Theoretical estimation and measurement of accuracy and variability in left ventricular volume and mass quantification using three-dimensional echocardiography

Accurate left ventricular (LV) volume and mass estimation is a strong predictor of cardiovascular morbidity and mortality. The authors propose that their technique of 3D echocardiography provides an accurate quantification of LV volume and mass, by reconstruction of 2D images into 3D volumes, thus avoiding the need for geometric assumptions. The authors compared the accuracy and variability in LV volume and mass measurement using 3D echocardiography with 2D echocardiography, using in vitro studies. Six operators measured the LV volume and mass of 7 porcine hearts, using both 3D and 2D techniques. Regression analysts was used to test accuracy results and an ANOVA test was used to compute variability in measurement. In the authors' theoretical analysis, they derive the equation for fractional variability in measurement of LV volume and mass using 3D echocardiography. This analysis shows that the fractional variability in LV volume and mass measurement depends on the number of image slices and the uncertainty in locating the edge between tissue and the surrounding fluid in the image. LV volume measurement accuracy was 9.8% (3D) and 18.4% (2D); LV mass measurement accuracy was 5% (3D) and 9.2% (2D). Variability in LV volume quantification with 3D echocardiography was %SEM_inter=13.5%; %SEM_intra=11.4%, and for 2D echocardiography was %SEM_inter=21.5%; %SEM_intra=19.1%. 3D echocardiography provided twice the accuracy for LV volume and mass measurement and half the variability for LV volume measurement as compared with 2D echocardiography. The authors' theoretical prediction of uncertainty in LV volume and mass measurement using 3D echocardiography agreed with their experimental results to within 13%