Accurate measurement of left ventricular ejection fraction by three-dimensional echocardiography - A comparison with radionuclide angiography

Background Three-dimensional echocardiography is a promising technique for calculation of left ventricular ejection fraction, because it allows its measurement without geometric assumptions. However, few data exist that study its reproducibility and accuracy in patients. Methods and Results Twenty-five patients underwent radio-nuclide angiography and three-dimensional echocardiography that used the rotational technique (2 degrees interval and ECG and respiratory gating). Left ventricular volume and ejection fraction were calculated by use of Simpson's rule at a slice thickness of 3 mm. Analyses were performed to define the largest slice thickness required for accurate calculation of left ventricular volume and ejection fraction. Three-dimensional echocardiography showed excellent correlation with radionuclide angiography for calculation of left ventricular ejection fraction (mean+/-SD, 38.9+/-19.8 and 38.5+/-18.0, respectively; r=.99); their mean difference was not significant (0.03+/-0.17; P=3), and they had a close limit of agreement (-0.385, 0.315). Intraobserver variability for radionuclide angiography and three-dimensional echocardiography was 4.2% and 2.6%, respectively, whereas interobserver variability was 6.2% and 5.3%, respectively. There was no significant difference between left ventricular volume adn ejection fraction calculated at a slice thickness of 3 mm and that calculated at different slice thicknesses up to 24 mm. However, the standard deviation of the mean difference showed a stepwise increase, particularly at thicknesses >15 mm. At a slice thickness of 15 mm, the probability of three-dimensional echocardiography to detect greater than or equal to 6% difference in ejection fraction was 80%. Conclusions Three-dimensional echocardiography has excellent correlation with radionuclide angiography for calculation of left ventricular ejection fraction in patients and has an observer variability similar to that of radionuclide angiography. We recommend the use of a 15-mm-thick slice for accurate and rapid measurement of left ventricular volume and ejection fraction.