, and tests of validity. Results The current research demonstrates a strong linear correlation between TCD and GA. Additionally, there was no notable disparity in TCD measurements between normal and IUGR fetuses with the same GA. There was an insignificant relationship between the TCD/AC ratio and GA, with a constant TCD/AC ratio in the third trimester of pregnancy in normal fetuses. The mean TCD/AC ratio was 14.72±0.89 (mean±standard deviation), and a cut-off value of 16.5 was determined to diagnose IUGR. Conclusion TCD can serve as a reliable measure for GA estimation during the third trimester in pregnant women with uncertain last menstrual period (LMP) or no dating scan and IUGR fetuses. In diagnosing IUGR, the TCD/AC ratio has demonstrated greater sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The TCD/AC ratio is a GA-independent measure that can be used to diagnose IUGR.

Determination of the Accuracy of Transcerebellar Diameter in Estimating Gestational Age in the Second and Third Trimesters of Pregnancy

Background Every antenatal woman and her treating doctor aim for a healthy newborn. In obstetrics, accurately determining the gestational age (GA) is a critical aspect of managing pregnancy and evaluating fetal growth and development. The transcerebellar diameter (TCD) is the greatest transverse measurement of the fetal cerebellum. The growth of the cerebellum is minimally affected by fluctuations in growth, making the TCD the most reliable measurement for predicting GA. The purpose of the present research is to determine the accuracy of TCD in estimating GA in the second and third trimesters of pregnancy. Materials and methods The study included 500 antenatal women at 18-40 weeks of gestation. We also measured TCD in addition to routine ultrasound parameters like biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). We used IBM SPSS Statistics for Windows, Version 22 (Released 2013; IBM Corp., Armonk, New York, United States) for statistical analysis. The collected data was subjected to statistical tests, including Pearson's correlation coefficient and coefficient of determination. We conducted a regression analysis and used correlation coefficients to compare each ultrasound-measured parameter with the GA. Results The current research demonstrates a significant linear relationship between the TCD and GA (r = 0.9865; p = 0.0001), a strong association between BPD and GA (r = 0.9541; p = 0.0001), between HC and GA (r = 0.9613; p = 0.0001), between AC and GA (r = 0.9489; p = 0.0001), and between FL and GA (r = 0.9697; p = 0.0001). TCD showed the best correlation with GA among all the biometric parameters. TCD showed a correct assessment of GA by the last menstrual period (LMP) in 479 (95.8%) antenatal women. Conclusion The current research concludes that the TCD can be utilized as an independent measure to determine GA in the second and third trimesters of pregnancy, particularly in cases where the LMP is unknown, no dating scan has been performed in the first trimester, initial assessment taking place in the third trimester and in fetuses with variations in head shape such as dolichocephaly and brachycephaly.

Fetal Gestational Age Estimation Using Ultrasonic Transverse Cerebellar Diameter in a Sub-Saharan African Population

Background

To explore the relationship between fetal Transverse Cerebellar Diameter (TCD) and menstrual gestational age (GA) and to generate normative references (nomogram) of the fetal TCD in some pregnant women in Southwest Nigeria.

Methods

Four hundred pregnant women with a singleton fetus between 14 and 38 weeks GA were enrolled. The TCD and other biometric parameters (biparietal diameter, head circumference, abdominal circumference, and femur length) as well as the cerebellar appearance were analyzed and correlated with the GA.

Results

The mean TCD increased from 13.3 ± 0.3 mm at 14 weeks to 52.3 ± 3.3 mm at 38 weeks of pregnancy. A strong positive correlation was observed between TCD and GA, which was best represented by a linear regression equation: Predicted GA = 0.557 × TCD + 8.840. The regression analysis indicated a statistically significant strong positive relationship between TCD and GA (r = 0.972 and P < 0.001). The cerebellar appearance based on shape and echogenicity was graded into Grade I: 230 fetuses (57.5%); Grade II: 74 fetuses (18.5%) and Grade III: 96 fetuses (24.0%). Median GA and TCD were 21 weeks and 21.2 mm for Grade I; 29 weeks and 35.5 mm for Grade II; and 35 weeks and 48.1 mm for Grade III, respectively.

Conclusion

The TCD increased in a linear fashion with advancing GA in the evaluated fetuses. The TCD is, therefore, a good marker for GA estimation. There is a gradual ultrasonographic change in fetal cerebellar appearance with advancing gestation.

The Role of Fetal MRI for Suspected Anomalies of the Posterior Fossa

BACKGROUND

Posterior fossa anomalies can be diagnostic dilemmas during the fetal period. The prognosis for different diagnoses of the posterior fossa varies widely. We investigated whether fetal magnetic resonance imaging (MRI) and prenatal neurology consultation led to an alternate prognosis for fetuses referred due to concern for a fetal posterior fossa anomaly and concordance between pre- and postnatal diagnoses.

METHODS

This is a retrospective study of cases referred to the Prenatal Pediatrics Institute at Children's National Hospital from January 2012 to June 2018 due to concern for posterior fossa anomaly. Each encounter was scored for change in prognosis based upon clinical and fetal MRI report. Postnatal imaging was compared with prenatal imaging when available.

RESULTS

In total, 180 cases were referred for fetal posterior fossa anomalies based on outside obstetric ultrasound and had both fetal MRI and a neurology consultation. Fetal MRI and neurology consultation resulted in a change in fetal prognosis in 70% of cases. The most common referral diagnosis in our cohort was Dandy-Walker continuum, but it was not often confirmed by fetal MRI. In complex cases, posterior fossa diagnosis and prognosis determined by fetal MRI impacted choices regarding pregnancy management. Postnatal imaging was obtained in 57 (47%) live-born infants. Fetal and postnatal prognoses were similar in 60%.

CONCLUSIONS

Fetal diagnosis affects pregnancy management decisions. The fetal-postnatal imaging agreement of 60% highlights the conundrum of balancing the timing of fetal MRI to provide the most accurate diagnosis of the posterior fossa abnormalities in time to make pregnancy management decisions.

Ultrasonographic measurement of the transcerebellar diameter for gestational age estimation in the third trimester

BACKGROUND

Ultrasonographic estimation of gestational age is done routinely by using fetal biometric parameters, such as the biparietal diameter (BPD), femur length (FL), abdominal circumference (AC), and head circumference (HC). Gestational dating by ultrasound is reliable in the 1st trimester, but discrepancies increase to more than 3 weeks in the 3rd trimester.

AIMS AND OBJECTIVES

To study the accuracy of gestational age estimation by the transcerebellar diameter (TCD) in the 3rd trimester of singleton pregnancies whose gestational age is known.

MATERIALS AND METHODS

A prospective study was carried out in the Department of Obstetrics and Gynecology at NDMC Medical College and Hindu Rao Hospital, Delhi, India, from October 2017 to May 2019 after obtaining clearance from the ethical committee. The study included 100 women aged 18-35 years with singleton pregnancies in the 3rd trimester with a gestational age ≥ 28 weeks; the women provided informed consent and filled in an F-form to rule out any sex determination of the baby. Only those women who had regular menstrual cycles 6 months before conception, who were sure of their last menstrual period (LMP), who had a gestational dating scan done up to 14 weeks, and for whom congenital malformation of the fetus had been ruled out by mid-trimester ultrasound were included. Gestational age was obtained for the measured BPD, HC, AC, FL, and TCD. A paired t-test was used for the comparison between the period of gestation (POG) by the 1st ultrasonography (USG) and that by the AC, BPD, FL, HC, and TCD.

RESULTS

The estimation of gestational age by the BPD becomes gradually less reliable after 32 weeks of pregnancy, that by the HC and FL after 36 weeks, and that by the AC after 28 weeks. Regression analysis was used to find a correlation of the various parameters, such as the POG by the 1st USG, BPD, HC, AC, FL, and TCD, with the POG by LMP. The correlation coefficient (r), coefficient of determination (R²), and p values were calculated. Of all the sonographic parameters for the estimation of gestational age, the TCD showed the highest correlation (r = 0.979; p < 0.0001) and the AC the lowest correlation.

CONCLUSION

The mean difference between the estimate of gestational age by the TCD and that by the 1st trimester USG increased from ± 1 day at weeks 28-32 to ± 1-2 days at weeks 32-36 and further increased to ± 6 days after 36 weeks of pregnancy, which was statistically significant. This indicated that the TCD could estimate gestational age within 6 days of near-term pregnancy. Thus, the TCD was a reliable parameter for the estimation of gestational age within 6 days of near-term pregnancy along with routine biometry and an alternative parameter for the evaluation of gestational age when the LMP is not known.

Estimation of gestational age using trans-cerebellar diameter: a sonographic study of a cohort of healthy pregnant women of Igbo ethnic origin in a suburb of Lagos, southwest Nigeria

AIM

To use a sonographic method to determine the usefulness of trans-cerebellar diameter (TCD) as an independent estimator of gestational age (GA).

METHODS

A convenience sample of 257 healthy pregnant women of Igbo ethnic origin with singleton normal pregnancy whose GA ranged from 16 to 40 weeks were examined. GA was calculated from the date of onset of the last menstrual period (LMP) and was used as the standard criterion, while the biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) were used to estimate GA. TCD was measured and employed to derive regression models utilized to assess GA.

RESULTS

The mean TCD was 32.0 ± 11.6 mm; TCD had a strong positive linear relationship with GA (R = 0.988; R² = 0. 975; P =  < 0.001). The GA that was estimated using regression models, which were derived using the sonographically measured TCD, was closer to the actual GA in the second and third trimesters of pregnancy than the GA estimated using other fetal parameters.

CONCLUSION

In a population of healthy pregnant women of Igbo ethnic origin living in Oshodi, Lagos State, Nigeria, the sonographically measured TCD was more accurate as a single estimator of GA than BPD, HC, AC, and FL in the late stages of pregnancy. Subject to further validation, the nomograms derived using TCD proposed in the present study could be used as reliable GA estimators in the late stages of pregnancy among women who are unsure of the date of onset of their LMP.

Significance of Foetal Transcerebellar Diameter in Foetal Biometry: A Pilot Study

INTRODUCTION

The most important parameter needed for appropriate management of pregnant women is accurate Gestational Age (GA). Routine sonographic estimation of GA by using Biparietal Diameter (BPD), Femur Length (FL), Abdominal Circumference (AC) and Head Circumference (HC) assumed important role in management of pregnancy. However, these parameters have limitations. BPD and HC are not reliable in case of moulding of foetal head in third trimester. Similarly, femur length is shortened in cases of achondroplasia. Transcerebellar Diameter (TCD) was developed as an alternative parameter of foetal brain growth and for estimation of GA.

AIM

To evaluate accuracy of predicting GA using Foetal Transcerebellar Diameter (TCD) and to compare between TCD and other existing parameters in evaluating GA in 15 to 40 weeks of gestation.

MATERIALS AND METHODS

A prospective study was carried out in 100 pregnant women between 15 to 40 weeks of gestation, who came for routine antenatal sonography. Transcerebellar diameter was measured along with routine parameters. Subjects were divided into two groups based on GA (15-28 and 29-40 weeks). Gestational age using TCD and other parameters was calculated and compared with gestational age based on Last Menstrual Period (LMP). Correlation between the GA by LMP with GA by other ultrasound parameters was done by using Karl Pearson's Correlation(r).

RESULTS

In 15-28 weeks, all parameters had nearly equal r-values. Among all parameters, TCD revealed highest correlation with value of 0.997. In 29-40 weeks, there was considerable difference in r-values. An r-value of 0.982 was noted, when the GA by TCD and LMP was compared, r-value of which is more than the other parameters. The least correlation was seen with BPD, r=0.951. The second most accurate correlation was seen with the FL with r-value of 0.981.

CONCLUSION

TCD is an accurate parameter in estimation of gestational age in second and third trimesters as its values are in close relation with that of GA by LMP. It is also better predictor of the gestational age when compared to other parameters especially in third trimester.

Sonographic Reference Values for Fetal Transverse Cerebellar Diameter in the Second and Third Trimesters in a Nigerian Population

This study aimed to establish reference values of fetal transverse cerebellar diameter (TCD) in a Nigerian population. A cross-sectional convenience study was carried out between June 2013 and May 2014 in Enugu, Nigeria. The sonographic examinations were performed on 697 pregnant women with gestational ages between 14 and 40 weeks. The TCD measurements were obtained from the proximal outer margin to the distal outer margin of cerebellum. The women’s last menstrual period, femur length, biparietal diameter, head circumference, and abdominal circumference were also recorded. The mean (standard deviation) TCD increased from 13.6 (2.2) mm to 27.3 (2.6) mm and 28.9 (2.0) mm to 42.9 (2.0) mm in the second and third trimesters, respectively. The relationship of TCD with gestational age obtained from last menstrual period, femur length, biparietal diameter, head circumference, and abdominal circumference was determined. The TCD had a strong correlation with gestational age ( r = .93; P < .05). Reference values for TCD were established for those patients who attended this clinic. This is a likely data set to use for future research that could focus on similar practices and in other regions of the country for possible generation of a nationwide nomogram.

Efficacy of Transcerebellar Diameter/Abdominal Circumference Versus Head Circumference/Abdominal Circumference in Predicting Asymmetric Intrauterine Growth Retardation

BACKGROUND

The high incidence of IUGR and its low recognition lead to increasing perinatal morbidity and mortality for which prediction of IUGR with timely management decisions is of paramount importance. Many studies have compared the efficacy of several gestational age independent parameters and found that TCD/AC is a better predictor of asymmetric IUGR.

AIM

To compare the accuracy of transcerebellar diameter/abdominal circumference with head circumference/abdominal circumference in predicting asymmetric intrauterine growth retardation after 20 weeks of gestation.

MATERIALS AND METHODS

The prospective study was conducted over a period of one year on 50 clinically suspected IUGR pregnancies who were evaluated with 3.5 MHz frequency ultrasound scanner by a single sonologist. BPD, HC, AC and FL along with TCD were measured for assessing the sonological gestational age. Two morphometric ratios- TCD/AC and HC/AC were calculated. Estimated fetal weight was calculated for all these pregnancies and its percentile was determined.

STATISTICAL METHODS

The TCD/AC and HC/AC ratios were correlated with advancing gestational age to know if these were related to GA. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy (DA) for TCD/AC and HC/AC ratios in evaluating IUGR fetuses were calculated.

RESULTS

In the present study, linear relation of TCD and HC in IUGR fetuses with gestation was noted. The sensitivity, specificity, PPV, NPV & DA were 88%, 93.5%, 77.1%, 96.3% & 92.4% respectively for TCD/AC ratio versus 84%, 92%, 72.4%, 95.8% & 90.4% respectively for HC/AC ratio in predicting IUGR.

CONCLUSION

Both ratios were gestational age independent and can be used in detecting IUGR with good diagnostic accuracy. However, TCD/AC ratio had a better diagnostic validity and accuracy compared to HC/AC ratio in predicting asymmetric IUGR.

Registration of 3D fetal neurosonography and MRI

We propose a method for registration of 3D fetal brain ultrasound with a reconstructed magnetic resonance fetal brain volume. This method, for the first time, allows the alignment of models of the fetal brain built from magnetic resonance images with 3D fetal brain ultrasound, opening possibilities to develop new, prior information based image analysis methods for 3D fetal neurosonography. The reconstructed magnetic resonance volume is first segmented using a probabilistic atlas and a pseudo ultrasound image volume is simulated from the segmentation. This pseudo ultrasound image is then affinely aligned with clinical ultrasound fetal brain volumes using a robust block-matching approach that can deal with intensity artefacts and missing features in the ultrasound images. A qualitative and quantitative evaluation demonstrates good performance of the method for our application, in comparison with other tested approaches. The intensity average of 27 ultrasound images co-aligned with the pseudo ultrasound template shows good correlation with anatomy of the fetal brain as seen in the reconstructed magnetic resonance image.

School-age effects of the newborn individualized developmental care and assessment program for preterm infants with intrauterine growth restriction: preliminary findings

BACKGROUND

The experience in the newborn intensive care nursery results in premature infants' neurobehavioral and neurophysiological dysfunction and poorer brain structure. Preterms with severe intrauterine growth restriction are doubly jeopardized given their compromised brains. The Newborn Individualized Developmental Care and Assessment Program improved outcome at early school-age for preterms with appropriate intrauterine growth. It also showed effectiveness to nine months for preterms with intrauterine growth restriction. The current study tested effectiveness into school-age for preterms with intrauterine growth restriction regarding executive function (EF), electrophysiology (EEG) and neurostructure (MRI).

METHODS

Twenty-three 9-year-old former growth-restricted preterms, randomized at birth to standard care (14 controls) or to the Newborn Individualized Developmental Care and Assessment Program (9 experimentals) were assessed with standardized measures of cognition, achievement, executive function, electroencephalography, and magnetic resonance imaging. The participating children were comparable to those lost to follow-up, and the controls to the experimentals, in terms of newborn background health and demographics. All outcome measures were corrected for mother's intelligence. Analysis techniques included two-group analysis of variance and stepwise discriminate analysis for the outcome measures, Wilks' lambda and jackknifed classification to ascertain two-group classification success per and across domains; canonical correlation analysis to explore relationships among neuropsychological, electrophysiological and neurostructural domains at school-age, and from the newborn period to school-age.

RESULTS

Controls and experimentals were comparable in age at testing, anthropometric and health parameters, and in cognitive and achievement scores. Experimentals scored better in executive function, spectral coherence, and cerebellar volumes. Furthermore, executive function, spectral coherence and brain structural measures discriminated controls from experimentals. Executive function correlated with coherence and brain structure measures, and with newborn-period neurobehavioral assessment.

CONCLUSION

The intervention in the intensive care nursery improved executive function as well as spectral coherence between occipital and frontal as well as parietal regions. The experimentals' cerebella were significantly larger than the controls'. These results, while preliminary, point to the possibility of long-term brain improvement even of intrauterine growth compromised preterms if individualized intervention begins with admission to the NICU and extends throughout transition home. Larger sample replications are required in order to confirm these results.

CLINICAL TRIAL REGISTRATION

The study is registered as a clinical trial. The trial registration number is NCT00914108.

Correlation of the fetal cerebellar volume with other fetal growth indices by three-dimensional ultrasound

OBJECTIVE

To verify the correlation of fetal cerebellar volume by three-dimensional ultrasound (3D US) with other indices of fetal growth in normal fetuses.

METHODS

This was a longitudinal prospective study involving 52 normal pregnant women between 20 and 32 weeks of gestation. The assessments of the fetal cerebellar volume were carried out at intervals of two weeks, and the method used was VOCAL (virtual organ computer-aided analysis) with a 30 degrees rotation angle. At each assessment, the following biometric indices were evaluated using the two-dimensional method: biparietal diameter, head circumference, transverse cerebellar diameter, femur length, and estimated fetal weight. We used Pearson's correlation coefficient to evaluate the correlation between fetal cerebellar volume and these indices; we also used polynomial regression analysis with fetal cerebellar volume as the dependent variable and the other indices as the independent variable.

RESULTS

The fetal cerebellar volume was highly correlated with gestational age (r = 0.94; p < 0.001) and with all other fetal growth indices (p < 0.001).

CONCLUSIONS

The assessment of the fetal cerebellar volume by 3D US is an important tool to evaluate fetal growth.

Aplicações da ultra-sonografia tridimensional na avaliação do cerebelo fetal

Nos últimos anos a ultra-sonografia tridimensional tem-se tornado um método de imagem de grande importância no diagnóstico em obstetrícia. Um de seus benefícios seria a maior sensibilidade, em relação ao ultra-som bidimensional, no diagnóstico de algumas malformações fetais. As potenciais aplicações desse novo método seriam uma maior acurácia na medida do volume de órgãos fetais, a possibilidade de rever volumes na ausência da paciente, a possibilidade de utilizar diferentes planos para avaliar determinada estrutura anatômica e a capacidade de transmissão de volumes para centros de referência. A avaliação ultra-sonográfica do cerebelo fetal é de extrema importância, pois, comprovadamente, alterações no seu desenvolvimento estão correlacionadas com alterações do crescimento fetal e anomalias congênitas. O objetivo desta atualização é demonstrar os métodos VOCAL™ e 3D XI™ na avaliação do cerebelo fetal, seus potenciais benefícios e o que há de mais atual na literatura a respeito deste assunto.

Sonographic maturation of third-trimester cerebellar foliation after birth

The development of cerebellar folia of third-trimester preterms has not been described with ultrasound before. We set out to determine normal development of the pons and cerebellar folia for future measurements of hypoplasia and atrophy. Study sonograms were made in preterms admitted to the neonatal intensive care unit with postmenstrual age (PMA) from 25 wk until term. On a weekly basis, transcranial measurements were made in the axial and coronal planes at the asterion with high-frequency transducers (8.5 and 13 MHz). The axial images showed the pons and fourth ventricle. The coronal images showed cerebellar folia and white matter. In the same coronal plane, the depth of cerebellar fissures at the rostral cerebellar convexity could be observed. A total of 172 cranial sonograms were performed on 98 neonates. The development of folia could be measured with ultrasound through the asterion. We showed that pons area, mean of three fissure depths, hemisphere area, and number of folia in the horizontal fissure correlated significantly with PMA. Hemisphere area described the same trend of growth as the transverse cerebellar diameter used in fetal sonography.

Fetal magnetic resonance imaging in the prenatal diagnosis of cerebellar hemorrhage

We report the case of a fetus with a sonographic mid-gestation diagnosis of hyperechogenic cerebellum suspected to be of hemorrhagic origin on fetal brain magnetic resonance imaging (MRI). No etiological factors for fetal hemorrhage were found other than a maternal heterozygocity for factor V Leiden. Following termination of the pregnancy, autopsy confirmed the prenatal diagnosis of massive cerebellar hemorrhage without underlying vascular anomaly. As an additional tool to ultrasonography, fetal brain MRI can affirm the hemorrhagic origin of hyperechogenic cerebellar lesions, especially by showing a high signal on T1-weighted images.

The fetal cerebellar vermis: anatomy and biometric assessment using volume contrast imaging in the C-plane (VCI-C)

OBJECTIVES

To describe the normal appearance and study the biometry of the fetal cerebellar vermis by three-dimensional (3D) volume contrast imaging in the coronal (C-) plane (VCI-C).

METHODS

A total of 203 normally developed fetuses were examined prospectively at 18-33 weeks' gestation. At the level of the view used to measure the transverse cerebellar diameter (TCD), a VCI-C plane was displayed to examine, using a transabdominal probe, the fetal mid-saggital vermis. The volumes acquired were stored for later review and measurement of the anteroposterior (AP) diameter, craniocaudal (CC) diameter and surface area of the cerebellar vermis. Each dataset was evaluated by two independent observers. Measurements as a function of gestational age (GA), biparietal diameter (BPD), head circumference (HC) and TCD were expressed by regression equations. Interobserver variability was evaluated. Nomograms were produced. In order to validate the use of VCI in fetal biometry, datasets from 57 patients were selected arbitrarily for comparison of their VCI-C measurements with those from mid-sagittal sections of a stored 3D multiplanar examination. Intraclass correlation was used to evaluate the agreement between these measurements.

RESULTS

The mean maternal age was 32 years. We were able to measure mid-sagittal CC diameter, mid-sagittal AP diameter and cerebellar vermis surface area in all fetuses. Interobserver variability analysis showed no significant differences between the two observers (P > 0.05). Measurements of the cerebellar vermis (AP diameter, CC diameter and surface area) correlated linearly with GA, BPD, HC and TCD (r > or = 0.82, P < 0.0001). CC and AP diameters estimated from the mid-sagittal section of the multiplanar measurements were significantly correlated with VCI-C measurements (r = 0.96, P < 0.00001 and r = 0.95, P < 0.00001, respectively).

CONCLUSIONS

VCI-C is a valuable tool, allowing intrauterine assessment of the normal appearance of the fetal cerebellar vermis. The nomograms developed in this study should enable accurate evaluation of the cerebellar vermis.