Transthoracic three-dimensional echocardiographic reconstruction of left and right ventricles: in vitro validation and comparison with magnetic resonance imaging

The association of Pulmonary Hypertension and right ventricular systolic function - updates in diagnosis and treatment

Right ventricular (RV) systolic function is an essential but neglected component in cardiac evaluation, and its importance to the contribution to overall cardiac function is undermined. It is not only sensitive to the effect of left heart valve disease but is also more sensitive to changes in pressure overload than the left ventricle. Pulmonary Hypertension is the common and well-recognized complication of RV systolic dysfunction. It is also the leading cause of pulmonary valve disease and right ventricular dysfunction. Patients with a high pulmonary artery pressure (PAP) and a low RV ejection fraction have a seven-fold higher risk of death than heart failure patients with a normal PAP and RV ejection fraction. Furthermore, it is an independent predictor of survival in these patients. In this review, we examine the association of right ventricular systolic function with Pulmonary Hypertension by focusing on various pathological and clinical manifestations while assessing their impact. We also explore new 2022 ESC/ERS guidelines for diagnosing and treating right ventricular dysfunction in Pulmonary Hypertension.

Comparison of Right Ventricular Function Between Three-Dimensional Transesophageal Echocardiography and Pulmonary Artery Catheter

OBJECTIVE

This study aimed to compare measurements of right ventricular function using three-dimensional transesophageal echocardiography (3D TEE), and pulmonary artery catheters (PACs) in patients undergoing cardiac surgery. The authors examined the practicality of using the 3D TEE.

DESIGN

Prospective observational.

SETTING

Cardiac operating room at a single university hospital.

PARTICIPANTS

All adult patients undergoing elective cardiac surgery at a single tertiary care university hospital over two years.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Right ventricular end-diastolic volume (RVEDV), right ventricular end-systolic volume (RVESV), stroke volume (SV), and right ventricular ejection fraction (RVEF) were measured with both 3D TEE and PACs. Assessments were performed using correlation coefficients, paired t tests, and Bland-Altman plots. Thirty-one patients participated in this study. Each measurement showed good agreement. RVEDV and RVESV were slightly lower on 3D TEE than on PAC (205.9 mL v 220.2 mL, p = 0.0018; 143.0 mL v 155.5 mL, p = 0.0143, respectively), whereas no significant differences were observed for SV and RVEF (31.0% v 31.1%, p = 0.0569; 61.6 mL v 66.9 mL, p = 0.92, respectively). Linear regression analysis showed high correlation between 3D TEE and PAC for RVEDV (r = 0.87) and RVESV (r = 0.81), and moderate correlation for SV (r = 0.67) and RVEF (r = 0.67). In the Bland-Altman plot, most patients were within the 95% limits of the agreement throughout all measurements.

CONCLUSION

A high correlation was found between measurements made with a PAC and with 3D TEE in the assessment of right ventricular function. Three-dimensional TEE would be a potential alternative to PAC for assessment of right ventricular function during intraoperative periods.

CT quantification of ventricular volumetric parameters based on semiautomatic 3D threshold-based segmentation in porcine heart and children with tetralogy of Fallot: accuracy and feasibility

Background

To investigate the accuracy and feasibility of CT in quantification of ventricular volume based on semiautomatic three-dimensional (3D) threshold-based segmentation in porcine heart and children with tetralogy of Fallot (TOF).

Methods

Eight porcine hearts were used in the study. The atria were resected and both ventricles of the eight porcine hearts were filled with solidifiable silica gel and performed CT scanning. The water displacement volume of silica gel casting mould was referred as gold standard of ventricular volume. Results of left and right ventricular volumes measured by CT were compared with reference standard. Twenty-three children diagnosed with TOF were retrospectively included. The ventricular volumetric parameters were assessed by cardiac CT before and 6 months after surgery.

Results

Left ventricular and right ventricular volumes of porcine hearts measured by CT were highly correlated to casting mould (r=0.845, p=0.008; r=0.933, p=0.001), and there were no statistically significant differences (t=−1.059, p=0.325; t=−1.121, p=0.299). In children with TOF, right ventricular end-systole volumes 6 months after operation were higher than that before surgery, 21.93±4.44 vs 19.80±4.52 mL/m2, p=0.001. Right ventricular ejection fractions 6 months after surgery were lower compared with that before surgery 59.79%±4.26% vs 63.05%±5.04%, p=0.000.

Conclusions

CT is able to accurately assess ventricular volumetric parameters based on semiautomatic 3D threshold-based segmentation. Both of the right and left ventricular volumetric parameters could be evaluated by CT in children with TOF.

Evaluation of Cardiac Magnetic Resonance as a Surrogate in ST-Segment Elevation Myocardial Infarction

Cardiac magnetic resonance imaging is an attractive noninvasive metric and has genuine potential to constitute a reliable surrogate end point in ST-elevation myocardial infarction. However, these measures must be demonstrated as a valid proxy to predict clinical outcome. In conclusion, the current review evaluates the utility of cardiac magnetic resonance as a surrogate measurement of myocardial infarct size, left ventricular function, microvascular obstruction, and myocardial salvage in ST-elevation myocardial infarction exploring the temporal relations specific to each assessment.

Right Ventricular Dimensions and Function: Why do we Need a More Accurate and Quantitative Imaging?

The right ventricle plays an important role in the morbidity and mortality of patients presenting with symptoms and signs of cardiopulmonary disease. This cardiac chamber has a unique crescent shape, which adds complexity to the quantification of its size and function. Until recently, little uniformity in echocardiographic imaging of the right heart existed because of a lack of familiarity with various techniques, and the enormous attention directed towards left heart quantification. Three-dimensional (3D) echocardiography, a major technological breakthrough in the field of cardiovascular imaging, provides several advantages over two-dimensional (2D) imaging in the quantitative evaluations of right ventricle because of its independence from any geometrical assumption. In this review, we focus on the contribution of this new modality to the evaluation of right ventricle.

Comparison of Simpson's method and three-dimensional reconstruction for measurement of right ventricular volume in patients with complete or corrected transposition of the great arteries

The right ventricular (RV) volume is commonly measured from magnetic resonance images using Simpson's method from the stack of short-axis images acquired for analysis of the left ventricle. We compared the RV volume measured using Simpson's method to the RV volume measured using 3-dimensional reconstruction and the piecewise smooth subdivision surface (PSSS) method. We studied 6 normal subjects and 18 patients whose right ventricles carried a systemic pressure load, 1/2 with dexto-transposition of the great arteries repaired with an atrial baffle and 1/2 with levo-transposition of the great arteries. The right ventricle was reconstructed from manually traced borders from the short- and long-axis views using the PSSS method. Simpson's analysis was performed on short-axis views alone. The RV volumes were smaller when analyzed using Simpson's method than using the PSSS method. The underestimation averaged 12 +/- 19 ml (7 +/- 12% of PSSS volume; p <0.001), without a significant difference between the groups. The ejection fraction was similar using both methods in patients with transposition of the great arteries and was overestimated in normal subjects. Image review revealed that the volume underestimation using Simpson's method was more frequently due to difficulty in interpreting the basal short-axis images than the apical images. In conclusion, to obtain accurate analysis of the short-axis views for RV volume measurement, it would be helpful to incorporate information from additional images, such as the long-axis views, to assist in delineating this chamber's complex anatomy.

Right ventricle three-dimensional echography in corrected tetralogy of fallot: accuracy and variability

AIMS

To evaluate right ventricular (RV) volume and ejection fraction (EF) in adult normal subjects and repaired tetralogy of Fallot (ToF) with 3D trans-thoracic echocardiography (3DE) and a semi-automatic border detection algorithm.

METHODS AND RESULTS

Fourteen healthy volunteers and 20 patients with repaired ToF (mean age 31 +/- 14) underwent 3DE and MRI within the same day. Right ventricular end-systolic volume (ESV) and end-diastolic volume (EDV) and EF were measured by two observers using 3DE and compared with MRI measurements. Intra- and interobserver variability of 3DE and agreement between both methods were evaluated using Bland-Altman analysis. Over or underestimation of 3DE in comparison to MRI was assessed using paired t-test. Intra- and interobserver variability of 3DE was excellent with intraclass coefficient of correlation (ICC) ranging from 0.85 to 0.99 and from 0.85 to 0.98, respectively. Three-dimensional echocardiography underestimated ESV and EDV (P < 0.001) but agreement between 3DE and MRI was excellent (ICC = 0.88 and 0.87, respectively). Ejection fraction was 47.7 +/- 7.8 with 3DE and 47.9 +/- 6.7 with MRI, agreement between both methods was good (ICC = 0.72).

CONCLUSION

Three-dimensional echocardiography combined to semi-automated quantification software shows fair agreement with MRI for RV volumes and EF measurement in patients with repaired ToF and adequate intra- and interobserver variability. These results suggest applicability for serial follow-up of patients with right heart congenital disease. However, the accuracy of 3DE echo diminishes with larger RV volumes, in part due to current difficulty to include the entire RV in the imaged sector. Technical progress in transducers beam geometry is likely to address this issue.

Assessment of right ventricular function by real-time three-dimensional echocardiography improves accuracy and decreases interobserver variability compared with conventional two-dimensional views

AIMS

Two-dimensional echocardiographic (2DE) assessment of right ventricular (RV) function is difficult, often resulting in inconsistent RV evaluation. Real-time three-dimensional echocardiography (RT3DE) allows the RV to be viewed in multiple planes, which can potentially improve RV assessment and limit interobserver variability when compared with 2DE.

METHODS AND RESULTS

Twenty-five patients underwent 2DE and RT3DE. Views of 2DE (RV inflow, RV short axis, and apical four-chamber) were compared with RT3DE views by four readers. RT3DE data sets were sliced from anterior-posterior (apical view) and from base to apex (short axis) to obtain six standardized planes. Readers recorded the RV ejection fraction (RVEF) from 2DE and RT3DE images. RVEF recorded by RT3DE (RVEF(3D)) and 2D (RVEF(2D)) were compared with RVEF by disc summation (RVEF(DS)), which was used as a reference. Interobserver variability among readers of RVEF(3D) and RVEF(2D) was then compared. Overall, mean RVEF(DS), RVEF(3D), and RVEF(2D) were 37 +/- 11%, 38 +/- 10%, 41 +/- 10%, respectively. The mean difference of RVEF(3D)-RVEF(DS) was significantly less than RVEF(2D)-RVEF(DS) (3.7 +/- 4% vs. 7.1 +/- 5%, P = 0.0066, F-test). RVEF(3D) correlated better with RVEF(DS) (r = 0.875 vs. r = 0.69, P = 0.028, t-test). RVEF(3D) was associated with a 39% decrease in interobserver variability when compared with RVEF(2D) [standard deviation of mean difference: 3.7 vs. 5.1, (RT3DE vs. 2DE), P = 0.018, t-test].

CONCLUSIONS

RT3DE provides improved accuracy of RV function assessment and decreases interobserver variability when compared with 2D views.

Accuracy of three-dimensional echocardiography in patients with prior anteroseptal myocardial infarction

BACKGROUND

Echocardiography is the most feasible modality for monitoring cardiac volume and function. However, conventional two-dimensional echocardiography (2DE) is frequently not accurate in measuring cardiac performance in cases of abnormal left ventricular wall motion, because of the geometric assumptions. Quantitative gated scintigraphy and magnetic resonance imaging are reliable modalities, but are expensive and not feasible for repetitive use. Real-time three-dimensional echocardiography (RT3DE) has been proved to be applicable in daily practice. The purpose of this study was to confirm the superiority of RT3DE to 2DE in assessing cardiac volume and function in patients with abnormal wall motion.

METHODS

The subjects were 41 patients with old anteroseptal myocardial infarction who underwent left ventricular volume and functional measurement by RT3DE, 2DE, and left ventriculography (LVG). End-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) from RT3DE and 2DE were measured and compared with results from LVG.

RESULTS

RT3DE correlated well with LVG in measurements of EDV, ESV, and EF (r = 0.815, 0.940, and 0.812, respectively; P < 0.001 each). Likewise, 2DE correlated with LVG, but underestimated left ventricular volume, particularly EDV (r = 0.652, 0.909, and 0.761, respectively; P < 0.001 each).

CONCLUSION

Values derived from RT3DE were closer to those from LVG than were values derived from 2DE. RT3DE provides important information on cardiac function in patients with prior anteroseptal myocardial infarction.

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.

A curvature-based approach for left ventricular shape analysis from cardiac magnetic resonance imaging

It is believed that left ventricular (LV) regional shape is indicative of LV regional function, and cardiac pathologies are often associated with regional alterations in ventricular shape. In this article, we present a set of procedures for evaluating regional LV surface shape from anatomically accurate models reconstructed from cardiac magnetic resonance (MR) images. LV surface curvatures are computed using local surface fitting method, which enables us to assess regional LV shape and its variation. Comparisons are made between normal and diseased hearts. It is illustrated that LV surface curvatures at different regions of the normal heart are higher than those of the diseased heart. Also, the normal heart experiences a larger change in regional curvedness during contraction than the diseased heart. It is believed that with a wide range of dataset being evaluated, this approach will provide a new and efficient way of quantifying LV regional function.

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.

Reproducibility of Right Ventricular Volumes and Ejection Fraction Using Real-time Three-Dimensional Echocardiography

OBJECTIVES

The nongeometric nature of the right ventricle (RV) makes it difficult to measure. We sought to determine whether real-time three-dimensional echocardiography (RT3DE) is superior to two-dimensional echocardiography (2DE) for the follow-up of RV function by validation vs cardiac MRI.

METHODS

RV volumes and ejection fraction (EF) were studied with 2DE (including area-length [A-L], the modified two-dimensional subtraction [2DS] method, and the Simpson method of discs), RT3DE, and MRI in 50 patients with left ventricular wall motion abnormalities, the results of which suggested possible RV infarction. Test-retest variation was performed by a complete restudy using a separate sonographer within 24 h without the alteration of hemodynamics or therapy. Interobserver and intraobserver variations were noted in a subgroup of 20 patients.

RESULTS

EF estimations were similar using each technique. The mean (+/- SD) MRI end-diastolic volume (87 +/- 22 mL) was only slightly underestimated by RT3DE (mean difference, -3 +/- 10; p < 0.05), with a greater mean difference for 2DE A-L (-29 +/- 10; p < 0.05), and the Simpson method of discs (-29 +/- 23; p < 0.05), and was greatly overestimated by 2DS (mean difference, 26 +/- 23; p < 0.05). Similarly, the mean MRI end-systolic volume (46 +/- 17 mL) was only slightly underestimated by RT3DE (-4 +/- 7; p < 0.05), compared with 2DE A-L (-16 +/- 8; p < 0.05) and the Simpson method of discs (-16 +/- 8; p < 0.05), and was overestimated by 2DS (14 +/- 13; p < 0.05). RT3DE findings had a higher correlation with each parameter than any 2DE technique. There was also good intraobserver and interobserver correlation between RT3DE by two sonographers. RT3DE had less test-retest variation of RV volumes and EF than any 2DE measure.

CONCLUSIONS

RT3DE is more accurate than two-dimensional approaches and reduces the test-retest variation of RV volumes and EF measurements in follow-up RV assessment.

Normal Values of Right Ventricular Size and Function by Real-time 3-Dimensional Echocardiography: Comparison with Cardiac Magnetic Resonance Imaging

BACKGROUND

Assessment of right ventricular function by 2-dimensional echocardiography (2DECHO) is difficult because of its complex shape. Real-time 3-dimensional echocardiography (RT3DECHO) may be superior.

METHODS

End-diastolic volume, end-systolic volume, stroke volume, and ejection fraction obtained by 2DECHO, RT3DECHO short-axis disk summation (DS), and RT3DECHO apical rotation were compared with cardiac magnetic resonance imaging in 71 healthy individuals.

RESULTS

RT3DECHO DS showed less volume underestimation compared with 2DECHO and RT3DECHO apical rotation. Test-retest variability for RT3DECHO DS end-diastolic volume, end-systolic volume, stroke volume, and ejection fraction were 3.3%, 8.7%, 10%, and 10.3%, respectively. Normal reference ranges of indexed volumes (mean +/- 2SD) for right ventricular end-diastolic volume, end-systolic volume, stroke volume, and ejection fraction were 38.6 to 92.2 mL/m(2), 7.8 to 50.6 mL/m(2), 22.5 to 42.9 mL/m(2), and 38.0% to 65.3%, respectively, for women and 47.0 to 100 mL/m(2), 23.0 to 52.6 mL/m(2), 14.2 to 48.4 mL/m(2), and 29.9% to 58.4%, respectively, for men.

CONCLUSIONS

RT3DECHO DS is superior to RT3DECHO apical rotation and 2DECHO for right ventricular quantification, and performs acceptably when compared with cardiac magnetic resonance imaging in healthy individuals.

Live 3D Echocardiography: A Replacement for Traditional 2D Echocardiography?

OBJECTIVE

We describe the development of real-time 3D imaging and review the previously used versions of 3D echocardiography so that the reader will appreciate why current developments truly do represent a quantum leap in the technology.

CONCLUSION

Three-dimensional echocardiography has now been shown to have several advantages over 2D echocardiography, particularly for volume measurements, visualization of septal defects, and whole-valve evaluation. Given these data, it is clear that 3D echocardiography is here to stay and soon will become part of routine echocardiographic examinations.

Time course of left ventricular volumes in severe congestive heart failure patients treated by optimized AV sequential left ventricular pacing alone--a 3-dimensional echocardiographic study

BACKGROUND

This study evaluates the acute and chronic resynchronizing effects of AV sequential left ventricular (LV) pacing on LV function in patients with impaired cardiac function and conduction disorders by 3-dimensional transesophageal echocardiography.

METHODS AND RESULTS

Twenty-nine patients with congestive heart failure, with LV ejection fraction (LVEF) < or = 30%, QRS duration > or = 120 milliseconds, and New York Heart Association Class II to IV, were implanted with a cardiac resynchronization device using an LV lead only, according to the invasively determined hemodynamic optimal pacing site and AV delay. Patients underwent 3-dimensional transesophageal echocardiography before randomization to treatment (baseline) and at 12-month follow-up (resynchronization--12 months). Three-dimensional volumes were acquired on resynchronization and during intermittent switch-off at intrinsic depolarization. The values of stroke volume were 43.2 +/- 13.3 (intrinsic-baseline), 51.7 +/- 17.4 (intrinsic--12 months), 57.2 +/- 15.6 (resynchronization-baseline), and 64.6 +/- 18.9 (resynchronization--12 months). Analysis of variance demonstrated a significant effect of resynchronization at different periods (P < .001) and a significant time effect (P < .05) for stroke volume. Similar results were observed with ejection fraction (LVEF). No effect was observed with LV end-diastolic volume, whereas a therapy effect with no time effect was observed with LV end-systolic volume.

CONCLUSIONS

A significant acute increase of LV stroke volume and LVEF was found by resynchronization by LV pacing alone. A continuous improvement of LV stroke volume and LVEF occurred with time of follow-up (reverse remodeling). The initial therapeutic effect persisted during 12-month follow-up independently of time of follow-up and QRS width. No significant decrease of LV end-diastolic size during chronic resynchronization was detected in contrast to previous studies with resynchronization by biventricular pacing.

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.

Left ventricular volume estimation for real-time three-dimensional echocardiography

The application of level set techniques to echocardiographic data is presented. This method allows semiautomatic segmentation of heart chambers, which regularizes the shapes and improves edge fidelity, especially in the presence of gaps, as is common in ultrasound data. The task of the study was to reconstruct left ventricular shape and to evaluate left ventricular volume. Data were acquired with a real-time three-dimensional (3-D) echocardiographic system. The method was applied directly in the three-dimensional domain and was based on a geometric-driven scheme. The numerical scheme for solving the proposed partial differential equation is borrowed from numerical methods for conservation law. Results refer to in vitro and human in vivo acquired 3-D + time echocardiographic data. Quantitative validation was performed on in vitro balloon phantoms. Clinical application of this segmentation technique is reported for 20 patient cases providing measures of left ventricular volumes and ejection fraction.

Three-dimensional echocardiographic measurement of left and right ventricular mass and volume: in vitro validation

INTRODUCTION

Three-dimensional (3D) echocardiography has been shown to offer highly accurate measurements of left ventricular (LV) volume and mass. The present study evaluated the accuracy of 3D surface reconstruction by the piecewise smooth subdivision method in measuring volume and mass not only in the LV but also in the more complexly shaped right ventricle (RV).

METHODS

3D echo scans were obtained of in vitro LV's (n = 15) and RVs (n = 10). From digitized images, ventricular borders were traced and used in surface reconstructions. Mass and volume determined from the reconstructions were compared to true volume and mass determined prior to imaging. Additionally casts of two RVs were made and laser-scanned. Distances between the laser-identified points on the RV surface and the corresponding 3D echo reconstructions were measured.

RESULTS

3D LV volume agreed well with the true volume (y = 0.99x + 1.73, r = 0.99, SEE = 3.35 ml, p < 0.0001), as did 3D LV mass (y = 0.99x - 4.71, r = 0.99, SEE = 9.85 g, p < 0.0001). 3D RV volume overestimated true volume (y = 1.11x + 1.77, r = 0.99, SEE = 3.36 ml, p < 0.001) by 6.23+/-3.70 ml (p < 0.0001). 3D mass agreed well with RV mass (y = 0.78x + 17.32, r2 = 0.93, SEE = 3.54 g, p < 0.0001). 3D echo reconstructions matched the laser-scanned RV closely with residual distances of 1.1+/-0.9 and 1.4+/-1.2 mm, respectively.

CONCLUSIONS

3D echo using freehand scanning combined with surface reconstruction by the piecewise smooth subdivision surface method enables accurate determination of LV mass and volume, of RV mass and volume, and of the RV's complex shape.

Three-dimensional echocardiographic measurement of left ventricular wall thickness: In vitro and in vivo validation

INTRODUCTION

Three-dimensional (3D) echocardiography has been shown to accurately measure left ventricular (LV) volume and mass. This study evaluated the accuracy of 3D echocardiography and the CenterSurface method for measuring LV wall thickness in vitro and in vivo.

METHOD

Three-dimensional echocardiography scans, obtained from 7 LV phantoms and subjects having healthy (n = 5) or diseased (n = 8) hearts, were digitized. Endocardial and epicardial borders were outlined and used in 3D LV reconstruction. In vitro wall thickness was compared with true micrometer measurements. Three-dimensional in vivo wall thickness was compared with 2-dimensional (2D) thickness measured by the centerline method.

RESULTS

The in vitro 3D echocardiography measurements agreed closely with true wall thickness (P <.0001), as did in vivo measurements (P <.0001).

CONCLUSION

Three-dimensional echocardiography reconstruction has previously been shown to provide accurate representation of LV shape in addition to volume and mass. This study demonstrates that the CenterSurface method provides accurate quantification of wall thickness.

Quantification of aortic regurgitation by real-time 3-dimensional echocardiography in a chronic animal model: computation of aortic regurgitant volume as the difference between left and right ventricular stroke volumes

BACKGROUND

The accuracy of conventional 2-dimensional echocardiographic and Doppler techniques for the quantification of valvular regurgitation remains controversial. In this study, we examined the ability of real-time 3-dimensional (RT3D) echocardiography to quantify aortic regurgitation by computing aortic regurgitant volume as the difference between 3D echocardiographic-determined left and right ventricular stroke volumes in a chronic animal model.

METHODS

Three to 6 months before the study, 6 sheep underwent surgical incision of one aortic valve cusp to create aortic regurgitation. During the subsequent open chest study session, a total of 25 different steady-state hemodynamic conditions were examined. Electromagnetic (EM) flow probes were placed around the main pulmonary artery and ascending aorta and balanced against each other to provide reference right and left ventricular stroke volume (RVSV and LVSV) data. RT3D imaging was performed by epicardial placement of a matrix array transducer on the volumetric ultrasound system, originally developed at the Duke University Center for Emerging Cardiovascular Technology. During each hemodynamic steady state, the left and right ventricles were scanned in rapid succession and digitized image loops stored for subsequent measurement of end-diastolic and end-systolic volumes. Left and right ventricular stroke volumes and aortic regurgitant volumes were then calculated and compared with reference EM-derived values.

RESULTS

There was good correlation between RT3D left and right ventricular stroke volumes and reference data (r = 0.83, y = 0.94x + 2.6, SEE = 9.86 mL and r = 0.63, y = 0.8x - 1.0, SEE = 5.37 mL, respectively). The resulting correlation between 3D- and EM-derived aortic regurgitant volumes was at an intermediate level between that for LVSV and that for RVSV (r = 0.80, y = 0.88x + 7.9, SEE = 10.48 mL). RT3D tended to underestimate RVSV (mean difference -4.7 +/- 5.4 mL per beat, compared with -0.03 +/- 9.7 mL per beat for the left ventricle). There was therefore a small overestimation of aortic regurgitant volume (4.7 +/- 10.4 mL per beat).

CONCLUSION

Quantification of aortic regurgitation through the computation of ventricular stroke volumes by RT3D is feasible and shows good correlation with reference flow data. This method should also be applicable to the quantification of other valvular lesions or single site intracardiac shunts where a difference between right and left ventricular cavity stroke volumes is produced.

Real-time 3-dimensional echocardiographic evaluation of left ventricular volume: correlation with magnetic resonance imaging--a validation study

BACKGROUND

The purpose of our study was to validate the ability of real-time 3-dimensional echocardiography (RT3D) to measure cardiac volume.

METHODS

We studied 25 patients with various cardiac disorders who had a regular heart rhythm and a good precordial echocardiographic window. Each patient underwent complete transthoracic echocardiography (TTE), RT3D, and magnetic resonance imaging (MRI) studies. Left ventricular dimension was calculated from slices of the whole left ventricle obtained by 7 different equidistant azimuth tilts. Planimetry of the endocardial (for volume data) and epicardium (for mass data) surface was performed for each azimuth tilt. The left ventricular end-diastolic volume (LVEDV) and the left ventricular end-systolic volume (LVESV) were calculated. The cardiac mass data were derived with the formula (Epicardial volume - LVEDV) x 1.055. The parameters of LVEDV, LVESV, stroke volume, ejection fraction, and cardiac mass were compared with those derived from MRI.

RESULTS

No statistically significant differences were found between the data from RT3D and MRI (P > or =.05). Good correlations were found between these two methods for left ventricle volume and mass measurements (r from 0.92 to 0.99). However, a weaker correlation was found with larger chamber sizes because extrapolation was necessary for the volume of myocardial segments that were not covered by the small sector angle.

CONCLUSIONS

For data acquisition, RT3D is faster than either TTE or MRI. It is also better than MRI for measuring cardiac volume and mass. To improve results with larger cardiac chamber sizes, enlargement of the sector angle will be necessary.

In vitro simulation and quantification of temporal jitter artifacts in ECG-gated dynamic three-dimensional echocardiography

The image quality of dynamic 3-D echocardiography is limited by temporal jitter artifacts that result from the asynchronous acquisition of video frames with the cardiac cycle. This paper analyzes the source and extent of these artifacts using in vitro studies. Dynamic 3-D images of a myocardial motion phantom were reconstructed and analyzed for eight cardiac motion patterns. The extent of temporal jitter artifacts was quantified, first, from the images by computing temporal jitter maps and, second, predicted from the motion waveforms. Temporal jitter appeared as a pattern of streak artifacts converging at the axis of rotation of the imaging plane, for the rotational scanning approach used in our study. The results of the experimental analysis techniques were compared with the waveform analysis using linear regression analysis. The least squares line showed good correlation between the data (r > 0.9) and its deviation from the line of identity was calculated to be <9%.

Determination of left ventricular volume, ejection fraction, and myocardial mass by real-time three-dimensional echocardiography

Reconstructed three-dimensional (3-D) echocardiography is an accurate and reproducible method of assessing left ventricular (LV) functions. However, it has limitations for clinical study due to the requirement of complex computer and echocardiographic analysis systems, electrocardiographic/respiratory gating, and prolonged imaging times. Real-time 3-D echocardiography has a major advantage of conveniently visualizing the entire cardiac anatomy in three dimensions and of potentially accurately quantifying LV volumes, ejection fractions, and myocardial mass in patients even in the presence of an LV aneurysm. Although the image quality of the current real-time 3-D echocardiographic methods is not optimal, its widespread clinical application is possible because of the convenient and fast image acquisition. We review real-time 3-D echocardiographic image acquisition and quantitative analysis for the evaluation of LV function and LV mass.

Quantitation of ventricular size and function: principles and accuracy of transthoracic rotational scanning

Two-dimensional echocardiography is a readily applicable method for the quantification of ventricular volumes. However, it is limited by assumptions regarding ventricular shape. Three-dimensional echocardiography has emerged as a more accurate and reproducible approach to ventricular volume and functional assessment compared with two-dimensional echocardiography. We review the principles of transthoracic rotational scanning and its clinical application for quantitative assessment of ventricular volume and function.

Comparison of septal defects in 2D and 3D echocardiography using active contour models

Three-dimensional ultrasound is emerging as a viable resource for the imaging of internal organs. Quantitative studies correlating ultrasonic volume measurements with MRI data continue to validate this modality as a more efficient alternative for 3D imaging studies. However, the processing required to form 3D images from a set of 2D images may result in a loss of spatial resolution and may give rise to artifacts. This paper examines a method of automatic feature extraction and data quantification in 3D data sets as compared with original 2D data. This work will implement an active contour algorithm to automatically extract the endocardial borders of septal defects in echocardiographic images, and compare the size of the defects in the original 2D images and the 3D data sets.

Three-dimensional transesophageal echocardiography (TEE) and other future directions

As faster imaging systems enter the market, three-dimensional echocardiography is gearing up to become a useful tool in assisting the clinician to image the heart in many innovative projections. What started out as a novel idea of displaying a three-dimensional anatomic picture of the heart now provides a multitude of views of the heart and its structures. Information gained from anatomic and dynamic data has helped clinicians and surgeons in making clinical decisions. In the future, this imaging modality may become a routine imaging modality for assessing cardiac pathology and may serve to increase understanding of the dynamics of the heart.

Validation of real-time three-dimensional echocardiography for quantifying left ventricular volumes in the presence of a left ventricular aneurysm: in vitro and in vivo studies

OBJECTIVES

To validate the accuracy of real-time three-dimensional echocardiography (RT3DE) for quantifying aneurysmal left ventricular (LV) volumes.

BACKGROUND

Conventional two-dimensional echocardiography (2DE) has limitations when applied for quantification of LV volumes in patients with LV aneurysms.

METHODS

Seven aneurysmal balloons, 15 sheep (5 with chronic LV aneurysms and 10 without LV aneurysms) during 60 different hemodynamic conditions and 29 patients (13 with chronic LV aneurysms and 16 with normal LV) underwent RT3DE and 2DE. Electromagnetic flow meters and magnetic resonance imaging (MRI) served as reference standards in the animals and in the patients, respectively. Rotated apical six-plane method with multiplanar Simpson's rule and apical biplane Simpson's rule were used to determine LV volumes by RT3DE and 2DE, respectively.

RESULTS

Both RT3DE and 2DE correlated well with actual volumes for aneurysmal balloons. However, a significantly smaller mean difference (MD) was found between RT3DE and actual volumes (-7 ml for RT3DE vs. 22 ml for 2DE, p = 0.0002). Excellent correlation and agreement between RT3DE and electromagnetic flow meters for LV stroke volumes for animals with aneurysms were observed, while 2DE showed lesser correlation and agreement (r = 0.97, MD = -1.0 ml vs. r = 0.76, MD = 4.4 ml). In patients with LV aneurysms, better correlation and agreement between RT3DE and MRI for LV volumes were obtained (r = 0.99, MD = -28 ml) than between 2DE and MRI (r = 0.91, MD = -49 ml).

CONCLUSIONS

For geometrically asymmetric LVs associated with ventricular aneurysms, RT3DE can accurately quantify LV volumes.

Left atrial volume assessed by transthoracic three dimensional echocardiography and magnetic resonance imaging: dynamic changes during the heart cycle in children

OBJECTIVE

To assess the dynamic changes in left atrial volume by transthoracic three dimensional echocardiography and compare the results with those obtained by magnetic resonance imaging (MRI).

DESIGN AND PATIENTS

30 healthy children (15 boys and 15 girls, aged 8 to 13 years) underwent examination by three dimensional echocardiography and MRI.

METHODS

Three dimensional echocardiography of the left atrium was performed using rotational acquisition of planes at 18 degrees intervals from the parasternal window with ECG gating and without respiratory gating. Volume estimation by MRI was performed with a slice thickness of 4-8 mm and ECG triggering during breath holding in deep inspiration. A left atrial time-volume curve was reconstructed in each child.

RESULTS

Left atrial maximum and minimum volumes averaged 24.0 ml/m(2) and 7. 6 ml/m(2) by three dimensional echocardiography, and 22.1 ml/m(2) and 11.9 ml/m(2) by MRI. The greater left atrial minimum volume in the latter was at least in part a result of breath holding. Dynamic changes in left atrial volume during the heart cycle were detectable by both methods. The higher temporal resolution of three dimensional echocardiography allowed a more precise evaluation of different phases.

CONCLUSIONS

Three dimensional echocardiography and MRI were both useful methods for studying the physiological volume changes in the left atrium in children. These methods may be used for further study of the systolic and diastolic function of the heart.

Evaluation of left ventricular systolic function by 3D echocardiography: a comparative study with X-ray angiography and radionuclide angiography

OBJECTIVE

the aim of this study was to evaluate left ventricular systolic function by 3D ultrasound as compared to with radionuclide and X-ray angiographies.

METHODS

one hundred and four patients were examinated by 3D ultrasound (3D-US) but only 72 examinations were successful. Thirty patients were investigated by 3D-US, M-mode US or bidimensional (2D) US, and X-ray angiography (group I) and 42 patients were investigated by 3D-US, M-mode, or 2D, and radionuclide angiography (group II).

RESULTS

the correlation between ejection fraction (EF) evaluated by 3D-US and reference methods was found to be good and similar for the two groups (r=0.75; P<10(-4) for group I and r=0.76; P<10(-4) for group II). The correlation between EF calculated by conventional 2D-US and by reference methods was lower (r=0.60; P=0.04 for group I and r=0.54; P=0.001 for group II). The correlation between EF evaluated by 3D- and 2D-US was modest (r=0. 55; P=0.001 for the whole group). The correlation between 3D-US left ventricle end-diastolic volume (EDV) and end-systolic volume (ESV) and those evaluated by X-ray angiography was also modest (r=0.33; NS for EDV and r=0.60; P<10(-4) for ESV). The correlations between EDV and ESV in 3D-US, and those evaluated from radionuclide angiography were fairly good and in the same range (r=0.76; P<10(-4) and r=0.87; P<10(-4)).

CONCLUSION

the 3D-US system using a rotating probe in an apical view is valuable for evaluation of left ventricular systolic function.

Three-dimensional echocardiography: assessment of inter- and intra-operator variability and accuracy in the measurement of left ventricular cavity volume and myocardial mass

Accurate left ventricular (LV) volume and mass estimation is a strong predictor of cardiovascular morbidity and mortality. We propose that our technique of 3D echocardiography provides an accurate quantification of LV volume and mass by the reconstruction of 2D images into 3D volumes, thus avoiding the need for geometric assumptions. We compared the accuracy and variability in LV volume and mass measurement using 3D echocardiography with 2D echocardiography, using in vitro studies. Six operators measured the LV volume and mass of seven porcine hearts, using both 3D and 2D techniques. Regression analysis was used to test the accuracy of results and an ANOVA test was used to compute variability in measurement. LV volume measurement accuracy was 9.8% (3D) and 18.4% (2D); LV mass measurement accuracy was 5% (3D) and 9.2% (2D). Variability in LV volume quantification with 3D echocardiography was %SEMinter = 13.5%, %SEMintra = 11.4%, and for 2D echocardiography was %SEMinter = 21.5%, %SEMintra = 19.1%. We derived an equation to predict uncertainty in measurement of LV volume and mass using 3D echocardiography, the results of which agreed with our experimental results to within 13%. 3D echocardiography provided twice the accuracy for LV volume and mass measurement and half the variability for LV volume measurement as compared with 2D echocardiography.

Initial clinical experience of real-time three-dimensional echocardiography in patients with ischemic and idiopathic dilated cardiomyopathy

The geometry of the left ventricle in patients with cardiomyopathy is often sub-optimal for 2-dimensional ultrasound when assessing left ventricular (LV) function and localized abnormalities such as a ventricular aneurysm. The aim of this study was to report the initial experience of real-time 3-D echocardiography for evaluating patients with cardiomyopathy. A total of 34 patients were evaluated with the real-time 3D method in the operating room (n = 15) and in the echocardiographic laboratory (n = 19). Thirteen of 28 patients with cardiomyopathy and 6 other subjects with normal LV function were evaluated by both real-time 3-D echocardiography and magnetic resonance imaging (MRI) for obtaining LV volumes and ejection fractions for comparison. There were close relations and agreements for LV volumes (r = 0.98, p <0.0001, mean difference = -15 +/- 81 ml) and ejection fractions (r = 0.97, p <0.0001, mean difference = 0.001 +/- 0.04) between the real-time 3D method and MRI when 3 cardiomyopathy cases with marked LV dilatation (LV end-diastolic volume >450 ml by MRI) were excluded. In these 3 patients, 3D echocardiography significantly underestimated the LV volumes due to difficulties with imaging the entire LV in a 60 degrees x 60 degrees pyramidal volume. The new real-time 3D echocardiography is feasible in patients with cardiomyopathy and may provide a faster and lower cost alternative to MRI for evaluating cardiac function in patients.

Left atrial volumes assessed by three- and two-dimensional echocardiography compared to MRI estimates

OBJECTIVES

The aim of the present study was to establish the accuracy and reproducibility of left atrial volume measurements by three-dimensional (3D) echocardiography compared to 2D biplane and monoplane measurements.

BACKGROUND

No echocardiographic technique is generally accepted as optimal for estimation of left atrial size.

METHODS

Left atrial volumes of 18 unselected cardiac patients were obtained with magnetic resonance imaging (MRI) (volumes 145 +/- 58 ml). These volumes were compared with those obtained with different echocardiographic methods: a multiplane 3D method based on 90 images acquired by apical probe rotation, a simplified 3D method using only the three standard apical views, and 2D biplane and monoplane methods based on area-length, disc summation and spherical formulas.

RESULTS

The echocardiographic methods significantly underestimated maximum left atrial volumes as obtained by MRI by 14-37% (p < 0.001). Accuracy, expressed as 1 SD of individual estimates around this systematic underestimation, was 25 to 27% for all methods, except for the 2D 2-chamber monoplane method (37%). Interobserver coefficient of variation was between 14 and 20% for all methods (n.s.).

CONCLUSION

All echocardiographic methods significantly underestimated left atrial volumes as obtained by MRI. A minor non-significant improvement in individual echocardiographic estimates by the 3D methods was obtained at the cost of more time consumption. In unselected patients ultrasound image quality precludes significant improvement of left atrial volume measurements by the applied 3D methods.

Regional assessment of wall curvature and wall stress in left ventricle with magnetic resonance imaging

Left ventricular functional abnormalities are associated with regional increases of wall stress and modifications of wall curvature. This study describes the integration of the short-axis and long-axis wall curvatures for determining peak systolic wall stress. Quantification was realized with cine magnetic resonance imaging (MRI) from the location of the endocardial and epicardial borders of the left ventricle on pairs of consecutive short-axis sections. Fifteen normal volunteers were subjected to cine MRI, and different methods of calculating peak systolic wall stress were compared. A short-axis analysis showed a 55 +/- 13% increase of the circumferential mean of the peak systolic wall stress between apical and basal sections. Regarding the curvature, no significant increase of wall stress was observed except on the septal wall (31 +/- 18%). Short-axis studies proved to be insufficient for determining the regional variations of left ventricular wall stress and for providing normal reference values for the location of abnormal regions in patients.

Real-time, three-dimensional echocardiography: feasibility of dynamic right ventricular volume measurement with saline contrast

BACKGROUND

The asymmetry and complex shape of the right ventricle have made it difficult to determine right ventricular (RV) volume with 2-dimensional echocardiography. Three-dimensional cardiac imaging improves visualization of cardiac anatomy but is also complex and time consuming. A newly developed volumetric scanning system holds promise of obviating past limitations.

METHODS

Real-time, transthoracic 3-dimensional echocardiographic images of the right ventricle were obtained with a high-speed volumetric ultrasound system that uses a 16:1 parallel processing schema from a 2.5 MHz matrix phased-array scanner to interrogate an entire pyramidal volume in real time. The instrumentation was used to measure RV volume in 8 excised canine hearts; dynamic real-time 3-dimensional images were also obtained from 14 normal subjects.

RESULTS

Three-dimensional images were obtained in vitro and in vivo during intravenous hand-agitated saline injection to determine RV volumes. The RV volumes by real-time 3-dimensional echocardiography are well correlated with those of drained in vitro (y = 1.26x - 9.92, r = 0.97, P <.0001, standard error of the estimate = 3.26 mL). For human subjects, the end-diastolic and end-systolic RV volumes were calculated by tracing serial cross-sectional, inclined C scans; functional data were validated by comparing the scans with conventional 2-dimensional echocardiographic indexes of left ventricular stroke volume.

CONCLUSIONS

These data indicate that RV volume measurements of excised heart by real-time 3-dimensional echocardiography are accurate and that beat-to-beat RV quantitative measurement applying this imaging method is possible. The new application of real-time 3-dimensional echocardiography presents the opportunity to develop new descriptors of cardiac performance.

Real-time, 3-dimensional echocardiography acquires all standard 2-dimensional images from 2 volume sets: a clinical demonstration in 45 patients

To test the hypothesis that real-time, 3-dimensional (3-D) echocardiography can obtain all standard 2-dimensional (2-D) views from acquisition of 2 volume sets, we scanned 45 patients (24 men, 21 women; mean age 49 +/- 17 years). This real-time 3-D device (VOLUMETRICS Medical Imaging, Durham, NC) uses a matrix phased array transducer in a 60 degree pyramidal volume. Images are displayed as 2 steerable, intersecting, conventional 2-D image sectors that can be oriented throughout 3-D space. By using this equipment, we were able to obtain 93.3% of standard views from a parasternal volume set and 85.2% of standard views from an apical volume set. The mean scanning time was 91 +/- 19 seconds for the parasternal volume set and 86 +/- 22 seconds for the apical volume set. We conclude that standard 2-D views can be obtained in the majority of patients by using this method. This equipment has the potential to substantially decrease the imaging time compared with the standard 2-D echocardiography.

Three-dimensional echocardiographic determination of left ventricular volumes and function by multiplane transesophageal transducer: dynamic in vitro validation and in vivo comparison with angiography and thermodilution

The goal of this study was to validate 3-dimensional echocardiography by multiplane transesophageal transducer for the determination of left ventricular volumes and ejection fraction in an in vitro experiment and to compare the method in vivo with biplane angiography and the continuous thermodilution method. In the dynamic in vitro experiment, we scanned rubber balloons in a water tank by using a pulsatile flow model. Twenty-nine measurements of volumes and ejection fractions were performed at increasing heart rates. Three-dimensional echocardiography showed a very high accuracy for volume measurements and ejection fraction calculation (correlation coefficient, standard error of estimate, and mean difference for end-diastolic volume 0.998, 2.3 mL, and 0.1 mL; for end-systolic volume 0.996, 2.7 mL, and 0.5 mL; and for ejection fraction 0.995, 1.0%, and -0.4%, respectively). However, with increasing heart rate there was progressive underestimation of ejection fraction calculation (percent error for heart rate below and above 100 bpm 0.59% and -8.6%, P < .001). In the in vivo study, left ventricular volumes and ejection fraction of 24 patients with symmetric and distorted left ventricular shape were compared with angiography results. There was good agreement for the subgroup of patients with normal left ventricular shape (mean difference +/-95% confidence interval for end-diastolic volume 5.2+/-6.7 mL, P < .05; for end-systolic volume -0.5+/-8.4 mL, P = not significant; for ejection fraction 2.4%+/-7.2%, P = not significant) and significantly more variability in the patients with left ventricular aneurysms (end-diastolic volume 23.1+/-56.4 mL, P < .01; end-systolic volume 5.6+/-41.0 mL, P = not significant; ejection fraction 4.9%+/-16.0%, P < .05). Additionally, in 20 critically ill, ventilated patients, stroke volume and cardiac output measurements were compared with measurement from continuous thermodilution. Stroke volume as well as cardiac output correlated well to thermodilution (r = 0.89 and 0.84, respectively, P < .001), although both parameters were significantly underestimated by 3-dimensional echocardiography (mean difference +/-95% confidence interval = -6.4+/-16.0 mL and -0.6+/-1.6 L/min, respectively, P < .005).

Three-dimensional fetal echocardiography

The complex anatomy and dynamics of the heart make it a challenging organ to image. The fetal heart is particularly difficult because it is located deep within the mother's abdomen and direct access to electrocardiographic information is difficult. Thus more complex imaging and analysis methods are necessary to obtain information regarding fetal cardiac anatomy and function. This information can be used for medical diagnosis, model development and theoretical validation. The objective of this article is to provide scientists and engineers with an overview of three-dimensional fetal echocardiography.

Three-dimensional echocardiographic evaluation of left ventricular volume: comparison of Doppler myocardial imaging and standard gray-scale imaging with cineventriculography--an in vitro and in vivo study

BACKGROUND

Standard gray-scale imaging (GSI), three-dimensional (3D) echocardiography has been shown to be superior to two-dimensional echocardiography in measuring left ventricular volume. However, the often relatively poor quality of transthoracic gray-scale data can limit the potential application of this technique. Doppler myocardial imaging (DMI) is a new ultrasound technique that potentially offers higher-quality 3D images with a transthoracic approach than the 3D GSI technique. This study was designed to compare the accuracy of standard GSI and DMI 3D left ventricular volume measurements in vitro and in vivo.

METHODS AND RESULTS

In vitro, the minimum and maximum volume of the contracting single-chamber, tissue-mimicking phantom was calculated by using both techniques. In vivo, GSI and DMI 3D left ventricular volume measurements were performed in 16 patients. End-diastolic and end-systolic left ventricular volumes were computed for both techniques and compared with those calculated by cineventriculography. In vitro, both methods tended to underestimate the true phantom volume, but the systematic error was smaller for DMI than for GSI (-1.2% +/- 1.5% vs. -4.3% +/- 3%; p < 0.01) and was more constant in the case of DMI over the range of different sizes of true volume. In vivo, for GSI the end-diastolic volume mean difference was -12.6 ml and the limits of agreement were +/-18 ml, and for DMI the corresponding values were -4.2 and +/- 10.6 ml, respectively. The difference for end-systole was -6.5 +/- 10.6 ml and -1.5 +/- 10 ml for GSI and DMI, respectively. The magnitude of the difference in volume measurement between 3D echocardiography and cineventriculography was significantly smaller when using the Doppler technique.

CONCLUSIONS

The results of this in vitro and in vivo study indicate that DMI is superior to GSI as a transthoracic acquisition technique for 3 D volume computation.

Comparison of left ventricular ejection fraction in congenital heart disease by visual versus algorithmic determination

Two-dimensional (2D) echocardiographic visual estimation of left ventricular (LV) ejection fraction (EF) in patients with acquired heart disease yields results that are comparable to those obtained by recommended algorithms. However, there is no information concerning its accuracy in congenital heart disease. This study compares applicability, accuracy, and reproducibility of LVEF by visual estimation with that by currently used algorithms (cylinder hemiellipsoid, ellipsoid biplane, and biplane method of disks) in 92 consecutive patients with congenital heart disease but unrepaired complete atrioventricular septal defect, univentricular heart, and hypoplastic left ventricle, using 3D echocardiography as the reference method. Visual estimation of LVEF could be applied in all cases. Because of technically inadequate 2D echocardiographic images for volume measurement, analysis for comparison could be performed in 71 patients (77%), aged 1 day to 47 years. The correlation between 3D echocardiographic and visual estimation was 0.91 (SEE 3.3%), cylinder hemiellipsoid, 0.86 (SEE 3.9%), ellipsoid biplane 0.87 (SEE 3.9%), and biplane method of disks 0.93 (SEE 3.2%). Intraobserver variability was similar for all 2D echo methods. Interobserver variability was greater for visual estimation. In conclusion, visual estimation of LVEF is applicable to most patients with congenital heart disease, yielding results that are comparable to those obtained by currently used 2D echocardiographic algorithms.

Measurement of left ventricular mass: methodology and expertise

The strong relation between increased left ventricular mass and cardiovascular events makes accurate measurement of left ventricular mass a high priority, especially in patients with hypertension. M-mode echocardiography is used most widely to measure left ventricular mass because of its wide availability, moderate expense, anatomic and prognostic validation and lack of radiation or claustrophobia; however, this technique is expertise-dependent and may give erroneous results in distorted ventricles. Two-dimensional and especially three-dimensional echocardiography increase the precision with which left ventricular mass is measured but they are more time-consuming and difficult to perform on a large scale. Magnetic resonance imaging provides highly accurate left ventricular mass measurements and permits tissue imaging but its use is limited by expensive, fixed facilities and claustrophobia. Cine computed X-ray tomography also measures left ventricular mass accurately and permits perfusion assessment with contrast injection but it involves radiation and the use of fixed facilities of limited availability. Understanding the strengths and limitations of available techniques can facilitate selection of the most appropriate method to measure left ventricular mass in a particular setting.