Three-Dimensional Echocardiography: Precision and Accuracy of Left Ventricular Volume Measurement Using Rotational Geometry with Variable Numbers of Slice Resolution

A hybrid echocardiography-CFD framework for ventricular flow simulations

Image-based CFD is a powerful tool to study cardiovascular flows while 2D echocardiography (echo) is the most widely used noninvasive imaging modality for the diagnosis of heart disease. Here, echo is combined with CFD, that is, an echo-CFD framework, to study ventricular flows. To achieve this, the previous 3D reconstruction from multiple 2D echo at standard cross sections is extended by: (a) reconstructing aortic and mitral valves from 2D echo and closing the left-ventricle (LV) geometry by approximating a superior wall; (b) incorporating the physiological assumption of the fixed apex as a reference (fixed) point in the 3D reconstruction; and (c) incorporating several smoothing algorithms to remove the nonphysical oscillations (ringing) near the basal section. The method is applied to echo from a baseline LV and one after inducing acute myocardial ischemia (AMI). The 3D reconstruction is validated by comparing it against a reference reconstruction from many echo sections while flow simulations are validated against the Doppler ultrasound velocity measurements. The sensitivity study shows that the choice of the smoothing algorithm does not change the flow pattern inside the LV. However, the presence of the mitral valve can significantly change the flow pattern during the diastole phase. In addition, the abnormal shape of a LV with AMI can drastically change the flow during diastole. Furthermore, the hemodynamic energy loss, as an indicator of the LV pumping performance, for different test cases is calculated, which shows a larger energy loss for a LV with AMI compared to the baseline one.

Three-Dimensional Echocardiography - Role in Clinical Practice and Future Directions

Echocardiography has become an extension of the physical examination in cardiovascular practice. Frequently, it is used to confirm a clinical diagnostic suspicion. Another important role is to detect the underlying cardiovascular lesion to explain a patient's symptom complex or an abnormality found on chest radiography, electrocardiography, or cardiac enzyme tests. Patients are referred to the echocardiography laboratory because of their symptoms or due to non-specific laboratory abnormalities, and echocardiographers are expected to provide a definite diagnosis or a therapeutic clue. The introduction of the matrix array transducer into clinical practice allowed the acquisition of three-dimensional (3D) datasets. 3D echocardiography (3DE) has many advantages over 2-dimensional echocardiography, such as: (1) improved visualization of the complex shapes and spatial relations between cardiac structures; (2) improved quantification of the cardiac volumes and function; and (3) improved display and assessment of valve dysfunction. 3DE is increasingly utilized during routine clinical practice. This review article is aimed to examine the current clinical utility and future directions of 3DE.

Incorporating three-dimensional echocardiography into clinical practice

Three-dimensional echocardiography (3DE) has many advantages over two-dimensional echocardiography, such as (1) improved visualization of the complex shapes and spatial relations between cardiac structures, (2) improved quantification of the cardiac volumes and function, and (3) improved display and assessment of valve dysfunction. The aim of this review article is to focus on the current clinical utility of 3DE.

Early change in left atrial function in patients treated with anthracyclines assessed by real-time three-dimensional echocardiography

Real-time three-dimensional echocardiography(RT-3DE) has allowed a better assessment of LA volumes and function. We sought to assess the early change in left atrial size and function in patients treated with anthracyclines using RT-3DE. 61 patients aged 44.9 ± 11.9 years with large B-cell non-Hodgkin lymphoma treated with doxorubicin were studied. Blood collection and echocardiography were performed at baseline and 1 day after completion of the chemotherapy. Global longitudinal strain (GLS), maximum, minimum and pre-atrial contraction LA volumes were measured and reservoir, conduit and booster pump function were assessed. Despite normal LVEF, passive emptying percent of total emptying (0.51 ± 0.14 vs. 0.40 ± 0.12, P < 0.001) and passive emptying index (0.29 ± 0.10 vs. 0.23 ± 0.06, P < 0.001) were remarkably reduced compared to baseline values, while active emptying percent of total emptying (0.49 ± 0.14 vs. 0.60 ± 0.12, P < 0.001) and active emptying index (0.41 ± 0.16 vs. 0.47 ± 0.16, P = 0.048) were increased. GLS (−21.64 ± 2.83 vs. −17.30 ± 2.50) was markedly reduced, cTnT levels was elevated from 0.005 ± 0.004 to 0.020 ± 0.026 ng/mL at the completion of chemotherapy (P all  < 0.001). Early LA functional change occur after doxorubicin exposure in patients with preserved LVEF, which could be detected by RT-3DE.

Semiautomatic quantification of left ventricular function by two-dimensional feature tracking imaging echocardiography. A comparison study with cardiac magnetic resonance imaging

OBJECTIVE

To evaluate the accuracy of a semiautomatic quantification of left ventricular (LV) volumes and ejection fraction (EF) using two-dimensional (2D) feature tracking imaging (FTI).

METHODS

Thirty-four consecutive subjects (11 patients with dilated cardiomyopathy, 13 with hypertrophic cardiomyopathy, and 10 subjects with no cardiac disease) underwent, on the same day, trans-thoracic echocardiography (TTE) examination, FTI, and cardiac magnetic resonance imaging (MRI), as gold standard, in order to quantify LV volumes and EF. The echocardiographic quantification of LV volumes and EF was determined from four- and two-chamber views using both standard TTE Biplane Simpson's method and a semiautomatic border detection based on FTI. Furthermore, the time for data analysis for each method was measured.

RESULTS

The time required for semiautomatic analysis of volumes and EF was significantly lower (P < 0.0001) by FTI (71 seconds) in comparison with standard biplane Simpson's method (93 seconds). LV volumes obtained by FTI were significant underestimated (P < 0.001) in comparison with MRI. Bland-Altman analysis of EDV and ESV using FTI and cardiac MRI showed a low level of agreement for EDV (mean difference = 40.8; SD = 39) and ESV (mean difference = 38.1; SD = 42). On the contrary, no significant difference between FTI and MRI in assessing the LVEF was found; furthermore, a very low bias (2 ± 12) by Bland-Altman analysis was found between FTI and cardiac MRI for the quantification of EF.

CONCLUSION

Semiautomatic quantification of LV volumes using FTI allows an accurate, rapid, easy and reliable assessment of LV EF and a rough estimation of LV volumes.

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.

Analysis of left ventricular changes after acute myocardial infarction using transthoracic real-time three-dimensional echocardiography

BACKGROUND

Little information is available regarding the relationship between three-dimensional (3-D) echocardiographic parameters in acute stage of acute myocardial infarction (AMI) and subsequent left ventricular (LV) remodeling after AMI.

METHODS

Consecutive patients with AMI were analyzed for echocardiographic predictors of subsequent LV remodeling after AMI using two-dimensional (2-D) echocardiography and real-time 3-D echocardiography at baseline and month 3 of follow-up. LV adverse and favorable remodeling were defined as a >10% and <or=10% increase in 3-D derived LV end diastolic volume index (LVEDVI) at 3 months' follow-up compared with baseline, respectively.

RESULTS

19 AMI patients underwent real-time 3-D echocardiography at baseline and at 3 months after AMI. In patients with favorable remodeling (n = 12), baseline, LVEDVI, LV end-systolic volume index (LVESVI) and LV stroke volume index (LVSVI) were significantly increased compared with patients with adverse remodeling. At 3 months of follow-up, patients with favorable remodeling had significant 3-D LVEDVI, LVESVI, and systolic sphericity index reductions compared to patients with adverse remodeling in which these variables were increased. Baseline clinical and echocardiographic variables were analyzed for the identification of favorable LV remodeling. Of these, LVESVI was the most predictive variable with sensitivity, specificity, and positive and negative predictive values for a cutoff value of >42 mL/m(2) of 75%, 71%, 75%, and 71%, respectively.

CONCLUSIONS

LVESVI assessed by 3-D echocardiography was the most predictive parameter indicating favorable LV remodeling after AMI. LV shape on contraction changed from elliptical shape to more globular in the adverse remodeling process after AMI.

Assessment of left atrial volume and function by real-time three-dimensional echocardiography

BACKGROUND

Determination of left atrial (LA) size and function is important in clinical decision-making. Calculation of LA volume (LAV) is the most accurate index of LA size.

AIM

To compare real-time 3-dimensional echocardiography (RT3DE) and 2-dimensional echocardiography (2DE) for calculation of LAV and function.

METHODS

Fifty patients were studied using 2DE and RT3DE for calculating LAV including: Maximum (V max), minimum (V min) and pre-atrial contraction (V pre A) volumes. For 2DE, the formula: LAV=8(A1) (A2)/3pi (L) was used, while for RT3DE, offline analysis was performed using commercially available software. LA function indices including Total Atrial Stroke Volume (TASV), active ASV (AASV), Total Atrial Emptying Fraction (TAEF), active AEF (AAEF), passive AEF (PAEF), and Atrial Expansion Index (AEI) were calculated.

RESULTS

Patients were classified into 2 equal groups: group I with normal V max (< 50 ml) and group II with V max (> or = 50 ml). Good correlation was obtained between RT3DE and 2DE for LAV (r=0.64, p=0.001) in group I and (r=0.83, p<0.0001) in group II. In group I, LAV and functions showed no significant difference by both techniques, while in group II, the V min and V pre A were significantly lower by RT3DE than 2DE (p=0.009, 0.006). TAEF, AEI, and PAEF indices were significantly higher by RT3DE than 2DE in group II.

CONCLUSION

RT3DE provides a reproducible assessment of active and passive LA function by volumetric cyclic changes. It is comparable and may be superior to 2DE due to its higher sensitivity to volume changes.

Quantitative assessment of left ventricular function with dual-source CT in comparison to cardiac magnetic resonance imaging: initial findings

Cardiac magnetic resonance imaging and echocardiography are currently regarded as standard modalities for the quantification of left ventricular volumes and ejection fraction. With the recent introduction of dual-source computedtomography (DSCT), the increased temporal resolution of 83 ms should also improve the assessment of cardiac function in CT. The aim of this study was to evaluate the accuracy of DSCT in the assessment of left ventricular functional parameters with cardiac magnetic resonance imaging (MRI) as standard of reference. Fifteen patients (two female, 13 male; mean age 50.8 +/- 19.2 years) underwent CT and MRI examinations on a DSCT (Somatom Definition; Siemens Medical Solutions, Forchheim, Germany) and a 3.0-Tesla MR scanner (Magnetom Trio; Siemens Medical Solutions), respectively. Multiphase axial CT images were analysed with a semiautomatic region growing algorithms (Syngo Circulation; Siemens Medical Solutions) by two independent blinded observers. In MRI, dynamic cine loops of short axis slices were evaluated with semiautomatic contour detection software (ARGUS; Siemens Medical Solutions) independently by two readers. End-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF) and stroke volume (SV) were determined for both modalities, and correlation coefficient, systematic error, limits of agreement and inter-observer variability were assessed. In DSCT, EDV and ESV were 135.8 +/- 41.9 ml and 54.9 +/- 29.6 ml, respectively, compared with 132.1 +/- 40.8 ml EDV and 57.6 +/- 27.3 ml ESV in MRI. Thus, EDV was overestimated by 3.7 ml (limits of agreement -46.1/+53.6), while ESV was underestimated by 2.6 ml (-36.6/+31.4). Mean EF was 61.6 +/- 12.4% in DSCT and 57.9 +/- 9.0% in MRI, resulting in an overestimation of EF by 3.8% with limits of agreement at -14.7 and +22.2%. Rank correlation rho values were 0.81 for EDV (P = 0.0024), 0.79 for ESV (P = 0.0031) and 0.64 for EF (P = 0.0168). The kappa value of inter-observer variability were amounted to 0.85 for EDV, ESV and EF. DSCT offers the possibility to quantify left ventricular function from coronary CT angiography datasets with sufficient diagnostic accuracy, adding to the value of the modality in a comprehensive cardiac assessment. The observed differences in the measured values may be due to different post-processing methods and physiological reactions to contrast material injection without beta-blocker medication.

Three-dimensional echocardiographic analysis of left ventricular function during hemodialysis

BACKGROUND

The effects of hemodialysis (HD) on left ventricular (LV) function have been studied by various echocardiographic techniques (M-mode, 2D echocardiography). These studies are hampered by a low accuracy of measurements because of geometric assumptions regarding LV shape. Three-dimensional echocardiography (3DE) overcomes this limitation.

METHODS

We tested the feasibility of 3DE assessment of LV function during HD. Conventional biplane Simpson rule (BSR) and single plane area length method (SPM) for LV function analysis were used as a reference.

RESULTS

12 HD patients were studied and in 10 (83%) a total of 80 3D datasets were acquired. In 3 patients, one dataset (4%) was of insufficient quality and excluded from analysis. Correlation between SPM, BSR and 3DE for calculation of end-diastolic (EDV, r = 0.89 and r = 0.92, respectively), end-systolic volume (ESV, r = 0.92 and r = 0.93, respectively) and for ejection fraction (EF, r = 0.90 and r = 0.88, respectively) was moderate. Limits-of-agreement results for EDV and ESV were poor with confidence intervals larger than 30 ml. Both 2DE methods underestimated end-diastolic and end-systolic volume, while overestimating ejection fraction.

CONCLUSION

3DE is feasible for image acquisition during HD, which opens the possibility for accurate and reproducible measurement of LV function during HD. This may improve the assessment of the acute effect of HD on LV performance, and guide therapeutic strategies aimed at preventing intradialytic hypotension.

Assessment of left ventricular function by cardiac ultrasound

Our understanding of the physical underpinnings of the assessment of cardiac function is becoming increasingly sophisticated. Recent developments in cardiac ultrasound permit exploitation of many of these newer physical concepts with current echocardiographic machines. This review will first focus on the current approach to the assessment of cardiovascular hemodynamics by cardiac ultrasound. The next focus will be the assessment of global cardiac mechanics in systole and diastole. Finally, relationships between the cardiac structure and regional myocardial function, and the way regional function can be quantified by ultrasound, will be presented. This review also discusses the clinical impact of echocardiography and its future directions and developments.

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 beta-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.

Rapid and Accurate Measurement of Left Ventricular Function with a New Second-Harmonic Fast-Rotating Transducer and Semi-Automated Border Detection

Measurement of left ventricular (LV) volume and function are the most common clinical referral questions to the echocardiography laboratory. A fast, practical, and accurate method would offer important advantages to obtain this important information. To validate a new practical method for rapid measurement of LV volume and function. We developed a continuous fast-rotating transducer, with second-harmonic capabilities, for three-dimensional echocardiography (3DE). Fifteen cardiac patients underwent both 3DE and magnetic resonance imaging (reference method) on the same day. 3DE image acquisition was performed during a 10-second breath-hold with a frame rate of 100 frames/sec and a rotational speed of 6 rotations/sec. The individual images were postprocessed with Matlab software using multibeat data fusion. Subsequently, with these images, 12 datasets per cardiac cycle were reconstructed, each comprising seven equidistant cross-sectional images for analysis in the new TomTec 4DLV analysis software, which uses a semi-automated border detection (ABD) algorithm. The ABD requires an average analysis time of 15 minutes per patient. A strong correlation was found between LV end-diastolic volume (r = 0.99; y = 0.95x - 1.14 ml; SEE = 6.5 ml), LV end-systolic volume (r = 0.96; y = 0.89x + 7.91 ml; SEE = 7.0 ml), and LV ejection fraction (r = 0.93; y = 0.69x + 13.36; SEE = 2.4%). Inter- and intraobserver agreement for all measurements was good. The fast-rotating transducer with new ABD software is a dedicated tool for rapid and accurate analysis of LV volume and function.

Freehand Three-Dimensional Echocardiography with Rotational Scanning for Measurements of Left Ventricular Volume and Ejection Fraction in Patients with Coronary Artery Disease

BACKGROUND

Measurement of left ventricular (LV) volumes and ejection fraction (EF) is important in managing patients with coronary artery disease (CAD). Introduction of free-hand three-dimensional echocardiography (3DE) system which is equipped with small magnetic tracking system and average rotational geometry for LV volumes may provide easy and accurate quantification of LV systolic function in CAD patients.

PURPOSE

To evaluate the feasibility and accuracy of LV volumes and EF measurement by free-hand 3DE with rotational geometry in patients with CAD.

METHODS AND RESULTS

The study subjects consisted of consecutive 25 patients with CAD who were scheduled for quantitative gated single-photon emission computed tomography (QGS). LV end-diastolic volume (EDV), end-systolic volume (ESV), and EF were determined by conventional two-dimensional echocardiography (2DE), 3DE, and QGS. Three-dimensional echocardiography data acquisition and analysis were possible in 22 of 25 subjects (feasibility 88%). In this 3DE system, image acquisition time was 2 minutes, and 5 minutes were needed for off-line analysis of LV volumes and EF. Correlations and the limits of agreement between 3DE and QGS (r = 0.97, 0.0 +/- 9.1 ml for EDV, r = 0.99, 0.0 +/- 5.0 ml for ESV, and r = 0.97, 0.5 +/- 3.3% for EF, respectively) were superior to those between 2DE and QGS (r = 0.85, 12.6 +/- 26.8 ml for EDV, r = 0.85, 9.7 +/- 26.1 ml for ESV, and r = 0.90, -1.3 +/- 6.9% for EF, respectively). Inter- and intra-observer variabilities of 3DE were smaller than that of 2DE (5% vs 10%, 5% vs 10% for EDV, 6% vs 13%, 5% vs 9% for ESV, and 4% vs 11%, 4% vs 6% for EF, respectively).

CONCLUSION

Three-dimensional echocardiography using magnetic tracking system and average rotational geometry offered a feasible and accurate method for quantification of LV volumes and EF in patients with CAD.

Accuracy of measurement of left ventricular volume and ejection fraction by new real-time three-dimensional echocardiography in patients with wall motion abnormalities secondary to myocardial infarction

Three-dimensional echocardiography is an ideal tool for the measurement of left ventricular (LV) volume because no geometric assumptions about LV shape are needed. The introduction of new real-time 3-dimensional echocardiography (RT3DE) has allowed rapid acquisition of a 3-dimensional dataset with good image quality. The purpose of this study was to examine the accuracy of RT3DE for the measurement of LV volume and ejection fraction in patients with wall motion abnormalities by using quantitative gated single-photon emission computed tomography (QGSPECT) as a reference standard. The study population consisted of 25 consecutive patients with wall motion abnormalities who underwent LV volume measurement by 2-dimensional echocardiography and by QGSPECT. LV volume and ejection fraction by RT3DE were measured offline by using the average rotation method. In 23 of 25 patients (92%), it was possible to measure 3-dimensional volume with RT3DE. RT3DE correlated well with QGSPECT in the measurement of end-diastolic volume and end-systolic volume (r = 0.97, mean difference 3.4 ml; r = 0.98, mean difference 2.0 ml, respectively), 2-dimensional echocardiography also correlated with QGSPECT but underestimated LV volume (r = 0.98, mean difference 21.1 ml; r = 0.98, mean difference 15.6 ml, respectively). Ejection fraction obtained by RT3DE had better agreement with that obtained by QGSPECT than that obtained by 2-dimensional echocardiography (r = 0.92, mean difference -0.2%; r = 0.89, mean difference -2.7%, respectively). RT3DE allows convenient and accurate estimation of LV volume and ejection fraction in patients with wall motion abnormalities.

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.

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

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

Rapid freehand scanning three-dimensional echocardiography: accurate measurement of left ventricular volumes and ejection fraction compared with quantitative gated scintigraphy

This study was performed to assess clinical feasibility of rapid freehand scanning 3-dimensional echocardiography (3DE) for measuring left ventricular (LV) end-diastolic and -systolic volumes and ejection fraction using quantitative gated myocardial perfusion single photon emission computed tomography as the reference standard. We performed transthoracic 2-dimensional echocardiography and magnetic freehand 3DE using a harmonic imaging system in 15 patients. Data sets (3DE) were collected by slowly tilting the probe (fan-like scanning) in the apical position. The 3DE data were recorded in 10 to 20 seconds, and the analysis was performed within 2 minutes after transferring the raw digital ultrasound data from the scanner. For LV end-diastolic and -systolic volume measurements, there was a high correlation and good agreement (LV end-diastolic volume, r = 0.94, P <.0001, standard error of the estimates = 21.6 mL, bias = 6.7 mL; LV end-systolic volume, r = 0.96, P <.0001, standard error of the estimates = 14.8 mL, bias = 3.9 mL) between gated single photon emission computed tomography and 3DE. There was an overall underestimation of volumes with greater limits of agreement by 2-dimensional echocardiography. For LV ejection fraction, regression and agreement analysis also demonstrated high precision and accuracy (y = 0.82x + 5.1, r = 0.93, P <.001, standard error of the estimates = 7.6%, bias = 4.0%) by 3DE compared with 2-dimensional echocardiography. Rapid 3DE using a magnetic-field system provides precise and accurate measurements of LV volumes and ejection fraction in human beings

Rapid three-dimensional echocardiography : clinically feasible alternative for precise and accurate measurement of left ventricular volumes

BACKGROUND

Clinical applicability of conventional ultrasonographic systems using mechanical adapters for 3D echocardiographic imaging has been limited by long acquisition and processing times. We developed a rapid (6-s) acquisition technique that collects apical tomograms using a continuously internally rotating transthoracic transducer. This study was performed to examine the clinical feasibility of rapid-acquisition 3D echocardiography to estimate left ventricular end-diastolic and end-systolic volumes using electron-beam computed tomography as the reference standard. Methods and Results-We collected a series of 6 to 11 apical echocardiographic tomograms, depending on heart rate, in 11 patients. There was good correlation, low variability, and low bias between rapid 3D echocardiography and electron-beam computed tomography for measuring left ventricular end-diastolic volume (r=0.96; standard error of the estimate, 21.34 mL; bias, -4.93 mL) and left ventricular end-systolic volume (r=0.96; standard error of the estimate, 14.78 mL; bias, -6.97 mL).

CONCLUSIONS

The rapid-acquisition 3D echocardiography extends the use of a multiplane, internally rotating handheld transducer so that it becomes a precise and clinically feasible tool for assessing left ventricular volumes and function. A rapid-image acquisition time of 6 s would allow repeated image collection during the course of a clinical echocardiographic examination. Additional work must address rapid and automated data processing.

Rapid Three-Dimensional Myocardial Contrast Echocardiography: Volumetric Quantitation of Nonperfused Myocardium After Intravenous Contrast Administration

Current acquisition methods for quantitative three-dimensional myocardial contrast echocardiography require long acquisition times and therefore require the invasive administration of deposit contrast agents administered intra-arterially or into the left atrium. This study addressed the feasibility of obtaining accurate and precise quantitative volumetric measurements of nonperfused myocardium after an intravenous bolus of echocardiographic contrast agent using a rapid three-dimensional myocardial contrast echocardiographic acquisition technique. An open-chest pig model of acute left anterior descending coronary artery (LAD) occlusion was used. After LAD ligature, an intravenous bolus of contrast agent was given and images were obtained over a 12-second period using a continuously rotating transducer placed at the apical position. There was no significant microbubble destruction during the rotational acquisition period as measured by differences in mean gray scale values of apical, mid, and basal myocardial regions between the first and last image frames of acquisition. Calculated volumes of nonperfused myocardium demonstrated significant agreement and correlation (mean difference +/- SD = -0.30 +/- 1.71 cm(3); r = 0.89; P < 0.01; y = 1.06x - 1.08) with anatomic specimens. When expressed as percent of total LV volume being nonperfused, the mean difference +/- SD was 2.1 +/- 3.6%, r = 0.94, P < 0.01, and y = 1.33x - 4.08. We conclude that accurate and precise measurements of nonperfused myocardium after an acute LAD coronary artery occlusion can be obtained after the intravenous bolus administration of a contrast material when a rapid 12-second acquisition with a continuously rotating transducer is used.

Evolving era of multidimensional medical imaging

Currently, computer-assisted imaging can visualize very fast or very slow nonvisible motion events. We can create measurable geometric representations of physiology, including transformation, blood flow velocity, perfusion, pressure, contractility, image features, electricity, metabolism, and a vast number of other constantly changing parameters. The greatest attribute is the ability to present physiologic phenomena as easily understood geometric images more suited to the human's four-dimensional comprehension of reality. The key research challenges are to discover new visual metaphors for representing information, understand the analysis tasks that they support, and associate relevant information to create new information.