Four-dimensional ultrasonography of the fetal heart with spatiotemporal image correlation

Fetal brain MR angiography at 1.5 T: a feasible study

PURPOSE

The use of magnetic resonance angiography (MRA) for assessing CNS fetal vasculature has been limited. The aim of this study was to determine the feasibility and added value of 2D time-of-flight (TOF) MRA of the fetal brain vasculature with a 1.5 T scanner.

METHODS

We conducted a prospective study (September 2018 to October 2022) by consecutively selecting pregnant women (≥ 18 years) with clinical indication to fetal brain MRI. On a 1.5 T scanner, a 2D TOF MRA acquisition was obtained at the end of the clinical protocol. Two neuroradiologists independently reviewed all MRIs; a qualitative scale of motion artifacts was applied to MRA images; represented vessels in MRA and T2 images were registered.

RESULTS

Thirty-five fetal brain MRIs. Mean maternal age: 32 years; mean fetal gestational age (GA): 31 weeks. Artifacts were found in 74% of MRA. The number of MRAs performed without artifacts increased with GA. On MRA, the identification of the majority of vessels increased with GA; statistical significance was reached in the identification of torcular Herophili (p = 0.026), vein of Galen (p < 0.001), internal cerebral veins (p = 0.002), basilar artery (p = 0.027), vertebral arteries (p = 0.025), and middle cerebral arteries (p = 0.044). Significantly, MRA depicted the sigmoid sinuses and internal jugular veins more frequently. Vascular pathology was found in 3/35 fetal brain MRIs.

CONCLUSION

Although artifacts were found in 74% of cases, MRA acquisitions were informative and of sufficient diagnostic quality in most studies. This technique may represent a valuable complimentary tool in CNS prenatal vascular studies.

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-placental MR angiography at 1.5 T and 3 T

OBJECTIVES

The objective of this work was to investigate the application of 2D Time-of-Flight (TOF) magnetic resonance angiography (MRA) to observe the placental vasculature at both 1.5 T and 3 T.

METHODS

Fifteen appropriate for gestational age (AGA) (GA: 29.7 ± 3.4 weeks; GA range: 23 and 6/7 weeks to 36 and 2/7 weeks) and eleven patients with an abnormal singleton pregnancy (GA: 31.4 ± 4.4 weeks; GA range: 24 weeks to 35 and 2/7 weeks) were recruited in the study. Three AGA patients were scanned twice at different gestational ages. Patients were scanned either at 3 T or 1.5 T using both T2-HASTE and 2D TOF to image the entire placental vasculature.

RESULTS

The umbilical, chorionic vessels, stem vessels, arcuate arteries, radial arteries, and spiral arteries were shown in most of the subjects. Hyrtl's anastomosis was found in two subjects in the 1.5 T data. The uterine arteries were observed in more than half of the subjects. For those patients scanned twice, the same spiral arteries were identified in both scans.

CONCLUSIONS

2D TOF is a technique that can be applied in studying the fetal-placental vasculature at both 1.5 T and 3 T.

A Diagnostic Dilemma: Transposition of the Great Arteries

Transposition of the great arteries (TGA) remains one of the most common and severe underdiagnosed congenital cardiac anomalies in the prenatal period. Unfortunately, despite advances in prenatal ultrasound screening, the detection rate of major congenital heart defects (CHDs) remains low. We present the case of a preterm male infant delivered limp with generalized cyanosis and in respiratory distress at 36 weeks gestation with postnatal echocardiography (ECHO) depicting dextro-TGA (d-TGA). Maternal prenatal targeted fetal anomaly ultrasonography at 18 weeks gestation showed abnormal right ventricle and right ventricular outflow tract. Subsequent two-time repeat fetal ECHO showed ventricular septal defect. This case represents how challenging and unrecognized critical CHDs can be. Furthermore, it highlights the need for clinicians to have a high index of suspicion when newborns present with clinical manifestations of critical CHDs and manage it accordingly to avoid severe complications.

Application of Semiautomatic Fetal Intelligent Navigation Echocardiography (FINE) in Twin Pregnancies: Half the Work or Twice the Effort?

OBJECTIVE

To assess the performance of fetal intelligent navigation echocardiography (FINE, 5D Heart™) for automated volumetric investigation of the fetal heart in twin pregnancies.

METHODS

Three hundred twenty-eight twin fetuses underwent fetal echocardiography in the second and third trimesters. Spatiotemporal image correlation (STIC) volumes were obtained for a volumetric investigation. The volumes were analyzed using the FINE software, and the data were investigated regarding image quality and many properly reconstructed planes.

RESULTS

Three hundred and eight volumes underwent final analysis. 55.8% of the included pregnancies were dichorionic twin pregnancies, and 44.2% were monochorionic twin pregnancies. The mean gestational age (GA) was 22.1 weeks, and the mean maternal BMI was 27.3 kg/m². The STIC-volume acquisition was successful in 100.0% and 95.5% of cases. The overall depiction rates of FINE were 96.5% (twin 1) and 94.7% (twin 2), respectively (p = 0.0849, not significant). In 95.9% (twin 1) and 93.9% (twin 2), at least 7 planes were reconstructed properly (p = 0.6056, not significant).

CONCLUSION

Our results indicate that the FINE technique used in twin pregnancies is reliable. No significant difference between the depiction rates of twin 1 and twin 2 could be detected. In addition, the depiction rates are as high as those derived from singleton pregnancies. Due to the challenges of fetal echocardiography in twin pregnancies (i.e., greater rates of cardiac anomaly and more difficult scans), the FINE technique might be a valuable tool to improve the quality of medical care in those pregnancies.

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.

Fetal intelligent navigation echocardiography (FINE) has superior performance compared to manual navigation of the fetal heart by non-expert sonologists

OBJECTIVES

Manual and intelligent navigation (i.e. fetal intelligent navigation echocardiography or FINE) by the operator are two methods to obtain standard fetal cardiac views from spatiotemporal image correlation (STIC) volumes. The objective was to compare the performance between manual and intelligent navigation (FINE) of the fetal heart by non-expert sonologists.

METHODS

In this prospective observational study, ten sonologists underwent formal training on both navigational methods. Subsequently, they were tested on their ability to obtain nine cardiac views from five STIC volumes of normal fetal hearts (19-28 gestational weeks) using such methods. The following parameters were determined for both methods: (1) success rate of obtaining nine cardiac views; (2) mean time to obtain nine cardiac views per sonologist; and (3) maximum number of cardiac views successfully obtained for each STIC volume.

RESULTS

All fetal cardiac images obtained from 100 STIC volumes (50 for each navigational method) were reviewed by an expert in fetal echocardiography. Compared to manual navigation, FINE was associated with a significantly: (1) higher success rate of obtaining eight (excluding the abdomen view) appropriate cardiac views (92-100% vs. 56-88%; all p<0.05); (2) shorter mean time (minute:seconds) to obtain nine cardiac views (2:11 ± 0:37 vs. 15:49 ± 7:44; p<0.0001); and (3) higher success rate of obtaining all nine cardiac views for a given STIC volume (86 vs. 14%; p<0.001).

CONCLUSIONS

When performed by non-expert sonologists, intelligent navigation (FINE) had a superior performance compared to manual navigation of the normal fetal heart. Specifically, FINE obtained appropriate fetal cardiac views in 92-100% of cases.

Prenatal diagnosis of ductal origin of distal pulmonary artery: presentation of three cases and literature review

Ductal origin of distal pulmonary artery (DODPA) is a rare congenital cardiovascular anomaly, with an incidence of approximately 1 in 200 000 people. It involves the proximal interruption of one pulmonary artery branch, with the distal part arising from the base of the brachiocephalic artery, via the ipsilateral ductus arteriosus (DA) and the intrapulmonary branch of the pulmonary artery is usually intact. If timely treatment is not provided after birth, it is very likely that, due to DA closure, severe hypoplasia will occur in the lung supplied by the abnormal pulmonary artery. Hence, prenatal diagnosis of DODPA is important to enable initiation of prostaglandin treatment and early rehabilitation of the affected lung. Herein, we report three cases of fetal DODPA diagnosed via two-dimensional (2D) ultrasonography combined with four-dimensional (4D) spatiotemporal image correlation. We also present a literature review, and explore the ultrasonographic findings and the importance of 2D and 4D ultrasonography in obtaining an accurate prenatal diagnosis of DODPA. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Maximal Reduction of STIC Acquisition Time for Volumetric Assessment of the Fetal Heart—Benefits and Limitations of Semiautomatic Fetal Intelligent Navigation Echocardiography (FINE) Static Mode

(1) Objective: To scrutinize the reliability and the clinical value of routinely used fetal intelligent navigation echocardiography (FINE) static mode (5DHeartStatic™) for accelerated semiautomatic volumetric assessment of the normal fetal heart. (2) Methods: In this study, a total of 296 second and third trimester fetuses were examined by targeted ultrasound. Spatiotemporal image correlation (STIC) volumes of the fetal heart were acquired for further volumetric assessment. In addition, all fetal hearts were scanned by a fast acquisition time volume (1 s). The volumes were analyzed using the FINE software. The data were investigated regarding the number of properly reconstructed planes and cardiac axis. (3) Results: A total of 257 volumes were included for final analysis. The mean gestational age (GA) was 23.9 weeks (14.3 to 37.7 weeks). In 96.9 (standard acquisition time, FINE standard mode) and 94.2% (fast acquisition time, FINE static mode) at least seven planes were reconstructed properly (p = 0.0961, not significant). Regarding the overall depiction rate, the standard mode was able to reconstruct 96.9% of the planes properly, whereas the static mode showed 95.2% of the planes (p = 0.0098). Moreover, there was no significant difference between the automatic measurement of the cardiac axis (37.95 + 9.14 vs. 38.00 + 8.92 degrees, p = 0.8827, not significant). (4) Conclusions: Based on our results, the FINE static mode technique is a reliable method. It provides similar information of the cardiac anatomy compared to conventional STIC volumes assessed by the FINE method. The FINE static mode has the potential to minimize the influence of motion artifacts during volume acquisition and might therefore be helpful concerning volumetric cardiac assessment in daily routine.

New and advanced features of fetal intelligent navigation echocardiography (FINE) or 5D heart

Congenital heart disease (CHD) is the leading organ-specific birth defect, as well as the leading cause of infant morbidity and mortality from congenital malformations. Therefore, a comprehensive screening examination of the fetal heart should be performed in all women to maximize the detection of CHD. Four-dimensional sonography with spatiotemporal image correlation (STIC) technology displays a cine loop of a complete single cardiac cycle in motion. A novel method known as Fetal Intelligent Navigation Echocardiography (or FINE) was previously developed to interrogate STIC volume datasets using "intelligent navigation" technology. Such method allows the automatic display of nine standard fetal echocardiography views required to diagnose most cardiac defects. FINE considerably simplifies fetal cardiac examinations and reduces operator dependency. It has both high sensitivity and specificity for the detection of CHD. Indeed, FINE has been integrated into several commercially available ultrasound platforms.Recently, eight novel and advanced features have been developed for the FINE method and they will be described herein. Such features can be categorized based upon their broad goals. The first goal is to simplify FINE further, and consists of the following features: (1) Auto fetal positioning (or FINE align); (2) Skip points; (3) Predictive cursor; (4) Static mode volume; and (5) Breech sweep. The second goal is to allow quantitative measurements to be performed on the cardiac views generated by FINE: (6) Automatic cardiac axis; and (7) Cardiac biometry. Finally, the last goal is to improve the success of obtaining fetal echocardiography view(s); and consists of (8) Maestro planar navigation.

Deep Learning-Based Computer-Aided Fetal Echocardiography: Application to Heart Standard View Segmentation for Congenital Heart Defects Detection

Accurate segmentation of fetal heart in echocardiography images is essential for detecting the structural abnormalities such as congenital heart defects (CHDs). Due to the wide variations attributed to different factors, such as maternal obesity, abdominal scars, amniotic fluid volume, and great vessel connections, this process is still a challenging problem. CHDs detection with expertise in general are substandard; the accuracy of measurements remains highly dependent on humans' training, skills, and experience. To make such a process automatic, this study proposes deep learning-based computer-aided fetal heart echocardiography examinations with an instance segmentation approach, which inherently segments the four standard heart views and detects the defect simultaneously. We conducted several experiments with 1149 fetal heart images for predicting 24 objects, including four shapes of fetal heart standard views, 17 objects of heart-chambers in each view, and three cases of congenital heart defect. The result showed that the proposed model performed satisfactory performance for standard views segmentation, with a 79.97% intersection over union and 89.70% Dice coefficient similarity. It also performed well in the CHDs detection, with mean average precision around 98.30% for intra-patient variation and 82.42% for inter-patient variation. We believe that automatic segmentation and detection techniques could make an important contribution toward improving congenital heart disease diagnosis rates.

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.

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.

Feasibility of Semiautomatic Fetal Intelligent Navigation Echocardiography for Different Fetal Spine Positions: A Matter of "Time"?

OBJECTIVES

We investigated the feasibility of a semiautomatic approach for assessments of the fetal heart (fetal intelligent navigation echocardiography [FINE]) in cases of optimal and unfavorable fetal spine positions.

METHODS

In this study, a total of 1693 spatiotemporal image correlation volumes of first-, second-, and third-trimester fetuses were evaluated by experts using the FINE approach. The data were analyzed regarding proper reconstruction of the diagnostic cardiac planes depending on the fetal spine position.

RESULTS

A total of 1531 volumes were included. The volumes were divided into 4 groups depending on the fetal spine position: 5-7 o'clock, 4 + 8 o'clock, 3 + 9 o'clock, and 2 + 10 o'clock. In total, 93.2% of the diagnostic planes were displayed properly. Between 5 and 7 o'clock, 94.9% of the diagnostic planes were displayed properly. The correct depiction rates in the other groups were 92.4% (4 + 8 o'clock; n = 538; P = 0.0027), 88.3% (3 + 9 o'clock; n = 156; P < .0001), and 87.3% (2 + 10 o'clock; n = 41; P = .0139). In total, the highest dropout rates were found in the sagittal planes: ductal arch, 13.9%; aortic arch, 10.5%; and venae cavae, 12.0%.

CONCLUSIONS

Based on our results, the FINE technique is an effective method, but its feasibility depends on the fetal position. The use of this semiautomatic work flow-based approach supports evaluation of the fetal heart in a standardized manner. Semiautomatic evaluation of the fetal heart might be useful in facilitating the detection of fetal cardiac anomalies.

Obstetric ultrasound: where are we and where are we going?

Diagnostic ultrasound (DUS) is, arguably, the most common technique used in obstetrical practice. From A mode, first described by Ian Donald for gynecology in the late 1950s, to B mode in the 1970s, real-time and gray-scale in the early 1980s, Doppler a little later, sophisticated color Doppler in the 1990s and three dimensional/four-dimensional ultrasound in the 2000s, DUS has not ceased to be closely associated with the practice of obstetrics. The latest innovation is the use of artificial intelligence which will, undoubtedly, take an increasing role in all aspects of our lives, including medicine and, specifically, obstetric ultrasound. In addition, in the future, new visualization methods may be developed, training methods expanded, and workflow and ergonomics improved.

Prenatal diagnosis of transposition of the great arteries: an updated review

Simple transposition of the great arteries (TGA) is a cyanotic heart disease that accounts for 5% to 7% of all congenital heart diseases. It is commonly underdiagnosed in utero, with prenatal detection rates of less than 50%. Simple TGA is characterized by ventriculoarterial discordance, atrioventricular concordance, and a parallel relationship of TGA. The prenatal diagnosis of TGA influences postnatal outcomes and therefore requires planned delivery and perinatal management. For these reasons, it is important to identify the key ultrasound markers of TGA to improve the prenatal diagnosis and consequently provide perinatal assistance. The presence of two vessels instead of three in the three-vessel tracheal view, a parallel course of TGA, and identification of the origin of each of TGA are the key markers for diagnosing TGA. In addition to the classical ultrasound signs, other two-dimensional ultrasound markers such as an abnormal right convexity of the aorta, an I-shaped aorta, and the "boomerang sign" may also be used to diagnose TGA in the prenatal period. When accessible, an automatic approach using four-dimensional technologies such as spatio-temporal image correlation and sonographically-based volume computer-aided analysis may improve the prenatal diagnosis of TGA. This study aimed to review the ultrasound markers that can be used in the antenatal diagnosis of TGA, with a focus on the tools used by ultrasonographers, the obstetric and fetal medicine team, and perinatal cardiologists to improve the diagnosis of this condition.

Semiautomatic Fetal Intelligent Navigation Echocardiography Has the Potential to Aid Cardiac Evaluations Even in Less Experienced Hands

OBJECTIVES

To investigate the interobserver and intraobserver variability and corresponding learning curve in a semiautomatic approach for a standardized assessment of the fetal heart (fetal intelligent navigation echocardiography [FINE]).

METHODS

A total of 30 stored spatiotemporal image correlation volume data sets of second-trimester fetuses were evaluated by 3 physicians with different levels of expertise in fetal echocardiography by using the FINE approach. Data were analyzed regarding the examination time and proper reconstruction of the diagnostic cardiac planes. The completions and numbers of correct depictions of all diagnostic planes were evaluated by a blinded expert (time t0). To determine interobserver and intraobserver variability, the volumes were reassessed after a 4-week training interval (time t1).

RESULTS

All operators were able to perform the investigation on all 30 volumes. At t0, the interobserver variability between the beginner and both the advanced (P = .0013) and expert (P < .0001) examiners was high. Focusing on intraobserver variability at t1, the beginner showed a marked improvement (P = .0087), whereas in advanced and expert hands, no further improvement regarding proper achievement of all diagnostic planes could be noticed (P > .999; P = .8383). The beginner also showed improvement in the mean investigation time (t0, 82.8 seconds; t1, 73.4 seconds; P = .0895); nevertheless, the advanced and expert examiners were faster in completing the examination (t1, advanced, 20.9 seconds; expert, 28.3 seconds; each P < .0001).

CONCLUSIONS

Based on our results, the FINE technique is a reliable and easily learned method. The use of this semiautomatic work flow-based approach supports evaluation of the fetal heart in a standardized and time-saving manner. A semiautomatic evaluation of the fetal heart might be useful in facilitating the detection of fetal cardiac anomalies.

Assessment of the quality of fetal heart standard views using the FAST, STAR, and FINE four-dimensional ultrasound techniques in the screening of congenital heart diseases

OBJECTIVE

To compare the quality of standard fetal echocardiographic views obtained by four-dimensional ultrasound with those obtained by the simple targeted arterial rendering (STAR) technique, four-chamber view swing technique (FAST), and fetal intelligent navigation echocardiography (FINE/5D Heart^® ) technique.

METHODS

This was a cross-sectional prospective study that included pregnant women between 22 and 34 weeks of gestation, with normal fetuses. Fetal heart volumes were acquired using spatio-temporal image correlation (STIC) with the fetal spine between 2 and 9 o'clock. The FAST/STAR techniques consist of the manipulation of STIC volumes by drawing OmniView^™ lines to obtain echocardiographic views. The FINE/5D Heart® technique uses intelligent navigation to automatically generate echocardiographic views. The quality of the images was classified as excellent, good, acceptable, and unacceptable. The analysis was performed using the Bonferroni multiple comparisons test.

RESULTS

The study included 101 pregnant women aged between 16 and 44 years. There was no mean difference in image quality between the techniques regarding fetal spine position in all echocardiographic views (P > .05). However, in the five-chamber, left ventricular outflow tract, right ventricular outflow tract, ductal arch, superior vena cava/inferior vena cava, and abdomen/stomach views, there was a statistically significant mean difference quality between the techniques, regardless of the spine position (P < .05). The best mean image quality was obtained by the FINE technique (P ≤ .016 for all fetal echocardiographic views).

CONCLUSION

The quality of the echocardiographic views obtained using the FINE technique was superior to that of those generated by the FAST/STAR techniques in normal fetuses.

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.

How to obtain diagnostic planes of the fetal central nervous system using three-dimensional ultrasound and a context-preserving rendering technology

The antenatal evaluation of the fetal central nervous system (CNS) is among the most difficult tasks of prenatal ultrasound (US), requiring technical skills in relation to ultrasound and image acquisition as well as knowledge of CNS anatomy and how this changes with gestation. According to the International Guidelines for fetal neurosonology, the basic assessment of fetal CNS is most frequently performed on the axial planes, whereas the coronal and sagittal planes are required for the multiplanar evaluation of the CNS within the context of fetal neurosonology. It can be even more technically challenging to obtain "nonaxial" views with 2-dimensional (2D) US. The modality of 3-dimensional (3D) US has been suggested as a panacea to overcome the technical difficulties of achieving nonaxial views. The lack of familiarity of most sonologists with the use of 3D US and its related processing techniques may preclude its use even where it could play an important role in complementing antenatal 2D US assessment. Furthermore, once a 3D volume has been acquired, proprietary software allows it to be processed in different ways, leading to multiple ways of displaying and analyzing the same anatomical imaging or plane. These are difficult to learn and time consuming in the absence of specific training. In this article, we describe the key steps for volume acquisition of a 3D US volume, manipulation, and processing with reference to images of the fetal CNS, using a newly developed context-preserving rendering technique.

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.

Assessment of Fetal Congenital Heart Diseases by 4-Dimensional Ultrasound Using Spatiotemporal Image Correlation: Pictorial Review

The aim of this pictorial review is to describe the technical advances achieved through the application of 4-dimensional (4D) ultrasound using spatiotemporal image correlation (STIC) over conventional 2-dimensional ultrasound in the prenatal detection of congenital heart disease (CHD). Spatiotemporal image correlation is a volume imaging technique that simplifies fetal heart studies while providing more diagnostic information than is typically available from traditional 2-dimensional studies. Four-dimensional software allows the study of cardiac anatomy and function during a single cardiac cycle and has greatly contributed to diagnostic enhancement of CHD. Color flow and power Doppler can be added to STIC in the study of vessel anatomy and to increase the detection of ventricular septal defects. Anatomical details of the fetus can be displayed in multiple images such as using computed tomography or magnetic resonance imaging. In addition, cardiac anatomy can be sectioned freely and reconstructed using different reformatting applications. Realistic views of the fetal heart, with particular emphasis on myocardium and endocardium cushion, can be reached using novel lightening techniques. Moreover, using 4D ultrasound, echolucent structures can be converted into solid voxels generating "digital casts" of the fetal heart that enhances the understanding of the great vessel relationships in the ventricular inflow and outflow tracts. Recently, sillhouette mode has shown to improve depth perception and resolution compared with conventional 3D power Doppler in the study of inflow and outflow tracts. Here, a gallery of prenatally detected CHD using 4D ultrasound with STIC and different applications is described.

Fetal Intelligent Navigation Echocardiography (FINE) Detects 98% of Congenital Heart Disease

OBJECTIVE

Fetal intelligent navigation echocardiography (FINE) is a novel method that automatically generates and displays 9 standard fetal echocardiographic views in normal hearts by applying intelligent navigation technology to spatiotemporal image correlation (STIC) volume data sets. The main objective was to determine the sensitivity and specificity of FINE in the prenatal detection of congenital heart disease (CHD).

METHODS

A case-control study was conducted in 50 fetuses with a broad spectrum of CHD (cases) and 100 fetuses with normal hearts (controls) in the second and third trimesters. Using 4-dimensional ultrasound with STIC technology, volume data sets were acquired. After all identifying information was removed, the data sets were randomly distributed to a different investigator for analysis using FINE. The sensitivity and specificity for the prenatal detection of CHD, as well as positive and negative likelihood ratios were determined.

RESULTS

The diagnostic performance of FINE for the prenatal detection of CHD was: sensitivity of 98% (49 of 50), specificity of 93% (93 of 100), positive likelihood ratio of 14, and negative likelihood ratio of 0.02. Among cases with confirmed CHD, the diagnosis with use of FINE completely matched the final diagnosis in 74% (37 of 50); minor discrepancies were seen in 12% (6 of 50), and major discrepancies were seen in 14% (7 of 50).

CONCLUSIONS

This is the first time the sensitivity and specificity of the FINE method in fetuses with normal hearts and CHD in the second and third trimesters has been reported. Because FINE identifies a broad spectrum of CHD with 98% sensitivity, this method could be used prenatally to screen for and diagnose CHD.

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.

2D versus 3D real time ultrasound with live xPlane imaging to visualize aortic and ductal arches: comparison between methods

Background

The diagnosis of congenital heart defects is challenging, especially for what concerns conotruncal anomalies. Indeed, although the screening techniques of fetal cardiac anomalies have greatly improved, the detection rate of conotruncal anomalies still remains low due to the fact that they are associated with a normal four-chamber view. Therefore, the study aimed to compare real-time three-dimensional echocardiography with live xPlane imaging with two-dimensional (2D) traditional imaging in visualizing ductal and aortic arches during routine echocardiography of the second trimester of gestation.

Methods

This was an observational prospective study including 114 women with uncomplicated, singleton pregnancies. All sonographic studies were performed by two different operators, of them 60 by a first level operator, while 54 by a second level operator. A subanalysis was run in order to evaluate the feasibility and the time needed for the two procedures according to fetal spine position and operator’s experience.

Results

The measurements with 2D ultrasound were performed in all 114 echocardiographies, while live xPlane imaging was feasible in the 78% of the cases, and this was mainly due to fetal position. The time lapse needed to visualize aortic and ductal arches was significantly lower when using 2D ultrasound compared to live xPlane imaging (29.56 ± 28.5 s vs. 42.5 ± 38.1 s, P = 0.006 for aortic arch; 22.14 ± 17.8 s vs. 37.1 ± 33.8 s, P = 0.001 for ductal arch), also when performing a subanalysis according to operators’ experience (P < 0.05 for all comparisons). Feasibility of live xPlane proved to be correlated with the position of the fetal spine and the operator’s experience.

Discussion

To find a reproducible and standardized method to detect fetal heart defects may bring a great benefit for both patients and operators. In this scenario live xPlane imaging is a novel method to visualize ductal and aortic arches. We found that the position of the fetal spine may affect the feasibility of the method since, when the fetal back is anterior or transverse, the visualization of the correct view of three-vessels and trachea in order to set the reference line properly becomes more challenging. In addition, the fetal spine position influences the duration of the ultrasound examination. Regarding operator’s skills and experience, in our study a first level operator was able to perform the complete 2D and xPlane examination in a lower number of cases compared to second level operators. In addition, the time required for the complete examination was higher for first level operators. This means that this technique is based on an adequate operators’ expertise.

Advances in fetal echocardiography

The development of fetal echocardiography and success in prenatal cardiac screening programs over the past 30 years has been driven by technical innovation and influenced by the different approaches of the various specialties practicing it. Screening for congenital heart defects no longer focuses on examining a limited number of pregnant women thought to be at increased risk, but instead forms an integrated part of a high-quality anatomical ultrasound performed in the second trimester using the 'five-transverse view' protocol. A prenatal diagnosis is feasible in almost all cardiac lesions and the advantages to parents and to health professionals are well recognized. Prenatal evaluation can usually determine the level of care required at delivery, thereby reducing perinatal morbidity. However, only half of the babies undergoing surgery within the first year of life have a prenatal detection, and practical training programs to support and provide feedback to sonographers remain essential for continued improvement.

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.

Color and power Doppler combined with Fetal Intelligent Navigation Echocardiography (FINE) to evaluate the fetal heart

OBJECTIVE

To evaluate the performance of color and bidirectional power Doppler ultrasound combined with Fetal Intelligent Navigation Echocardiography (FINE) in examining the fetal heart.

METHODS

A prospective cohort study was conducted of fetuses in the second and third trimesters with a normal heart or with congenital heart disease (CHD). One or more spatiotemporal image correlation (STIC) volume datasets, combined with color or bidirectional power Doppler (S-flow) imaging, were acquired in the apical four-chamber view. Each successfully obtained STIC volume was evaluated by STICLoop™ to determine its appropriateness before applying the FINE method. Visualization rates for standard fetal echocardiography views using diagnostic planes and/or Virtual Intelligent Sonographer Assistance (VIS-Assistance®) were calculated for grayscale (removal of Doppler signal), color Doppler and S-flow Doppler. In four cases with CHD (one case each of tetralogy of Fallot, hypoplastic left heart and coarctation of the aorta, interrupted inferior vena cava with azygos vein continuation and asplenia, and coarctation of the aorta with tricuspid regurgitation and hydrops), the diagnostic potential of this new technology was presented.

RESULTS

A total of 169 STIC volume datasets of the normal fetal heart (color Doppler, n = 78; S-flow Doppler, n = 91) were obtained from 37 patients. Only a single STIC volume of color Doppler and/or a single volume of S-flow Doppler per patient were analyzed using FINE. Therefore, 60 STIC volumes (color Doppler, n = 27; S-flow Doppler, n = 33) comprised the final study group. Median gestational age at sonographic examination was 23 (interquartile range, 21-27.5) weeks. Color Doppler FINE generated nine fetal echocardiography views (grayscale) using (1) diagnostic planes in 73-100% of cases, (2) VIS-Assistance in 100% of cases, and (3) a combination of diagnostic planes and/or VIS-Assistance in 100% of cases. The rate of generating successfully eight fetal echocardiography views with appropriate color and S-flow Doppler information was 89-100% and 91-100% of cases, respectively, using a combination of diagnostic planes and/or VIS-Assistance. However, the success rate for the ninth echocardiography view (i.e. superior and inferior venae cavae) was 33% and 30% for color and S-flow Doppler, respectively. In all four cases of CHD, color Doppler FINE demonstrated evidence of abnormal fetal cardiac anatomy and/or hemodynamic flow.

CONCLUSIONS

The FINE method applied to STIC volumes of normal fetal hearts acquired with color or bidirectional power Doppler information can generate successfully eight to nine standard fetal echocardiography views (via grayscale, color Doppler or power Doppler) in the second and third trimesters. In cases of CHD, color Doppler FINE demonstrates successfully abnormal anatomy and/or Doppler flow characteristics. Published 2017. This article is a U.S. Government work and is in the public domain in the USA. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Non-invasive Evaluation of Right Ventricular Function with Real-Time 3-D Echocardiography

The aim of this study was to evaluate the accuracy and feasibility of real-time 3-D echocardiography (3-DE) in assessing right ventricular (RV) systolic function. A latex balloon was inserted into the right ventricle of 20 freshly harvested pig hearts which were then passively driven by a pulsatile pump apparatus. The RV global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS) and RV ejection fraction (RVEF), derived from 3-DE, as well as the RVEF obtained from 2-D echocardiography (2-DE) were quantified at different stroke volumes (30-70 mL) and compared with sonomicrometry data. In all comparisons, 3-D GLS, GCS, GAS, 2-D RVEF and 3-D RVEF exhibited strong correlations with sonomicrometry data (r = 0.89, 0.79, 0.74, 0.80, and 0.93, respectively; all p values < 0.001). Bland-Altman analyses revealed slight overestimations of echo-derived GLS, GCS, 2-DE RVEF and 3-DE RVEF compared with sonomicrometry values (bias = 1.55, 2.72, 3.59 and 2.21, respectively). Furthermore, there is better agreement among GLS, 3-D RVEF and the sonomicrometry values than between GCS and 2-D RVEF. Real-time 3-DE is more feasible and accurate for assessing RV function than 2-DE. GLS is a potential alternative parameter for quantifying RV systolic function.

Feasibility assessment for successfully visualizing the fetal heart utilizing spatiotemporal image correlation

PURPOSE

Spatiotemporal image correlation (STIC) is an excellent imaging modality for observing the fetal heart. High-quality STIC volume data are needed for an antenatal anatomic survey to diagnose congenital heart disease. We aimed to clarify the causes of unsuccessful STIC volume data acquisition and describe a more accurate, efficient STIC examination.

METHODS

This cross-sectional study of 1124 women with fetuses assessed risk factors for unsuccessful acquisition of STIC volume data. Logistic regression analysis quantified the relation between unsuccessful acquisition and clinical variables, including maternal body mass index (BMI), shadowing artifacts due to unexpected fetal limb movement (SAU), estimated fetal weight (EFW), gestational age (GA), use of volume rendering images in four-dimensional ultrasonography (4D-US), fetal heart rate (FHR), maternal age, anterior placenta, and prior lower abdominal surgery.

RESULTS

STIC volume data acquisition was unsuccessful in 210 of 1124 (18.6%) cases. SAU, BMI ≥ 28 kg/m², not using volume rendering images in 4D-US, EFW ≥ 1300 g, and anterior placenta were independent risk factors for unsuccessful STIC data acquisition.

CONCLUSIONS

Avoiding SAU was the most important factor for accurate, efficient STIC evaluations for diagnosing congenital heart disease antenatally. The risk was not explained by lack of sonographer proficiency. Volume rendering images in 4D-US is a promising approach to successful acquisition of STIC volume data.

Prenatal Diagnosis of Dextrocardia with Complex Congenital Heart Disease Using Fetal Intelligent Navigation Echocardiography (FINE) and a Literature Review

Fetal dextrocardia is a type of cardiac malposition where the major axis from base to apex points to the right side. This condition is usually associated with a wide spectrum of complex cardiac defects. As a result, dextrocardia is conceptually difficult to understand and diagnose on prenatal ultrasound. The advantage of four-dimensional sonography with spatiotemporal image correlation (STIC) is that this modality can facilitate fetal cardiac examination. A novel method known as fetal intelligent navigation echocardiography (FINE) allows automatic generation of nine standard fetal echocardiography views in normal hearts by applying intelligent navigation technology to STIC volume datasets. In fetuses with congenital heart disease, FINE is also able to demonstrate abnormal cardiac anatomy and relationships when there is normal cardiac axis and position. However, this technology has never been applied to cases of cardiac malposition. We report herein for the first time, a case of fetal dextrocardia and situs solitus with complex congenital heart disease in which the FINE method was invaluable in diagnosing multiple abnormalities and defining complex anatomic relationships. We also review the literature on prenatal sonographic diagnosis of dextrocardia (with an emphasis on situs solitus), as well as tricuspid atresia with its associated cardiac features.

Reference Ranges of Fetal Cardiac Biometric Parameters Using Three-Dimensional Ultrasound with Spatiotemporal Image Correlation M Mode and Their Applicability in Congenital Heart Diseases

To determine reference values for fetal heart biometric parameters using the spatiotemporal image correlation (STIC) M mode and their applicability in congenital heart diseases (CHDs). A cross-sectional prospective study was conducted with 300 singleton pregnancies between 20 and 33 + 6 weeks of gestation. Right ventricular wall thickness (RVWT), interventricular septum thickness (IVST), and left ventricular wall thickness (LVWT) were measured off-line using the STIC-M mode with the cursor perpendicular to the interventricular septum. Polynomial regressions adjusted with the coefficient of determination (R ²) were performed. The curves were applied to 14 fetuses with structural CHD. For the reproducibility calculations, the concordance correlation coefficient (CCC) was used. The mean RVWT, IVST, and LVWT were 0.34 ± 0.09 cm, 0.28 ± 0.09 cm, and 0.30 ± 0.07 cm, respectively. There was correlation between RVWT, IVST, and LVWT and gestational age (GA): RVWT = -0.002 + 0.013 × GA (R ² = 0.33), IVST = -0.011 + 0.011 × GA (R ² = 0.25), and LVWT = 0.056 + 0.009 × GA (R ² = 0.26). RVWT, IVST, and LVWT were altered (<5th or >95th percentile) in 5/14, 5/14, and 7/14 of the fetuses with CHD, respectively. For RVWT, IVST, and LVWT, intra-observer (CCC = 0.86, 0.85, and 0.87, respectively) and inter-observer (CCC = 0.86, 0.86, and 0.86, respectively) reproducibility were good/moderate. The reference ranges determined for fetal heart biometric parameters using STIC-M had good intra- and inter-observer reproducibility and were applicable to fetuses with CHD.

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.

Evaluation of fetal cardiac valve anomalies by four-dimensional echocardiography with spatiotemporal image correlation (4DSTIC)

BACKGROUND

Prenatal diagnosis of cardiac valve anomalies challenged most screening sonographers. The purpose of the study was to evaluate the use of four-dimensional echocardiography with spatiotemporal image correlation (4DSTIC) in detecting normal and abnormal fetal cardiac valves.

METHODS

Forty-three cases of confirmed cardiac valve anomalies identified by two-dimensional echocardiography (2DE) were retrospectively reviewed in this study. Additional 121 confirmed normal fetuses were included as controls. Four-dimensional volumes were acquired from each fetus using a transverse sweep. Four-dimensional rendered images were retrieved from the volumes for each of the cardiac valves for the normal fetuses and for the intended valves for fetuses with valve malformations.

RESULTS

The visualization rates of cardiac valves retrieved from 4D volumes in the normal fetuses ranged from 72.5% to 97.5% before 33 gestational weeks and from 46.3% to 80.5% in late pregnancy. Furthermore, 4D rendered images were successfully obtained in 38 of 43 (88.4%) fetuses with cardiac valve lesions.

CONCLUSIONS

The 4D images and cine loops displayed the valves anatomy vividly in both normal and abnormal fetuses, including some subtle malformations which were not identified by traditional 2DE. The standardized protocol we propose herein was important in obtaining the 4D images from the volumes. The 4D modality allows a better visualization of fetal cardiac valves and should be considered a valuable addition to traditional 2DE imaging.

Screening for Congenital Heart Disease

Compared with the assessment of most fetal anatomic structures, the assessment of the fetal heart during routine obstetric screening represents a diagnostic challenge for sonographers and interpreting physicians. This is due to a number of factors: the structural complexity of the heart, the rate at which it moves, the position of the fetus relative to the transducer, and variations in assessment protocols used by sonographers and physicians. The fetal heart is a relatively small and complex structure, as seen in an early second-trimester sonogram. In some forms of congenital heart disease, the abnormality may be detectable within only a relatively small fraction of the heart volume. Congenital heart disease represents a range of structural defects, a number of which have specific sonographic features that can be identified during routine assessment. Many approaches have been proposed to improve the assessment of the fetal heart, including specific still images, color Doppler, 3D imaging techniques, and cineloops.

A Prospective Study of the Use of Fetal Intelligent Navigation Echocardiography (FINE) to Obtain Standard Fetal Echocardiography Views

OBJECTIVE

To evaluate the performance of Fetal Intelligent Navigation Echocardiography (FINE) applied to spatiotemporal image correlation (STIC) volume datasets of the normal fetal heart in generating standard fetal echocardiography views.

METHODS

In this prospective cohort study of patients with normal fetal hearts (19-30 gestational weeks), one or more STIC volume datasets were obtained of the apical four-chamber view. Each STIC volume successfully obtained was evaluated by STICLoop™ to determine its appropriateness before applying the FINE method. Visualization rates for standard fetal echocardiography views using diagnostic planes and/or Virtual Intelligent Sonographer Assistance (VIS-Assistance®) were calculated.

RESULTS

One or more STIC volumes (total n = 463) were obtained from 246 patients. A single STIC volume per patient was analyzed using the FINE method. In normal cases, FINE was able to generate nine fetal echocardiography views using: (1) diagnostic planes in 76-100% of the cases, (2) VIS-Assistance® in 96-100% of the cases, and (3) a combination of diagnostic planes and/or VIS-Assistance® in 96-100% of the cases.

CONCLUSION

FINE applied to STIC volumes can successfully generate nine standard fetal echocardiography views in 96-100% of cases in the 2nd and 3rd trimesters. This suggests that the technology can be used as a method of screening for congenital heart disease.

Magnetic resonance angiography of fetal vasculature at 3.0 T

Magnetic resonance angiography has not been used much previously for visualizing fetal vessels in utero for reasons that include a contraindication for the use of exogenous contrast agents, maternal respiratory motion and fetal motion. In this work, we report the feasibility of using an appropriately modified clinical time-of-flight magnetic resonance imaging sequence for non-contrast angiography of human fetal and placental vessels at 3.0 T. Using this 2D angiography technique, it is possible to visualize fetal vascular networks in late pregnancy.

KEY POINTS

• 3D-visualization of fetal vasculature is feasible using non-contrast MRA at 3.0 T. • Visualization of placental vasculature is also possible with this method. • Fetal MRA can serve as a vascular localizer for quantitative MRI studies. • This method can be extended to 1.5 T.

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.

Intelligent navigation to improve obstetrical sonography

'Manual navigation' by the operator is the standard method used to obtain information from two-dimensional and volumetric sonography. Two-dimensional sonography is highly operator dependent and requires extensive training and expertise to assess fetal anatomy properly. Most of the sonographic examination time is devoted to acquisition of images, while 'retrieval' and display of diagnostic planes occurs rapidly (essentially instantaneously). In contrast, volumetric sonography has a rapid acquisition phase, but the retrieval and display of relevant diagnostic planes is often time-consuming, tedious and challenging. We propose the term 'intelligent navigation' to refer to a new method of interrogation of a volume dataset whereby identification and selection of key anatomical landmarks allow the system to: 1) generate a geometrical reconstruction of the organ of interest; and 2) automatically navigate, find, extract and display specific diagnostic planes. This is accomplished using operator-independent algorithms that are both predictable and adaptive. Virtual Intelligent Sonographer Assistance (VIS-Assistance®) is a tool that allows operator-independent sonographic navigation and exploration of the surrounding structures in previously identified diagnostic planes. The advantage of intelligent (over manual) navigation in volumetric sonography is the short time required for both acquisition and retrieval and display of diagnostic planes. Intelligent navigation technology automatically realigns the volume, and reorients and standardizes the anatomical position, so that the fetus and the diagnostic planes are consistently displayed in the same manner each time, regardless of the fetal position or the initial orientation. Automatic labeling of anatomical structures, subject orientation and each of the diagnostic planes is also possible. Intelligent navigation technology can operate on conventional computers, and is not dependent on specific ultrasound platforms or on the use of software to perform manual navigation of volume datasets. Diagnostic planes and VIS-Assistance videoclips can be transmitted by telemedicine so that expert consultants can evaluate the images to provide an opinion. The end result is a user-friendly, simple, fast and consistent method of obtaining sonographic images with decreased operator dependency. Intelligent navigation is one approach to improve obstetrical sonography. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Prospective evaluation of the fetal heart using Fetal Intelligent Navigation Echocardiography (FINE)

OBJECTIVE

To evaluate prospectively the performance of Fetal Intelligent Navigation Echocardiography (FINE) applied to spatiotemporal image correlation (STIC) volume datasets of the normal fetal heart.

METHODS

In all women between 19 and 30 weeks' gestation with a normal fetal heart, an attempt was made to acquire STIC volume datasets of the apical four-chamber view if the following criteria were met: (1) fetal spine located between 5- and 7-o'clock positions; (2) minimal or absent shadowing (including a clearly visible transverse aortic arch); (3) absence of fetal breathing, hiccups, or movement; and (4) adequate image quality. Each STIC volume successfully acquired was evaluated by STICLoop™ to determine its appropriateness before applying the FINE method. Visualization rates of fetal echocardiography views using diagnostic planes and/or Virtual Intelligent Sonographer Assistance (VIS-Assistance®) were calculated.

RESULTS

One or more STIC volumes (365 in total) were obtained successfully in 72.5% (150/207) of women undergoing ultrasound examination. Of the 365 volumes evaluated by STICLoop, 351 (96.2%) were considered to be appropriate. From the 351 STIC volumes, only one STIC volume per patient (n = 150) was analyzed using the FINE method, and consequently nine fetal echocardiography views were generated in 76-100% of cases using diagnostic planes only, in 98-100% of cases using VIS-Assistance only, and in 98-100% of cases when using a combination of diagnostic planes and/or VIS-Assistance.

CONCLUSIONS

In women between 19 and 30 weeks' gestation with a normal fetal heart undergoing prospective sonographic examination, STIC volumes can be obtained successfully in 72.5% of cases. The FINE method can be applied to generate nine standard fetal echocardiography views in 98-100% of these cases using a combination of diagnostic planes and/or VIS-Assistance. This suggests that FINE could be implemented in fetal cardiac screening programs. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

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.

Three-dimensional ultrasound of the fetus: how does it help?

Three-dimensional ultrasonography (3-D US) was introduced to the field of fetal imaging in the early 1990s. Since then several publications have described potential applications for the diagnosis of congenital malformations as well as organ volumetry. This article reviews basic principles of 3-D US as well as its clinical applicability to prenatal diagnosis of abnormalities involving the face, spine and skeletal system, as well as potential applications of 3-D US for fetal cardiovascular and neuroimaging. Limitations related to motion artifacts, acoustic shadowing and barriers to clinical implementation of 3-D US in clinical practice are addressed.

The Ultrasonic Microsurgical Anatomical Comparative Study of the CHD Fetuses and Their Clinical Significance

The aim of our study was to increase the detection rate of fetal cardiac malformations for congenital heart disease (CHD). The ultrasonic and microanatomical methods were combined to study the CHD cases firstly, which could provide the microsurgical anatomical basis to the prenatal ultrasonic diagnosis which was used in suspected CHD and help the sonographer to improve the quality of fetal cardiac diagnosis. We established the ultrasonic standard section of the 175 complex CHD cases and collected the fetal echocardiography image files. The induced/aborted fetuses were fixed by 4% paraformaldehyde and dissected by the ultrasonic microsurgical anatomy. This research could obtain the fetal cardiac anatomic cross-sectional images which was consistent with the ultrasonic standard section and could clearly show the internal structure of the vascular malformation that optimized the ultrasound examination individually. This method could directly display the variation of the CHD fetal heart clearly and comprehensively help us to understand the complex fetal cardiac malformation from the internal structure of the vascular malformation which was consolidated by the anatomical basis of the fetal heart. This study could improve the integrity and accuracy of the prenatal cardiac ultrasound examination tremendously.