Accuracy of three-dimensional echocardiography with unrestricted selection of imaging planes for measurement of left ventricular volumes and ejection fraction

Quantitative three-dimensional echocardiographic analysis of the bicuspid aortic valve and aortic root: A single modality approach

BACKGROUND

Patients with bicuspid aortic valves (BAV) are heterogeneous with regard to patterns of root remodeling and valvular dysfunction. Two-dimensional echocardiography is the standard surveillance modality for patients with aortic valve dysfunction. However, ancillary computed tomography or magnetic resonance imaging is often necessary to characterize associated patterns of aortic root pathology. Conversely, the pairing of three-dimensional (3D) echocardiography with novel quantitative modeling techniques allows for a single modality description of the entire root complex. We sought to determine 3D aortic valve and root geometry with this quantitative approach.

METHODS

Transesophageal real-time 3D echocardiography was performed in five patients with tricuspid aortic valves (TAV) and in five patients with BAV. No patient had evidence of valvular dysfunction or aortic root pathology. A customized image analysis protocol was used to assess 3D aortic annular, valvular, and root geometry.

RESULTS

Annular, sinus and sinotubular junction diameters and areas were similar in both groups. Coaptation length and area were higher in the TAV group (7.25 ±  0.98 mm and 298 ± 118 mm² , respectively) compared to the BAV group (5.67 ± 1.33 mm and 177 ± 43 mm² ; P = .07 and P = .01). Cusp surface area to annular area, coaptation height, and the sub- and supravalvular tenting indices did not differ significantly between groups.

CONCLUSIONS

Single modality 3D echocardiography-based modeling allows for a quantitative description of the aortic valve and root geometry. This technique together with novel indices will improve our understanding of normal and pathologic geometry in the BAV population and may help to identify geometric predictors of adverse remodeling and guide tailored surgical therapy.

Measurement of Ejection Fraction by Cardiac Magnetic Resonance Imaging and Echocardiography to Monitor Doxorubicin-Induced Cardiotoxicity

Doxorubicin is a standard treatment option for breast cancer, lymphoma, and leukemia, but its benefits are limited by its potential for cardiotoxicity. The primary objective of this study was to compare cardiac magnetic resonance imaging (CMRI) versus echocardiography (ECHO) to detect a reduction in left ventricular ejection function, suggestive of doxorubicin cardiotoxicity. We studied eligible patients who were 18 years or older, who had breast cancer or lymphoma, and who were offered treatment with doxorubicin with curative intent dosing of 240 to 300 mg/m ² body surface area between March 1, 2009 and October 31, 2013. Patients underwent baseline CMRI and ECHO. Both imaging studies were repeated after four cycles of treatment. Ejection fraction (EF) calculated by both methods was compared and analyzed with the inferential statistical Student's t test. Twenty-eight eligible patients were enrolled. Two patients stopped participating in the study before undergoing baseline CMRI; 26 patients underwent baseline ECHO and CMRI. Eight of those 26 patients declined posttreatment studies, so the final study population was 18 patients. There was a significant difference in EF pre- and posttreatment in the CMRI group ( p  = 0.009) versus the ECHO group that showed no significant differences in EF ( p  = NS). It appears that CMRI is superior to ECHO for detecting doxorubicin-induced reductions in cardiac systolic function. However, ECHO is less expensive and more convenient for patients because of its noninvasive character and bedside practicality. A larger study is needed to confirm these findings.

Prognostic value of real-time three-dimensional echocardiography compared to two-dimensional echocardiography in patients with systolic heart failure

Heart failure (HF) is associated with morbidity and mortality. Real-time three-dimensional echocardiography (RT3DE) may offer additional prognostic data in patients with HF. The study aimed to evaluate the prognostic value of real-time three-dimensional echocardiography (RT3DE). This is a prospective study that included 89 patients with HF and left ventricular ejection fraction (LVEF) < 0.50 who were followed for 48 months. Left atrium and ventricular volumes and functions were evaluated by RT3DE. TDI and two-dimensional echocardiography parameters were also obtained. The endpoint was a composite of death, heart transplantation and hospitalization for acute decompensated HF. The mean age was 55 ± 11 years, and the LVEF was 0.32 ± 0.10. The composite endpoint occurred in 49 patients (18 deaths, 30 hospitalizations, one heart transplant). Patients with outcomes had greater left atrial volume (40 ± 16 vs. 32 ± 12 mL/m²; p < 0.01) and right ventricle diameter (41 ± 9 vs. 37 ± 8 mm, p = 0.01), worse total emptying fraction of the left atrium (36 ± 13% vs. 41 ± 11%; p = 0.03), LVEF (0.30 ± 0.09 vs. 0.34 ± 0.11; p = 0.02), right ventricle fractional area change (34.8 ± 12.1% vs. 39.2 ± 11.3%; p = 0.04), and greater E/e' ratio (19 ± 9 vs. 16 ± 8; p = 0.04) and systolic pulmonary artery pressure (SPAP) (50 ± 15 vs. 36 ± 11 mmHg; p < 0.01). In multivariate analysis, LVEF (OR 4.6; CI 95% 1.2-17.6; p < 0.01) and SPAP (OR 12.5; CI 95% 1.8-86.9; p < 0.01) were independent predictors of patient outcomes. LVEF and the SPAP were independent predictors of outcomes in patients with HF.

Transthoracic 3D echocardiographic left heart chamber quantification in patients with bicuspid aortic valve disease

Integration of volumetric heart chamber quantification by 3D echocardiography into clinical practice has been hampered by several factors which a new fully automated algorithm (Left Heart Model, (LHM)) may help overcome. This study therefore aims to evaluate the feasibility and accuracy of the LHM software in quantifying left atrial and left ventricular volumes and left ventricular ejection fraction in a cohort of patients with a bicuspid aortic valve. Patients with a bicuspid aortic valve were prospectively included. All patients underwent 2D and 3D transthoracic echocardiography and computed tomography. Left atrial and ventricular volumes were obtained using the automated program, which did not require manual contour detection. For comparison manual and semi-automated measurements were performed using conventional 2D and 3D datasets. 53 patients were included, in four of those patients no 3D dataset could be acquired. Additionally, 12 patients were excluded based on poor imaging quality. Left ventricular end-diastolic and end-systolic volumes and ejection fraction calculated by the LHM correlated well with manual 2D and 3D measurements (Pearson's r between 0.43 and 0.97, p < 0.05). Left atrial volume (LAV) also correlated significantly although LHM did estimate larger LAV compared to both 2DE and 3DE (Pearson's r between 0.61 and 0.81, p < 0.01). The fully automated software works well in a real-world setting and helps to overcome some of the major hurdles in integrating 3D analysis into daily practice, as it is user-independent and highly reproducible in a group of patients with a clearly defined and well-studied valvular abnormality.

Cardiac Imaging in Chronic Kidney Disease Patients

Cardiovascular disease is highly prevalent and it is associated with high morbidity and mortality rates in patients with chronic kidney disease (CKD). The implementation of various imaging modalities may help to risk stratify these patients with a potential ease on the burden of complications and the rising costs of care. In this article we review some of the modern imaging techniques to diagnose cardiac disease in patients affected by CKD.

Methods used for the assessment of LV systolic function: common currency or tower of Babel?

The last decade has produced a proliferation of techniques for the assessment of left ventricular systolic function, and there now seems to be more choice than seems rational for the questions that we need answers to. In some instances, simple estimation is all that is required-the risk stratification process is inexact, as emphasised by the variety of modalities used to characterise ejection fraction (EF) in studies that validated the efficacy of treatments selected on the basis of EF. Nonetheless, while technical advances often cause disruption and confusion, it would be wrong to dismiss them as lacking benefit. The purpose of this review is to try to provide rational grounds for selecting both test modality and physiological parameter in various specific clinical situations.

Tissue Doppler, triplane echocardiography, and speckle tracking echocardiography: different ways of measuring longitudinal myocardial velocity and deformation parameters. A comparative clinical study

AIMS

The aim of our study was to compare global and segmental longitudinal myocardial velocity and deformation obtained from three different echocardiographic techniques of postprocessing analysis (two-dimensional tissue Doppler imaging (2D TDI), triplane tissue Doppler imaging (3D TDI), and speckle tracking echocardiography (STE)), in a group of consecutive subjects referred to echocardiography with different clinical indications, and to assess their reproducibility.

METHODS AND RESULTS

Standard echocardiograms with high frame rate gray-scale images and color coded TDI apical views, and a single beat TDI triplane apical section of the left ventricle were acquired at two different times. Longitudinal velocity and deformation parameters were obtained in postprocessing in 103 subjects from TDI and STE derived curves, and absolute values were compared to test the variability of the three techniques. All the measures were repeated twice, for a test-retest study. The times to peak velocity and deformation were similar by TDI and STE; other parameters showed significant difference (P < 0.05), both for global and segmental analysis. Reproducibility (expressed by the coefficient of variation and the coefficient of correlation r, in a large part of cases > 0.9) was acceptable, meaning that measures obtained at two different times did not differ significantly in between.

CONCLUSION

TDI and speckle tracking are both feasible and reproducible. Myocardial velocity and deformation parameters obtained with them are significantly different. STE is the most reproducible technique, whereas TDI based measurements are lower reproducible. STE can easily be used during clinical follow up for its feasibility and high reproducibility.

Cardiac toxicity screening by echocardiography in healthy volunteers: a study of the effects of diurnal variation and use of a core laboratory on the reproducibility of left ventricular function measurement

BACKGROUND

In investigational medicinal products testing centers (IMP), reliable methods for monitoring early signs of cardiotoxicity of a potential new drug in healthy volunteers are essential. This study examines what levels of left ventricular ejection fraction (LVEF) variance can be achieved with two-dimensional echocardiography (2DE) in a core laboratory versus a site laboratory. Diurnal variability of LVEF and diastolic parameters were also reviewed.

METHODS AND RESULTS

64 healthy males, (age range 18-40 years), with optimal echo windows were recruited. Two-dimensional and tissue Doppler (TDI) echocardiography was performed by one dedicated sonographer using an Acuson Sequoia C256 machine. Heart rate and blood pressure were recorded simultaneously. Echocardiograms were performed at set time points (0, 1, 4, and 20 hours) on all subjects. The images were analyzed independently by one on-site, unblinded, sonographer reader (site lab) and one experienced off-site blinded physician over reader (core lab). The core lab showed significantly less variance in LVEF measurements than the site lab (5.5% vs. 19.9%). There was no significant diurnal variation in mean blood pressure, LVEF or E:A ratio measurements over 20 hours.

CONCLUSIONS

The core lab had better reproducibility and significantly less variance in LVEF measurements by 2DE than the site lab. There was no diurnal variation in LV function measurement.

Real-time three-dimensional echocardiographic assessment of left ventricular remodeling index in patients with hypertensive heart disease and coronary artery disease

Left ventricular remodeling index (LVRI) was assessed in patients with hypertensive heart disease (HHD) and coronary artery disease (CAD) by real-time three-dimensional echocardiography (RT3DE). RT3DE data of 18 patients with HHD, 20 patients with CAD and 22 normal controls (NC) were acquired. Left ventricular end-diastolic volume (EDV) and left ventricular end-diastolic epicardial volume (EDVepi ) were detected by RT3DE and two-dimensional echocardiography Simpson biplane method (2DE). LVRI (left ventricular mass /EDV) was calculated and compared. The results showed that LVRI measurements detected by RT3DE and 2DE showed significant differences inter-groups (P<0.01). There was no significant difference in NC group (P>0.05), but significant difference in HHD and CAD intra-group (P<0.05). There was good positive correlations between LVRI detected by RT3DE and 2DE in NC and HHD groups (r=0.69, P<0.01; r=0.68, P<0.01), but no significant correlation in CAD group (r=0.30, P>0.05). It was concluded that LVRI derived from RT3DE as a new index for evaluating left ventricular remodeling can provide more superiority to LVRI derived from 2DE.

Relative importance of errors in left ventricular quantitation by two-dimensional echocardiography: insights from three-dimensional echocardiography and cardiac magnetic resonance imaging

BACKGROUND

The accuracy of left ventricular (LV) volumes and ejection fraction (EF) on two-dimensional echocardiography (2DE) is limited by image position (IP), geometric assumption (GA), and boundary tracing (BT) errors.

METHODS

Real-time three-dimensional echocardiography (RT3DE) and cardiac magnetic resonance imaging (CMR) were used to determine the relative contribution of each error source in normal controls (n = 35) and patients with myocardial infarctions (MIs) (n = 34). LV volumes and EFs were calculated using (1) apical biplane disk summation on 2DE (IP + GA + BT errors), (2) biplane disk summation on RT3DE (GA + BT errors), (3) 4-multiplane to 8-multiplane surface approximation on RT3DE (GA + BT errors), (4) voxel-based surface approximation on RT3DE (BT error alone) and (5) CMR. By comparing each method with CMR, the absolute and relative contributions of each error source were determined.

RESULTS

IP error predominated in LV volume quantification on 2DE in normal controls, whereas GA error predominated in patients with MIs. Underestimation of volumes on 2DE was overcome by increasing the number of imaging planes on RT3DE. Although 4 equidistant image planes were acceptable, the best results were achieved with voxel-based RT3DE. For EF estimation, IP error predominated in normal controls, whereas BT error predominated in patients with MIs. Nevertheless, one third of the EF estimation error in patients with MIs was due to a combination of IP and GA errors, both of which may be addressed using RT3DE.

CONCLUSIONS

The relative contribution of each source of LV quantitation error on 2DE was defined and quantified. Each source of error differed depending on patient characteristics and LV geometry.

Left ventricular volume measurement with echocardiography: a comparison of left ventricular opacification, three-dimensional echocardiography, or both with magnetic resonance imaging

AIMS

Both contrast enhanced (CE) two-dimensional echocardiography (2DE) and three-dimensional echocardiography (3DE) have been proposed as techniques to improve the accuracy of left ventricular (LV) volume measurements. We sought to examine the accuracy of non-contrast (NC) and CE-2DE and 3DE for calculation of LV volumes and ejection fraction (EF), relative to cardiac magnetic resonance imaging (MRI).

METHODS AND RESULTS

We studied 50 patients (46 men, age 63 +/- 10 year) with past myocardial infarction who underwent echocardiographic assessment of LV volume and function. All patients sequentially underwent NC-2DE followed by NC-3DE. CE-2DE and CE-3DE were acquired during contrast infusion. Resting echocardiographic image quality was evaluated on the basis of NC-2DE. The mean LV end-diastolic volume (LVEDV) of the group by MRI was 207 +/- 79 mL and was underestimated by 2DE (125 +/- 54 mL, P = 0.005), and less by CE-2DE (172 +/- 58 mL, P = 0.02) or 3DE (177 +/- 64 mL, P = 0.08), but EDV was comparable by CE-3DE (196 +/- 69 mL, P = 0.16). Limits of agreement with MRI were similar for NC-3DE and CE-2DE, with the best results for CE-3D. Results were similar for calculation of LVESV. Patients were categorized into groups of EF (< or =35, 35-50, >50%) by MRI. NC-2DE demonstrated a 68% agreement (kappa 0.45, P = 0.001), CE-2DE a 62% agreement (kappa 0.20, P = 136), NC-3DE a 74% agreement (kappa 0.39, P = 0.005) and CE-3DE an 80% agreement (kappa 0.56, P < 0.001).

CONCLUSION

CE-2DE is analogous to NC-3DE in accurate categorization of LV function. However, CE-3DE is feasible and superior to other NC- and CE-techniques in patients with previous infarction.

Comparison of different views with three-dimensional echocardiography: apical views offer superior visualization compared with parasternal and subcostal views

Studies seeking to validate real-time three-dimensional echocardiography (3DE) with regard to cardiac function and dimensions have almost exclusively used apical views. However, it has never been examined whether apical views are preferable to parasternal or subcostal views. In the present study, we compared the feasibility of 3DE volumetric measurements of the four heart chambers in three different views. We included 40 patients planned for a routine two-dimensional transthoracic echocardiography examination (2DE). All patients were scanned with both 2DE and 3DE (Sonos 7500; Philips Medical Systems Andover, MA, USA). Parasternal, apical and subcostal views were used for 3DE. Volumes were calculated using manual tracing in 16 planes. 2DE was performed in parasternal longaxis, subcostal and apical four- and two-chamber views. Manual tracing was used for area calculations. To be judged fully traceable, 5/6 (85%) or more of the ventricular and atrial walls had to be adequately visualized in each plane. The left ventricle and left atrium were adequately visualized in the 3DE apical view in 34 (85%) and 40 (100%) patients, respectively. Visualization of the right atrium was adequate in 31 (78%) patients, whereas the right ventricle was adequately visualized in only 12 (30%) patients. The apical view of 3DE provided superior visualization of all four heart chambers compared with the parasternal and subcostal views, when applying a slight off-axis approach for both ventricles when needed. Thus, in the present study, there was no incremental value of assessment of chamber volumes in the parasternal and subcostal views.

Flow-volume loops derived from three-dimensional echocardiography: a novel approach to the assessment of left ventricular hemodynamics

Background

This study explores the feasibility of non-invasive evaluation of left ventricular (LV) flow-volume dynamics using 3-dimensional (3D) echocardiography, and the capacity of such an approach to identify altered LV hemodynamic states caused by valvular abnormalities.

Methods

Thirty-one patients with moderate-severe aortic (AS) and mitral (MS) stenoses (21 and 10 patients, respectively) and 10 healthy volunteers underwent 3D echocardiography with full volume acquisition using Philips Sonos 7500 equipment. The digital 3D data were post- processed using TomTec software. LV flow-volume loops were subsequently constructed for each subject by plotting instantaneous LV volume data sampled throughout the cardiac cycle vs. their first derivative representing LV flow. After correction for body surface area, an average flow-volume loop was calculated for each subject group.

Results

Flow-volume loops were obtainable in all subjects, except 3 patients with AS. The flow-volume diagrams displayed clear differences in the form and position of the loops between normal individuals and the respective patient groups. In patients with AS, an "obstructive" pattern was observed, with lower flow values during early systole and larger end-systolic volume. On the other hand, patients with MS displayed a "restrictive" flow-volume pattern, with reduced diastolic filling and smaller end-diastolic volume.

Conclusion

Non-invasive evaluation of LV flow-volume dynamics using 3D-echocardiographic data is technically possible and the approach has a capacity to identify certain specific types of alteration of LV flow-volume pattern caused by valvular abnormalities, thus reflecting underlying hemodynamic states specific for these abnormalities.

Real-time three-dimensional echocardiography in aortic stenosis: a novel, simple, and reliable method to improve accuracy in area calculation

AIMS

The aim of the study was to validate a novel formula for aortic area, based on the principle of continuity equation (CE), that substitutes Doppler-derived stroke volume (SV) by SV directly measured with real-time three-dimensional (RT3D) echo and semi-automated border detection. RT3D has proved outstanding accuracy for left ventricular volume calculation. So far, however, neither this potential has been applied to haemodynamic assessment, nor RT3D has succeeded in the evaluation of aortic valve disease.

METHODS AND RESULTS

Aortic area was measured in 41 patients with aortic stenosis using Gorlin's equation, Hakki's formula, Doppler CE, two-dimensional Simpson's volumetric method, and by the novel RT3D method. RT3D has the best linear association and absolute agreement with Gorlin of all non-invasive methods r = 0.902, intraclass correlation coefficient (ICC) = 0.846, better than CE (r = 0.646, ICC = 0.626) and two-dimensional volumetric method (r = 0.627, ICC = 0.378). Linear and Passing-Bablok regression show that RT3D fits better to Gorlin (r(2) = 0.814) than CE (r(2) = 0.417) and two-dimensional method (r(2) = 0.393). Its accuracy is comparable to Hakki's formula, routinely employed in catheter laboratories. Inter- and intraobserver agreements (ICC) were, respectively, 0.732 and 0.985, better than CE (0.662, 0.857). RT3D also grades most efficiently the severity of aortic stenosis as mild, moderate, or severe (weighted kappa = 0.932). RT3D underestimates aortic area (95% CI 0.084-0.193). ROC curves, however, show that the optimal cutoff point to consider aortic stenosis severity remains close to 1 cm(2) (1.06 cm(2)).

CONCLUSIONS

RT3D is more accurate than CE and than two-dimensional volumetric methods to calculate area and to grade the severity of aortic stenosis. Area obtained by three-dimensional echo is slightly underestimated, but its range is clinically negligible.

How many planes are required to get an accurate and timesaving measurement of left ventricular volume and function by real-time three-dimensional echocardiography in acute myocardial infarction?

To derive the optimal cutting planes of real-time 3-D echocardiography (RT-3DE) for measuring left ventricular volume and ejection fraction (EF) in the presence of left ventricular regional wall motion abnormalities, 14 open-chest dogs were studied with RT-3DE full volume imaging and 2-D echocardiography (2DE) after left anterior descending coronary arteries were occluded for 90 min. Left ventricular end diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV) and EF were measured off-line with 2DE and RT-3DE (2-, 4- and 8-plane) methods. The autopsy EDV was estimated by the volume of saline solution injected into the excised heart and served as the reference volume (RefV) for comparison with EDV measured by 2DE and RT-3DE. Agreement analysis was performed according to the method of Bland and Altman. There were excellent correlations between 2DE, RT-3DE (2-plane) and RT-3DE (4-plane) methods on one hand, and RT-3DE (8-plane) method on the other in the measurements of EDV, ESV and SV (r = 0.84-0.99). However, 2DE and RT-3DE (2-plane) measurements significantly underestimated RT-3DE (8-plane) (p < 0.01), whereas no significant differences between RT-3DE (4-plane) and RT-3DE (8-plane) were found in terms of EDV, ESV and SV measurements. The values of EF determined by 2DE, RT-3DE (2-plane) and RT-3DE (4-plane) methods correlated highly with that by RT-3DE (8-plane) (r = 0.82-0.98) and there was no significant difference between the two measurements. EDV values determined by 2DE, RT-3DE (2-plane), RT-3DE (4-plane) and RT-3DE (8-plane) correlated highly with RefV (r = 0.84, r = 0.92, r = 0.94 and r = 0.97, respectively) and there was no significant difference between RefV and EDV by RT-3DE (4-plane) and RT-3DE (8-plane). In contrast, EDV measured by 2DE and RT-3DE (2-plane) methods underestimated RefV significantly (p < 0.01). In conclusion, RT-3DE allows reliable and reproducible measurement of left ventricular volume and EF, even in the presence of left ventricular regional wall motion abnormalities. RT-3DE (4-plane) is the method of choice for an accurate and timesaving quantification of left ventricular volume and function.

Reconstructed Versus Real-time 3-Dimensional Echocardiography: Comparison with Magnetic Resonance Imaging

BACKGROUND

The accuracy, reproducibility, and test-retest reliability of 3-dimensional (3D) echocardiography (3DE) with 3D reconstruction (3DR) and real-time (RT) imaging (RT 3DE) exceed that of 2-dimensional echocardiography (2DE). However, image quality with RT 3DE is inferior to 2DE and we sought to determine whether this justified ongoing use of 3DR.

METHODS

Unselected patients (n = 30, 22 men, age 66 +/- 7 years) presenting to the echocardiography laboratory for left ventricular (LV) evaluation were studied with 2DE and RT 3DE; 3DR images were obtained using external localization. The 3D measurements and reconstructions were obtained offline. Magnetic resonance images (MRI) were obtained using true free induction, steady state precession during breath hold and 3D volumes and ejection fraction (EF) were measured using 3D software. A separate cohort of 20 patients (13 men, age 60 +/- 12 years) was measured for test-retest variation.

RESULTS

All echocardiographic measures underestimated LV volumes and EF compared with MRI, but this was least with RT 3DE. End-diastolic volume by MRI (168 +/- 54 mL) was underestimated by RT 3DE (-15 +/- 31, P = .02), 3DR (-26 +/- 33, P < .01), and 2DE (-57 +/- 40, P < .01). Similarly, end-systolic volume by MRI (86 +/- 50 mL) was underestimated by RT 3DE (-15 +/- 31, P = .02), 3DR (-26 +/- 33, P < .01), and 2DE (-57 +/- 40, P < .01). However, EF measurements were similar with each method. Test-retest variation was less and interobserver and intraobserver correlations were better with RT 3DE for volumes and EF, compared with 3DR and 2DE.

CONCLUSIONS

Despite limitations of image quality, RT 3DE is the most feasible and accurate approach for LV volume and EF measurements and follow-up LV assessment in daily practice.

Quantification of right ventricular volumes and function by real time three-dimensional echocardiographic longitudinal axial plane method: validation in the clinical setting

BACKGROUND

Measurement of right ventricular (RV) volumes and right ventricular ejection fraction (RVEF) by three-dimensional echocardiographic (3DE) short-axis disc summation method has been validated in multiple studies. However, in some patients, short-axis images are of insufficient quality for accurate tracing of the RV endocardial border. This study examined the accuracy of long-axis analysis in multiple planes (longitudinal axial plane method) for assessment of RV volumes and RVEF.

METHODS

3DE images were analyzed in 40 subjects with a broad range of RV function. RV end-diastolic (RVEDV) and end-systolic volumes (RVESV) and RVEF were calculated by both short-axis disc summation method and longitudinal axial plane method.

RESULTS

Excellent correlation was obtained between the two methods for RVEDV, RVESV, and RVEF (r = 0.99, 0.99, 0.94, respectively; P < 0.0001 for all comparisons).

CONCLUSION

3DE longitudinal-axis analysis is a promising technique for the evaluation of RV function, and may provide an alternative method of assessment in patients with suboptimal short-axis images.

Volume stitching in three-dimensional echocardiography: distortion analysis and extension to real time

Three-dimensional (3D) echocardiography is challenging due to limitation of the data acquisition rate caused by the speed of sound. ECG-gated stitching of data from several cardiac cycles is a possible technique to achieve higher resolution. The aim of this work is two-fold: it is, firstly, to provide a method for real-time presentation of stitched echocardiographic images acquired over several cardiac cycles and, secondly, to demonstrate that the geometrical distortion of the images is decreased when stitching is applied to 3D ultrasonic data of the left ventricle (LV). We present a volume stitching algorithm that merges data from N consecutive heart cycles into an assembled data volume. The assembly is performed in real time, making immediate volume rendering of the full volume possible. In-vivo images acquired with this technique are presented. Through simulations with a kinematic model of the LV wall, geometrical distortion and volume estimation errors due to long image capture time was quantified for 3D recordings of the LV. Curves showing the variation throughout the cardiac cycle of the maximal geometrical distortion in the LV walls are presented, as well as curves showing the volume estimates compared with the true LV volume of the model. We conclude that real-time display of stitched 3D ultrasound data is feasible and that it is an adequate technique for increasing the volume acquisition rate at a given spatial resolution. Furthermore, the geometrical distortion decreases substantially for data with higher volume rate and, for a full scan of the LV, stitching over at least four cycles is recommended.

Comparison of two- and three-dimensional echocardiography with sequential magnetic resonance imaging for evaluating left ventricular volume and ejection fraction over time in patients with healed myocardial infarction

Echocardiographic follow-up of left ventricular (LV) volumes is difficult because of the test-retest variation of 2-dimensional echocardiography (2DE). We investigated whether the accuracy and reproducibility of real-time 3-dimensional echocardiography (RT3DE) would make this modality more feasible for serial follow-up of LV measurements. We performed 2DE and RT3DE and cardiac magnetic resonance imaging (MRI) in 50 patients with previous infarction and varying degrees of LV function (44 men; 61 +/- 11 years of age) at baseline and after 1-year follow-up. Images were obtained during breath-hold and measurements of LV volumes and ejection fraction were made offline. Over follow-up, end-diastolic volume decreased from 192 +/- 53 to 187 +/- 60 ml (p <0.01), end-systolic volume decreased from 104 +/- 51 to 95 +/- 53 ml (p <0.01), and ejection fraction increased from 48 +/- 12% to 51 +/- 12% (p <0.01). MRI showed that LV mass shrank from 183 +/- 39 to 182 +/- 37 g (p <0.01). The correlation between change in RT3DE and change in MRI was greater than the correlations of 2DE with MRI for measurement of end-diastolic volume (r = 0.47 vs 0.02, p <0.01), end-systolic volume (r = 0.44 vs 0.17, p <0.01), and ejection fraction (r = 0.58 vs -0.03, p <0.01). The change in end-diastolic volume between baseline and follow-up with RT3DE (-4 +/- 20, p <0.01) was similar to that with MRI but was unrecognized by 2DE (4 +/- 19, p = 0.09). There was good test-retest and inter- and intraobserver correlation within RT3DE for volumes, ejection fraction, and mass. In conclusion, if sequential measurement of LV volumes is used to guide management decisions, 3DE appears preferable to 2DE.

Real-time Three-dimensional Color Doppler Echocardiography Overcomes the Inaccuracies of Spectral Doppler for Stroke Volume Calculation

Real-time 3-dimensional echocardiography is increasingly used in clinical cardiology. Studies have been shown that this technique can be accurately used to assess both cardiac mass and chamber volumes. We review the work showing that real-time 3-dimensional Doppler echocardiography can be used to accurately calculate intracardiac flow volumes that can potentially be used to assess cardiac function, intracardiac shunt, and valve regurgitation.

Accuracy and feasibility of online 3-dimensional echocardiography for measurement of left ventricular parameters

BACKGROUND

The availability of automated online software may increase the feasibility of real-time 3-dimensional (3D) echocardiography (3DE) for left ventricular (LV) volume calculation in clinical practice. We sought to compare offline and online approaches with magnetic resonance imaging (MRI).

METHODS

Patients who presented to the clinical laboratory for evaluation of LV parameters (n = 110, 94 men, age 63 +/- 10 years) were studied with 2-dimensional echocardiography, online and offline 3DE, and MRI. The 3DE measurements were obtained by a semiautomated LV border detection based on tracing (online) and edge detection (offline). MRI images were obtained using true free induction steady-state precession during breath hold, with measurement of 3D volumes and ejection fraction (EF).

RESULTS

All echocardiographic techniques underestimated LV volumes, but EF estimations were similar. The best correlation was between MRI versus offline 3DE. The correlation of online 3DE with MRI was significantly better than 2-dimensional echocardiography (end-diastolic volume (EDV) z = 4.2, end-systolic volume (ESV) z = 4.44, EF z = 4.32; all P < .01). However, correlation of offline 3DE with MRI was significantly better than online 3DE (EDV z = 2.57, P < .05; ESV z = 2.42, P < .05; EF z = 3.82, P < .01). Images were considered to be good quality (endocardium visualized in all walls) in 49 patients; discrepancies between online and offline 3DE and MRI were similar in good- and poor-quality images. Wall-motion abnormalities were present in 98 patients; discrepancies with MRI were similar in patients with and without abnormal wall motion.

CONCLUSIONS

Online measurement of LV volumes is feasible and more accurate than with 2-dimensional echocardiography. Although the offline approach is more accurate, it is also more time-consuming.

Normal Range of Human Left Ventricular Volumes and Mass Using Steady State Free Precession MRI in the Radial Long Axis Orientation

BACKGROUND

The radial long-axis orientation for the measurement of left ventricular (LV) volume and mass has been shown to have advantages over the short-axis orientation. Previous work has highlighted the need for technique specific normal ranges. The purpose of this study was therefore to establish normal ranges of LV volume and mass for the radial long-axis orientation.

MATERIALS AND METHODS

Forty normal subjects (20 males, average age 32.3, age range 19-58; 20 females, average age 37.4, age range 21-54) were examined utilising a steady state free precession (SSFP) pulse sequence. Two observers analysed the images independently using in-house validated software.

RESULTS

The normal ranges for LV end-diastolic volume measurements after adjustment to body surface area (BSA) were 62-120 ml for males and 58-103 ml for females. LV mass indexed to BSA ranged from 50-86 g for males and 36-72 g for females. The normal range for ejection fraction was 49-73% for males and 54-73% for females.

CONCLUSION

A gender specific normal range using SSFP in the radial long-axis orientation was established.

Rapid online quantification of left ventricular volume from real-time three-dimensional echocardiographic data

AIMS

Determination of left ventricular (LV) volumes and ejection fraction (EF) from two-dimensional echocardiographic (2DE) images is subjective, time-consuming, and relatively inaccurate because of foreshortened views and the use of geometric assumptions. Our aims were (1) to validate a new method for rapid, online measurement of LV volumes from real-time three-dimensional echocardiographic (RT3DE) data using cardiac magnetic resonance (CMR) as the reference and (2) to compare its accuracy and reproducibility with standard 2DE measurements.

METHODS AND RESULTS

CMR, 2DE, and RT3DE datasets were obtained in 50 patients. End-systolic and end-diastolic volumes (ESV and EDV) were calculated from the 2DE images using biplane method of disks. ES and ED RT3DE datasets were analysed using prototype software designed to automatically detect the endocardial surface using a deformable shell model and calculate ESV and EDV from voxel counts. 2DE and RT3DE-derived volumes were compared with CMR (linear regression, Bland-Altman analysis). In most patients, analysis of RT3DE data required <2 min per patient. RT3DE measurements correlated highly with CMR (r: 0.96, 0.97, and 0.93 for EDV, ESV, and EF, respectively) with small biases (-14 mL, -6.5 mL, -1%) and narrow limits of agreement (SD: 17 mL, 16 mL, 6.4%). 2DE measurements correlated less well with CMR (r: 0.89, 0.92, 0.86) with greater biases (-23 mL, -15 mL, 1%) and wider limits of agreement (SD: 29 mL, 24 mL, 9.5%). RT3DE resulted in lower intra-observer (EDV: 7.9 vs. 23%; ESV: 7.6 vs. 26%) and inter-observer variability (EDV: 11 vs. 26%; ESV: 13 vs. 31%).

CONCLUSION

Semi-automated detection of the LV endocardial surface from RT3DE data is suitable for clinical use because it allows rapid, accurate, and reproducible measurements of LV volumes, superior to conventional 2DE methods.

Assessment of global left ventricular function: comparison of cardiac multidetector-row computed tomography with angiocardiography

OBJECTIVE

Evaluation of left ventricular function using electrocardiogram (ECG)-gated multidetector row CT (MDCT) by using 3 different volumetric assessment methods in comparison to assessment of the left ventricular function by invasive ventriculography.

METHODS

Thirty patients with suspected or known coronary artery disease underwent MDCT coronary angiography with retrospective ECG cardiac gating. Raw data were reconstructed at the end-diastolic and end-systolic periods of the heart cycle. To calculate the volumes of the left ventricle, 3 methods were applied: The 3-dimensional data set (3D), the geometric hemisphere cylinder (HC), and the geometric biplane ellipsoid (BE) methods. End-diastolic volumes (EDV), end-systolic volumes (ESV), the stroke volumes (SV), and ejection fractions (EF) were calculated. The left ventricular volumetric data from the 3 methods were compared with measurements from left ventriculography (LVG).

RESULTS

The best results were obtained using the 3D method; EDV (r = 0.73), ESV (r = 0.88), and EF (r = 0.76) correlated well with the LVG data. The EDV volumes did not differ significantly between LVG and the 3D method (P = 0.24); however, ESV, SV, and EF differed significantly. The ESV were significantly overestimated (P < 0.01), leading to an underestimation of the SV (P < 0.01) and the EF (P < 0.01). The HC method resulted in the greatest overestimation of the volumes. The EDV and the ESV were 31.8 +/- 37.6% and 136.4 +/- 92.9% higher than the EDV and ESV volumes obtained by LVG. Bland-Altman analysis showed systematic overestimation of the ESV using the HC method.

CONCLUSION

MDCT with retrospective cardiac ECG gating allows the calculation of left ventricular volumes to estimate systolic function. The 3D method had the highest correlation with LVG. However, the overestimation of the ESV is significant, which led to an underestimation of the SV and the EF.

Comparison of left ventricular volumes and ejection fractions measured by three-dimensional echocardiography versus by two-dimensional echocardiography and cardiac magnetic resonance in patients with various cardiomyopathies

End-diastolic volume and end-systolic volume were measured in 35 consecutive patients with cardiomyopathy using 2-dimensional (2-D) and 3-dimensional (3-D) echocardiography (2, 4, and 8 planes) and cardiac magnetic resonance imaging. Three-dimensional echocardiography correlates better with magnetic resonance imaging than does 2-D echocardiography. Its accuracy improves with the increase in the number of planes used. Two-dimensional echocardiography underestimates volumes, mainly in the subgroup with an ejection fraction of <50%, whereas 3-D echocardiography does not, if enough planes are used. However, in patients with an end-diastolic volume > or =150 ml, the underestimation of 3-D echocardiography is statistically significant. Increasing the number of planes to 8 reduces this bias. Conversely, patients with an end-diastolic volume <150 ml are accurately studied with just 4 planes.

Reproducibility and accuracy of echocardiographic measurements of left ventricular parameters using real-time three-dimensional echocardiography

OBJECTIVES

We sought to determine whether assessment of left ventricular (LV) function with real-time (RT) three-dimensional echocardiography (3DE) could reduce the variation of sequential LV measurements and provide greater accuracy than two-dimensional echocardiography (2DE).

BACKGROUND

Real-time 3DE has become feasible as a standard clinical tool, but its accuracy for LV assessment has not been validated.

METHODS

Unselected patients (n = 50; 41 men; age, 64 +/- 8 years) presenting for evaluation of LV function were studied with 2DE and RT-3DE. Test-retest variation was performed by a complete restudy by a separate sonographer within 1 h without alteration of hemodynamics or therapy. Magnetic resonance imaging (MRI) images were obtained during a breath-hold, and measurements were made off-line.

RESULTS

The test-retest variation showed similar measurements for volumes but wider scatter of LV mass measurements with M-mode and 2DE than 3DE. The average MRI end-diastolic volume was 172 +/- 53 ml; LV volumes were underestimated by 2DE (mean difference, -54 +/- 33; p < 0.01) but only slightly by RT-3DE (-4 +/- 29; p = 0.31). Similarly, end-systolic volume by MRI (91 +/- 53 ml) was underestimated by 2DE (mean difference, -28 +/- 28; p < 0.01) and by RT-3DE (mean difference, -3 +/- 18; p = 0.23). Ejection fraction by MRI was similar by 2DE (p = 0.76) and RT-3DE (p = 0.74). Left ventricular mass (183 +/- 50 g) was overestimated by M-mode (mean difference, 68 +/- 86 g; p < 0.01) and 2DE (16 +/- 57; p = 0.04) but not RT-3DE (0 +/- 38 g; p = 0.94). There was good inter- and intra-observer correlation between RT-3DE by two sonographers for volumes, ejection fraction, and mass.

CONCLUSIONS

Real-time 3DE is a feasible approach to reduce test-retest variation of LV volume, ejection fraction, and mass measurements in follow-up LV assessment in daily practice.

Real-time three-dimensional echocardiography to construct clinically ready, load-independent indices of myocardial contractile performance

BACKGROUND

Real-time 3-dimensional echocardiography (RT3DE) reliably determines intracardiac chamber volumes without left ventricular (LV) geometric assumptions, yet clinical assessment of contractile performance is often on the basis of potentially inaccurate, load-dependent indices such as ejection fraction.

METHODS

In 6 chronically instrumented dogs, RT3DE estimated LV volumes at various loading conditions. Preload recruitable stroke work and end-systolic pressure-volume relationships were constructed. RT3DE-derived indices were compared with similar relationships determined by sonomicrometry.

RESULTS

Highly linear preload recruitable stroke work and end-systolic pressure-volume relationships were constructed by RT3DE and sonomicrometry. Mean preload recruitable stroke work slopes correlated between methods, but volume intercepts differed as a result of geometric assumptions of sonomicrometry. Conversely, RT3DE-derived end-systolic pressure-volume relationships did not correlate well with sonomicrometry.

CONCLUSIONS

These data are unique in reporting load-independent measures of LV performance using RT3DE. These techniques would strengthen evaluation of LV function after myocardial ischemia or cardiac operation, in which frequent changes in ventricular geometry or loading conditions confound functional assessment by more traditional methods.

A visual approach for the accurate determination of echocardiographic left ventricular ejection fraction by medical students

BACKGROUND

Previously published reports show that there is significant intraobserver, interobserver, and interinstitutional variability in the determination of left ventricular (LV) ejection fraction (EF) by echocardiography. With the increased deployment of echocardiography (eg, handheld devices), there exists a need for developing a simple, intuitive approach for evaluating LVEF that allows a wider range of physicians to accurately and rapidly determine LVEF.

OBJECTIVE

We sought to create a system for assessing LVEF that relies on recognition and matching of patterns, rather than on mathematic calculations and geometric assumptions.

METHODS

A library of videoclips of cardiac function was compiled from 54 patients who spanned the spectrum of LVEF. LVEFs were calculated for these patients using standard echocardiographic methods, with further validation of a subsample using cardiac magnetic resonance imaging measurement of LVEF. The library of images was used to create a software tool for assessing LVEF on the basis of a "template-matching" approach. The software tool was then tested on medical students (N=13) to determine whether it enabled relatively untrained individuals to make accurate LVEF estimates.

RESULTS

Using a template-matching approach for interpretation of echocardiograms, medical students were able to accurately estimate LVEF after only a limited introduction to echocardiography. Their LVEF estimates showed good correlation and agreement with gold standard (r = 0.88, standard square of the estimate = 6.0, limits of agreement = +12.0%, -15.6%).

CONCLUSIONS

A new visual approach for assessing cardiac function using template matching can accurately estimate LVEF. With minimal training, medical students can make LVEF estimates that correlate well with gold standard. The application of this new approach includes allowing for the interpretation of LVEF from echocardiograms to be performed by a broader spectrum of physicians.

Three-dimensional echocardiographic determination of cardiac output at rest and under dobutamine stress: comparison with thermodilution measurements in the ischemic pig model

Determination of cardiac output is a potentially important clinical application of three-dimensional (3-D) echocardiography since it could replace invasive measurements with the Swan-Ganz-catheter. To date, there are no studies available to determine whether cardiac output measured by thermodilution can be predicted reliably under changing hemodynamic conditions. Fifteen pigs with ischemic myocardium were examined under four hemodynamic conditions at rest and under pharmacological stress with 5, 10, and 20 microg/kg/min dobutamine. The 3-D datasets were recorded by means of transesophageal echocardiography. The endocardial definition was enhanced by administering the contrast agent FS069 (Optison). Cardiac output was calculated as the product of stroke volume (end-diastolic - end-systolic volume) and heart rate. The invasive measurements were performed with a continuous thermodilution system. In general, there was moderate correlation between 3-D echocardiography and thermodilution(r = 0.72, P < 0.001). At rest, the 3-D echocardiographic measurements were slightly but significantly lower than the invasive measurements (mean difference 0.6 +/- 0.5L/min,P < 0.001). Under stress with 5, 10, and 20 microg/kg/min dobutamine, there was a marked increase in the deviation (1.3 +/- 0.5L/min,P < 0.001; 1.6 +/- 0.7 L/min,P < 0.001; and 2.1 +/- 1.1L/min,P < 0.001, respectively). The deviation was based on two factors: (1). Under stress, the decreasing number of frames per cardiac cycle acquired with 3-D echocardiography led to imprecise recording of end-diastolic and end-systolic volumes, and thus to an underestimation of cardiac output. At least 30 frames per cardiac cycle are needed to eliminate this effect. (2). There is a systematic difference between 3-D echocardiographic and invasive measurements, which is independent of the imaging rate. This is based on an overestimation of the true values by thermodilution. In conclusion, cardiac output can be determined correctly by 3-D echocardiography for normal heart rates at rest. At elevated heart rates, the temporal resolution of 3-D systems currently available is not adequate for reliable determination. In performing and evaluating future clinical comparative studies, the systematic difference between 3-D echocardiography and thermodilution, based on overestimation by thermodilution, must be taken into account.

Cine MRI using steady state free precession in the radial long axis orientation is a fast accurate method for obtaining volumetric data of the left ventricle

In this study we assessed the use of a steady state free precession (SSFP) cine sequence in a series of radially orientated long axis slices for the measurement of left ventricular volumes and mass. We validated the radial long axis approach in phantoms and ex vivo porcine hearts and applied it to normal volunteers and patients using the SSFP and turbo gradient-echo (TGE) sequences. High quality images were obtained for analysis, and the measured volumes with radial long axis SSFP sequence correlated well with short axis TGE and SSFP volumes (r > 0.98). The best interobserver agreement for left ventricular volumes was obtained using SSFP in the long axis radial orientation (variability < 2.3%). We conclude that this combination of sequence and scan orientation has intrinsic advantages for image analysis due to the improved contrast and the avoidance of errors associated with the basal slice in the short axis orientation.

Patient motion compensation during transthoracic 3-D echocardiography

Bulk patient motion during transthoracic 3-D echocardiography (3DE) produces image plane misregistration and errors in left ventricular (LV) volume and ejection fraction (EF). To correct for patient motion, we used a magnetic locating system to track both the ultrasound transducer and the chest wall of the patient, so images could be registered in a patient-centered coordinate system ("correction"). Fourteen subjects each underwent 3DE, with deliberate patient motion, to measure LV volume and EF. Results were compared to magnetic resonance imaging (MRI). Without correction, 3DE differed significantly from MRI (EF: r = 0.78, SEE = 5.8%). Application of correction increased 3DE accuracy, despite patient motion (EF: r = 0.91, SEE = 3.7%), to a level comparable to that of 3DE in the absence of motion (EF: r = 0.93, SEE = 3.5%). Patient motion during 3DE examination can be corrected using a magnetic spatial location system.