Three-dimensional echocardiography: in-vitro validation of a new, voxel-based method for rapid quantification of ventricular volume in normal and aneurysmal left ventricles

Validation of 3D echocardiographic volume detection of left atrium by human cadaveric casts

BACKGROUND

Left atrial volume is a prognostic factor in cardiac pathologies. We aimed to validate left atrial volume detection with 3D and 2D echocardiography (3DE and 2DE) by human cadaveric casts. 3DE facilitates measurement of atrial volume without geometrical assumptions or dependence on imaging angle in contrast to 2DE methods.

METHODS

For method validation, six water-filled balloons were submerged in a 20-l water tank and their volumes were measured with 3DE. Seven human cadaveric left atrial casts were prepared of silicone and were transformed into ultrasound-permeable casts. Casts were imaged in the same setting, so that 3DE and 2DE of casts represented transthoracic apical view. Left ventricle analysis softwares GE 4D Auto LVQ and TomTec 4D LV-Function were used for 3DE volumetry.

RESULTS

Balloon volumes ranged 37 to 255 ml (mean 126 ml). 3DE resulted in an excellent volumetric agreement with balloon volumes, absolute bias was - 3.7 ml (95% CI -5.9 to - 1.4). Atrial cast volumes were 38 to 94 ml (mean 56.6 ml). 3DE and 2DE volumes were excellently correlated with cast volumes (r = 0.96 to 0.99). Biases were for GE 4D LVQ -0.7 ml (95% CI -6.1 to 4.6), TomTec 4D LV-Function 3.3 ml (- 1.9 to 8.5) and 2DE 2.9 ml (- 4.0 to 9.9). 3DE resulted in lower limits of agreement and showed no volume-related bias in contrast to area-length method.

CONCLUSIONS

We conclude that measurement of human cadaveric left atrial cast volumes by 3DE is in excellent agreement with true cast volumes.

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.

Evaluation of the accuracy and reliability of two 3-dimensional sonography methods in volume measurement of small structures: an in vitro phantom study

PURPOSE

To evaluate the accuracy and reliability of two 3-dimensional (3D) ultrasound imaging and measurement techniques in volume measurements using custom-made phantoms.

METHODS

A total of 20 phantoms with irregular-shaped test objects of known volume (2-9.7 ml) were constructed. The phantoms were scanned using an automated mechanical 3D sonography technique and a free-hand 3D sonography technique. The volumes of the test objects were measured with "parallel planes" and "rotating planes" techniques, respectively. The measured volumes were compared with the actual volumes of the test objects. To evaluate inter- and intraoperator measurement variability, the phantoms were scanned twice by 2 different operators.

RESULTS

Both the automated mechanical and the free-hand 3D sonography techniques were accurate and reliable. Automated mechanical 3D sonography with the parallel planes technique (accuracy, 81.5-83.4%; reproducibility, 91.1%; repeatability, 98.8-99.1%) was slightly more accurate and reliable than the free-hand rotating planes technique (accuracy, 74.7-84.2%; reproducibility, 88.4%; repeatability, 97.3-98%), but the differences were not statistically significant.

CONCLUSION

Both the automated and freehand volume measurement techniques evaluated in this study are accurate and reliable.

A giant inferoposterior true aneurysm of the left ventricle mimicking a pseudoaneurysm

A left ventricular aneurysm (LVA) is most commonly the result of myocardial infarction, usually involving the anterior wall. A left ventricular pseudoaneurysm (LVPSA) or false aneurysm forms when cardiac rupture is contained by adherent pericardium or scar tissue. The accurate diagnosis, although difficult to establish, is an important one to make because these aneurysms are prone to rupture. In this article, we report a challenging case of a cardiac aneurysm a year after a coronary bypass operation which could not be definitively diagnosed despite of imaging with different techniques including echocardiography, coronary angiography, left ventriculography and magnetic resonance imaging (MRI). The patient underwent a second cardiac surgery, the aneurysm was resected, the mitral valve was replaced and the defect in the ventricular wall was repaired. Because of the combined diagnostic capabilities like detailed and functional pathoanatomy and aneurysmal wall characterization, MRI seems to have multiple advantages in differential diagnosis.

Impact of catheter ablation on pulmonary vein morphology and mechanical function

INTRODUCTION

Previous reports have documented that radiofrequency catheter ablation of pulmonary veins induces a significant increase in the peak velocity of transvenous blood flow. Although the magnitude of the increase infers a state of pulmonary vein stenosis, there have been no reports of direct visualization of the ablation zone.

METHODS AND RESULTS

In each of 23 subjects, the myocardium investing one or more pulmonary veins (total of 42 veins) was electrically isolated by applying a confluent circumferential ablation lesion to the atrial side of the venoatrial junction. Doppler measurements of transvenous flow velocity were made before and after ablation using phased-array intracardiac echocardiography. Direct visualization of the ablation zone was performed using rotating intracardiac echocardiography, permitting assessment of shape, cross-sectional area, phasic variation in cross-sectional area, and wall thickness. In a subset of 5 subjects, a more detailed assessment of the ablation and contiguous regions was performed using three-dimensional echocardiography (rotating transducer). Prior to ablation, venoatrial junctions demonstrated noncircular shape and marked phasic variation in cross-sectional area. There was a trivial transvenous pressure gradient. After ablation, there was a significant increase in both anterograde and retrograde flow velocities and pressure gradient, the magnitudes of which were inversely proportional to the preablation and postablation areas. Direct visualization of the ablation zone revealed circumferential wall swelling, reduced cross-sectional area, and diminishment in phasic variation in cross-sectional area. Similar observations were made at contiguous nonablated sites, diminishing in magnitude as a function of distance.

CONCLUSION

Pulmonary vein ablation induces significant acute changes in morphology and mechanical function that extend beyond the ablation zone.

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 Using a Novel Matrix Array Transducer

Three-dimensional echocardiography has multiple advantages over two-dimensional echocardiography, such as accurate left ventricular quantification and improved spatial relationships. However, clinical use of three-dimensional echocardiography has been impeded by tedious and time-consuming methods for data acquisition and post-processing. A newly developed matrix array probe, which allows real-time three-dimensional imaging with instantaneous on-line volume-rendered reconstruction, direct manipulation of thresholding, and cut planes on the ultrasound unit may overcome the aforementioned limitations. This report will review current methods of three-dimensional data acquisition, emphasizing the real-time methods and clinical applications of the new matrix array probe.

Quantification of left ventricular volumes and ejection fraction using freehand transthoracic three-dimensional echocardiography: comparison with magnetic resonance imaging

OBJECTIVES

Our aim was to validate 3-dimensional echocardiography (3DE) for assessment of left ventricular (LV) end-diastolic volume, end-systolic volume (ESV), stroke volume, and ejection fraction (EF) using the freehand-acquisition method. Furthermore, LV volumes by breath hold-versus free breathing-3DE acquisition were assessed and compared with magnetic resonance imaging (MRI).

METHODS

From the apical position, a fan-like 3DE image was acquired during free breathing and another, thereafter, during breath hold. In 27 patients, 28 breath hold- and 24 free breathing-3DE images were acquired. A total of 17 patients underwent both MRI and 3DE. MRI contours were traced along the outer endocardial contour, including trabeculae, and along the inner endocardial contour, excluding trabeculae, from the LV volume.

RESULTS

All 28 (100%) breath hold- and 86% of free breathing-3DE acquisitions could be analyzed. Intraobserver variation (percentual bias +/- 2 SD) of end-diastolic volume, ESV, stroke volume, and EF for breath-hold 3DE was, respectively, 0.3 +/- 10.2%, 0.3 +/- 14.6%, 0.1 +/- 18.4%, and -0.1 +/- 5.8%. For free-breathing 3DE, findings were similar. A significantly better interobserver variability, however, was observed for breath-hold 3DE for ESV and EF. Comparison of breath-hold 3DE with MRI inner contour showed for end-diastolic volume, ESV, stroke volume, and EF, a percentual bias (+/- 2 SD) of, respectively, -13.5 +/- 26.9%, -17.7 +/- 47.8%, -10.6 +/- 43.6%, and -1.8 +/- 11.6%. Compared with the MRI outer contour, a significantly greater difference was observed, except for EF.

CONCLUSIONS

3DE using the freehand method is fast and highly reproducible for (serial) LV volume and EF measurement, and, hence, ideally suited for clinical decision making and trials. Breath-hold 3DE is superior to free-breathing 3DE regarding image quality and reproducibility. Compared with MRI, 3DE underestimates LV volumes, but not EF, which is mainly explained by differences in endocardial contour tracing by MRI (outer contour) and 3DE (inner contour) of the trabecularized endocardium. Underestimation is reduced when breath-hold 3DE is compared with inner contour analysis of the MRI dataset.