ACCURATE MEASUREMENT OF LEFT-VENTRICULAR EJECTION FRACTION BY 3-DIMENSIONAL ECHOCARDIOGRAPHY - A COMPARISON WITH RADIONUCLIDE ANGIOGRAPHY

Background Three-dimensional echocardiography is a promising technique for calculation of left ventricular ejection fraction, because it all ows its measurement without geometric assumptions. However, few data e xist that study its reproducibility and accuracy in patients. Methods and Results Twenty-five patients underwent radio-nuclide angiography a nd three-dimensional echocardiography that used the rotational techniq ue (2 degrees interval and ECG and respiratory gating). Left ventricul ar volume and ejection fraction were calculated by use of Simpson's ru le at a slice thickness of 3 mm. Analyses were performed to define the largest slice thickness required for accurate calculation of left ven tricular volume and ejection fraction. Three-dimensional echocardiogra phy showed excellent correlation with radionuclide angiography for cal culation 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 agreemen t (-0.385, 0.315). Intraobserver variability for radionuclide angiogra phy and three-dimensional echocardiography was 4.2% and 2.6%, respecti vely, whereas interobserver variability was 6.2% and 5.3%, respectivel y. There was no significant difference between left ventricular volume adn ejection fraction calculated at a slice thickness of 3 mm and tha t 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 t han or equal to 6% difference in ejection fraction was 80%. Conclusion s Three-dimensional echocardiography has excellent correlation with ra dionuclide angiography for calculation of left ventricular ejection fr action 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 ejec tion fraction.