Four-dimensional ultrasonography of the fetal heart using color Doppler spatiotemporal image correlation.

OBJECTIVE: To describe clinical and research applications of 4-dimensional imaging of the fetal heart using color Doppler spatiotemporal image correlation. METHODS: Forty-four volume data sets were acquired by color Doppler spatiotemporal image correlation. Seven subjects were examined: 4 fetuses without abnormalities, 1 fetus with ventriculomegaly and a hypoplastic cerebellum but normal cardiac anatomy, and 2 fetuses with cardiac anomalies detected by fetal echocardiography (1 case of a ventricular septal defect associated with trisomy 21 and 1 case of a double-inlet right ventricle with a 46,XX karyotype). The median gestational age at the time of examination was 21 3/7 weeks (range, 19 5/7-34 0/7 weeks). Volume data sets were reviewed offline by multiplanar display and volume-rendering methods. Representative images and online video clips illustrating the diagnostic potential of this technology are presented. RESULTS: Color Doppler spatiotemporal image correlation allowed multiplanar visualization of ventricular septal defects, multiplanar display and volume rendering of tricuspid regurgitation, volume rendering of the outflow tracts by color and power Doppler ultrasonography (both in a normal case and in a case of a double-inlet right ventricle with a double-outlet right ventricle), and visualization of venous streams at the level of the foramen ovale. CONCLUSIONS: Color Doppler spatiotemporal image correlation has the potential to simplify visualization of the outflow tracts and improve the evaluation of the location and extent of ventricular septal defects. Other applications include 3-dimensional evaluation of regurgitation jets and venous streams at the level of the foramen ovale.     

Validation of volume and mass assessments for human fetal heart imaging by 4-dimensional spatiotemporal image correlation echocardiography: in vitro balloon model experiments.

OBJECTIVE: This study was designed to validate a slow-sweep real-time 4-dimensional (4D) spatiotemporal image correlation method for producing quantitatively accurate dynamic fetal heart images using an in vitro pulsatile balloon model and apparatus. METHODS: To model fetal heart chambers, asymmetric double-walled finger stalls (tips of surgical latex gloves) were used and attached to a laboratory-designed circuit that allowed calibrated changes in the inner balloon volume as well as an intermediate gel mass interposed between the 2 layers. The water-submerged model was attached to a small-volume pulsatile pump to produce phasic changes in volume within the inner balloon at a fixed rate. A sonography system with 4D spatiotemporal image correlation (STIC) capabilities was used for 3-dimensional (3D) and 4D data acquisition. Volume data were analyzed by customized radial summation techniques with 4D data analysis software and compared with known volumes and masses. RESULTS: Fifty-six individual volumes ranging from 2.5 to 10 mL were analyzed. Volume and mass measurements with 4D STIC were highly correlated (R2 > 0.90). The mean percentage error was better (<6%) for volumes exceeding 4 mL and was as low as 0.3% for 6-mL estimations. Measurements in the diastolic phase were the most accurate, followed by mass estimations equivalent to chamber walls. There was a wider range of percentage error in the lowest volumes tested (2.5 mL), which might have arisen from difficulties in spatial resolution or distortions from within the model apparatus itself. Resolution limitations of 4D technology in combination with extremely small volume targets may explain higher error rates at these small volumes. CONCLUSIONS: Four-dimensional STIC is an acceptably accurate method for volume and mass estimations in the ranges comparable with mid- and late-gestation fetal hearts. It is particularly accurate for diastolic estimations, for chamber wall mass measurements, and at volumes of greater than 2.5 mL. This study validates use of 4D STIC technology to overcome the limitations of nongated 3D technology for phasic and quantitative assessments in fetal echocardiography.     

Four-dimensional sonography with B-flow imaging and spatiotemporal image correlation for visualization of the fetal heart

PURPOSE: To use B-flow imaging with 4-dimensional (4D) sonography and spatiotemporal image correlation (STIC) in the evaluation of normal fetal heart and congenital heart disease during pregnancy. METHOD: Volume data sets of the fetal heart were acquired with automated transverse and longitudinal sweeps of the anterior chest wall. We studied 13 normal fetuses and 2 fetuses with congenital heart disease (1 double-outlet right ventricle and 1 hypoplastic left heart syndrome) at gestation ages ranging from 13 to 39 weeks using transabdominal 4D B-flow sonography with STIC (4D BF-STIC). RESULTS: 4D BF-STIC demonstrated dynamic angiographic features in both normal and abnormal fetal hearts. 4D BF-STIC images could not be obtained in 2 normal fetuses at 18.1 and 33.1 weeks because of the high fetal heart rate and inappropriate fetal position. In normal fetal heart, characteristic hemodynamic changes in both atria and ventricles were clearly demonstrated in systole and diastole. 4D BF-STIC also allowed visualization of the relationship, size, and course of the outflow tracts, thus helping the examiner to better understand the relationships between the vessels. In a case of hypoplastic left heart syndrome, dramatic hemodynamic changes including the right atrium, right ventricle, and pulmonary artery were evident. In a case of double-outlet right ventricle with ventricular septal defect, left-to-right shunt flow through a ventricular septal defect was clearly shown, as were great arteries originating in parallel from the right ventricle. CONCLUSION: 4D BF-STIC provides a means of real-time 3-dimensional evaluation of fetal intracardiac and extracardiac hemodynamics in the second and third trimesters. This novel technique assists in the evaluation of fetal cardiac hemodynamics and may play an important role in future fetal cardiac research and in the evaluation of congenital heart disease in the fetus.     

A new approach to fetal echocardiography: digital casts of the fetal cardiac chambers and great vessels for detection of congenital heart disease.

OBJECTIVE: The purpose of this study was to describe a method of 4-dimensional (4D) reconstruction of the cardiac chambers and outflow tracts using a combination of spatiotemporal image correlation, "inversion mode," and "B-flow" imaging. METHODS: Spatiotemporal image correlation and the inversion mode were used in the examination of the volume data sets of 23 fetuses with congenital heart anomalies. A subset was also examined with B-flow imaging using the gradient light algorithm. Digital reconstructions from abnormal hearts were compared with a library obtained from fetuses without abnormalities. RESULTS: Rendered images of the 4-chamber view using the inversion mode were characterized by: (1) echogenic chambers; (2) sharp delineation of chamber contours when compared with 2-dimensional (2D) images; and (3) distinct display of the myocardium, interventricular septum, interatrial septum, and mitral and tricuspid valves as anechoic structures. Ventricular septal defects, abnormal differential insertion of the atrioventricular valves, and valve atresia were well visualized with the inversion mode. The application of inversion mode or B-flow imaging to 4D rendering of the outflow tracts resulted in "digital casts" displaying the spatial relationships between the outflow tracts as well as the connections between the great arteries and ventricular chambers. The spatial relationships and communications among cardiac structures cannot be visualized with conventional 2D ultrasonography. CONCLUSIONS: The application of spatiotemporal image correlation, inversion mode, and B-flow imaging generates information about the anatomy and pathologic characteristics of the fetal heart (digital casts) that cannot be obtained with 2D fetal echocardiography. We propose that these modalities enhance the information provided by ultrasonographic interrogation of the fetal heart and will improve prenatal diagnosis.     

A novel algorithm for comprehensive fetal echocardiography using 4-dimensional ultrasonography and tomographic imaging.

OBJECTIVE: Tomographic ultrasound imaging (TUI) is a new display modality that allows simultaneous visualization of up to 8 parallel anatomic planes. This study was designed to determine the role of a novel algorithm combining spatiotemporal image correlation and TUI to visualize standard fetal echocardiographic planes. METHODS: Volume data sets from fetuses with and without congenital heart defects (CHDs) were examined with a novel algorithm that allows simultaneous visualization of the 3-vessel and trachea view, the 4-chamber view, and outflow tracts. Visualization rates for these planes as well as the ductal arch and 5-chamber view were calculated. RESULTS: (1) Two hundred twenty-seven volume data sets from fetuses without (n = 138) and with (n = 14) CHDs were reviewed; (2) among fetuses without CHDs, the 4-chamber view, 5-chamber view, ductal arch, 3-vessel and trachea view, left outflow tract, and short axis of the aorta were visualized in 99% (193/195), 96.9% (189/195), 98.5% (192/195), 88.2% (172/195), 93.3% (182/195), and 87.2% (170/195) of the volume data sets, respectively; (3) these views were visualized in 85% (17/20), 80% (16/20), 65% (13/20), 55% (11/20), 55% (11/20), and 70% (14/20) of the volume data sets, respectively, from fetuses with CHDs; and (4) simultaneous visualization of the short axis of the aorta, 3-vessel and trachea view, left outflow tract, and 4-chamber view was obtained in 78% (152/195) of the volume data sets from fetuses without CHDs and in 40% (8/20) of those with CHDs. CONCLUSIONS: The 3-vessel and trachea view, the 4-chamber view, and both outflow tracts can be simultaneously visualized using a novel algorithm combining spatiotemporal image correlation and TUI.     

A systematic approach to the use of the multiplanar display in evaluation of abnormal vascular connections to the fetal heart using 4-dimensional ultrasonography.

OBJECTIVE: The multiplanar display is a modality that allows the simultaneous visualization of 3 orthogonal planes from volume data sets obtained with 3- and 4-dimensional ultrasonography. Simultaneous display of standard views used in fetal echocardiography and their orthogonal planes may provide novel ultrasonographic views for examination of the fetal heart and its vascular connections. This study was designed to determine the clinical utility of the multiplanar display in the examination of abnormal vascular connections to the fetal heart. METHODS: We reviewed 4-dimensional volume data sets, acquired with the spatiotemporal image correlation technique, from patients with abnormal vascular connections to the fetal heart. Multiplanar views of the fetal heart were used to simultaneously display standard planes used in fetal echocardiography and their corresponding orthogonal planes. RESULTS: This study included 4 volume data sets from fetuses with confirmed abnormal vascular connections to the heart, including: (1) an interrupted inferior vena cava with azygos or hemiazygos vein continuation; (2) a persistent left superior vena cava draining into a dilated coronary sinus; and (3) a dilated superior vena cava associated with a thoracic lymphangioma. Simultaneous visualization of orthogonal planes displaying abnormal vascular connections to the fetal heart facilitated identification of the abnormal vessels and their spatial relationships with other vascular structures. CONCLUSIONS: Multiplanar imaging can be used to assess abnormal vascular connections to the fetal heart and may provide novel ultrasonographic planes for fetal echocardiography using 3- and 4-dimensional ultrasonography.     

The role of the sagittal view of the ductal arch in identification of fetuses with conotruncal anomalies using 4-dimensional ultrasonography.

OBJECTIVE: Conotruncal anomalies represent one fifth of all congenital heart defects (CHDs) detected in the fetus. However, the spatial relationship of the great vessels is incorrectly defined in about 20% of these cases. The sagittal view of the ductal arch is considered a standard ultrasonographic view in fetal echocardiography and can be easily visualized using 4-dimensional (4D) ultrasonography. This study was designed to determine the role of this ultrasonographic plane for the prenatal diagnosis of conotruncal anomalies. METHODS: We reviewed 4D volume data sets, acquired with the spatiotemporal image correlation technique, from fetuses with and without confirmed conotruncal anomalies. The visualization rate of the sagittal view of the ductal arch was compared among groups using standardized multiplanar views. RESULTS: This study included 183 volume data sets from fetuses in the following groups: (1) normal echocardiographic findings (n = 130); (2) conotruncal anomalies (n = 18); and (3) other CHDs (n = 35). Volumes of poor image quality were excluded from analysis (8.2% [15/183]). The visualization rate of the sagittal view of the ductal arch was significantly lower in fetuses with conotruncal anomalies (5.6% [1/18]) than that in fetuses without abnormalities (93.1% [108/116]) and that in fetuses with other CHDs (79.4% [27/34]; P < .01). Absence of visualization of the sagittal view of the ductal arch was associated with a likelihood ratio of 9.44 (95% confidence interval, 5.8-15.5) to have conotruncal anomalies. CONCLUSIONS: The sagittal view of the ductal arch may play an important role in the screening and prenatal diagnosis of conotruncal anomalies in 4D ultrasonography.     

时间空间相关成像联合5D Heart智能导航技术用于正常胎儿心脏超声筛查

目的 评估时间空间相关成像（STIC）联合5D Heart智能导航技术在正常胎儿心脏超声筛查中的应用价值。方法 由医师甲采用常规二维超声和STIC联合5D Heart智能导航技术对114胎正常胎儿进行心脏超声筛查,记录2种检查方法采集图像所用时间,并对相同的9个切面进行评分;1周后,医师甲再次、医师乙首次对STIC联合5D Heart智能导航技术的图像质量进行评分。比较2种检查方法对各切面显示合格率,分析同一医师和不同医师间图像质量评分的一致性。结果 2胎因胎动明显无法确定智能导航点位置而被排除。胎儿心脏容积图像和常规二维超声图像的采集时间分别为（94.76±35.21）s和（595.88±139.29）s,差异有统计学意义（P<0.001）。STIC联合5D Heart智能导航技术与常规二维超声对胎儿四腔心、五腔心、右心室流出道、三血管气管、主动脉弓、动脉导管弓切面的显示合格率差异无统计学意义（P均>0.05）;STIC联合5D Heart智能导航技术对胃泡水平腹部横切面、左心室流出道切面的显示合格率低于常规二维超声检查（P均<0.05）。不同医师间（除三血管气管和主动脉弓切面）及同一医师不同时间（除主动脉弓切面）对容积数据进行分析后各切面的评分一致性好（Kappa均>0.75）。结论 STIC联合5D Heart智能导航技术可缩短检查时间;9个胎儿心脏切面图像质量能够满足胎儿心脏超声筛查需要,用于正常胎儿心脏超声筛查的可行性和可重复性均好。     

Role of tomographic ultrasound imaging with spatiotemporal image correlation for identifying fetal ventricular septal defects

OBJECTIVE: The purpose of this study was to test the possibility of diagnosing ventricular septal defects (VSDs) by using tomographic ultrasound imaging (TUI) on 4-dimensional volumes of the fetal chest obtained with spatiotemporal image correlation and the color Doppler function. METHODS: We retrospectively evaluated the 4-dimensional spatiotemporal image correlation volumes of 8 fetuses with VSDs (single in 7 and double in 1) between 20 and 33 weeks' gestation. The data were analyzed to determine whether VSDs were correctly identified in at least 1 of 7 automatically generated TUI displays. RESULTS: All of the included VSDs were correctly identified with the use of an interslice distance in the TUI function ranging from 0.8 to 2 mm without the need to further manipulate the volume. CONCLUSIONS: This automatic approach shows good retrieval of diagnostic cardiac planes in fetuses with VSDs, which may improve the diagnostic accuracy for this disease.     

Real-time 3-dimensional fetal echocardiography with an instantaneous volume-rendered display: early description and pictorial essay.

OBJECTIVE: Random fetal motion, rapid fetal heart rates, and cumbersome processing algorithms have limited reconstructive approaches to 3-dimensional fetal cardiac imaging. Given the recent development of real-time, instantaneous volume-rendered sonographic displays of volume data, we sought to apply this technology to fetal cardiac imaging. METHODS: We obtained 1 to 6 volume data sets on each of 30 fetal hearts referred for formal fetal echocardiography. Each volume data set was acquired over 2 to 8 seconds and stored on the system's hard drive. Rendered images were subsequently processed to optimize translucency, smoothing, and orientation and cropped to reveal "surgeon's eye views" of clinically relevant anatomic structures. Qualitative comparison was made with conventional fetal echocardiography for each subject. RESULTS: Volume-rendered displays identified all major abnormalities but failed to identify small ventricular septal defects in 2 patients. Important planes and views not visualized during the actual scans were generated with minimal processing of rendered image displays. Volume-rendered displays tended to have slightly inferior image quality compared with conventional 2-dimensional images. CONCLUSIONS: Real-time 3-dimensional echocardiography with instantaneous volume-rendered displays of the fetal heart represents a new approach to fetal cardiac imaging with tremendous clinical potential.     

Role of Sonographic Automatic Volume Calculation in Measuring Fetal Cardiac Ventricular Volumes Using 4‐Dimensional Sonography

Objective. The purpose of this study was to compare the agreement and reliability of virtual organ computer‐aided analysis (VOCAL) and sonographic automatic volume calculation (sonoAVC) for measurements of ventricular volume from fetal heart data sets acquired by 4‐dimensional sonography with spatiotemporal image correlation (STIC). Methods. We studied 45 volumes from fetuses with normal (n = 30) and abnormal (n = 15) hearts. Spatiotemporal image correlation data sets were frozen in end systole and end diastole, and ventricular volumes were measured with VOCAL and sonoAVC. The stroke volume was calculated from these measurements. Reliability and agreement of the two techniques were evaluated with intraclass correlation coefficients (ICCs), and proportionate Bland‐Altman plots were constructed. The time necessary to complete the measurements with either technique was compared. Intraobserver and interobserver agreement of measurements was calculated. Results. All data sets could be measured with both techniques. A high degree of reliability was observed between VOCAL and sonoAVC (left ventricular stroke volume ICC, 0.978; 95% confidence interval [CI], 0.957–0.989; right ventricular stroke volume ICC, 0.985; 95% CI, 0.972–0.992). The time necessary to measure the stroke volume was significantly shorter with sonoAVC (2.8 versus 11.7 minutes; P < .0001) than with VOCAL. Bland‐Altman tests showed no clinically significant mean percent differences between stroke volume measurements obtained from each ventricle by the same observer or by 2 independent observers using either VOCAL or sonoAVC. Conclusions. There was good agreement between cardiac volumes measured with VOCAL and sonoAVC. Sonographic automatic volume calculation represents a rapid technique for estimating fetal stroke volume and promises to become the method of choice.     

First-trimester diagnosis of conjoined twins aided by spatiotemporal image correlation

A case of conjoined twins after frozen embryo transfer at early blastocyst stage is described. The diagnosis was made early at 7 weeks by vaginal sonography and later confirmed by spatiotemporal image correlation with power Doppler. The value of spatiotemporal image correlation with Doppler in facilitating an early diagnosis of conjoined twinning is discussed.     

应用空间-时间成像相关技术行胎儿心脏产前筛查的可行性探讨

目的探讨空间-时间成像相关（STIC）技术在临床胎儿心脏产前筛奄应用及推广的可行性。方法对2007年11月至2008年12月在我院行超声心动图检查的心脏畸形高危胎儿214例（经二维心脏超声检查诊断为正常胎儿心脏）,尽最在无胎动时扶取有效的STIC容积数据,应用Uittenbogaard等提出的获取条件评分方法加以改良后进行STIC容积数据采集评分,最高分为10分,6分以t（含6分）为成功获得,6分以下为未成功获得。根据是否能清晰显示心脏各部分结构将所有成功获得的STIC容积信息被分为临床不可用、临床可用和临床最佳。结果根据STIC容积采集评分标准,采集的胎儿心脏容积信息评分结果为149例（69．6％）成功获得容积数据,65例（30．4％）朱成功获得;影响成功率因素中,胎动因素最常见;将研究的前半年和后半年两个时间段的成功率进行比较,后半年的成功获得率明显提高（P〈0．05）。对采集的胎儿心脏容积信息进行临床效果评价,临床效果最佳为27例（12．6％）,临床可用为139例（65．0％）,临床不吖用为48例（22．4％）;将研究的前半年和后半年两个时间段的临床价值评价结果进行比较,后半年的临床效果最伟率和临床可用牢明显提高（P〈0．05）。结论STIC技术在临床实践中获取临床最佳效果率较低,限制了其在临床上的广泛应用和推广。增加对STIC技术采集和应用的熟练程度和技巧则会明显改善信息采集的成功率和质量。     

Spatiotemporal image correlation artifacts in an in vitro model

An experimental in vitro setting with a latex miniature balloon was designed to test the accuracy of volumetric measurements by spatiotemporal image correlation. Two-dimensional images clearly showed the round balloon as a thin echogenic ring in a translucent area. Four-dimensional reconstructed images, however, showed a severely distorted balloon. The artifacts disappeared when the surroundings of the balloons were made echogenic, mimicking the in vivo setting. We hypothesize that the artifacts were the result of gating errors. These experiments can be relevant for analysis of spatiotemporal image correlation volumes in daily practice.     

高分辨率血流成像联合时间-空间关联成像评估胎儿静脉系统异常研究进展

胎儿静脉系统变异种类较多,且易伴发复杂心血管畸形;产前超声针对胎儿静脉系统进行检查具有重要意义。高分辨率血流成像(HD-Flow)联合时间-空间关联成像(STIC)不仅能显示胎儿静脉系统微细血流,还可实时显示其空间走行和血流方向。本文就HD-Flow联合STIC评估胎儿静脉系统异常的研究进展进行综述。     

Application of automated sonography on 4-dimensional volumes of fetuses with transposition of the great arteries

OBJECTIVE: The purpose of this study was to assess, in second-trimester fetuses with transposition of the great arteries (TGA), the performance of software (sonographically based volume computer-aided analysis) that automatically retrieves diagnostic cardiac planes from a 4-dimensional volume of the fetal chest obtained with spatiotemporal image correlation. METHODS: We retrospectively evaluated the 4-dimensional spatiotemporal image correlation volumes of 12 fetuses with TGA (complete TGA, 10 cases; correct TGA, 2 cases). The data were analyzed to determine whether the target diagnostic planes, that is, cardiac plane 1 (left ventricle outflow tract) and cardiac plane 2 (right ventricle outflow tract), were correctly identified in at least 1 of the 7 automatically generated tomographic sonographic image displays and whether they allowed diagnosis of TGA. RESULTS: In 9 of 10 fetuses with complete TGA, target diagnostic cardiac plane 1 showed a branching arterial vessel (pulmonary artery) arising from the left ventricle, whereas in 7 of 10 fetuses, the aorta arising from the right ventricle was shown. In both cases with correct TGA, the pulmonary artery starting from the morphologic left ventricle was shown, whereas in 1 of 2, the connection of the aorta with the morphologic right ventricle was found. In all of the fetuses with TGA, a ventricular arterial connection anomaly was shown in either cardiac plane 1 or 2. CONCLUSIONS: This automatic approach shows good retrieval of diagnostic cardiac planes in fetuses with TGA, which may improve diagnostic efficacy for this disease.