Comparison of ventricular volume and mass measurements from B- and C-scan images with the use of real-time 3-dimensional echocardiography: studies in an in vitro model

Elevational spatial compounding for enhancing image quality in echocardiography

INTRODUCTION

Echocardiography is commonly used in clinical practice for the real-time assessment of cardiac morphology and function. Nevertheless, due to the nature of the data acquisition, cardiac ultrasound images are often corrupted by a range of acoustic artefacts, including acoustic noise, speckle and shadowing. Spatial compounding techniques have long been recognised for their ability to suppress common ultrasound artefacts, enhancing the imaged cardiac structures. However, they require extended acquisition times as well as accurate spatio-temporal alignment of the compounded data. Elevational spatial compounding acquires and compounds adjacent partially decorrelated planes of the same cardiac structure.

METHODS

This paper employs an anthropomorphic left ventricle phantom to examine the effect of acquisition parameters, such as inter-slice angular displacement and 3D sector angular range, on the elevational spatial compounding of cardiac ultrasound data.

RESULTS AND CONCLUSION

Elevational spatial compounding can produce substantial noise and speckle suppression as well as visual enhancement of tissue structures even for small acquisition sector widths (2.5° to 6.5°). In addition, elevational spatial compounding eliminates the need for extended acquisition times as well as the need for temporal alignment of the compounded datasets. However, moderate spatial registration may still be required to reduce any tissue/chamber blurring side effects that may be introduced.

Fetal heart ventricular mass obtained by STIC acquisition combined with inversion mode and VOCAL

OBJECTIVE

Estimation of fetal heart ventricular mass is important for fetal cardiac evaluation in cases of structural or functional cardiac disorders or extracardiac factors. It may be used with other cardiac parameters to ascertain the severity and prognosis of such disorders, or the nature and timing of intervention. We applied a novel technique combining spatiotemporal image correlation (STIC) with three-dimensional inversion mode and Virtual Organ Computer-aided AnaLysis (VOCAL™) for fetal cardiac mass assessment in healthy fetuses in the second and third trimesters.

METHODS

STIC acquisition was performed during fetal quiescence with the abdomen uppermost, at an angle of 30-50°, without color Doppler mapping. Myocardial volume measurements were performed in postprocessing using VOCAL mode, set to 15°. Beginning with the heart in four-chamber view at end diastole, a trace was drawn manually including the myocardium and interventricular septum. Inversion mode colors the intraventricular (anechoic, fluid-filled) voxels; this intraventricular volume was subtracted automatically from the total. Mass was determined by multiplying the result by the estimated fetal myocardial density (1.050 g/cm(3) ). The process was repeated for right and left ventricles.

RESULTS

Data from 106 fetuses at 21-38 weeks' gestation were obtained and scatterplots of fetal cardiac ventricular mass distribution were created. Several cases of fetuses with disordered cardiac ventricle (supraventricular tachycardia, hypoplastic left heart syndrome, dilated cardiomyopathy, twin-to-twin transfusion syndrome, Ebstein anomaly, non-immune hydrops fetalis, septate right atrium and diaphragmatic hernia) were examined. Ventricular mass parameters were markedly affected as compared with normal cases of similar gestational age.

CONCLUSIONS

STIC acquisition combined with inversion mode and VOCAL is a feasible method of cardiac ventricular mass quantification. This methodology may have added value in fetal cardiac evaluation in cases of anatomic malformation or cardiac dysfunction, or in cases of maternal diabetes.

Rapid and accurate quantification of right ventricular volume and stroke volume by real-time 3-dimensional triplane echocardiography

BACKGROUND

Previous studies have demonstrated that 3-Dimensional (3-D) echocardiography can determine right ventricular (RV) volume accurately. However, this technique has not been feasible in everyday clinical practice because of the necessity of time-consuming off-line processes.

HYPOTHESIS

A newly developed real-time 3-D triplane echocardiography, which acquires 3 apical rotational cross-sectional images simultaneously, holds the promise to resolve these problems.

METHODS AND RESULTS

Sixteen excised formalin fixed porcine hearts and 24 healthy human subjects underwent real-time 3-D triplane echocardiography. In an anatomic in vitro study, the actual volume of RV was obtained by spilling water in the RV cavity into a graduated cylinder for measurement, which served as a reference standard for comparison. For healthy subjects, the RV stroke volume (SV) was measured by triplane echocardiography which was compared with the left ventricular (LV) SV obtained by conventional 2-Dimensional echocardiography (2-DE). Excellent correlation and agreement between 3-D triplane imaging derived RV volume and the actual one for excised porcine hearts were observed (r = 0.979, p < 0.001, mean difference 2.2 mL). In healthy human subjects, good correlation and agreement between 3-D triplane imaging derived RV SV and LV SV measured by 2-DE were obtained (r = 0.970, p < 0.001, mean difference 5.9 mL).

CONCLUSIONS

Real-time 3-D triplane echocardiography provides us a new method for rapid and accurate quantification of RV volume. Furthermore, this new method holds the promise for evaluating RV volume and SV in routine clinical practice.

Three-dimensional Echocardiographic Evaluation of Right Ventricular Volume and Function in Pediatric Patients: Validation of the Technique

The right ventricle (RV) is the main ventricular chamber in many congenital heart diseases before and after surgical correction, and it is the most important determinant of outcome in postoperative tetralogy of Fallot and other complex malformations. Unfortunately its irregular crescentic shape does not allow the use of the geometric assumption used for the left ventricle. Many methods have been suggested in the literature to overcome this problem, none fully reliable. The introduction of volume-rendered 3-dimensional (3D) reconstruction of echocardiography images provides a tool for the direct measurement of cardiac chambers, not based on geometric assumptions. The aim of this research study was to determine the accuracy of 3D echocardiography (3DE) to measure RV volumes in pediatric patients with secundum atrial septal defects, compared with direct volume measurements performed during the intervention. We performed 3DE study in the operating department, with the patient anesthetized, intubated, and ventilated before the surgical procedure. Sequential 2-dimensional echocardiographic images for subsequent 3D rendering were acquired using an ultrasound machine with a transthoracic 4-MHz rotational or 5-MHz transesophageal omniplane probe; in the last 5 patients a machine was used that was equipped with a 3600-crystal real-time 3D probe. To validate the 3DE measurements, these were compared with the volume of the RV directly measured in the operating department, at the end of the surgical procedure, injecting saline solution through the tricuspid valve, using a graduate syringe. Among 25 pediatric patients enrolled in the study, with an age range of 1 and 14 years (mean 4 years) and a weight range of 8.5 to 57.4 kg (mean 18.6 kg), in 23 a mean of 3 echocardiographic acquisitions were performed and compared with the direct measurement. A close comparison was found between RV volumes measured by 3DE and direct volume measurements (P < .00001). The regression line, shifted toward the y axis, which describes the 3DE volumes, indicated that the echocardiographic measures overestimate the surgical ones. In our study this overestimation had the mean of 9% with values comprised between 3% and 19%. The coefficient of repeatability was 4.79 mL with all the values within this range (2 SD of the mean). We conclude that 3DE provides an accurate measurement of RV volume in pediatric patients with RV volume overload. It is a reliable, noninvasive, and nongeometric method of evaluation of the volume of this chamber, and can be considered a precious tool in the armamentarium of the pediatric cardiologist.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Volume measurement of a pediatric ventricular phantom model using three-dimensional echocardiography

PURPOSE

Volume measurement of the ventricle is necessary to evaluate cardiac function. Accurate volume measurement of the ventricle by three-dimensional (3D) echocardiography will mark a new step in pediatric cardiovascular diagnosis and treatment. We studied volume measurement of a pediatric ventricular model using 3D echocardiography.

METHODS

The ultrasonic diagnostic setup used in this study comprised a Philips Sonos 7500 ultrasound system with an electronic sector probe of a ×4 matrix phased array transducer. The ventricular model was made from a latex surgical glove. The tip of the third finger of the glove was cut off and fixed to a manifold. The ventricular model was gently placed in a reservoir filled with water. Volumes of physiological saline solution ranging from 2 ml to 50 ml in 2-ml increments were injected into the ventricular model and examined. Twenty-five ultrasound images of the ventricular model were obtained using 4D Cardio View RT 1.2 software.

RESULTS

There was excellent correlation and agreement between the injected volumes and the calculated volumes (Y = -0.539 + 1.005X, r = 0.997, four cut plane; Y = -0.191 + 1.006X, r = 0.997, eight cut plane). Thus, accurate volume measurement of the ventricular model by 3D echocardiography was confirmed.

CONCLUSIONS

Our study demonstrated that 3D echocardiography is highly accurate for volume measurement in a pediatric ventricular model (for volumes of 2 to 50 ml) under static conditions.

Real-time 3-Dimensional Doppler Echocardiography for the Assessment of Stroke Volume: An In Vivo Human Study Compared with Standard 2-Dimensional Echocardiography

BACKGROUND

Invasive monitors and noninvasive 2-dimensional echocardiography are the standard clinical methods for stroke volume (SV) and cardiac output computation. We studied the use of real-time color Doppler 3-dimensional (3D) echocardiography (3DE) for the assessment of SV in human beings.

METHODS

In all, 55 pediatric and adult patients with good transthoracic windows and a normal aortic valve were studied. Real-time 3DE color Doppler volumes incorporating the left ventricular outflow tract and aortic valve were taken. SV was calculated from the color Doppler data in the 3DE DICOM dataset. This was compared with 2-dimensional echocardiography SV calculation from the pulsed wave velocity through the aortic valve along with the left ventricular outflow tract diameter.

RESULTS

Five patients were excluded because of mismatching of the 3D color Doppler segments in the 3D volume. The 3D Doppler volumes from the remaining 50 patients were analyzed. There was good correlation between the patients' averaged 3DE SV calculations and the 2-dimensional echocardiography pulsed wave SV estimation (y = 0.84x + 7.8, r2 = 0.90).

CONCLUSION

Real-time 3D Doppler echocardiography can be used to accurately calculate SV and cardiac output, compared with conventional pulsed Doppler measurement, in pediatric and adult patients from transthoracic imaging.

The Accuracy of Left Ventricular Mass Determined by Real-time Three-dimensional Echocardiography in Chronic Animal and Clinical Studies: A Comparison with Postmortem Examination and Magnetic Resonance Imaging

Real-time 3-dimensional echocardiography (RT3DE), 2-dimensional echocardiography (2DE), and M-mode echocardiography were performed in 28 sheep with cardiac pathologies and 27 patients with heart disease to demonstrate the superiority of RT3DE over M-mode and 2DE for the determination of left ventricular mass. Postmortem examination and magnetic resonance imaging were used as a reference standard for the animal and clinical studies, respectively. In the animal study, the highest concordance correlation (0.92) was obtained between the actual weight of left ventricular mass and that estimated by RT3DE (0.69 for 2DE and 0.77 for M-mode, P < .001). In the clinical study, RT3DE also provided the best concordance correlation with left ventricular mass determined by magnetic resonance imaging (0.91 for RT3DE, 0.83 for 2DE, and 0.38 for M-mode; P < .0001).

Rapid full volume data acquisition by real-time 3-dimensional echocardiography for assessment of left ventricular indexes in children: A validation study compared with magnetic resonance imaging

OBJECTIVE

We sought to assess the feasibility, accuracy, and reproducibility of a rapid full volume acquisition strategy using real-time (RT) 3-dimensional (3D) echocardiography (3DE) for measurement of left ventricular (LV) volumes, mass, stroke volume (SV), and ejection fraction (EF) in children.

METHODS

A total of 19 healthy children (mean 10.6 +/- 2.8 years, 11 male and 9 female) were prospectively enrolled in this study. RT 3DE was performed using an ultrasound system to acquire full volume 3D dataset from the apical window with electrocardiographic triggering in 8 s/dataset. The images were processed offline using software. The LV endocardial and epicardial borders were traced manually to derive LV end-systolic volume, end-diastolic volume, mass, SV, and EF. Magnetic resonance imaging (MRI) studies were performed on a 1.5-T scanner using a breath hold 2-dimensional cine-FIESTA (fast imaging employing steady-state acquisition) sequence.

RESULTS

All RT 3DE and MRI data were acquired successfully for analysis. Measurements of LV end-systolic volume, end-diastolic volume, mass, SV, and EF by RT 3DE correlated well by Pearson regression ( r = 0.86-0.97, P < .001) and agreed well by Bland-Altman analysis with MRI. The interobserver and intraobserver variability of RT 3DE measurements were less than 5%.

CONCLUSIONS

This prospective study demonstrated that RT 3DE measurements of LV end-systolic volume, end-diastolic volume, mass, SV, and EF in children using rapid full volume acquisition strategy are feasible, accurate, and reproducible and are comparable with MRI measurements.

The use of live three-dimensional Doppler echocardiography in the measurement of cardiac output

OBJECTIVES

The purpose of this study was to investigate whether cardiac output (CO) could be accurately computed from live three-dimensional (3-D) Doppler echocardiographic data in an acute open-chested animal preparation.

BACKGROUND

The accurate measurement of CO is important in both patient management and research. Current methods use invasive pulmonary artery catheters or two-dimensional (2-D) echocardiography or esophageal aortic Doppler measures, with the inherent risks and inaccuracies of these techniques.

METHODS

Seventeen juvenile, open-chested pigs were studied before undergoing a separate cardiopulmonary bypass procedure. Live 3-D Doppler echocardiography images of the left ventricular outflow tract and aortic valve were obtained by epicardial scanning, using a Philips Medical Systems (Andover, Massachusetts) Sonos 7500 Live 3-D Echo system with a 2.5-MHz probe. Simultaneous CO measurements were obtained from an ultrasonic flow probe placed around the aortic root. Subsequent offline processing using custom software computed the CO from the digital 3-D Doppler DICOM data, and this was compared to the gold standard of the aortic flow probe measurements.

RESULTS

One hundred forty-three individual CO measurements were taken from 16 pigs, one being excluded because of severe aortic regurgitation. There was good correlation between the 3-D Doppler and flow probe methods of CO measurement (y = 1.1x - 9.82, R(2) = 0.93).

CONCLUSIONS

In this acute animal preparation, live 3-D Doppler echocardiographic data allowed for accurate assessment of CO as compared to the ultrasonic flow probe measurement.

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.

Real-time 3-dimensional echocardiography for quantification of the difference in left ventricular versus right ventricular stroke volume in a chronic animal model study: Improved results using C-scans for quantifying aortic regurgitation

OBJECTIVE

The purpose of our study was to test the applicability of calculating the difference between left ventricular (LV) and right ventricular (RV) stroke volume (SV) for assessing the severity of aortic (Ao) regurgitation (AR) using a real-time 3-dimensional (3D) echocardiographic (RT3DE) imaging system.

METHODS

The Ao valve was incised in 5 juvenile sheep, 6 to 10 weeks before the study, to produce AR (mean regurgitant fraction = 0.50). Simultaneous hemodynamic and RT3DE images were obtained on open-chest animals with Ao and pulmonary flows derived by Ao and pulmonary electromagnetic flowmeters balanced against each other. Four stages (baseline, volume loading, sodium nitroprusside, and angiotensin infusion) were used to produce a total of 16 different hemodynamic states. Epicardial scanning was done with a 2.5-MHz probe to sequentially record first the RV and then the LV cavities. Cavity volumes from the 3D echocardiography data were determined from angled sector planes (B-scans) and parallel cutting planes (C-scans, which are planes perpendicular to the direction of the volume interrogation). AR volumes were determined from 3D images by computing and then subtracting RV SVs from LV SVs and then these were compared with electromagnetic flowmeter-derived SV and regurgitant volumes.

RESULTS

There was close correlation between RV and LV SVs of the RT3DE and electromagnetic methods (C-scans: LV, r = 0.98, standard error of the estimate [SEE] = 2.62 mL, P =.0001; RV, r = 0.89, SEE = 2.67 mL, P <.0001; and B-scans: LV, r = 0.95, SEE = 3.55 mL, P =.0001; RV, r = 0.77, SEE = 2.78 mL, P =.0003). Because of the small size of the RV in this model, the correlation was closer for C-scans than B-scans for RV SV. AR volume estimation also showed that C-scan (r = 0.93, SEE = 4.23 mL, P <.0001) had closer correlation than B-scan (r = 0.89, SEE = 4.87 mL, P <.0001). However, B-scan-derived AR fraction showed closer correlation than did C-scan (r = 0.82 vs r = 0.85, respectively).

CONCLUSION

In this animal model, RT3DE imaging had the ability to reliably quantify both LV (B- and C-scans) and RV SVs and to assess the severity of AR.

Determination of Asymmetric Cavity Volumes Using Real-Time Three-Dimensional Echocardiography: An In Vitro Balloon Model Study

OBJECTIVES

We designed a new in vitro model to test the accuracy and reproducibility of real-time three-dimensional (RT3D) ultrasound imaging for determining a variety of asymmetric cavity volumes with aneurysm.

METHODS

Fifteen individual balloon models mimicking ventricular aneurysm were filled with water (170-322.5 ml) without air bubbles and kept in a compressor pump. Compression of the models produced only a change in shape of the balloon and no change in volume. The models were scanned with RT3D echocardiography (RT3DE) and the images recorded on an optical disk. Volumes were measured off line in two phases; maximal compression, where there was maximal change in shape and nil compression, where there was minimal or no change in shape. Volumes were measured by manual tracing technique of the inner border of B-scan images and compared with the drained volume of water from the balloon.

RESULTS

There was a high correlation between the drained volume and measured volume at maximal compression (equivalent to end-systole, r = 0.99, y = 0.99x + 3.69, SEE = 6.5 ml), between the drained volume and measured volume at nil compression (equivalent to end-diastole, r = 0.99, y = 0.94x + 12.07, SEE = 5.9 ml), and between volumes measured at maximal and nil compressions (r = 0.99, y = 0.94x + 10.55, SEE = 4.6 ml).

CONCLUSION

The results of this experiment show that RT3DE can accurately measure the volumes of a variety of asymmetric ventricular cavities.

Validation of a volumic reconstruction in 4-d echocardiography and gated SPECT using a dynamic cardiac phantom

A dynamic cardiac phantom was used as a reference to compare the volumes reconstructed with 4-D echocardiography and gated single-photon emission computed tomography (SPECT). 4-D echocardiography used a new prototype of rotating scan head to acquire ultrasound (US) images during a cardiac cycle, associated with a new protocol (left ventricular 4-D or LV 4-D) to reconstruct the volume deformations of the heart as a function of time. Gated SPECT data were acquired with a standard single-head gamma camera, and the reconstructions were carried out using the Mirage software released by Segami. The influences of different LV 4-D parameters were tested and analyzed. End-diastolic volume, end-systolic volume, and ejection fraction were measured using both LV 4-D and gated SPECT. Results obtained showed a straight correlation between the two examinations. The agreement confirmed the relevance of the comparisons. This study is an initial step before conducting clinical trials to exhaustively compare the two modalities.

Accuracy of real-time three-dimensional echocardiography for quantifying right ventricular volume: static and pulsatile flow studies in an anatomic in vitro model

OBJECTIVE

The complex structural geometry of the right ventricle hinders accurate assessment of right ventricular volume and function on conventional two-dimensional echocardiography. We sought to evaluate the accuracy of real-time three-dimensional echocardiography for quantifying the volume of the right ventricle in an in vitro experimental study.

METHODS

We developed 39 anatomically accurate latex phantoms of human and porcine right ventricles (range, 24-108 mL) for 39 static and 10 pulsatile models. Real-time three-dimensional scanning was performed with the models placed in a water bath and with a 3.5-MHz probe. In the dynamic models a pulsatile flow pump generated 2 different stroke volumes (29 and 64 mL/beat). Static chamber volumes and stroke volumes were verified by water displacement, which served as a reference standard. Three-dimensional echo right ventricle volumes were determined by tracing derived B- and C-scans, using the Simpson rule.

RESULTS

Multiple regression analyses showed an excellent correlation between real-time three-dimensional echocardiographic determinations and the static volumes (B-scan, r = 0.99; C-scan, r = 0.98; P < .001), as well as stroke volumes in the dynamic model (B-scan, r = 0.90; C-scan, r = 0.86; P < .001). However, the C-scans tended to underestimate cavity and stroke volumes more than the B-scans (mean difference for static volume: B-scan, 1.4% +/- 9.8%; C-scan, -7.4% +/- 8.0%; P < .001; mean difference for stroke volumes: B-scan, 3.0% +/- 19.1%; C-scan, -2.5% +/- 20.9%; P < .001).

CONCLUSIONS

Real-time three-dimensional echocardiography can accurately quantify right ventricle cavity volumes and stroke volumes without geometric assumptions.