Lynn Weinert

Quantitative Assessment of Left Ventricular Size and Function Side-by-Side Comparison of Real-Time Three-Dimensional Echocardiography and Computed Tomography With Magnetic Resonance Reference

Background— Cardiac CT (CCT) and real-time 3D echocardiography (RT3DE) are being used increasingly in clinical cardiology. CCT offers superb spatial and contrast resolution, resulting in excellent endocardial definition. RT3DE has the advantages of low cost, portability, and live 3D imaging without offline reconstruction. We sought to compare both CCT and RT3DE measurements of left ventricular size and function with the standard reference technique, cardiac MR (CMR). Methods and Results— In 31 patients, RT3DE data sets (Philips 7500) and long-axis CMR (Siemens, 1.5 T) and CCT (Toshiba, 16-slice MDCT) images were obtained on the same day without β-blockers. All images were analyzed to obtain end-systolic and end-diastolic volumes and ejection fractions using the same rotational analysis to eliminate possible analysis-related differences. Intertechnique agreement was tested through linear regression and Bland-Altman analyses. Repeated measurements were performed to determine intraobserver and interobserver variability. Both CCT and RT3DE measurements resulted in high correlation (r2>0.85) compared with CMR. However, CCT significantly overestimated end-diastolic and end-systolic volumes (26 and 19 mL; P<0.05), resulting in a small but significant bias in ejection fraction (−2.8%). RT3DE underestimated end-diastolic and end-systolic volumes only slightly (5 and 6 mL), with no significant bias in EF (0.3%; P=0.68). The limits of agreement with CMR were comparable for the 2 techniques. The variability in the CCT measurements was roughly half of that in either RT3DE or CMR values. Conclusions— CCT provides highly reproducible measurements of left ventricular volumes, which are significantly larger than CMR values. RT3DE measurements compared more favorably with the CMR reference, albeit with higher variability.

Fast Measurement of Left Ventricular Mass With Real-Time Three-Dimensional Echocardiography Comparison With Magnetic Resonance Imaging

Background—Left ventricular (LV) mass is an important predictor of morbidity and mortality, especially in patients with systemic hypertension. However, the accuracy of 2D echocardiographic LV mass measurements is limited because acquiring anatomically correct apical views is often difficult. We tested the hypothesis that LV mass could be measured more accurately from real-time 3D (RT3D) data sets, which allow offline selection of nonforeshortened apical views, by comparing 2D and RT3D measurements against cardiac MR (CMR) measurements. Methods and Results—Echocardiographic imaging was performed (Philips 7500) in 21 patients referred for CMR imaging (1.5 T, GE). Apical 2- and 4-chamber views and RT3D data sets were acquired and analyzed by 2 independent observers. The RT3D data sets were used to select nonforeshortened apical 2- and 4-chamber views (3DQ-QLAB, Philips). In both 2D and RT3D images, LV long axis was measured; endocardial and epicardial boundaries were traced, and mass was calculated by use of the biplane method of disks. CMR LV mass values were obtained through standard techniques (MASS Analysis, GE). The RT3D data resulted in significantly larger LV long-axis dimensions and measurements of LV mass that correlated with CMR better (r=0.90) than 2D (r=0.79). The 2D technique underestimated LV mass (bias, 39%), whereas RT3D measurements showed only minimal bias (3%). The 95% limits of agreement were significantly wider for 2D (52%) than RT3D (28%). Additionally, the RT3D technique reduced the interobserver variability (37% to 7%) and intraobserver variability (19% to 8%). Conclusions—RT3D imaging provides the basis for accurate and reliable measurement of LV mass.

Volumetric Quantification of Global and Regional Left Ventricular Function From Real-Time Three-Dimensional Echocardiographic Images

Background—Real-time 3D echocardiographic (RT3DE) data sets contain dynamic volumetric information on cardiac function. However, quantification of left ventricular (LV) function from 3D echocardiographic data is performed on cut-planes extracted from the 3D data sets and thus does not fully exploit the volumetric information. Accordingly, we developed a volumetric analysis technique aimed at quantification of global and regional LV function. Methods and Results—RT3DE images obtained in 30 patients (Philips 7500) were analyzed by use of custom software based on the level-set approach for semiautomated detection of LV endocardial surface throughout the cardiac cycle, from which global and regional LV volume (LVV)–time and wall motion (WM)–time curves were obtained. The study design included 3 protocols. In protocol 1, time curves obtained in 16 patients were compared point-by-point with MRI data (linear regression and Bland-Altman analyses). Global LVV correlated highly with MRI (r=0.98; y=0.99x+2.3) with minimal bias (1.4 mL) and narrow limits of agreement (±20 mL). WM correlated highly only in basal and midventricular segments (r=0.88; y=0.85x+0.7). In protocol 2, we tested the ability of this technique to differentiate populations with known differences in LV function by studying 9 patients with dilated cardiomyopathy and 9 normal subjects. All calculated indices of global and regional systolic and diastolic LV function were significantly different between the groups. In protocol 3, we tested the feasibility of automated detection of regional WM abnormalities in 11 patients. In each segment, abnormality was detected when regional shortening fraction was below a threshold obtained in normal subjects. The automated detection agreed with expert interpretation of 2D WM in 86% of segments. Conclusions—Volumetric analysis of RT3DE data is clinically feasible and allows fast, semiautomated, dynamic measurement of LVV and automated detection of regional WM abnormalities.

Quantification of left ventricular volumes using three-dimensional echocardiographic speckle tracking: comparison with MRI

AIMS Although the utility of two-dimensional (2D) speckle tracking echocardiography (STE) to quantify left ventricular (LV) volume has been demonstrated, this methodology is limited by foreshortened views, geometric modelling, and the assumption that speckles can be tracked from frame to frame, despite their out of plane motion. To circumvent these limitations, a three-dimensional (3D) speckle tracking algorithm was recently developed. Our goal was to evaluate the accuracy of the new 3D-STE side by side with 2D-STE using cardiac magnetic resonance (CMR) as a reference. METHODS AND RESULTS Apical two- and four-chamber views (A2C and A4C) and real-time 3D datasets (Toshiba Artida 4D System) obtained in 43 patients with a wide range of LV size and function were analysed to measure LV end-systolic and end-diastolic volumes (ESV and EDV) using 2D and 3D-STE techniques. Short-axis CMR images (Siemens 1.5T scanner) acquired on the same day were analysed to obtain ESV and EDV reference values using the method of disks approximation. Reproducibility of both STE techniques was assessed using repeated measurements. While 2D-STE correlated well with CMR (r: 0.72-0.88), it underestimated LV volumes with relatively large biases (10-30 mL) and wide limits of agreement (SD: 36-51 mL), with A2C-derived measurements being worse than A4C values. The 3D-STE measurements showed higher correlation with CMR (0.87-0.92), and importantly smaller biases (1-16 mL) and narrower limits of agreement (SD: 28-37 mL). In addition, 3D-STE showed lower inter- and intra-observer variability (11-14% and 12-13%), than 2D-STE (16-17% and 12-16%, respectively). CONCLUSION This is the first study to validate the new 3D-STE technique for LV volume measurements and demonstrate its superior accuracy and reproducibility over previously used 2D-STE technique.

Echocardiographic Quantification of Regional Left Ventricular Wall Motion With Color Kinesis

BACKGROUND Color kinesis is a new technology for the echocardiographic assessment of left ventricular wall motion based on acoustic quantification. This technique automatically detects endocardial motion in real time by using integrated backscatter data to identify pixel transitions from blood to tissue during systole on a frame-by-frame basis. In this study, we evaluated the feasibility and accuracy of quantitative segmental analysis of color kinesis images to provide objective evaluation of regional systolic endocardial motion. METHODS AND RESULTS Two-dimensional echocardiograms were obtained in the short-axis and apical four-chamber views in 20 normal subjects and 40 patients with regional wall motion abnormalities. End-systolic color overlays superimposed on the gray scale images were obtained with color kinesis to color encode left ventricular endocardial motion throughout systole on a frame-by-frame basis. These color-encoded images were divided into segments by use of custom software. In each segment, pixels of different colors were counted and displayed as stacked histograms reflecting the magnitude and timing of regional endocardial excursion. In normal subjects, histograms were found to be highly consistent and reproducible. The patterns of contraction obtained in normal subjects were used as a reference for the objective automated interpretation of regional wall motion abnormalities, defined as deviations from this pattern. The variability in the echocardiographic interpretation of wall motion between two experienced readers was similar to the diagnostic variability between the consensus of the two readers and the automated interpretation. CONCLUSIONS Color kinesis is a promising new tool that may be used clinically to improve the qualitative and quantitative evaluation of spatial and temporal aspects of global and regional wall motion. In this initial study, segmental analysis of color kinesis images provided accurate, automated, and quantitative diagnosis of regional wall motion abnormalities.

Real-Time Three-Dimensional Transesophageal Echocardiography in Valve Disease: Comparison With Surgical Findings and Evaluation of Prosthetic Valves

BACKGROUND Recently, a novel real-time 3-dimensional (3D) matrix-array transesophageal echocardiographic (3D-MTEE) probe was found to be highly effective in the evaluation of native mitral valves (MVs) and other intracardiac structures, including the interatrial septum and left atrial appendage. However, the ability to visualize prosthetic valves using this transducer has not been evaluated. Moreover, the diagnostic accuracy of this new technology has never been validated against surgical findings. This study was designed to (1) assess the quality of 3D-MTEE images of prosthetic valves and (2) determine the potential value of 3D-MTEE imaging in the preoperative assessment of valvular pathology by comparing images with surgical findings. METHODS Eighty-seven patients undergoing clinically indicated transesophageal echocardiography were studied. In 40 patients, 3D-MTEE images of prosthetic MVs, aortic valves (AVs), and tricuspid valves (TVs) were scored for the quality of visualization. For both MVs and AVs, mechanical and bioprosthetic valves, the rings and leaflets were scored individually. In 47 additional patients, intraoperative 3D-MTEE diagnoses of MV pathology obtained before initiating cardiopulmonary bypass were compared with surgical findings. RESULTS For the visualization of prosthetic MVs and annuloplasty rings, quality was superior compared with AV and TV prostheses. In addition, 3D-MTEE imaging had 96% agreement with surgical findings. CONCLUSIONS Three-dimensional matrix-array transesophageal echocardiographic imaging provides superb imaging and accurate presurgical evaluation of native MV pathology and prostheses. However, the current technology is less accurate for the clinical assessment of AVs and TVs. Fast acquisition and immediate online display will make this the modality of choice for MV surgical planning and postsurgical follow-up.

Effects of aging on left atrial reservoir, conduit, and booster pump function: a multi-institution acoustic quantification study

OBJECTIVE To assess the feasibility of measuring left atrial (LA) function with acoustic quantification (AQ) and then assess the effects of age and sex on LA reservoir, conduit, and booster pump function. PATIENTS AND SETTING 165 subjects without cardiovascular disease, 3–79 years old, were enrolled by six tertiary hospital centres. INTERVENTIONS Continuous LA AQ area data were acquired and signal averaged to form composite waveforms which were analysed off-line. MAIN OUTCOME MEASURES Parameters of LA performance according to age and sex. RESULTS Signal averaged LA waveforms were sufficiently stable and detailed to allow automated analysis in all cases. An age related increase in LA area was noted. LA reservoir function did not vary with age or sex. All parameters of LA passive and active emptying revealed a significant age dependency. Overall, the passive emptying phase accounted for 66% of total LA emptying ranging from 76% in the youngest to 44% in the oldest decade. LA contraction accounted for 34% of atrial emptying in all subjects combined with the older subjects being more dependent on atrial booster pump function. When adjusted for atrial size, there were no sex related differences in LA function. CONCLUSIONS LA reservoir, conduit, and booster pump function can be assessed with automated analysis of signal averaged LA area waveforms. As LA performance varies with age, establishment of normal values should enhance the evaluation of pathologic states in which LA function is important.

Segmental analysis of color kinesis images: new method for quantification of the magnitude and timing of endocardial motion during left ventricular systole and diastole.

BACKGROUND We describe a method for objective assessment of left ventricular (LV) endocardial wall motion based on Color Kinesis, a new echocardiographic technique that color-encodes pixel transitions between blood and myocardial tissue. METHODS AND RESULTS We developed a software that analyzes Color Kinesis images and provides quantitative indices of magnitude and timing of regional endocardial motion. Images obtained in 12 normal subjects were used to evaluate the variability in each index. Esmolol, dobutamine, and atropine were used to track variations in LV function in 14 subjects. Objective evaluation of wall motion was tested in 20 patients undergoing dobutamine stress testing. Regional fractional area change, displacement, and radial shortening were displayed as histograms and time curves. Global function was assessed by calculating magnitude and timing of peak ejection or filling rates and mean time of ejection or filling. Patterns of endocardial motion were consistent between normal subjects. Fractional area change and peak ejection rate decreased with esmolol and increased with dobutamine. Time to peak ejection and mean time of contraction were prolonged with esmolol and shortened with dobutamine. Using atropine, we proved that our findings with dobutamine were not secondary to its chronotropic effects. Dobutamine induced regional wall motion abnormalities in 10 patients in 38 segments diagnosed conventionally. Segmental analysis detected abnormalities in 36 of these 38 segments and in an additional 5 of 322 segments. CONCLUSIONS Analysis of Color Kinesis images allows fast, objective, and automated evaluation of regional wall motion sensitively enough to evaluate clinical dobutamine stress data. This method has significant potential in the diagnosis of myocardial ischemia.

Quantitative evaluation of regional left ventricular function using three-dimensional speckle tracking echocardiography in patients with and without heart disease.

Although 2D speckle tracking echocardiography (STE) has been shown useful for the assessment of regional left ventricular (LV) function, it is limited by its 2D nature. Our goal was to evaluate new 3D-STE software by comparing regional wall motion (RWM) measurements against 2D-STE, and testing its ability to identify RWM abnormalities. 2D and real-time 3D datasets obtained in 32 subjects were analyzed to measure radial, longitudinal and rotational indices of displacement and strain. Segments were classified as normal or abnormal using cardiac MRI. 3D-STE and 2D-STE indices did not correlate well and showed wide limits of inter-technique agreement despite the minimal biases. In normal segments, 3D-STE showed: (1) higher displacements, due the out-of-plane motion component; (2) smaller SDs, indicating tighter normal ranges; (3) gradual decrease in displacement and reversal in rotation from base to apex. In abnormal segments, all 3D-STE indices were reduced. In conclusion, this is the first study to evaluate the new 3D-STE technique for measurements of RWM indices and demonstrate its superiority over 2D-STE.

Multimodality Comparison of Quantitative Volumetric Analysis of the Right Ventricle

Real-time 3D echocardiography (RT3DE), cardiac magnetic resonance (CMR) and cardiac computed tomography (CCT) can quantify right ventricular (RV) volume and overcome the limitations 2D echocardiography that stem from the unique geometry of the right ventricle. We tested a new technique for volumetric analysis of the right ventricle designed for RT3DE, CMR and CCT (TomTec) on images obtained in RV-shaped phantoms and in 28 patients with a range of RV geometry who underwent RT3DE, CMR and CCT imaging on the same day. In-vitro measurements showed that: (1) volumetric analysis of CMR images yielded the most accurate measurements; (2) CCT measurements showed slight (4%) but consistent overestimation; (3) RT3DE measurements showed small underestimation, but considerably wider margins of error. In patients, both RT3DE and CCT measurements correlated highly with the CMR reference (r-values 0.79–0.89) and showed the same trends noted in-vitro. In conclusion, eliminating analysis-related inter-modality differences allowed fare comparisons and highlighted the unique limitations of each modality. Understanding these differences promises to aid in the functional assessment of the right ventricle.