An algorithm based on OmniView technology to reconstruct sagittal and coronal planes of the fetal brain from volume datasets acquired by three-dimensional ultrasound

Validation of an automatic software in assessing fetal brain volume from three dimensional ultrasonographic volumes: Comparison with manual analysis

OBJECTIVE

This study was aimed to test the agreement between a manual and an automatic technique in measuring fetal brain volume (FBV) from three-dimensional (3D) fetal head datasets.

METHODS

FBV were acquired independently by two operators from low risk singleton pregnancies at a gestational age between 19 and 34 weeks. FBV measurements were obtained using an automatic software (Smart ICV™) and manually by Virtual Organ Computer-aided AnaLysis (VOCAL™). Intraclass correlation coefficient (ICC) were calculated to assess reliability, while bias and agreement were evaluate by examining Bland-Altman plots. The time spent in measuring volumes was calculated and values obtained compared.

RESULTS

Sixty-three volumes were considered for the study. In all the included volumes successful volume analysis were obtained with both techniques. Smart ICV™ showed a high intra-observer (0.996; 95% CI 0.994-0.998) and inter-observer (ICC 0.995; 95% CI 0.991-0.997). An excellent degree of reliability was found when the two techniques were compared (ICC 0.995; 95% CI 0.987-0.998). The time required to perform FBV was significantly lower for Smart ICV™ than VOCAL™ (8.2 ± 4.5 vs. 121.3 ± 19.0 s; p < 0.0001).

CONCLUSIONS

The measurement of FBV is feasible with both manual and automatic techniques. Smart ICV™ showed an excellent intra- and inter-observer reliability associated with a valuable agreement with volume measurements obtained manually with VOCAL™. Volumes may be measured significantly faster with smart ICV™ than manually and this automatic software has the potential to become the preferred methods for the assessment of FBV.

Computational methods for the analysis of early-pregnancy brain ultrasonography: a systematic review

BACKGROUND

Early screening of the brain is becoming routine clinical practice. Currently, this screening is performed by manual measurements and visual analysis, which is time-consuming and prone to errors. Computational methods may support this screening. Hence, the aim of this systematic review is to gain insight into future research directions needed to bring automated early-pregnancy ultrasound analysis of the human brain to clinical practice.

METHODS

We searched PubMed (Medline ALL Ovid), EMBASE, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and Google Scholar, from inception until June 2022. This study is registered in PROSPERO at CRD42020189888. Studies about computational methods for the analysis of human brain ultrasonography acquired before the 20th week of pregnancy were included. The key reported attributes were: level of automation, learning-based or not, the usage of clinical routine data depicting normal and abnormal brain development, public sharing of program source code and data, and analysis of the confounding factors.

FINDINGS

Our search identified 2575 studies, of which 55 were included. 76% used an automatic method, 62% a learning-based method, 45% used clinical routine data and in addition, for 13% the data depicted abnormal development. None of the studies shared publicly the program source code and only two studies shared the data. Finally, 35% did not analyse the influence of confounding factors.

INTERPRETATION

Our review showed an interest in automatic, learning-based methods. To bring these methods to clinical practice we recommend that studies: use routine clinical data depicting both normal and abnormal development, make their dataset and program source code publicly available, and be attentive to the influence of confounding factors. Introduction of automated computational methods for early-pregnancy brain ultrasonography will save valuable time during screening, and ultimately lead to better detection, treatment and prevention of neuro-developmental disorders.

FUNDING

The Erasmus MC Medical Research Advisor Committee (grant number: FB 379283).

The application of three-dimensional ultrasound with reformatting technique in the diagnosis of fetal cleft lip/palate

OBJECTIVE

To evaluate the clinical value of three-dimensional ultrasound (3D-US) with reformatting technique in the diagnosis of fetal cleft lip/palate (CL/P), especially those involving the secondary palate.

METHODS

A total of 113 fetuses suspected with cleft lip (CL) on two-dimensional ultrasound (2D-US) were further evaluated by 2D-US and 3D-US with reformatting technique, in order to clarify the type of oral cleft. Lesions were classified as cleft lip (CL), cleft lip and alveolus (CLA), and cleft lip and palate (CLP) (including primary and secondary palate). All fetuses were followed until birth or termination of pregnancy. The diagnostic accuracies of 2D-US and 3D-US with reformatting technology were compared.

RESULTS

Both 2D-US and 3D-US with reformatting successfully detected CLs in the final 103 participants. Among these, 29, 25, and 49 cases were confirmed to have CL, CLA, and CLP, respectively. CL, CLA, and CLP were diagnosed by 2D-US in 34, 66, and 3 cases, respectively, and by 3D-US with reformatting technology in 31, 27, and 45 cases, respectively. The sensitivities of 2D-US and 3D-US with reformatting technology in the diagnosis of CLA were 80% (20/25) and 92.0% (23/25), respectively, and the difference was not statistically significant. For CLP, however, the sensitivities were 6.1% (3/49) and 91.8% (45/49), respectively (P < .001).

CONCLUSIONS

Both 2D-US and 3D-US with reformatting technique have high diagnostic accuracy for CL and CLA. However, 3D-US has a much higher diagnostic accuracy for CLP.

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.

Assessing lateral uterine wall defects and residual myometrial thickness after cesarean section

OBJECTIVE

Lateral wall ruptures in women with a history of cesarean section are less common but more complicated than anterior wall ruptures. Residual myometrial thickness (RMT) is believed to be valuable for assessing the probability of ruptures. This study aimed to assess the utility of OmniView (a sonographic reslicing technique) in evaluating the lateral uterine wall after cesarean section and evaluate the relationship between lateral and anterior wall RMT using OmniView and sagittal two-dimensional ultrasound.

STUDY DESIGN

This cross-sectional study examined changes in both the anterior and lateral uterine wall in women with a history of cesarean section in the past 12-18 months. OmniView with volume contrast imaging with a 2-mm slice thickness was used to generate coronal planes, and the OmniView RMT (OV-RMT) was calculated as a percentage. Blinded to the OV-RMT results, sonographic multiplanar views were used to acquire the optimum sagittal plane for evaluating the RMT, and the sagittal RMT (S-RMT) was calculated as a percentage. The reproducibility of OV-RMT and S-RMT between two observers was tested using interclass correlation (ICC). The relationship between two variables was tested using Spearman's rank correlation.

RESULTS

In 208 recruited patients, the prevalence of lateral uterine wall defects was 79 %. The interobserver and intraobserver reproducibility of S-RMT and OV-RMT had ICC coefficients over 0.9 with a p-value <0.001. S-RMT and OV-RMT did not follow a normal distribution, and the medians were significantly different (55.5 and 85.7, respectively). Spearman's rank correlation between OV-RMT and S-RMT had a rho (ρ) value of 0.24 (p < 0.05). Passing-Bablok regression had an intercept of 47.95 and a slope of 0.65.

CONCLUSION

OmniView can be used to assess lateral uterine wall defects, and OV-RMT is a reproducible and reliable method for quantifying this assessment. The RMT on the coronal plane was independently more intact than that on the sagittal plane, which might account for the lower incidence of lateral ruptures. Further studies could reveal a critical OV-RMT value that is safe for a trial of labor.

Towards automated extraction of 2D standard fetal head planes from 3D ultrasound acquisitions: A clinical evaluation and quality assessment comparison

Introduction

Clinical evaluation of deep learning (DL) tools is essential to compliment technical accuracy metrics. This study assessed the image quality of standard fetal head planes automatically-extracted from three-dimensional (3D) ultrasound fetal head volumes using a customised DL-algorithm.

Methods

Two observers retrospectively reviewed standard fetal head planes against pre-defined image quality criteria. Forty-eight images (29 transventricular, 19 transcerebellar) were selected from 91 transabdominal fetal scans (mean gestational age = 26 completed weeks, range = 20⁺⁵–32⁺³ weeks). Each had two-dimensional (2D) manually-acquired (2D-MA), 3D operator-selected (3D-OS) and 3D-DL automatically-acquired (3D-DL) images. The proportion of adequate images from each plane and modality, and the number of inadequate images per plane was compared for each method. Inter and intra-observer agreement of overall image quality was calculated.

Results

Sixty-seven percent of 3D-OS and 3D-DL transventricular planes were adequate quality. Forty-five percent of 3D-OS and 55% of 3D-DL transcerebellar planes were adequate.

Seventy-one percent of 3D-OS and 86% of 3D-DL transventricular planes failed with poor visualisation of intra-cranial structures. Eighty-six percent of 3D-OS and 80% of 3D-DL transcerebellar planes failed due to inadequate visualisation of cerebellar hemispheres. Image quality was significantly different between 2D and 3D, however, no significant difference between 3D-modalities was demonstrated (p < 0.005). Inter-observer agreement of transventricular plane adequacy was moderate for both 3D-modalities, and weak for transcerebellar planes.

Conclusion

The 3D-DL algorithm can automatically extract standard fetal head planes from 3D-head volumes of comparable quality to operator-selected planes. Image quality in 3D is inferior to corresponding 2D planes, likely due to limitations with 3D-technology and acquisition technique.

Implications for practice

Automated image extraction of standard planes from US-volumes could facilitate use of 3DUS in clinical practice, however image quality is dependent on the volume acquisition technique.

A novel technique to assess fetal corpus callosum by two-dimensional axial plane

OBJECTIVE

The definition of new normal values of the corpus callosum (CC) in axial sonographic scans and evaluation of their feasibility in diagnosing abnormal CC.

METHODS

A cross-sectional study assessed CC from 20-gestational-week to full-term. CC observations across three axial planes (the largest CC length plane, trans-genu-and-splenium plane, and trans-body plane) were developed. The largest CC length, genu and splenium thickness, and body width and thickness were compared with compound scatter plots. Ultrasonographic features of normal and abnormal CC were described and the feasibility of the new approach studied. Intra-class correlation coefficient (ICC) was used for assessing the intra- and inter-observer agreements.

RESULTS

Six hundred seventy normal and 42 abnormal fetuses from 20-gestational-week to full-term were studied. The mean normal and abnormal group maternal ages were 30.46 ± 4.36 years and 29.69 ± 4.49 years (p = 0.269). The success rate in obtaining satisfactory axial planes reached 100% but only 13.9% for sagittal plane in the normal group. The success rate of abnormal cases obtaining satisfactory axial planes was 100% and 59.5% by sagittal plane (p < 0.05). The compound scatter plots of abnormal and normal groups showed that the largest CC length and body width were significantly lower in normal fetuses, and the thickness of the genu and splenium with CC hypoplasia was significantly lower than normal fetuses. The intra- and inter-observer agreements were reproducible (all ICC > 0.850).

CONCLUSIONS

The feasibility of incorporating an evaluation of CC into routine anatomical screening was demonstrated. Additionally, a focused examination of the craniocerebral axial planes exploring CC at the time of central nervous system scanning might facilitate CC anomaly detection.

KEY POINTS

• Three axial planes with direct CC measurements can detect CC anomalies more accurately compared with indirect CC signs. Besides, this method is simpler, more convenient, and time-saving compared with the sagittal plane. • Assessing fetal CC on the axial plane helps clinicians to diagnose fetuses with abnormal CC. • A prospective single-center study showed that our new technique provides enough diagnostic confidence.

Automatic display of fetal brain planes and automatic measurements of fetal brain parameters by transabdominal three-dimensional ultrasound

OBJECTIVE

The primary purpose of this study was to evaluate the effectiveness of a three-dimensional (3D) software tool (smart planes) for displaying fetal brain planes, and the secondary purpose was to evaluate its accuracy in performing automatic measurements.

MATERIAL AND METHODS

This prospective study included singleton fetuses with a gestational age (GA) greater than 18 weeks. Transabdominal two-dimensional ultrasound (2DUS) and 3D smart planes images were respectively used to obtain the basic planes of the fetal brain, with five parameters measured. The images, by either two-dimensional (2D) manual or 3D automatic operation, were reviewed by two experienced sonographers. The agreements between two measurements were analyzed.

RESULTS

A total of 226 cases were included. The rates of successful detection by automatic display were as high as 80%. There was substantial agreement between the measurements of the biparietal diameter, head circumference and transcerebellar diameter, but poor agreement between the measurements of cisterna magna and lateral ventricle width.

CONCLUSIONS

Smart Planes might be valuable for the rapid evaluation of fetal brain, because it simplifies the evaluation process. However, the technology requires improvement. In addition, this technology cannot replace the conventional manual US scans; it can only be used as an additional approach.

5D CNS+ Software for Automatically Imaging Axial, Sagittal, and Coronal Planes of Normal and Abnormal Second-Trimester Fetal Brains

The purpose of this study was to test new 5D CNS+ software (Samsung Medison Co, Ltd, Seoul, Korea), which is designed to image axial, sagittal, and coronal planes of the fetal brain from volumes obtained by 3-dimensional sonography. The study consisted of 2 different steps. First in a prospective study, 3-dimensional fetal brain volumes were acquired in 183 normal consecutive singleton pregnancies undergoing routine sonographic examinations at 18 to 24 weeks' gestation. The 5D CNS+ software was applied, and the percentage of adequate visualization of brain diagnostic planes was evaluated by 2 independent observers. In the second step, the software was also tested in 22 fetuses with cerebral anomalies. In 180 of 183 fetuses (98.4%), 5D CNS+ successfully reconstructed all of the diagnostic planes. Using the software on healthy fetuses, the observers acknowledged the presence of diagnostic images with visualization rates ranging from 97.7% to 99.4% for axial planes, 94.4% to 97.7% for sagittal planes, and 92.2% to 97.2% for coronal planes. The Cohen κ coefficient was analyzed to evaluate the agreement rates between the observers and resulted in values of 0.96 or greater for axial planes, 0.90 or greater for sagittal planes, and 0.89 or greater for coronal planes. All 22 fetuses with brain anomalies were identified among a series that also included healthy fetuses, and in 21 of the 22 cases, a correct diagnosis was made. 5D CNS+ was efficient in successfully imaging standard axial, sagittal, and coronal planes of the fetal brain. This approach may simplify the examination of the fetal central nervous system and reduce operator dependency.

Three-dimensional ultrasonography by means of HDlive rendering in the first trimester of pregnancy: A pictorial review

Our objective was to describe early embryo/fetus anatomy and abnormalities provided by three and four-dimensional (3D/4D) ultrasound using HDlive rendering technology in the first trimester of pregnancy. Normal and pathologic embryonic and fetal volume data set with postprocessing using HDlive rendering mode. Virtual fetoscopic imaging of the normal and pathologic fetus even at early stage of development with increasing maternal-fetal bonding process. HDlive represents a novel and valuable lightening system for 3D/4D ultrasound application that may aid the prenatal interpretation of early congenital malformations although limitations and cautions are still needed for inclusion in obstetric clinical practice.

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.

Role of 3-D ultrasound in clinical obstetric practice: evolution over 20 years

The use of 3-D ultrasound in obstetrics has undergone dramatic development over the past 20 years. Since the first publications on this application in clinical practice, several 3-D ultrasound techniques and rendering modes have been proposed and applied to the study of fetal brain, face and cardiac anatomy. In addition, 3-D ultrasound has improved calculations of the volume of fetal organs and limbs and estimations of fetal birth weight. And furthermore, angiographic patterns of fetal organs and the placenta have been assessed using 3-D power Doppler ultrasound quantification. In this review, we aim to summarize current evidence on the clinical relevance of these methodologies and their application in obstetric practice.

Dilated intracranial translucency and Blake's pouch cyst: first-trimester ultrasound markers of occipital cephalocele diagnosed using novel three-dimensional reslicing technique

Abnormal intracranial translucency (IT) (fourth ventricle) and a Blake's pouch cyst with normal brain stem cavity may be valuable first-trimester call signs of defects in the skull base. Here, we report a case of presumptive two-dimensional sonographic diagnosis of occipital cephalocele that was posed at the time of 11-13 weeks aneuploidy scan. The two-dimensional sonographic finding elicited a detailed fetal neuroscan that was performed using either multiplanar mode or a novel three-dimensional reslicing and lightening technique. The use of three-dimensional sonographic software and offline "navigation" within the volume of interest enabled operators to capture a diagnostic snapshot of the condition, enhancing quality imaging and early detection of the encephalic lesion.

Second trimester fetal neurosonography: reconstructing cerebral midline anatomy and anomalies using a novel three-dimensional ultrasound technique

OBJECTIVE

To describe the application of a novel 3D ultrasound reconstructing technique (OMNIVIEW) that may facilitate the evaluation of cerebral midline structures at the second trimester anatomy scan.

METHODS

Fetal cerebral midline structures from 300 consecutive normal low-risk pregnant women were studied prospectively by 2D and 3D ultrasound between 19-23 weeks of gestation. All the newborn infants underwent pediatric follow-up and were considered normal up to 2 years of life. In addition, five confirmed pathologic cases were evaluated and the abnormal features using this technique are described in this clinical series.

RESULTS

Off-line volume data sets displaying the corpus callosum and the cerebellar vermis anatomy were accurately reconstructed in 98.5% and 96% of cases from sagittal and axial planes, respectively. For pathological cases, an agreement rate of 0.96 and 0.91 for midsagittal and axial planes, respectively, was observed.

CONCLUSIONS

This study demonstrates the feasibility of including 3D ultrasound as an adjunct technique for the evaluation of cerebral midline structures in the second trimester fetus. Future prospective studies will be necessary to evaluate if the application of this novel 3D reconstructing technique as a step forward following 2D second trimester screening scan will improve the prenatal detection of cerebral midline anomalies in the low-risk pregnant population.

Quantitative evaluation of the fetal cerebellar vermis using the median view on three-dimensional ultrasound

OBJECTIVE

The purpose of this study was to investigate the effectiveness for quantitative evaluation of cerebellar vermis using three-dimensional (3D) ultrasound and to establish a nomogram for Chinese fetal vermis measurements during gestation.

METHODS

Sonographic examinations were performed in normal fetuses and in cases suspected of the diagnosis of vermian rotation. 3D median planes were obtained with both OMNIVIEW and tomographic ultrasound imaging.

RESULTS

Measurements of the cerebellar vermis were highly correlated between two-dimensional and 3D median planes. The diameter of the cerebellar vermis follows growth approximately predicted by the quadratic regression equation. The normal vermis was almost parallel to the brain stem, with the average angle degree to be <2° in normal fetuses. The average angle degree of the 9 cases of vermian rotation was >5°.

CONCLUSIONS

Three-dimensional median planes are obtained more easily than two-dimensional ones, and allow accurate measurements of the cerebellar vermis. The 3D approach may enable rapid assessment of fetal cerebral anatomy in standard examination. Measurements of cerebellar vermis may provide a quantitative index for prenatal diagnosis of posterior fossa malformations.

Reference ranges for vertebral body areas of the fetal lumbosacral spine on 3-dimensional sonography using volume contrast imaging with OmniView

OBJECTIVES; The purpose of this study was to establish reference ranges for vertebral body areas of the fetal lumbosacral spine in the coronal plane on 3-dimensional sonography using volume contrast imaging with OmniView (GE Healthcare, Zipf, Austria). METHODS; An observational cross-sectional study was conducted on 576 healthy pregnant women at gestational ages of 20 weeks to 34 weeks 6 days. Volume contrast imaging with OmniView was used to measure the vertebral body areas (L1-L5, S1, and S2) by positioning a curved line along the fetal lumbosacral spine. To create reference ranges, first- and second-degree linear regression models adjusted using residual analysis and the coefficient of determination (R(2)) were created. To assess reproducibility, two examiners evaluated 40 random volumes using the intraclass correlation coefficient. RESULTS; The mean areas of the vertebral bodies were 102.72 (range, 25-254), 107.29 (range, 30-245), 105.10 (range, 31-231), 99.09 (range, 31-211), 87.74 (range, 11-178), 65.80 (range, 18-161), and 46.54 (range, 12-129) mm(2) for L1, L2, L3, L4, L5, S1, and S2, respectively. In the intraobserver and interobserver reproducibility assessments, intraclass correlation coefficients of greater than 0.80 were found for all fetal vertebral body areas. CONCLUSIONS; Reference values for fetal lumbosacral spine vertebral body areas were determined by 3-dimensional sonography using volume contrast imaging with OmniView, and they were shown to be reproducible.