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

How accurately, reproducibly, and efficiently can we measure left ventricular indices using M-mode, 2-dimensional, and 3-dimensional echocardiography in children?

BACKGROUND

Measurements of left ventricular (LV) size, mass, and function are the most common and important tasks for echocardiography in clinical practice and research in children with congenital and acquired heart diseases. There are little data to compare the utility of M-mode (MM), 2-dimensional (2D), and 3-dimensional (3D) echocardiographic techniques for quantification of LV indices. The objective of the study was to assess the accuracy, reproducibility, and efficiency of these echocardiographic methods for measurement of LV indices in children.

METHODS

A prospective study was conducted in 20 consecutive children (mean 10.6 +/- 2.8 years, 11 male and 9 female subjects) using conventional MM, 2D, and real-time 3D echocardiography (RT3DE). A Sonos 7500 system (Philips Medical Systems, Andover, MA) was used. M-mode and 2DE measurements were made according to the American Society of echocardiography recommendations. To include the entire LV for volumetric measurement, full-volume 3D data sets were acquired from 4 electrocardiogram gated subvolumes. The 3DE measurements were made off-line manually using 4-plane and 8-plane algorithms by 4D Echo-View (TomTec Imaging Systems, Munich, Germany) and a semiautomated algorithm by QLAB (Philips Medical Systems). Magnetic resonance imaging studies were also performed to determine the LV indices by a disk summation method based on the Simpson principle.

RESULTS

The correlation and agreement between MM, 2D, and RT3D echocardiography and magnetic resonance imaging measurements are good (r = 0.81-0.97) for the 3 methods. The correlation was superior for RT3DE compared with 2DE and MM. The correlation and agreement were similar for the three 3DE methods. The intra- and interobserver variabilities ranged from MM (4.3%-4.8% and 7.0%-8.7%), 2DE (3.3%-4.5% and 5.5%-7.3%), and 3DE (0.4%-2.3%, and 0.2%-4.8%). The total time (acquisition and analysis) used for MM measurements was the least compared with 2DE and 3DE. The total time for 3DE using the semiautomated algorithms was not significantly different compared with that for 2DE.

CONCLUSIONS

Our study showed that MM provides the most efficient assessment of LV indices but is the least accurate and reproducible technique compared with 2DE and 3DE. Three-dimensional echocardiography using both automated and manual analysis algorithm is superior to MM and 2DE for measurements of LV indices, and the automated 3DE algorithm is as efficient as 2DE. Therefore, 3DE using the automated algorithm is the method of choice for quantification of LV indices.

Quantification of regional volume and systolic function of the left ventricle by real-time three-dimensional echocardiography

Real-time three-dimensional (3D) echocardiography (RT-3DE) provides a unique technique to evaluate left ventricular regional function in a 3D format. We aimed to explore whether the left ventricular segmental volume and systolic function is uniform and to establish normal values of volume and systolic function parameters of 16 regions in healthy subjects. RT-3DE was performed in 41 normal subjects and four-dimensional (4D)-left ventricle (LV) analysis software and a TomTec workstation were used to analyze data for regional end-diastolic volume (EDV(R)), regional end-systolic volume (ESV(R)), regional stroke volume (SV(R)), regional ejection fraction (EF(R)), ratio of SV(R) to global SV (SV(R/G)) and ratio of SV(R) to global EDV (EF(R/G)). All regional volume and systolic function parameters were not uniform among the left ventricular walls. They all increased in the order of inferior, posterior, lateral, septal, anterior and antero-septal walls with an increasing trend from the apical, middle to basal segments. The systolic function (EF(R), SV(R/G) and EF(R/G)) of the anterior and antero-septal walls was significantly higher than that of the lateral, inferior and posterior walls. And the intra- and interobserver variability for EDV(R), ESV(R), SV(R/G) and EF(R/G) ranged from 2.9% to 5.8%. In conclusion, the regional volume and systolic function of the left ventricle is not uniform and, therefore, a normal left ventricle cannot be regarded as a symmetric model for assessing the regional systolic function. This information may improve the accuracy of RT-3DE techniques in the assessment of the left ventricular regional function. (E-mail: zhangyun@sdu.edu.cn and yaogh@yahoo.com).

A comparison between QLAB and TomTec full volume reconstruction for real time three-dimensional echocardiographic quantification of left ventricular volumes

OBJECTIVES

To compare the interobserver variability and accuracy of two different real time three-dimensional echocardiography (RT3DE) analyzing programs.

METHODS

Forty-one patients (mean age 56 +/- 11 years, 28 men) in sinus rhythm with a cardiomyopathy and adequate 2D image quality underwent RT3DE and magnetic resonance imaging (MRI) within one day. Off-line left ventricular (LV) volume analysis was performed with QLAB V4.2 (semiautomated border detection with biplane projections) and TomTec 4D LV analysis V2.0 (primarily manual tracking with triplane projections and semiautomated border detection).

RESULTS

Excellent correlations (R(2) > 0.98) were found between MRI and RT3DE. Bland-Altman analysis revealed an underestimated LV end-diastolic volume (LV-EDV) for both TomTec (-9.4 +/- 8.7 mL) and QLAB (-16.4 +/- 13.1 ml). Also, an underestimated LV end-systolic volume (LV-ESV) for both TomTec (-4.8 +/- 9.9 mL) and QLAB (-8.5 +/- 14.2 mL) was found. LV-EDV and LV-ESV were significantly more underestimated with QLAB software. Both programs accurately calculated LV ejection fraction (LV-EF) without a bias. Interobserver variability was 6.4 +/- 7.8% vs. 12.2 +/- 10.1% for LV-EDV, 7.8 +/- 9.7% vs. 13.6 +/- 11.2% for LV-ESV, and 7.1 +/- 6.9% vs. 9.7 +/- 8.8% for LV-EF for TomTec vs. QLAB, respectively. The analysis time was shorter with QLAB (4 +/- 2 minutes vs. 6 +/- 2 minutes, P < 0.05).

CONCLUSIONS

RT3DE with TomTec or QLAB software analysis provides accurate LV-EF assessment in cardiomyopathic patients with distorted LV geometry and adequate 2D image quality. However, LV volumes may be somewhat more underestimated with the current QLAB software version.

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.

Assessment of left ventricular mass and volumes by three-dimensional echocardiography in patients with or without wall motion abnormalities: comparison against cine magnetic resonance imaging

AIM

To evaluate if three-dimensional echocardiography (3-DE) is as accurate and reproducible as cine magnetic resonance imaging (cMR) in estimating left ventricular (LV) parameters in patients with and without wall motion abnormalities (WMA).

METHODS

83 patients (33 with WMA) underwent 3-DE and cMR. 3-DE datasets were analysed using a semi-automatic contour detection algorithm. The accuracy of 3-DE was tested against cMR in the two groups of patients. All measurements were made twice by two different observers.

RESULTS

LV mass by 3-DE was similar to that obtained by cMR (149 (SD 42) g vs 148 (45) g, p = 0.67), with small bias (1 (28) g) and excellent interobserver agreement (-2 (31) g vs 4 (26) g). The two measurements were also highly correlated (r = 0.94), irrespective of WMA. End-diastolic and end-systolic LV volumes and ejection fraction by 3-DE and cMR were highly correlated (r = 0.97, 0.98, 0.94, respectively). Yet, 3-DE underestimated cMR end-diastolic volumes (167 (68) ml vs 187 (70) ml, p<0.001) and end-systolic volumes (88 (56) ml vs 101 (65) ml, p<0.001), but yielded similar ejection fractions (50% (14%) vs 50% (16%), p = 0.23).

CONCLUSION

3-DE permits accurate determination of LV mass and volumes irrespective of the presence or absence of WMA. LV parameters obtained by 3-DE are also as reproducible as those obtained by cMR. This suggests that 3-DE can be used to follow up patients with LV hypertrophy and/or remodelling.

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.

Assessment of left ventricular dyssynchrony with real-time 3-dimensional echocardiography: comparison with Doppler tissue imaging

We studied the usefulness and reproducibility of real-time 3-dimensional (3D) echocardiography (RT3DE) for evaluating left ventricular (LV) dyssynchrony, and compared its results with Doppler tissue image (DTI) indices. Full-volume RT3DE data sets and 2-dimensional DTI from apical window were obtained in 122 participants. Using fast 3D border detection software, time to minimum systolic volume (Tmsv) was semiautomatically calculated in each region from a 17-segment model. Several dyssynchrony indices were then calculated: Tmsv-16SD, the SD of Tmsv in 16 of 17 segments, excluding the apical cap; Tmsv-12SD, the SD of Tmsv of 6 basal and 6 middle segments; and Tmsv-6SD, the SD of Tmsv of 6 basal segments. These dyssynchrony indices of RT3DE were then compared with two dyssynchrony indices measured by DTI: time to peak systolic velocity (TTPV)-12SD, the SD of time to peak systolic velocity of 12 LV segments; and time to cross over point of temporal axis (TTCO)-12SD, the SD of time to crossover point of temporal axis. RT3DE data was quantitatively analyzed in 117 of 122 patients. Tmsv-16SD (35 +/- 34 milliseconds) was significantly longer compared with Tmsv-12SD (27 +/- 30 milliseconds, P < .001) or Tmsv-6SD (23 +/- 28 milliseconds, P < .001). Tmsv-16SD increased significantly with the severity of LV systolic dysfunction. Fair correlation was noted among TTPV-12SD, TTCO-12SD, and Tmsv-16SD (r = 0.71, r = 0.73) and between Tmsv-16SD and LV ejection fraction (r = 0.80). Concordance rate between TTPV-12SD and Tmsv-16SD for detecting LV dyssynchrony was 79%. The corresponding value between TTCO-12SD and Tmsv-16SD was 80%. In conclusion, Tmsv-16SD correlated well with DTI-derived LV dyssynchrony indices. In addition to LV remodeling, fast border detection RT3DE provides useful parameters for evaluating LV dyssynchrony.

History of echocardiography and its future applications in medicine

This review concisely presents the chronology of events that shaped the development of echocardiography. The concept of "seeing" structures using "sound" dates back to the 1920s, when ultrasound produced by piezoelectric crystals was used to detect flaws in metals. In the early 1950s, Hertz and Edler described the use of ultrasound for assessing mitral-valve disease. Subsequently, Harvey Feigenbaum in the 1960s standardized the clinical use of M-mode echocardiography for quantitative assessment of left-ventricular dimensions. The advent of 2-dimensional echocardiography (1970s), pulsed Doppler (1970s), and color Doppler (1980s) introduced new methods for routine assessment of cardiac anatomy and hemodynamics at bedside. Flexible scopes and superior transducers further paved the way to the application of transesophageal echocardiography. Tissue Doppler and contrast echocardiography recently have emerged as important tools for evaluation of regional myocardial function and blood flow. Miniaturization and the ability to pack thousands of crystals in an electronic array have transformed the application of 3-dimensional echocardiography into a bedside tomographic tool. At the current pace of development, echocardiography will be able to provide complete assessment of the heart in terms of its anatomy, coronary flow, and physiology. Training people and making it available at every bedside may be the only remaining challenges.

Echocardiography in Heart Failure

Echocardiography is well qualified to meet the growing need for noninvasive imaging in the expanding heart failure (HF) population. The recently-released American College of Cardiology/American Heart Association guidelines for the diagnosis and management of HF labeled echocardiography "the single most useful diagnostic test in the evaluation of patients with HF...," because of its ability to accurately and noninvasively provide measures of ventricular function and assess causes of structural heart disease. It can also detect and define the hemodynamic and morphologic changes in HF over time and might be equivalent to invasive measures in guiding therapy. In this article we will discuss: 1) the clinical uses of echocardiography in HF and their prognostic value; 2) the use of echocardiography to guide treatment in HF patients; and 3) promising future techniques for echocardiographic-based imaging in HF. In addition, we will highlight some of the limitations of echocardiography.

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 left ventricular volumes and function in patients with cardiomyopathies by real-time three-dimensional echocardiography: a head-to-head comparison between two different semiautomated endocardial border detection algorithms

OBJECTIVE

We evaluated two different commercially available real-time 3-dimensional echocardiographic semiautomated border detection algorithms for left ventricular (LV) volume analysis in patients with cardiomyopathy and distorted LV geometry.

METHODS

A total of 53 patients in sinus rhythm with various types of cardiomyopathy (mean age 56 +/- 11 years, 28 men) and adequate 2-dimensional image quality were included. The real-time 3-dimensional echocardiographic multiplane interpolation (MI) and full volume reconstruction (FVR) methods were used for LV volume analysis. Magnetic resonance imaging was used as the reference method.

RESULTS

A strong correlation (R(2) > 0.95) was found for all LV volume and ejection fraction measurements by either real-time 3-dimensional echocardiographic method. Analysis time was shorter with the FVR method (6 +/- 2 vs 15 +/- 4 minutes, P < .01) as compared with the MI method. Bland-Altman analysis showed greater underestimation of end-diastolic and end-systolic volumes by MI compared with FVR. For the MI method a bias of -24.0 mL (-15.0% of the mean) for end-diastolic volume and -11.3 mL (-18.0% of the mean) for end-systolic volume was found. For FVR analysis these values were -9.9 mL (-6.0% of the mean) and -5.0 mL (-9.0% of the mean), respectively. Ejection fraction was similar for the MI and FVR method with a mean difference compared with magnetic resonance imaging of 0.6 (1.0%) and 0.8 (1.3%), respectively.

CONCLUSION

In patients with cardiomyopathy, distorted LV geometry, and good 2-dimensional image quality, the FVR method is faster and more accurate than the MI method in assessment of LV volumes.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Three-Dimensional Echocardiographic Evaluation of the Heart Chambers: Size, Function, and Mass

The major advantage of three-dimensional (3D) ultrasound imaging of the heart is the improvement in the accuracy of the echocardiographic evaluation of cardiac chamber volumes, which is achieved by eliminating the need for geometric modeling and the errors caused by foreshortened 2D views. In this article, we review the literature that has provided the scientific basis for the clinical use of 3D ultrasound imaging of the heart in the assessment of cardiac chamber size, function, and mass, and discuss its potential future applications.

The expanding role of left ventricular functional assessment using gated myocardial perfusion SPECT: the supporting actor is stealing the scene

BACKGROUND

Gating of single-photon emission computed tomography (SPECT) has significantly improved the reliability and diagnostic accuracy of myocardial perfusion imaging. The functional parameters derived from this technique, mainly left ventricular volumes and ejection fraction, have been demonstrated to be accurate and reproducible. They are able to increase the detection of severe and extensive coronary artery disease and show a significant incremental prognostic power over perfusion abnormalities. Therefore, the importance given to gated SPECT functional data has progressively grown.

DISCUSSION

This circumstance has further expanded the indications for myocardial perfusion imaging and strengthened its position among the different imaging modalities. Moreover, several studies show that the evaluation of ventricular function may have a leading part in justifying the execution of perfusion scintigraphy in various clinical conditions.

AIM

Aim of this review is to describe this evolution of gated SPECT functional assessment from a supporting rank with respect to perfusion, to a main actor position in the field of cardiac imaging.

Real-time three-dimensional echocardiography: technological gadget or clinical tool?

The complex anatomy of cardiac structures requires three-dimensional spatial orientation of images for a better understanding of structure and function, thereby improving image interpretation. Real-time three-dimensional echocardiography is a recently developed technique based on the design of an ultrasound transducer with a matrix array that rapidly acquires image data in a pyramidal volume. The simultaneous display of multiple tomographic images allows three-dimensional perspective and the anatomically correct examination of any structure within the volumetric image. As a consequence, it is less operator-dependent and hence more reproducible. Dedicated software systems and technologies are based on high-performance computers designed for graphic handling of three-dimensional images by providing possibilities beyond those obtainable with echocardiography. This methodology allows simultaneous display of multiple superimposed planes in an interactive manner as well as a quantitative assessment of cardiac volumes and ventricular mass in a three-dimensional format without a pre-established assumption of cardiac chamber geometry. In addition, myocardial contraction and/or perfusion abnormalities are clearly identified. Finally, real-time three-dimensional colour Doppler flow mapping enables complete visualisation of the regurgitant jet and new ways of assessing regurgitant lesion severity. Thus, this technique expands the abilities of non-invasive cardiology and may open new doors for the evaluation of cardiac diseases. In this article, current and future clinical applications of real-time three-dimensional echocardiography are reviewed.

Actualización en técnicas de imagen cardiaca. Ecocardiografía, resonancia magnética en cardiología y tomografía computarizada con multidetectores

This article contains a review of the most significant publications on non-invasive recent cardiac imaging techniques in 2005. The increasing importance of technological innovation in echocardiography is reflected in the sections on three dimensional echocardiography, contrast echocardiography, and myocardial deformation measurement techniques (i.e., strain echocardiography). The most important developments affecting cardiology in the techniques of magnetic resonance imaging and multidetector computed tomography are also summarized. This review ends with a detailed description of the contributions made by imaging techniques to the diagnosis of aortic disease.

Three-Dimensional Echocardiography

Over the past 3 decades, echocardiography has become a major diagnostic tool in the arsenal of clinical cardiology for real-time imaging of cardiac dynamics. More and more, cardiologists' decisions are based on images created from ultrasound wave reflections. From the time ultrasound imaging technology provided the first insight into the human heart, our diagnostic capabilities have increased exponentially as a result of our growing knowledge and developing technology. One of the most significant developments of the last decades was the introduction of 3-dimensional (3D) imaging and its evolution from slow and labor-intense off-line reconstruction to real-time volumetric imaging. While continuing its meteoric rise instigated by constant technological refinements and continuing increase in computing power, this tool is guaranteed to be integrated in routine clinical practice. The major proven advantage of this technique is the improvement in the accuracy of the echocardiographic evaluation of cardiac chamber volumes, which is achieved by eliminating the need for geometric modeling and the errors caused by foreshortened views. Another benefit of 3D imaging is the realistic and unique comprehensive views of cardiac valves and congenital abnormalities. In addition, 3D imaging is extremely useful in the intraoperative and postoperative settings because it allows immediate feedback on the effectiveness of surgical interventions. In this article, we review the published reports that have provided the scientific basis for the clinical use of 3D ultrasound imaging of the heart and discuss its potential future applications.

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.

Clinical utility of contrast-enhanced echocardiography

Over the past three decades, echocardiography has become a major diagnostic tool in the arsenal of clinical cardiology for real-time imaging of cardiac dynamics. More and more, cardiologists' decisions are based on images created from ultrasound wave reflections. From the time ultrasound imaging technology provided the first insight into a human heart, our diagnostic capabilities have increased exponentially as a result of our growing knowledge and developing technologies. One of the most intriguing developments that brought about a decade-long combination of expectations and disappointments was the introduction of echocardiographic contrast agents. Despite repeated waves of controversy regarding the readiness of this technology for clinical use, it has overcome multiple hurdles and currently provides useful clinical information that helps cardiologists to diagnose heart disease accurately. Since the initial reports on the use of ultrasound contrast media such as agitated saline or renografin, the major advances in the field of contrast echocardiography have included (1) the development of stable perfluorocarbon-filled microbubbles, frequently referred to as second-generation contrast agents; and (2) the development of contrast-targeted nonlinear imaging modes, such as harmonic imaging, pulse inversion, and power modulation, which allow consistent real-time visualization of these agents. These contrast agents in conjunction with the new imaging technology constitute powerful tools that improve our ability to evaluate left ventricular function and myocardial perfusion, and allow differential diagnosis of thrombi and intravascular masses. In this manuscript, we briefly review some of the literature that has provided the scientific basis for the use of echocardiographic contrast agents in the context of these important variables.