Rendering in fetal cardiac scanning: the intracardiac septa and the coronal atrioventricular valve planes

Evaluation of cardiac contractility of fetuses from pregestational diabetes mellitus pregnancies by three-dimensional ultrasound

OBJECTIVE

This study aimed to evaluate cardiac contractility in fetuses from pregestational diabetes mellitus pregnancies by three-dimensional ultrasound using spatiotemporal image correlation in rendering mode.

METHODS

A retrospective cross-sectional study was performed on 40 fetuses from nondiabetic pregnancies and 28 pregestational diabetic pregnancies between 20 and 33 weeks and 6 days. Cardiac contractility was assessed by measuring the ventricular myocardial area in diastole subtracted from the ventricular myocardial area in systole.

RESULTS

Pregestational diabetic pregnancies had a lower maternal age than nondiabetic pregnancies (26.7 vs. 39.9 years, p=0.019). Cardiac contractility in fetuses from diabetic and nondiabetic pregnancies was similar (p=0.293). A moderately positive and significant correlation was observed between gestational age and cardiac contractility (r=0.46, p=0.0004). A 1-week increase in gestational age was responsible for a 0.1386 cm2 increase in cardiac contractility.

CONCLUSION

Cardiac contractility as evaluated by three-dimensional ultrasound using spatiotemporal image correlation in rendering mode showed no significant differences across fetuses with and without pregestational diabetes.

Area of the Fetal Ascending and Descending Aorta by Spatiotemporal Image Correlation in the Rendering Mode: Reproducibility and Comparison with Pregestational Diabetic Mothers

Background

The objective of this study was to assess the ascending and descending aorta area measurements by three-dimensional (3D) ultrasound using spatiotemporal image correlation (STIC) in the rendering mode comparing these measurements with pregestational diabetic mothers and assessing the reproducibility of the method.

Methods

We carried out a retrospective cross-sectional study with 58 normal and nine fetuses from pregestational diabetic mothers between 20 and 33 + 6 weeks of gestation. Fetal heart volumes were acquired at the level of four-chamber view to obtain the reconstructed planes for the ascending and descending aorta areas in the rendering mode. Linear regression was performed to assess the correlation between the fetal aorta areas and gestational age (GA). To assess the intra- and interobserver reproducibility, we used the concordance correlation coefficient (CCC).

Results

The mean ascending and descending aorta areas were 0.12 (0.02-0.48) and 0.11 (0.04-0.39) cm2 in normal fetuses, respectively. There was a moderate positive correlation between GA and ascending aorta area measurements (0.005676*GA - 0.01283; r = 0.53, P < 0.0001) and strong positive correlation between GA and descending aorta area (0.01095*GA - 0.1581; r = 0.68, P < 0.0001). We observed a weak intra- and interobserver reproducibility with CCC ranging from 0.05 to 0.91. The mean difference in the ascending and descending aorta area measurements of normal and fetuses of pregestational diabetic mothers was -0.03 cm2 (P = 0.276) and -0.03 cm2 (P = 0.231), respectively.

Conclusion

The fetal ascending and descending aorta area measurements obtained by 3D ultrasound using STIC in the rendering mode increased with GA in normal fetuses. The method showed weak intra- and interobserver reproducibility.

Fetal heart foramen ovale area by three-dimensional ultrasound using stic in the rendering mode: reference range and applicability in congenital heart diseases

To determine reference values for the foramen ovale (FO) area of fetal hearts by three-dimensional (3D) ultrasound using spatio-temporal image correlation (STIC) method in the rendering mode, as well as applicability in fetuses with congenital heart disease (CHD). A retrospective and prospective study was performed of 242 normal fetuses and 36 fetuses with CHD between 20 and 33 + 6 weeks of gestation. The FO area was determined in the four-chamber view with manual delineation. To determine the reference curve of the FO area as a function of gestational age (GA), a linear regression model was utilized with an adjusted coefficient of determination (R²). For intra- and interobserver reproducibility calculations, the concordance correlation coefficient (CCC) was used. The mean ± standard deviation (SD) of the FO measurement area was 21.2 ± 1.8 and 48.1 ± 1.9 mm² at 20 and 33 weeks' gestation, respectively. A linear correlation was observed between the FO area and GA (1.924*GA - 17.95; R² = 0.91). Good intra- (CCC = 0.97) and interobserver (CCC = 0.94) agreement was observed for the FO area measurement. The mean difference in FO area between normal and CHD fetuses was - 14.4 mm² (p < 0.001). Reference values for the FO area of fetal hearts were determined by 3D ultrasound using STIC in the rendering mode. This method showed good intra- and interobserver reproducibility and could be used to assess different CHD types.

Assessment of fetal heart aortic and pulmonary valve annulus area by three-dimensional ultrasonography: reference curves and applicability in congenital heart diseases

OBJECTIVES

To determine reference curves for fetal aortic and pulmonary valve annulus area by three-dimensional ultrasonography using the spatio-temporal image correlation (STIC) in the rendering mode, and to ascertain its applicability in congenital heart disease (CHD).

METHODS

We performed a retrospective cross-sectional study of 328 normal fetuses and 42 fetuses with CHD between 20 and 33 weeks 6 days of gestation. The outflow plane view of the great vessels was used to measure the areas of the valvar annuli, and the measurements were performed in systole. A linear regression model adjusted according to the determination coefficient (R²) was utilized to construct the reference intervals. The concordance correlation coefficient (CCC) was used to calculate the reproducibility of the mitral and tricuspid valve areas.

RESULTS

The mean ± standard deviation (SD) of the aortic and pulmonary valve annulus areas ranged from 6.6 ± 1.2 to 32.9 ± 1.1 mm² and 10.7 ± 1.3 to 40.3 ± 1.2 mm², respectively. We observed a linear relationship and strong positive correlation between the area of the aortic and pulmonary valve annuli with r=0.97 and 0.96, respectively. Good intra (CCC=0.99) and interobserver agreement (CCC=0.98) was observed for the measurement of the aortic valve annulus area. A good intra (CCC=0.99) and interobserver (CCC=0.97) agreement was also observed for the measurement of the pulmonary valve annulus area. The mean ± SD of the difference of the areas of the aortic and pulmonary valve annuli between the normal fetuses and those with CHD were -1.801 ± 1.429 mm² (p=0.208) and -1.033 ± 1.467 mm² (p<0.0001), respectively.

CONCLUSIONS

The reference curves for the areas of the aortic and pulmonary valve annuli of fetal hearts were determined, and showed good inter and intraobserver reproducibility. The constructed reference curves showed applicability in different types of CHD.

Visualization of the arterial valve morphology and number of leaflets in a fetus with common arterial trunk by spatiotemporal image correlation imaging

Spatiotemporal imaging correlation (STIC) technology has been employed to visualize the fetal heart for close to two decades, but the additional value of the technology remains debatable. The value of the technology in identifying the morphology of the cardiac valves is being recognized. We report a 21-week gestational age fetus with common arterial trunk where STIC imaging enabled us to identify a bicuspid arterial valve.

Evaluation of fetal foramen ovale blood flow by pulsed Doppler ultrasonography combined with spatiotemporal image correlation : To define the normal reference range of fetal foramen ovale blood volume for each gestational age: a cross-sectional study

Objective

The objective of this study was to determine fetal foramen ovale blood flow utilizing pulsed Doppler combined with spatiotemporal image correlation.

Methods

A cross-sectional study was performed in 440 normal fetuses between 20 and 40 weeks of gestation. In order to calculate foramen ovale blood flow, the foramen ovale flow velocity–time integral was obtained by pulsed Doppler ultrasonography, and the foramen ovale area was measured by using spatiotemporal image correlation rendering mode. Foramen ovale blood flow was calculated as the product of the foramen ovale area and the velocity–time integral.

Results

Gestational age-specific reference ranges are given for the absolute blood flow (ml/min) of foramen ovale, showing an exponential increase from 20 to 30 weeks of gestation, and a flat growth trend during the last trimester, while the weight-indexed flow (ml/min/kg) of foramen ovale decreased significantly. The median weight-indexed foramen ovale blood flow was 320.82 ml/min/kg (mean 319.1 ml/min/kg; SD 106.33 ml/min/kg).

Conclusions

The reference range for fetal foramen ovale blood flow was determined from 20 to 40 weeks of gestation. The present data show that the volume of foramen ovale blood flow might have a limited capacity to increase during the last trimester.

Reference range of fetal myocardial area by three-dimensional ultrasonography and its applicability in fetuses of pre-gestational diabetic women

Objective To determine the reference range for the myocardial area in healthy fetuses using three-dimensional (3D) ultrasonography and validate these results in fetuses of pregnant women with pre-gestational diabetes mellitus (DM). Methods This cross-sectional retrospective study included 168 healthy pregnant women between gestational weeks 20 and 33+6 days. The myocardial area was measured using spatio-temporal image correlation (STIC) in the four-chamber view. Polynomial regression models were used, and the goodness of fit of the models were evaluated by the coefficient of determination (R2). Intra- and inter-observer reproducibility was determined using the concordance correlation coefficient (CCC). Validation was performed in 30 pregnant women with pre-gestational DM. Results There was a strong correlation (R2=0.71, P<0.0001) between myocardial area and gestational age. There was good intra- and inter-observer reproducibility, with a CCC of 0.86 and 0.83, respectively. However, there was no significant difference in the mean myocardial area between healthy fetuses and fetuses of women with pre-gestational DM (0.11 cm2, P=0.55). Conclusion The reference range was determined for the myocardial area in fetuses, and there was no significant difference in this variable between healthy fetuses and the fetuses of women with pre-gestational DM.

Spatio-temporal image correlation rendering mode visualizes the specific location and surrounding structure of ventricular septal defect

The limitations of traditional two-dimensional (2D) echocardiography in accurate diagnosis of ventricular septal defect (VSD) prompt the necessity of spatio-temporal image correlation (STIC) technology. Our study attemped to reconstruct the volume data of VSD using STIC rendering mode, and dynamically display the specific location and surrounding structure of VSD, in order to assist conventional 2D echocardiography. A total of 20 fetuses diagnosed as VSD using 2D echocardiography were enrolled in our study. Multiplane imaging mode was applied to obtain 2D four-chamber view, five-chamber view, and main artery short-axis view. STIC rendering mode was performed to collect volume data and visualize the shape, specific location and surrounding structure of VSD. A more detailed VSD classification for 20 VSD cases was identified. Based on the specific location and surrounding structure under STIC images, they were further subdivided into different types. STIC rendering mode intuitively showed the specific shape and surrounding structure of VSD. STIC technology can be used for definite classification and diagnosis of VSD, combining with 2D echocardiography to make a better therapeutic intervention in clinical practice. Clin. Anat. 32:408-420, 2019. © 2019 Wiley Periodicals, Inc.

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.

Electronic spatiotemporal image correlation improves four-dimensional fetal echocardiography

OBJECTIVES

To compare the efficiency of electronic spatiotemporal image correlation (eSTIC) with that of conventional STIC to acquire four-dimensional (4D) fetal cardiac volumes of diagnostic quality.

METHODS

This was a randomized controlled trial of 100 patients in mid-gestation with normal sonograms. In half of the cases, STIC volumes of the fetal heart were obtained with a conventional mechanical 4D probe and in the remaining cases eSTIC volumes were obtained with an electronic 4D probe. Examinations were kept within the timeframe allotted for a standard examination of fetal anatomy, and a maximum of two attempts were made at obtaining a 4D cardiac volume. Datasets were stored on a computer and subsequently analyzed and categorized as being of optimal, satisfactory or inadequate quality, depending on whether or not it was possible to perform an extended basic cardiac examination, including obtaining a three vessels and trachea view, as well as a clear reconstruction of both the aortic and ductal arches in the sagittal plane.

RESULTS

The eSTIC volume datasets were more frequently of optimal or satisfactory diagnostic quality compared with conventional STIC (94% vs 76%, P < 0.0001). Failure to obtain an eSTIC volume of adequate quality was in all cases the consequence of an unfavorable position of the fetus.

CONCLUSIONS

Compared with a standard mechanical probe, the electronic 4D probe facilitates acquisition of sonographic cardiac volumes in mid-trimester fetuses. In our hands, eSTIC volumes of optimal or satisfactory diagnostic quality, allowing a detailed offline evaluation of the fetal heart, were obtained in more than 90% of cases within the time frame of a standard examination of fetal anatomy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

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.

Consistent reconstruction of 4D fetal heart ultrasound images to cope with fetal motion

PURPOSE

4D ultrasound imaging of the fetal heart relies on reconstructions from B-mode images. In the presence of fetal motion, current approaches suffer from artifacts, which are unrecoverable for single sweeps.

METHODS

We propose to use many sweeps and exploit the resulting redundancy to automatically recover from motion by reconstructing a 4D image which is consistent in phase, space, and time. An interactive visualization framework to view animated ultrasound slices from 4D reconstructions on arbitrary planes was developed using a magnetically tracked mock probe.

RESULTS

We first quantified the performance of 10 4D reconstruction formulations on simulated data. Reconstructions of 14 in vivo sequences by a baseline, the current state-of-the-art, and the proposed approach were then visually ranked with respect to temporal quality on orthogonal views. Rankings from 5 observers showed that the proposed 4D reconstruction approach significantly improves temporal image quality in comparison with the baseline. The 4D reconstructions of the baseline and the proposed methods were then inspected interactively for accessibility to clinically important views and rated for their clinical usefulness by an ultrasound specialist in obstetrics and gynecology. The reconstructions by the proposed method were rated as 'very useful' in 71% and were statistically significantly more useful than the baseline reconstructions.

CONCLUSIONS

Multi-sweep fetal heart ultrasound acquisitions in combination with consistent 4D image reconstruction improves quality as well as clinical usefulness of the resulting 4D images in the presence of fetal motion.

Is the short axis view of the fetal heart useful in improving the diagnostic accuracy of outlet ventricular septal defects?

OBJECTIVES

Outlet ventricular septal defects (VSDs) are usually suspected on the five-chamber view of the fetal heart; however, postnatal confirmation occurs only in a small number of cases. The aim of this study was to evaluate if the systematic assessment of the short axis view may improve the prediction of prenatally detected outlet VSDs.

METHODS

Cases where isolated outlet VSD was suspected on the five-chamber view were assessed by using the short axis scanning plane for confirmation of the defect. Postnatal assessment was performed within 2 weeks from birth at our Paediatric Cardiology Unit.

RESULTS

An outlet VSD was suspected at five-chamber view in 23 fetuses. Postnatal confirmation of the VSD occurred in 14 cases where the defect was prenatally detected both on the five chamber and the short axis views. VSDs were not confirmed at postnatal assessment only in two cases where outlet VSD was suspected on both views, whereas all the seven cases with a suspected VSD on the five-chamber view only turned out to be false positives.

CONCLUSION

The short axis view of the fetal heart seems useful in confirming the presence of outlet VSDs. © 2016 John Wiley & Sons, Ltd.

Three- and four-dimensional ultrasound in fetal echocardiography: an up-to-date overview

Congenital heart diseases (CHD) are the most commonly overlooked lesions in prenatal screening programs. Real-time two-dimensional ultrasound (2DUS) is the conventionally used tool for fetal echocardiography. Although continuous improvements in the hardware and post-processing software have resulted in a good image quality even in late first trimester, 2DUS still has its limitations. Four-dimensional ultrasound with spatiotemporal image correlation (STIC) is an automated volume acquisition, recording a single three-dimensional (3D) volume throughout a complete cardiac cycle, which results in a four-dimensional (4D) volume. STIC has the potential to increase the detection rate of CHD. The aim of this study is to provide a practical overview of the possibilities and (dis)advantages of STIC. A review of literature and evaluation of the current status and clinical value of 3D/4D ultrasound in prenatal screening and diagnosis of congenital heart disease are presented.

How to Acquire Cardiac Volumes for Sonographic Examination of the Fetal Heart: Part 2

The effective performance of fetal cardiac examination using spatiotemporal image correlation (STIC) technology requires 2 essential steps: volume acquisition and postprocessing. An important prerequisite is training sonologists to acquire high-quality volume data sets so that when analyzed, such volumes are informative. This article is part 2 of a series on 4-dimensional sonography with STIC. Part 1 focused on STIC technology and its features, the importance of operator training/experience and acquisition of high-quality STIC volumes, factors that affect STIC volume acquisition rates, and general recommendations on performing 4D sonography with STIC. In part 2, we discuss a detailed and practical stepwise approach for STIC volume acquisition, along with methods to determine whether such volumes are appropriate for analysis.

How to Acquire Cardiac Volumes for Sonographic Examination of the Fetal Heart: Part 1

Four-dimensional sonography with spatiotemporal image correlation (STIC) technology allows acquisition of a fetal cardiac volume data set and displays a cine loop of a complete single cardiac cycle in motion. Part 1 of this 2-part article reviews STIC technology and its features, the importance of operator training/experience, and acquisition of high-quality STIC volumes, as well as factors that affect STIC volume acquisition rates. We also propose a detailed and practical stepwise approach to performing 4-dimensional sonography with STIC and begin herein by providing general recommendations. Part 2 will discuss specifics of the approach, along with how to determine whether such volumes are appropriate for analysis.

Prenatal Visualization of the Pulmonary and Aortic Valves and Leaflets Is Feasible Using 4-Dimensional Sonography

OBJECTIVES

The purpose of this study was to determine whether the morphologic characteristics and area of the semilunar valves in healthy fetuses and fetuses with cardiac defects can be visualized by using spatiotemporal image correlation (STIC).

METHODS

Spatiotemporal image correlation volumes from 74 healthy fetuses were recorded in 5 examinations between the 15th and 36th weeks of pregnancy. Second, we recorded STIC volumes from 64 fetuses with various cardiac defects. The quality of the volumes was rated. The areas of the aortic and pulmonary valves were measured in systole by rendering the valves on 4-dimensional sonography. The number of leaflets was examined. Longitudinal data analysis using linear mixed models was performed.

RESULTS

Two hundred ninety-three volumes from normal hearts were examined. In 82.5%, the quality of the normal volumes was sufficient. Visualization of the valve opening was feasible in 96.1% of the normal hearts and 97.4% of the abnormal hearts. The success rate of visualization of the pulmonary and aortic valve leaflets was dependent on the gestational age, with the highest percentage (72.1% in normal hearts) at 19 to 24 weeks. Longitudinal regression analysis showed a positive relationship of the aortic and pulmonary valve areas with gestational age (P < .0001) and fetal biometric measurements (P < .0001). Fifty-eight abnormal volumes were examined. Cardiac defects with abnormal valve areas due to aortic and pulmonary stenosis could be clearly visualized by using STIC.

CONCLUSIONS

Examination of the morphologic characteristics of the semilunar valves using STIC is feasible, which is difficult when using 2-dimensional sonography. With increasing implementation of 4-dimensional sonography, the understanding of rendered images might be useful for anyone practicing fetal echocardiography.

Evaluating Spatiotemporal Image Correlation Technology as a Tool for Training Nonexpert Sonographers to Perform Examinations of the Fetal Heart

OBJECTIVES

We aimed to evaluate the use of spatiotemporal image correlation (STIC) as a tool for training nonexpert examiners to perform screening examinations of the fetal heart by acquiring and examining STIC volumes according to a standardized questionnaire based on the 5 transverse planes of the fetal heart.

METHODS

We conducted a prospective study at 2 tertiary care centers. Two sonographers without formal training in fetal echocardiography received theoretical instruction on the 5 fetal echocardiographic transverse planes, as well as STIC technology. Only women with conditions allowing 4-dimensional STIC volume acquisitions (grayscale and Doppler) were included in the study. Acquired volumes were evaluated offline according to a standardized protocol that required the trainee to mark 30 specified structures on 5 required axial planes. Volumes were then reviewed by an expert examiner for quality of acquisition and correct identification of specified structures.

RESULTS

Ninety-six of 112 pregnant women examined entered the study. Patients had singleton pregnancies between 20 and 32 weeks' gestation. After an initial learning curve of 20 examinations, trainees succeeded in identifying 97% to 98% of structures, with a highly significant degree of agreement with the expert's analysis (P < .001). A median of 2 STIC volumes for each examination was necessary for maximal structure identification. Acquisition quality scores were high (8.6-8.7 of a maximal score of 10) and were found to correlate with identification rates (P = .017).

CONCLUSIONS

After an initial learning curve and under expert guidance, STIC is an excellent tool for trainees to master extended screening examinations of the fetal heart.

Viewing rate and reproducibility of papillary muscle areas in foetal atrioventricular valves using spatio-temporal image correlation in the rendering mode in congenital heart disease

OBJECTIVE

To assess the viewing rate and reproducibility of areas of the papillary muscles (PMs) of foetal atrioventricular valves using spatio-temporal image correlation (STIC) in the rendering mode in congenital heart disease (CHD).

METHODS

We retrospectively reviewed 40 4D-STIC volume datasets from different foetal CHD cases at a gestational age of 18w6d–35w6d. The following papillary muscles (PMs) were assessed: antero-lateral (MPAL) and postero-medial (MPPM) to the mitral valve and antero-superior (MPAS), inferior (MPI) and septal (MPS) to the tricuspid valve. To assess the valve viewing rate, percentages (%) were used. The concordance correlation coefficient (CCC) was used to assess inter-observer reliability.

RESULTS

Two independent observers concluded that a complete examination of the PMs was impossible in 11 cases, yielding a viewing rate of 72.5%. The complete examination of the PMs of the tricuspid and mitral valves was possible by both examiners in 33/40 (82.5%) and 32/40 (80.0%) cases, respectively. We observed moderate to good inter-observer reliability with CCCs of 0.95, 0.92, 0.97, 0.96 and 0.97 for MPS, MPI, MPAS, MPAL and MPPM, respectively.

CONCLUSION

The viewing rate of PM areas in different CHDs using STIC in the rendering mode was moderate. The inter-observer reproducibility was moderate to good for all PM areas.

Prenatal examination of the area and morphology of the atrioventricular valves using four-dimensional ultrasound in normal and abnormal hearts

OBJECTIVE

Our aim is to evaluate the feasibility to examine the morphology and area of the atrioventricular (AV) valves in normal fetuses and fetuses with cardiac defects using spatiotemporal image correlation (STIC).

METHODS

Atrioventricular valves were analyzed longitudinally in STIC volumes of 74 normal fetuses between the 15th and 36th week of pregnancy. The valve area was measured in a rendered view in diastole, the number of valve leaflets in systole. Longitudinal data analysis was performed using linear mixed models. Fifty fetuses with cardiac defects were examined.

RESULTS

Examination of 355 STIC volumes of normal fetuses showed in 82.5% sufficient quality. The tricuspid valve leaflets were seen in 200 (68.3%) volumes and the mitral valve leaflets in 219 (74.7%) volumes. The tricuspid valve showed in 61.1% a round, 29.0% rectangle, and 8.9% elliptical shape and the mitral valve in 60.1% round, 28.0% rectangle, and 10.9% elliptical. Regression analysis revealed a positive relationship of the valve area with gestational age (p < 0.0001). Most heart defects with stenosis showed an area below the 5th percentile.

CONCLUSION

Prenatal examination of the morphology and area of the AV valves using four-dimensional ultrasound is feasible. A rectangular valve opening is normal, which was visualized in about one third of the normal fetuses.

4D Fetal Echocardiography in Clinical Practice

Spatiotemporal image correlation (STIC) is a technique that acquires the fetal cardiac volumes, and then analyzes it offline in both multiplanar and rendered modes, using both static and moving images from a four-dimensional (4D) cine sequence simulating a full cardiac cycle. Spatiotemporal image correlation makes it possible to evaluate cardiac structures and their vascular connections, is less operator dependent, and allows cardiac volumes to be sent to specialists in tertiary centers for examination. Spatiotemporal image correlation can be combined with other software techniques, such as virtual organ computer-aided analysis (VOCAL) and automatic volume calculation (SonoAVC), to calculate cardiac function parameters. It can also be used in association with Omniview® in order to obtain standard echocardiographic planes using simple targets arterial rendering (STAR) and four-chamber view and swing technique (FAST). Recently, fetal intelligent navigation echocardiography (FINE), acquired from 3D STIC volumes, has made it possible to automatically obtain nine standard echocardiographic planes. In this article, we review the chief applications of 4D echocardiography using STIC technique in clinical practice.

How to cite this article

Araujo Júnior E, Tedesco GD, Carrilho MC, Peixoto AB, Carvalho FHC. 4D Fetal Echocardiography in Clinical Practice. Donald School J Ultrasound Obstet Gynecol 2015;9(4): 382-396.

Viewing rate and reference ranges for papillary muscle areas of the fetal heart using four-dimensional ultrasound in the rendering mode

OBJECTIVES

The aims of this study were to assess the viewing rate and determine reference ranges ​​for the papillary muscle areas in the fetal atrio-ventricular valves using four-dimensional (4D) ultrasound and spatio-temporal image correlation (STIC) in the rendering mode.

METHODS

This cross-sectional prospective study included 310 4D STIC volume data sets of normal fetuses between 18 weeks 0 day and 34 weeks 0 day of gestation. The papillary muscles were antero-lateral (MPAL) and postero-medial (MPPM) to the mitral valve and antero-superior (MPAS), inferior (MPI) and septal (MPS) to the tricuspid valve. Polynomial regressions were built to determine the reference ranges, and adjustments were made using the determination coefficient (R(2) ). To assess inter-observer reproducibility, the intra-class correlation coefficient (ICC) was used.

RESULTS

Identification of the papillary muscles was possible in 89.3% patients. The best-fit regression equations between papillary muscle areas and gestational age were second degree. The inter-observer reproducibility was good (ICC: 0.98 to MPAS, 0.97 to MPI, 0.98 to MPS, 0.98 to MPAL and 0.97 to MPPM).

CONCLUSIONS

Identification of the papillary muscles of the fetal valves was possible in most of the 4D STIC volume data sets, enabling the determination of reference ranges using the rendering mode. The reference ranges ​​for the papillary muscle areas were determined.

Fetal myocardial wall area: constructing a reference range by means of spatiotemporal image correlation in the rendering mode

OBJECTIVE

To establish the reference range of the myocardial wall area in the fetus using three-dimensional ultrasound in the rendering mode.

METHODS

A prospective, cross-sectional study including 371 singleton, uncomplicated pregnancies at 20 weeks 0 day to 33 weeks 6 days of gestation was carried out. Cardiac volumes were obtained using spatiotemporal image correlation (STIC) at the level of the four-chamber view. The end-diastolic myocardial area of the both ventricles was measured manually. The intraclass correlation coefficient (ICC) was used to assess intra- and interobserver concordance.

RESULTS

The mean myocardial area of the fetal right ventricular (RV) wall ranged from 0.86 ± 0.23 cm(2) at 20 weeks 0 day to 2.75 ± 0.69 cm(2) at 33 weeks 6 days of gestation. The mean myocardial area of the fetal left ventricular (LV) wall ranged from 0.82 ± 0.20 cm(2) at 20 weeks 0 day to 2.49 ± 0.59 cm(2) at 33 weeks 6 days of gestation. In addition, intra- and interobserver concordance for the myocardial area of the RV and LV walls was good, with ICC values of 0.94, 0.95, 0.85, and 0.93, respectively.

CONCLUSIONS

The reference range for the myocardial area of the RV and LV walls was determined by cardio-STIC in the rendering mode at 20 weeks 0 day to 33 weeks 6 days of gestation, with good concordance between values.

Diagnosis and treatment of fetal cardiac disease: a scientific statement from the American Heart Association

BACKGROUND

The goal of this statement is to review available literature and to put forth a scientific statement on the current practice of fetal cardiac medicine, including the diagnosis and management of fetal cardiovascular disease.

METHODS AND RESULTS

A writing group appointed by the American Heart Association reviewed the available literature pertaining to topics relevant to fetal cardiac medicine, including the diagnosis of congenital heart disease and arrhythmias, assessment of cardiac function and the cardiovascular system, and available treatment options. The American College of Cardiology/American Heart Association classification of recommendations and level of evidence for practice guidelines were applied to the current practice of fetal cardiac medicine. Recommendations relating to the specifics of fetal diagnosis, including the timing of referral for study, indications for referral, and experience suggested for performance and interpretation of studies, are presented. The components of a fetal echocardiogram are described in detail, including descriptions of the assessment of cardiac anatomy, cardiac function, and rhythm. Complementary modalities for fetal cardiac assessment are reviewed, including the use of advanced ultrasound techniques, fetal magnetic resonance imaging, and fetal magnetocardiography and electrocardiography for rhythm assessment. Models for parental counseling and a discussion of parental stress and depression assessments are reviewed. Available fetal therapies, including medical management for arrhythmias or heart failure and closed or open intervention for diseases affecting the cardiovascular system such as twin-twin transfusion syndrome, lung masses, and vascular tumors, are highlighted. Catheter-based intervention strategies to prevent the progression of disease in utero are also discussed. Recommendations for delivery planning strategies for fetuses with congenital heart disease including models based on classification of disease severity and delivery room treatment will be highlighted. Outcome assessment is reviewed to show the benefit of prenatal diagnosis and management as they affect outcome for babies with congenital heart disease.

CONCLUSIONS

Fetal cardiac medicine has evolved considerably over the past 2 decades, predominantly in response to advances in imaging technology and innovations in therapies. The diagnosis of cardiac disease in the fetus is mostly made with ultrasound; however, new technologies, including 3- and 4-dimensional echocardiography, magnetic resonance imaging, and fetal electrocardiography and magnetocardiography, are available. Medical and interventional treatments for select diseases and strategies for delivery room care enable stabilization of high-risk fetuses and contribute to improved outcomes. This statement highlights what is currently known and recommended on the basis of evidence and experience in the rapidly advancing and highly specialized field of fetal cardiac care.

Feasibility of detection of the 3-vessel and trachea view using 3-dimensional sonographic volumes

OBJECTIVES

The purpose of this study was to investigate the ability to depict the 4-chamber and 3-vessel and trachea views of the fetal heart using 3-dimensional sonography.

METHODS

Three-dimensional color Doppler volumes of the fetal heart were acquired prospectively in 31 fetuses between 19 and 25 gestational weeks. The initial plane consisted of the 4-chamber view. Postprocessing included navigation within the volume solely in plane A in the caudal direction to visualize the stomach and in the cephalic direction to the plane of the 3-vessel and trachea view to visualize the pulmonary artery, the aorta, the V shape and color of the arches, the superior vena cava, and the trachea. The feasibility of showing these organs was evaluated.

RESULTS

The estimated time for volume acquisition and manipulation was about 60 seconds. The detection rates for the 4-chamber view, stomach, 3-vessel view, trachea, and V sign were 100%, 93.5%, 92.0%, 77.4%, and 83.9%, respectively, with interobserver agreement of 0.76 to 1.0.

CONCLUSIONS

We describe a simple technique in which a single sweep on 3-dimensional sonography starting at the level of the 4-chamber view can visualize the situs, stomach, 4-chamber view, and transverse view of the outflow tracts of the heart.

Three-dimensional HDlive rendering images of the fetal heart

Our objective is to describe our experience with reconstruction of normal fetal cardiac structures and congenital heart anomalies using the 3-D HDlive rendering mode with spatiotemporal image correlation (STIC). Four normal fetuses and three fetuses with congenital heart anomalies (Ebstein's anomaly, hypoplastic left heart syndrome and tetralogy of Fallot) at 25-35 wk of gestation were studied using the 3-D HDlive rendering mode with STIC. In normal fetuses, the natural appearance of the dynamic motion of the foramen ovale flap and both atrioventricular valves was clearly visualized in real time in the four-chamber view. Moreover, new, realistic sensations of each leaflet of atrioventricular valves and semilunar valves of the pulmonary artery were obtained in the en face view of both atrioventricular valves and great vessels. In the case of Ebstein's anomaly, the procedure rendered the natural and anatomically realistic appearance of significantly low attachment of the tricuspid valve and atrialized portion of the right ventricle. In hypoplastic left heart syndrome, thickened tricuspid and dysplastic pulmonary valves were clearly revealed. In tetralogy of Fallot, an overriding aorta and ventricular septal defect were realistically depicted. The 3-D HDlive rendering mode with STIC provides entirely new visual experiences for obstetricians and pediatric cardiologists owing to the anatomically realistic depiction of normal and abnormal fetal cardiac structures of the beating heart.

Performance of different scan protocols of fetal echocardiography in the diagnosis of fetal congenital heart disease: a systematic review and meta-analysis

OBJECTIVE

The rapid progress in fetal echocardiography has lead to early detection of congenital heart diseases. Increasing evidences have shown that prenatal diagnosis could be life saving in certain cases. However, there is no agreement on which protocol is most adaptive diagnostic one. Thus, we use meta-analysis to conduct a pooled performance test on 5 diagnostic protocols.

METHODS

We searched PUBMED, EMBASE, the Cochrane Central Register of Controlled Trials and WHO clinical trails registry center to identify relevant studies up to August, 2012. We performed meta-analysis in a fixed/random-effect model using Meta-disc 1.4. We used STATA 11.0 to estimate the publication bias and SPSS 17.0 to evaluate variance.

RESULTS

We use results from 81 studies in 63 articles to analyze the pooled accuracy. The overall performance of pooled sensitivities of spatiotemporal image correlation (STIC), extend cardiac echography examination (ECEE) and 4 chambers view + outflow tract view + 3 vessels and trachea view (4 CV+OTV+3 VTV) were around 0.90, which was significant higher than that of 4 chambers view + outflow tract view or 3 vessels and trachea view (4 CV+OTV/3 VTV) and 4 chambers view (4 CV). Unfortunately the pooled specificity of STIC was 0.92, which was significant lower than that of other 4 protocols which reached at 1.00. The area under the summary receiver operating characteristic curves value of STIC, ECEE, 4 CV+OTV+3 VTV, 4 CV+OTV/3 VTV and 4 CV were 0.9700, 0.9971, 0.9983, 0.9929 and 0.9928 respectively.

CONCLUSION

These results suggest a great diagnostic potential for fetal echocardiography detection as a reliable method of fetal congenital heart disease. But at least 3 sections view (4 CV, OTV and 3 VTV) should be included in scan protocol, while the STIC can be used to provide more information for local details of defects, and can not be used to make a definite diagnosis alone with its low specificity.

Application of spatio-temporal image correlation technology in the diagnosis of fetal cardiac abnormalities

Congenital heart disease is the birth defect with the highest incidence in China. Its timely and accurate prenatal diagnosis is critical for appropriate perinatal and postnatal management and salvage treatment. With improvements in the diagnostic capabilities of ultrasound and clinical manipulation techniques, prenatal diagnosis is conducted increasingly early and with greater accuracy. However, the representations of tiny blood vessels and the determination of abnormal spatial structures in the fetal period continue to cause difficulties in prenatal diagnosis. In theory, spatio-temporal image correlation (STIC) technology is able to compensate for the defects of previous traditional two-dimensional (2D) ultrasound and improve the diagnostic accuracy. The aim of the present study was to investigate the clinical application value of STIC technology combined with traditional 2D ultrasound in the diagnosis of fetal cardiac abnormalities. A total of 1,286 fetuses were subjected to sequential echocardiographic examination, during which STIC technology was used to collect heart volume data and carry out image post-processing and off-line analysis. In addition, the prenatal and postnatal echocardiography results were compared with the pathology results following the induced labor of fetuses with cardiac abnormalities. The sensitivity, specificity, misdiagnosis rate and rate of missed diagnosis for the STIC technology in the diagnosis of prenatal fetal cardiac abnormalities were 97.4, 99.6, 0.4 and 2.6%, respectively. The total coincidence rate was 99.2% and the positive and negative predictive values were 97.9 and 99.4%, respectively; the statistics for the consistency check of the STIC technology in the diagnosis of fetal cardiac abnormalities are κ=0.991, P=0.000. STIC technology combined with fetal echocardiography may be used for the definite diagnosis of fetal heart malformations, with high sensitivity and specificity.

Reference range for fetal interventricular septum area by means of four-dimensional ultrasonography using spatiotemporal image correlation

OBJECTIVE

To determine reference range for fetal interventricular septum area by means of 3-dimensional ultrasonography (3DUS) using the spatiotemporal image correlation (STIC) method.

METHODS

A prospective, cross-sectional study was conducted on 328 normal pregnant women between the 18th and 33rd gestational weeks. To obtain the interventricular septum area, a virtual plane was used, with the green line (region of interest) adjacent to the external margin of the septum, which was manually delimited. To evaluate the correlation of the septum area with the gestational age, different regression modes were evaluated. The intraclass correlation coefficient was used to evaluate the interobserver reproducibility.

RESULTS

The interventricular septum area showed correlation with the gestational age (r = 0.81). The mean increased from 0.47 ± 0.10 cm² in the 18th week to 2.42 ± 1.13 cm² in the 33rd week of gestation. The mathematical equation that best represented this correlation was provided by linear regression: interventricular septum area = 0.0511 × gestational age (R² = 0.095). The interobserver reproducibility was good, with bias of 0.01 cm², precision of 0.07 cm² and absolute limits of agreement of -0.14 and +0.15 cm².

CONCLUSIONS

Reference range for fetal interventricular septum area were determined by means of 3DUS using STIC in the rendering mode and were shown to be reproducible.

Reference ranges of atrioventricular valve areas by means of four-dimensional ultrasonography using spatiotemporal image correlation in the rendering mode

OBJECTIVE

This study aims to determine reference curves for fetal atrioventricular valve areas by means of three-dimensional ultrasound using the spatiotemporal image correlation (STIC) software.

METHODS

This was a cross-sectional prospective study on 328 normal fetuses between the 18th and the 33rd weeks of pregnancy. In order to obtain valve areas, the four heart chambers plane was used with the fetus in a dorsal posterior position. To construct reference ranges, a linear regression model was used, adjusted according to the coefficient of determination (R(2)). To calculate the reproducibility of the tricuspid valve area, the intraclass coefficient correlation (ICC) was used.

RESULTS

The mean areas of the tricuspid and mitral valves ranged from 0.19 ± 0.08 and 0.20 ± 0.10 cm(2) in the 18th week to 0.93 ± 0.31 and 1.06 ± 0.39 cm(2) in the 33rd week, respectively. The intra-observer and interobserver reproducibility was excellent with ICC = 0.997 and 0.933, respectively.

CONCLUSIONS

Reference curves for fetal atrioventricular valve areas were determined and presented good reproducibility.

Can live xPlane imaging of the in-plane view of interventricular septum be used to detect fetal conotruncal anomalies?

OBJECTIVE

To evaluate the feasibility of live xPlane imaging visualizing the in-plane view of IVS in the screening of the fetal conotruncal anomalies.

METHOD

One hundred and fifty-two consecutive normal singleton fetuses and forty-eight fetal cardiac defects (27 conotruncal and 21 non-conotruncal cases), were enrolled in this study. The in-plane view of IVS was firstly acquired with live xPlane imaging and then judged whether it is normal or not by one operator. The focus was put on observing the relationship of pulmonary artery and aorta. The comparison between conotruncal and non-conotruncal anomalies in demonstrating the relationship of pulmonary artery and aorta was performed.

RESULT

There were 27 cases of conotruncal anomalies enrolled in this study and 19 cases (70.4%) had the abnormal relationship of aorta and pulmonary artery in the in-plane view of IVS. In 21 cases of non-conotruncal CHDs, however, there were only 5 cases (23.8%) had the abnormal relationship in the in-plane view of IVS (p < 0.001).

CONCLUSION

Live xPlane imaging of the in-plane view of IVS is feasible to detect the fetal conotruncal anomalies, which may potentially be a useful tool for the non-experienced operators to screen the fetal conotruncal anomalies.

Comparison of real-time three-dimensional echocardiography and spatiotemporal image correlation in assessment of fetal interventricular septum

OBJECTIVE

To compare the role of real-time 3DE and STIC technology in assessment of the fetal IVS.

METHODS

Fifty pregnant women with singleton pregnancies were invited to attend this study. All the fetuses were examined by both spatiotemporal image correlation and real-time three-dimensional echocardiography. There were totally six images of IVS obtained for each fetus: live xPlane image, live 3D image, multiplanar image and rendered image with the four-chamber view as the starting plane, multiplanar image and rendered image with the sagittal view of the fetal thorax as the starting plane. These images were grouped into six groups and randomized within each group for the further analysis. The images were scored and compared according to the image quality, the outline of the fetal IVS and motion artefact. The operator was also asked to judge whether VSD existed or not and the results were compared with the final diagnosis. The sensitivity, specificity, false positive percentage, positive likelihood ratio, false negative percentage and negative likelihood ratio of each group were also calculated.

RESULTS

There were 15 cases with VSD and four cases without VSD in CHD fetus and 31 cases of normal fetus enrolled in this study. A total 300 images of the lateral view of fetal IVS were obtained and grouped into six groups. The image quality in the group of STIC with the four-chamber view as the starting plane is much worse than the group of STIC with the sagittal view as the starting plane and real-time three-dimensional echocardiography (P < 0.05). There were no significant differences in image quality between the group of STIC with the sagittal view as the starting plane and real-time three-dimensional echocardiography (P > 0.05).

CONCLUSION

The image quality of real-time 3DE is similar to the images acquired by STIC from the sagittal view and superior to that obtained by STIC from the four-chamber view. However, real-time 3DE has no motion artefact, which has the potentials to improve the detection rate of fetal VSD.

Functional assessment of the fetal heart: a review

The purpose of this review is to evaluate the current modalities available for the assessment of fetal cardiac function. The unique anatomy and physiology of the fetal circulation are described, with reference to the difference between in-utero and ex-utero life. M-mode, early/atrial ratio, myocardial performance index, three-dimensional and four-dimensional ultrasound, tissue Doppler including strain and strain rate, speckle tracking, magnetic resonance imaging and venous flow assessment are described. The modalities are analyzed from the perspective of the clinician and certain questions are posed. Does the modality assess systolic function, diastolic function or both? Is it applicable to both ventricles? Does it require extensive post-processing or additional hardware, or does it make use of technology already available to the average practitioner? The reproducibility and reliability of the techniques are evaluated, with reference to their utility in clinical decision-making. Finally, directions for future research are proposed.

Interobserver agreement in detailed prenatal diagnosis of congenital heart disease by telemedicine using four-dimensional ultrasound with spatiotemporal image correlation

OBJECTIVE

To evaluate the clinical accuracy of four-dimensional (4D) echocardiography in the detailed prenatal diagnosis of congenital heart disease (CHD) in a telemedicine setting.

METHODS

Ten second-trimester spatiotemporal image correlation (STIC) volumes were sent to three observers in different tertiary care centers with expertise in 4D echocardiography. The 10 volumes were selected based on the type of diagnosis to cover a wide spectrum of CHD anomalies, and also included one normal fetal heart. Observers were asked to provide the diagnosis, the postprocessing modalities used and the time spent on examination, and to give a rating of the confidence for the diagnosis on a 5-point Likert scale. They were free to consult other colleagues, including pediatric cardiologists, but were blinded to the prenatal diagnosis and the neonatal outcome. A diagnostic scoring system was used to evaluate different aspects of the heart defects. The results were compared with neonatal echocardiography or postmortem findings ('gold standard').

RESULTS

In two cases all observers correctly diagnosed all details of the volume datasets. The observer with the best performance reached perfect agreement in six cases and nearly perfect agreement in three. The volumes were most frequently studied by sectional planes and were analyzed in a median time of 11.0 (range, 2.5-30.0) min. The median confidence score was 4.0 (range, 1.0-5.0).

CONCLUSIONS

In a telemedicine setting using STIC volumes, fetal cardiac anomalies can be diagnosed correctly by an expert. However, details required for adequate counseling and planning of postnatal care may be missed. STIC by telemedicine is a promising modality, although not accurate enough for exclusive use in clinical decision making regarding treatment, prognosis or termination of pregnancy.

Simple targeted arterial rendering (STAR) technique: a novel and simple method to visualize the fetal cardiac outflow tracts

OBJECTIVE

To describe a novel and simple technique—simple targeted arterial rendering (STAR)—to visualize the fetal cardiac outflow tracts from dataset volumes obtained with spatiotemporal image correlation (STIC) and applying a new display technology (OmniView).

METHODS

We developed a technique to image the outflow tracts by drawing three dissecting lines through the four-chamber view of the heart contained in a STIC volume dataset. Each line generated the following plane: (a) Line 1: ventricular septum en face with both great vessels (pulmonary artery anterior to the aorta); (b) Line 2: pulmonary artery with continuation into the longitudinal view of the ductal arch; and (c) Line 3: long-axis view of the aorta arising from the left ventricle. The pattern formed by all three lines intersecting approximately through the crux of the heart resembles a star. The technique was then tested in 50 normal fetal hearts at 15.3–40.4 weeks' gestation. To determine whether the technique could identify planes that departed from the normal images, we tested the technique in four cases with proven congenital heart defects (ventricular septal defect (VSD), transposition of great vessels, tetralogy of Fallot and pulmonary atresia with intact ventricular septum).

RESULTS

The STAR technique was able to generate the intended planes in all 50 normal cases. In the abnormal cases, the STAR technique allowed identification of the VSD, demonstrated great vessel anomalies and displayed views that deviated from what was expected from the examination of normal hearts.

CONCLUSIONS

This novel and simple technique can be used to visualize the outflow tracts and ventricular septum en face in normal fetal hearts. Inability to obtain expected views or the appearance of abnormal views in the generated planes should raise the index of suspicion for congenital heart disease involving the great vessels and/or the ventricular septum. The STAR technique may simplify examination of the fetal heart and could reduce operator dependency.

Collaborative study on 4-dimensional echocardiography for the diagnosis of fetal heart defects: the COFEHD study

OBJECTIVE

Congenital anomalies are the leading cause of infant mortality in the United States, and congenital heart defects (CHDs) are the most common type of birth defects. Recently, 4-dimensional ultrasonography (4DUS) with spatiotemporal image correlation (STIC) has been introduced for fetal echocardiography. Accumulating evidence indicates that 4DUS with STIC may facilitate the examination of the fetal heart. Our objectives were to determine the accuracy of 4DUS for the diagnosis of CHDs and the agreement among centers.

METHODS

This study included 7 centers with expertise in 4D fetal echocardiography. Fetuses with and without confirmed heart defects were scanned between 18 and 26 weeks, and their volume data sets were uploaded onto a centralized file transfer protocol server. Intercenter agreement was determined using a κ statistic for multiple raters.

RESULTS

Ninety volume data sets were randomly selected for blinded analysis. Overall, the median (range) sensitivity, specificity, positive and negative predictive values, and false-positive and -negative rates for the identification of fetuses with CHDs were 93% (77%-100%), 96% (84%-100%), 96% (83%-100%), 93% (79%-100%), 4.8% (2.7%-25%), and 6.8% (5%-22%), respectively. The most frequent CHDs were conotruncal anomalies (36%). There was excellent intercenter agreement (κ = 0.97).

CONCLUSIONS

(1) Four-dimensional volume data sets can be remotely acquired and accurately interpreted by different centers. (2) Among centers with technical expertise, 4DUS is an accurate and reliable method for fetal echocardiography.

Four-dimensional echocardiography with B-flow imaging and spatiotemporal image correlation in the assessment of congenital heart defects

OBJECTIVE

The objective of the present study was to evaluate the role of four-dimensional ultrasound with B-flow imaging and spatiotemporal image correlation (STIC) in the detection of congenital heart defects.

METHODS

Automated longitudinal and transverse sweeping of the fetal chest was utilized to obtain the volume datasets of the heart. Among the fetuses recruited in the study, 20 were normal and 13 were fetuses with congenital heart anomalies. Reconstructed images of abnormal hearts were compared with those of normal fetuses.

RESULTS

Of the 20 normal fetuses, all extracardiac vessels such as aorta, pulmonary artery, ductus artery, inferior vena cava, and ductus venosus could be detected on reconstructed images of 16 fetuses. In five normal cases, a four-dimensional image was recorded to allow simultaneous visualization of all four pulmonary veins. In the 13 fetuses with cardiac anomalies, four-dimensional sonography with B-flow imaging and STIC detected the 'digital casts' of the outflow tracts, great arteries, and veins draining into the heart. These results demonstrate spatial relationship among these structures which provide important anatomical information.

CONCLUSIONS

The use of four-dimensional ultrasound examination with B-flow imaging and STIC is a very useful technique in identifying anatomical features of different congenital cardiac anomalies.

Real-time three-dimensional echocardiography using a matrix probe with live xPlane imaging of the interventricular septum

OBJECTIVE

To describe a technique to rapidly visualize the in-plane view of the fetal interventricular septum (IVS) to enable the identification of a ventricular septal defect (VSD).

METHODS

One hundred and fifty-one women were invited to participate after their routine fetal morphology scan, including four suspected to have congenital cardiac defects which were confirmed postnatally. A standard examination protocol using real-time three-dimensional (3D) echocardiography with live xPlane imaging was developed. The ability of this new technology to examine the ventricular septum was investigated.

RESULTS

The in-plane view of the fetal IVS was visualized successfully in 150 (99.3%) cases by real-time 3D echocardiography with live xPlane imaging, including 82 (54.3%) cases with the spine posterior and 68 (45.7%) cases with the spine anterior. The in-plane view of the IVS successfully visualized the VSDs in three fetuses with VSD and displayed the intact IVS in one fetus with transposition of the great arteries without VSD.

CONCLUSION

We describe live xPlane imaging, a simple method for the real-time assessment of the in-plane view of the IVS that has the potential to enhance the diagnostic accuracy of fetal cardiac examination.

Spatio-temporal image correlation (STIC) used by general obstetricians is marginally clinically effective compared to 2D fetal echocardiography scanning by experts

OBJECTIVES

To assess the effectiveness of spatio-temporal image correlation (STIC) used by general obstetricians as compared with 2D scanning.

METHODS

As many as 30 pregnant women at 17-21 weeks' gestation were enrolled. 2D ultrasound was performed by a fetal echocardiologist; STIC was performed by a general obstetrician. Time, accuracy of measurement of diameter of great vessels and quality of the pictures obtained by the two methods were compared.

RESULTS

The mean time required by 2D ultrasound was significantly shorter than that by STIC (5.2 +/- 1.9 min vs 9.8 +/- 2.7 min; P < 0.001). The measurement of the diameter of the great vessels showed some difference but the mean score of the pictures obtained by both methods were not significantly different. By using 2D ultrasound, acceptable quality pictures were obtained in 51.9, 44.4 and 51.9% of cases for 4-chamber, 5-chamber and 3-vessel views, respectively. Meanwhile by using STIC, the percentages were 77.8, 59.3 and 37%.

CONCLUSION

Our study suggested that STIC used by general obstetricians to check normality of fetal cardiac structures at 17-21 weeks' gestation has marginal clinical effectiveness when compared to 2D scanning by a fetal echocardiologist, and should need some improvement before it can be used as a tool to expand a fetal cardiac screening program.

Cardiac screening by STIC: can sonologists performing the 20-week anomaly scan pick up outflow tract abnormalities by scrolling the A-plane of STIC volumes?

OBJECTIVE

To assess whether medically qualified sonologists with low-to-intermediate scanning experience are able to detect major abnormalities of the outflow tracts by reviewing the A-plane of cardiac volume datasets acquired with spatiotemporal image correlation (STIC).

METHODS

Fourteen sonologists of low-to-intermediate scanning experience were recruited among residents and colleagues involved in the screening ultrasound clinic at our referral center. Basic criteria for selection were: ability to perform the 20-week anomaly scan and to assess the four-chamber view, inability to perform extended cardiac screening (outflows); willingness to participate in the study. These sonologists attended a 2-hour lesson on: a) how the outflow tract views can be abnormal, and b) how to use a laptop and the dedicated software to review cardiac volumes in the A-plane only. After this briefing, each of them, independently, reviewed 26 preselected volumes at a workstation (from 16 normal fetuses and 10 with outflow tract abnormalities), without knowing how many of them were normal. After reviewing each volume, the sonologist was asked to define the outflow tract views as normal or abnormal and, if willing, to hypothesize the anomaly. The sequence of cases was changed for each participant. The time allotted for review of the volumes was 1 hour (about 2 min per case).

RESULTS

Of the 364 diagnoses from review of the volumes, 116 (31.9%) were true positives, 195 (53.6%) were true negatives, 29 (8.0%) were false positives and 24 (6.6%) were false negatives. The sensitivity, specificity and positive and negative predictive values were 83%, 87%, 80% and 89%, respectively. Individual diagnostic accuracy ranged from 66 to 100% (median, 85.5%) and individual detection rate from 50 to 100% (median, 85%). The detection rate per single congenital heart disease ranged from 50% (for TGA with intact ventricular septum) to 100% (for DORV, DORV with pulmonary atresia and TGA with ventricular septal defect). There was no correlation between detection rate and alignment of the four-chamber view with the ultrasound beam (apical vs. transverse).

CONCLUSIONS

In this preliminary study, we have demonstrated that sonologists with low-to-intermediate experience of anomaly ultrasound screening in the second trimester and no experience of insonating the outflow tracts were able to identify outflow tract abnormalities by reviewing the A-plane of cardiac volume datasets, after detailed briefing.

A systematic analysis of the feasibility of four-dimensional ultrasound imaging using spatiotemporal image correlation in routine fetal echocardiography

OBJECTIVES

To investigate the feasibility of incorporating spatiotemporal image correlation (STIC) into a tertiary fetal echocardiography program.

METHODS

During the study period all pregnant women fitting our inclusion criteria were enrolled consecutively. Four sonographers participated in the study, one of whom had substantial previous experience of STIC volume acquisition and three of whom did not. STIC volumes were acquired within the time slot allocated for the usual examination and all attempts were recorded. STIC volumes were assessed on acquisition conditions, the quality (as defined by a checklist of cardiac structures that could be visualized), and the rendering abilities. Furthermore, possible learning effects and the influence of experience with STIC on volume acquisition were studied.

RESULTS

STIC volume acquisition was successful in 75.7% (112/148) of cases in which it was attempted. The more experienced sonographer had a higher success rate in STIC volume acquisition (experienced vs. less experienced, 88.4% vs. 70.5%, P = 0.02). Of all analyzed STIC volumes, 64.8% were of high or sufficient quality. STIC volume quality and rendering ability correlated strongly with the acquisition conditions. High-quality STIC volumes successfully rendered the intracardiac septa in 84.6% of cases. The coronal atrioventricular plane was rendered in 12/26 cases (46.2%).

CONCLUSIONS

This study shows that incorporation of STIC volume acquisition into the daily practice of a tertiary fetal echocardiography program is feasible. Sonographers do not have to be specifically experienced in three- or four-dimensional ultrasound imaging to acquire high-quality STIC volumes. For successful STIC acquisition and subsequent successful analysis, correct acquisition conditions are of major importance. Finally, our results demonstrate that STIC is as susceptible as conventional two-dimensional ultrasound imaging to individual variations and limitations in scanning windows.

Two- and four-dimensional echocardiography with B-flow imaging and spatiotemporal image correlation in prenatal diagnosis of isolated total anomalous pulmonary venous connection

OBJECTIVES

To explore whether the use of four dimensional (4D) ultrasound examination with B-flow imaging and spatiotemporal image correlation (STIC) can supply additional information with respect to two-dimensional (2D) gray-scale and color Doppler echocardiography in the prenatal characterization of isolated total anomalous pulmonary venous connection (TAPVC).

METHODS

The study population comprised a group of three TAPVC fetuses that had been examined exclusively by conventional echocardiography, and a group of four additional cases initially identified by conventional echocardiography and examined further by 4D ultrasonography; a thorough postnatal work-up was available for all fetuses.

RESULTS

At our center, isolated TAPVC was found in seven of 1040 fetuses with cardiac defects (0.67%). Anomalous drainage was supracardiac to the innominate vein in three cases, cardiac to the coronary sinus in two, and infracardiac to the portal vein in the remaining two cases. An evident asymmetry between left heart and right heart structures was observed in 4/7 cases. The confluence of the anomalous pulmonary veins (PVs) was visualized in 4/7 cases and the connecting vertical vein was identified in 3/5 cases at 2D echocardiography. 4D ultrasound imaging with B-flow imaging and STIC clearly visualized the anomalous PV confluence and the draining vertical vein in all four cases examined.

CONCLUSION

2D and color Doppler echocardiography appears to diagnose reliably TAPVC, albeit with some limitations in thorough assessment of the pathology, depending on the anatomy of the defect, on the technical adequacy of the equipment used and on the experience of the operator. 4D ultrasound examination with B-flow imaging and STIC is apparently able to facilitate identification of the anatomical features of TAPVC, thus supplying additional information over that provided by 2D fetal sonography.

Fetal cardiac ventricle volumetry in the second half of gestation assessed by 4D ultrasound using STIC combined with inversion mode

OBJECTIVE

Quantification of fetal heart ventricle volume can aid in the evaluation of functional and anatomical aspects of congenital heart disease. The aim of this study was to establish nomograms for ventricular volume using three-dimensional (3D) inversion mode ultrasonography with the spatio-temporal image correlation (STIC) modality and to calculate ejection fraction and stroke volume.

METHODS

The fetal heart was scanned using the STIC modality, during fetal quiescence with abdomen uppermost, at an angle of 30-50 degrees , without color Doppler flow mapping. In post-processing, starting with the classic four-chamber view plane in the A-frame, the reference point was moved to the center of the ventricle. The operator used the edit volume followed by Virtual Organ Computer-aided AnaLysis (VOCAL) mode options; in manual trace the VOCAL settings were set to 15 degrees . The trace was drawn and included the myocardium; inversion mode thresholding provided the volume of the intraventricular (anechoic) voxels within the region of interest. The total volume and the intraventricular volume were displayed. The process was repeated for right (R) and left (L) ventricles at end diastole (EDV) and end systole (ESV). The stroke volume (SV = EDV - ESV) and ejection fraction (EF = SV/EDV) were calculated from these measurements. Intraclass correlation was used to evaluate intra- and interobserver agreement.

RESULTS

One hundred fetuses ranging from 20 + 5 to 40 + 0 gestational weeks were included in the study. In addition, six fetuses diagnosed during the study period with a cardiac anomaly were examined and their ventricular volumes compared with those of the main study group. LEDV ranged from a mean of 0.53 cm(3) at midgestation to a mean of 3.96 cm(3) at term. LESV ranged from a mean of 0.17 cm(3) at midgestation to 1.56 cm(3) at term. REDV ranged from a mean of 0.68 cm(3) at midgestation to a mean of 5.44 cm(3) at term. RESV ranged from a mean of 0.26 cm(3) at midgestation to 2.29 cm(3) at term. Total stroke volume ranged from a mean of 0.78 cm(3) at midgestation to a mean of 5.5 cm(3) at term. The mean right : left ventricle ratio was 1.4, and left ejection fraction ranged from 42.5 to 86% in these fetuses. Nomograms were created for RESV, LESV, REDV, LEDV and total stroke volumes vs. estimated fetal weight and gestational age. Intra- and interobserver agreement reached 96%.

CONCLUSIONS

3D inversion mode sonography combined with STIC represents a simple and reproducible method for estimating fetal cardiac ventricle volume. This innovative methodology may add to overall evaluation of cardiac volume and function, and improve our understanding of normal and abnormal cardiac structure, as well as the severity and prognosis of cardiac lesions.

Four-dimensional sonography of the fetal heart with spatiotemporal image correlation directed at the interventricular septum

OBJECTIVE

The purpose of this report is to describe a new technique to visualize the fetal interventricular cardiac septum in its entirety in a uniform fashion.

METHODS

Using spatiotemporal image correlation, a technique of volume data manipulation is described to produce standard long-axis, short-axis, and "face-on" views of the interventricular septum.

RESULTS

Using the detailed description of volume data manipulation, examples of large and small ventricular septal defects are presented.

CONCLUSIONS

By using a standardized technique of volume manipulation, complete assessment of the interventricular septum is accomplished. Incorporating the technique into routine fetal heart evaluation is easily accomplished and may aid in the fetal diagnosis of ventricular septal defects.