Fetal cardiac interventricular septum: volume assessment by 3D/4D ultrasound using spatio-temporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL)

Comparison of Left Ventricular Stroke Volume in 2nd- and 3rd-Trimester Fetuses Measured by the Product of VTI and Aortic Annular Area With That Assessed by Simpson's Single-Plane Rule Using the STE Technique

OBJECTIVES

The aim of the study was to compare left ventricle stroke volume in healthy, eutrophic fetuses in the 2nd and 3rd trimesters evaluated using the velocity time integral and aortic annulus area with left ventricular stroke volume measured using Simpson's single-plane rule and to determine the discrepancy equation.

METHODS

The study included 354 fetuses. In each fetus, during the same examination, simultaneous assessment of stroke volume was performed by pulsed-wave Doppler using the product of the velocity time integral and aortic annulus area and by the fetalHQ® software using Simpson's single-plane rule. The Mann-Whitney U test was used to compare the "product-derived" stroke volume and stroke volume using fetalHQ® software values in the 2nd and 3rd trimesters separately. The agreement between the two methods were verified using Bland-Altman analysis. A linear regression model was used to obtain the discrepancy equation.

RESULTS

In the 2nd trimester, the mean percentage difference between both the techniques showed that the stroke volume values determined using pulsed-wave Doppler were, on average, 88% higher than the stroke volume values determined using fetalHQ®. The upper limit of agreement between the compared techniques was approximately 146% and the lower limit of agreement was equal to 29.6%. In the 3rd trimester, the results indicated that the stroke volume values determined using pulsed-wave Doppler were, on average, 76% higher than the stroke volume values determined using fetalHQ®. The upper limit of agreement between the compared techniques was approximately 129% and the lower limit of agreement was 23%. Based on the results of the linear regression models, discrepancy formulas of the stroke volume values were obtained. The equations to calculate the predicted mean and standard deviations were used to compute the reference intervals for the mean, 5th and 95th centiles.

CONCLUSION

The calculation of left ventricular stroke volume using pulsed Doppler has higher result in relation to stroke volume determined using Simpson's rule significantly. The aortic annulus area showed a higher correlation regarding stroke volume than the velocity time integral in both the 2nd and 3rd trimesters. Stroke volume increased with the increase in aortic annulus area, whereas the velocity time integral remained relatively constant. The retrospective analysis of the collected material enabled the determination of the discrepancy equation.

Artificial intelligence applied to fetal MRI: A scoping review of current research

Artificial intelligence (AI) is defined as the development of computer systems to perform tasks normally requiring human intelligence. A subset of AI, known as machine learning (ML), takes this further by drawing inferences from patterns in data to 'learn' and 'adapt' without explicit instructions meaning that computer systems can 'evolve' and hopefully improve without necessarily requiring external human influences. The potential for this novel technology has resulted in great interest from the medical community regarding how it can be applied in healthcare. Within radiology, the focus has mostly been for applications in oncological imaging, although new roles in other subspecialty fields are slowly emerging.In this scoping review, we performed a literature search of the current state-of-the-art and emerging trends for the use of artificial intelligence as applied to fetal magnetic resonance imaging (MRI). Our search yielded several publications covering AI tools for anatomical organ segmentation, improved imaging sequences and aiding in diagnostic applications such as automated biometric fetal measurements and the detection of congenital and acquired abnormalities. We highlight our own perceived gaps in this literature and suggest future avenues for further research. It is our hope that the information presented highlights the varied ways and potential that novel digital technology could make an impact to future clinical practice with regards to fetal MRI.

Fetal Interventricular Septum Volume Evaluated by Three-Dimensional Ultrasound Using Spatiotemporal Image Correlation and Virtual Organ Computer-Aided Analysis in Fetuses From Pre-Gestational Diabetes Mellitus Pregnant Women

BACKGROUND

To assess the interventricular septum (IVS) volume of fetuses from pre-gestational diabetes mellitus (DM) pregnant women by 3-dimensional ultrasound using spatiotemporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL) methods.

METHODS

This was a prospective cross-sectional study of 45 fetuses from pre-gestational DM and 45 fetuses from healthy pregnant women (controls). Only singleton pregnancies between 20 and 34 + 6 weeks of gestation were included. The fetal IVS volumes were obtained off-line using STIC and VOCAL methods. To analyze differences among variables, the Student’s t-test and Mann-Whitney U test were used. The correlation among continuous variables was determine using Spearman’s correlation test (r).

RESULTS

The median of fetal IVS volume was significantly higher in pre-gestational DM than in healthy pregnant women (0.3 cm³ vs. 0.2 cm³, p = 0.032). A strong positive correlation was observed between fetal IVS volume and gestational age at the time of ultrasound examination (r = 0.75, R² = 0.48, p < 0.0001) and between fetal IVS volume and estimated fetal weight (r = 0.63, R² = 0.37, p < 0.0001). No significant correlation was noted between fetal IVS volume and glycated hemoglobin levels (r = −0.16, R² = 0.01, p = 0.540) in the pre-gestational DM pregnant women.

CONCLUSIONS

Significant differences were observed in fetal IVS volumes between pre-gestational and healthy mothers, with higher values in the fetuses of pre-gestational DM pregnant women.

Artificial Intelligence in Obstetric Ultrasound: An Update and Future Applications

Artificial intelligence (AI) can support clinical decisions and provide quality assurance for images. Although ultrasonography is commonly used in the field of obstetrics and gynecology, the use of AI is still in a stage of infancy. Nevertheless, in repetitive ultrasound examinations, such as those involving automatic positioning and identification of fetal structures, prediction of gestational age (GA), and real-time image quality assurance, AI has great potential. To realize its application, it is necessary to promote interdisciplinary communication between AI developers and sonographers. In this review, we outlined the benefits of AI technology in obstetric ultrasound diagnosis by optimizing image acquisition, quantification, segmentation, and location identification, which can be helpful for obstetric ultrasound diagnosis in different periods of pregnancy.

References Values of Fetal Heart Myocardial Volume by Three-Dimensional Ultrasound using Spatiotemporal Image Correlation and Virtual Organ Computer-Aided Analysis Methods and Their Applicability in Pregestational Diabetic Women

OBJECTIVE

To determine reference values for myocardial volume of the fetal heart using three-dimensional ultrasound with spatiotemporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL) and to assess their applicability in women with pregestational diabetes.

STUDY DESIGN

This retrospective cross-sectional study included 177 normal pregnant women with fetuses between 20^0/7 and 33^6/7 weeks of age. Fetal cardiac volumes were collected using the STIC method, and myocardial volume was obtained by subtraction of the intracavitary volumes using the VOCAL 30-degree method. Intra- and interobserver reproducibility values were determined using the concordance correlation coefficient (CCC). Sixteen women with pregestational diabetes mellitus were evaluated for validation.

RESULTS

There was a strong correlation between fetal myocardial volume and gestational age (R ² = 0.82). Intra- and interobserver reproducibility values were excellent and moderate, respectively, with CCCs of 0.99 and 0.83, respectively. There was no significant difference in mean fetal myocardial volume between normal pregnant women and those with pregestational diabetes (p = 0.64).

CONCLUSION

Reference values for myocardial volume of the fetal heart were determined in normal pregnant women and were not statistically different from those in women with pregestational diabetes mellitus.

Quantified growth of the human embryonic heart

The size and growth patterns of the components of the human embryonic heart have remained largely undefined. To provide these data, three-dimensional heart models were generated from immunohistochemically stained sections of ten human embryonic hearts ranging from Carnegie stage 10 to 23. Fifty-eight key structures were annotated and volumetrically assessed. Sizes of the septal foramina and atrioventricular canal opening were also measured. The heart grows exponentially throughout embryonic development. There was consistently less left than right atrial myocardium, and less right than left ventricular myocardium. We observed a later onset of trabeculation in the left atrium compared to the right. Morphometry showed that the rightward expansion of the atrioventricular canal starts in week 5. The septal foramina are less than 0.1 mm² and are, therefore, much smaller than postnatal septal defects. This chronological, graphical atlas of the growth patterns of cardiac components in the human embryo provides quantified references for normal heart development. Thereby, this atlas may support early detection of cardiac malformations in the foetus.This article has an associated First Person interview with the first author of the paper.

Fetal Cardiac Function and Ventricular Volumes Determined by Three-Dimensional Ultrasound Using STIC and VOCAL Methods in Fetuses from Pre-gestational Diabetic Women

To assess the fetal cardiac function and ventricular volumes by three-dimensional (3D) ultrasound using spatio-temporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL) methods in fetuses from pre-gestational diabetic women. This was a prospective and cross-sectional study that evaluated 53 fetuses from pre-gestational diabetic women and 53 fetuses from healthy mothers between 20 and 34 weeks of gestation. Only fetuses with no structural or genetic abnormalities and singleton pregnant women were included in this study. The fetal cardiac volumes were assessed by STIC and VOCAL methods. The ejection fraction, stroke volume, and cardiac output were calculated from these measurements to evaluate fetal cardiac function. The Mann-Whitney U test was performed to compare the two groups. For calculation of intra- and interobserver reproducibility's, we used concordance correlation coefficients. The mean differences in the right atrial volumes between the diabetic and normal groups ranged from 0.05 mL to 0.1 mL (p = 0.917 and 0.355, respectively). The median of left atrium (LA) volume measurement in pre-gestational diabetic group was significantly lower than healthy mothers (LA: 0.62 vs. 0.68 mL; p < 0.001). The fetal right and left ventricular volumes were similar in both groups. No significant differences in ejection fraction, stroke volume and cardiac output were observed (p value range 0.086-0.815). The majority of fetal atrial/ventricular volumes showed good intra- and interobserver reliabilities. Conversely, the majority cardiac function parameters showed poor intra- and interobserver agreements. STIC and VOCAL methods gave reproducible quantitative results for fetal atrial and ventricular volumes. Significant differences in fetal left atrial volumes were observed between the two groups, which be related to LA atrial dysfunction and /or left ventricle (LV) compliance, reflecting earlier stages of cardiac dysfunction.

Electronic versus conventional spatiotemporal image correlation (STIC) fetal echocardiography: a direct comparison

Objectives: Recent advances in Spatial Temporal Image Correlation (STIC) 4 D fetal echocardiography include the application of eSTIC based on electronic probe image acquisition. We aimed to directly compare the performance of conventional STIC versus eSTIC technique (B-Mode and color Doppler imaging) during off-line reconstruction of STIC/eSTIC fetal heart volume pairs.Methods: Pairs of B-Mode and Color Doppler STIC volumes were acquired sequentially by firstly conventional (STIC) followed by electronic (eSTIC) probes during 33 consecutive obstetric scans at median 23 (range 13-31) gestational weeks. The resulting 66 fetal heart volume pairs were assessed blindly off-line by a fetal cardiologist who documented feasibility of reconstruction, presence of motion artifacts, subjective image quality on a 4-level scale: 1-best to 4-non-diagnostic and morphological diagnosis, to enable a paired comparison of STIC and eSTIC in the same fetus under similar scanning conditions.Results: eSTIC volumes had higher temporal resolution (37 vs. 24 frames per second, p < .001), less motion during acquisition (12 vs. 20 cases, O.R. 7.0, p = .002) and better average image quality (1.9 vs. 2.2, p = .006) compared to STIC volumes. More diagnostic reconstructions were achieved by eSTIC (n = 55, 86%) than STIC (n = 52, 78.8%), p = .001), in a comparable analysis time (mean 4.96 vs. 4.94 min). During a comparison of image quality of the original acquisition (A) and reconstructed planes (B and C planes) e STIC was superior in 22 (33%), 39 (59%) and 21 (38%) volumes, respectively, with the remaining cases being of similar quality (<10% in each plane in favor of STIC). Imaging mode and gestational age had a similar impact on both eSTIC and STIC performance: diagnostically acceptable studies in 49 (75.8%) vs. 48 (72.2%) by B-Mode, 60 (90.9%) vs. 56 (84.8%) by Color Doppler Mode, 8 (62.5%) vs. 10 (50%) in early scans, 38 (95%) vs. 38 (95%) in mid-gestation scans, and 7 (70%) vs. 6 (60%) in third trimester scans. Eight obstetric scans identified a fetus with a cardiac variant or structural abnormality. Diagnostic concordance of the two STIC approaches was comparable (40/48 concordant interpretations, kappa 0.657) all confirmed by fetal and/or postnatal echocardiography.Conclusions: eSTIC was associated with more effective 4 D fetal heart reconstruction due to reduced motion artifacts and superior image quality in all planes, when compared to STIC. Early gestation reconstructions were not generally successful using either technology. Further study is needed to define the cost-effectiveness and diagnostic impact of eSTIC over conventional STIC and their role over, or in addition to, screening 2 D fetal echocardiography by appropriately trained sonographers.

Fetal cardiac function by three-dimensional ultrasound using 4D-STIC and VOCAL - an update

Three- and four-dimensional (3D/4D) ultrasonography with spatio-temporal image correlation (4D-STIC) allows obtaining fetal cardiac volumes and their static and real-time analysis in multiplanar and rendering modes. Cardiac biometrics and Doppler-echocardiographic parameters for evaluation of fetal heart function, including cardiac output and stroke volume, can be analyzed using M-mode, two-dimensional (2D), and 3D/4D cardiac ultrasound. In recent years, functional echocardiography has been used to study fetuses without a structurally cardiac defect but who are at risk of heart failure due to the presence of extra-cardiac conditions, such as, fetal growth restriction, tumors/masses, twin-to-twin transfusion syndrome, fetal anemia (Rh alloimmunization), congenital infections, or maternal diabetes mellitus. The assessment of cardiac function provides important information on hemodynamic status and can help optimize the best time for delivery and reduce perinatal morbidity and mortality. Since 2003, with the advent of the 4D-STIC software, it is possible to evaluate the fetal heart in multiplanar, and rendering modes. This technology associated with virtual organ computer-aided analysis (VOCAL) enables determining the ventricular volume (end-diastole, end-systole), the stroke-volume, the ejection fraction, and the cardiac output of each ventricle. Since 2004, several studies demonstrated that the 4D-STIC and VOCAL had good reproducibility to measure cardiac volumes This study reviews published studies that evaluated the fetal cardiac function by 3D ultrasound using 4D-STIC and VOCAL software.

Evaluation of right ventricular volume and systolic function in normal fetuses using intelligent spatiotemporal image correlation

BACKGROUND

Heart defects are the most common congenital malformations in fetuses. Fetal cardiac structure and function abnormalities lead to changes in ventricular volume. As ventricular volume is an important index for evaluating fetal cardiovascular development, an effective and reliable method for measuring fetal ventricular volume and cardiac function is necessary for accurate ultrasonic diagnosis and effective clinical treatment. The new intelligent spatiotemporal image correlation (iSTIC) technology acquires high-resolution volumetric images. In this study, the iSTIC technique was used to measure right ventricular volume and to evaluate right ventricular systolic function to provide a more accurate and convenient evaluation of fetal heart function.

AIM

To investigate the value of iSTIC in evaluating right ventricular volume and systolic function in normal fetuses.

METHODS

Between October 2014 and September 2015, a total of 123 pregnant women received prenatal ultrasound examinations in our hospital. iSTIC technology was used to acquire the entire fetal cardiac volume with off-line analysis using QLAB software. Cardiac systolic and diastolic phases were defined by opening of the atrioventricular valve and the subsequent closure of the atrioventricular valve. The volumetric data of the two phases were measured by manual tracking and summation of multiple slices and recording of the right ventricular end-systolic volume and the right ventricular end-diastolic volume. The data were used to calculate the right stroke volume, the right cardiac output, and the right ejection fraction. The correlations of changes between the above-mentioned indices and gestational age were analyzed. The right ventricular volumes of 30 randomly selected cases were measured twice by the same sonographer, and the intra-observer agreement measurements were calculated.

RESULTS

Among the 123 normal fetuses, the mean right ventricular end-diastolic volume increased from 0.99 ± 0.34 mL at 22 wk gestation to 3.69 ± 0.36 mL at 35⁺⁶ wk gestation. The mean right ventricular end-systolic volume increased from 0.43 ± 0.18 mL at 22 wk gestation to 1.36 ± 0.22 mL at 35⁺⁶ wk gestation. The mean right stroke volume increased from 0.62 ± 0.29 mL at 22 wk gestation to 2.33 ± 0.18 mL at 35⁺⁶ wk gestation. The mean right cardiac output increased from 92.23 ± 40.67 mL/min at 22 wk gestation to 335.83 ± 32.75 mL/min at 35⁺⁶ wk gestation. Right ventricular end-diastolic volume, right ventricular end-systolic volume, right stroke volume, and right cardiac output all increased with gestational age and the correlations were linear (P < 0.01). Right ejection fraction had no apparent correlation with gestational age (P > 0.05).

CONCLUSION

Fetal right ventricular volume can be quantitatively measured using iSTIC technology with relative ease and high repeatability. iSTIC technology is expected to provide a new method for clinical evaluation of fetal cardiac function.

The first Fetal Echocardiography experience for Prenatal diagnosis of Congenital Heart Disease in Lebanon: Successes and challenges

Objectives

To describe the first Lebanese fetal echocardiography experience for prenatal diagnosis of congenital heart diseases (CHD), showcase successes, and hurdles.

Methods

This was a retrospective study from January 2014 to December 2017. A total of 350 fetal echocardiograms for 299 fetuses were performed at the Children’s Heart Center at the American University of Beirut, the only fetal center in Lebanon. Data were collected regarding diagnosis, reasons for referral, and timing of referral.

Results

The mean gestational age at presentation was 25.3 weeks (standard deviation 4.9 weeks). The primary reasons for referral were abnormal anomaly scan (81 27%), history of previous child with CHD (48 16%), and pre-existing maternal congenital heart disease (15 5%). A total of 144 fetal echocardiograms were normal and 155 patients were diagnosed prenatally with CHD giving a detection rate of 44%. The most identified cardiac lesions were ventricular septal defects (31, 20%), atrial septal defects (15, 9.7%). Significant CHD defined as major abnormalities which would impact pregnancy and future quality of life of the baby were identified in 78 fetuses, with a detection rate of 22%.

Conclusion

High rates of detection are mainly due to low rates of referral when indicated and possibly parental anxiety regarding CHD diagnosis.

Four-Dimensional Ultrasound for Evaluating Newborn Cardiac Output: A Pilot Study of Healthy Infants

BACKGROUND

There is currently no reliable non-invasive method of measuring cardiac output in neonatal intensive care. Spatiotemporal image correlation (STIC) is a novel four-dimensional (4D) ultrasound technique that was developed to assess the foetal heart, and it may be a useful way to assess neonatal haemodynamics.

OBJECTIVE

This study aimed to evaluate the feasibility and reproducibility of determining neonatal cardiac output using STIC ultrasound in newborn infants.

DESIGN

Infants were recruited opportunistically from a neonatal intensive care unit and then examined by 2 independent observers. STIC was used to obtain images of the heart. End-diastolic and end-systolic ventricular volumes were measured using virtual organ computer-aided analysis (VOCAL) and used to calculate cardiac output. Reproducibility was assessed with intraclass correlation coefficients (ICC) and agreement with Bland-Altman analysis.

RESULTS

Twenty-four clinically stable infants of 34-43 weeks corrected gestational age were assessed. Both observers successfully acquired 4D STIC volumes in all infants. Left ventricular output showed good reproducibility, with an intra-observer ICC of 0.86 (0.69-0.94) and inter-observer ICC of 0.87 (0.70-0.95). Right ventricular output also showed good reproducibility, with an intra-observer ICC of 0.88 (0.70-95) and inter-observer ICC of 0.84 (0.63-0.93).

CONCLUSIONS

Determining cardiac output using 4D STIC ultrasound is feasible and reproducible in well newborn infants. With further evaluation, this technique may provide valuable information about haemodynamic status in newborn infants requiring intensive care.

4D fetal echocardiography-An update

With the introduction of the electronic 4-dimensional and spatial-temporal image Correlation (e-STIC), it is now possible to obtain large volume datasets of the fetal heart that are virtually free of artifact. This allows the examiner to use a number of imaging modalities when recording the volumes that include two-dimensional real time, power and color Doppler, and B-flow images. Once the volumes are obtained, manipulation of the volume dataset allows the examiner to recreate views of the fetal heart that enable examination of cardiac anatomy. The value of this technology is that a volume of the fetal heart can be obtained, irrespective of the position of the fetus in utero, and manipulated to render images for interpretation and diagnosis. This article presents a summary of the various imaging techniques and provides clinical examples of its application used for prenatal diagnosis of congenital heart defects and abnormal cardiac function.

Evaluation of fetal heart geometry during pregnancy by three-dimensional ultrasound using the STIC rendering mode

OBJECTIVE

To determine fetal heart geometry during pregnancy using three-dimensional (3D) ultrasound and the spatiotemporal image correlation (STIC) rendering mode.

METHODS

This prospective, cross-sectional study evaluated 250 normal singleton pregnancies from 20 to 33 weeks and 6 days of gestation. STIC rendering was used to calculate the eight angles of the fetal heart: apex, base, mitral valve, tricuspid valve, left ventricle, right ventricle, left atrium, and right atrium angles. The concordance correlation coefficient (CCC) was used for intra- and inter-observer tests.

RESULTS

The average ± SD maternal age was 31.7 ± 4.9 years, and the average gestational age was 26.3 ± 4.2 weeks. There was little variation in fetal heart angles using STIC rendering according to the gestational age, with determination coefficient (R² ) values of 0.01 for the apex and mitral valve angles and <0.01 for the base, tricuspid valve, left ventricle, right ventricle, left atrium, and right atrium angles. Moderate/good intra- and inter-observer concordance was observed for the measurement of fetal heart angles using STIC rendering, and the obtained CCC varied from 0.74 to 0.93.

CONCLUSION

The fetal heart geometry did not present significant variations during pregnancy using 3D ultrasound and the STIC rendering mode.