FREEHAND 3-DIMENSIONAL ECHOCARDIOGRAPHY FOR DETERMINATION OF LEFT-VENTRICULAR VOLUME AND MASS IN PATIENTS WITH ABNORMAL VENTRICLES - COMPARISON WITH MAGNETIC-RESONANCE-IMAGING

Objective: The objective of this study was to validate the freehand th ree-dimensional echocardiographic method in patients with abnormal ven tricular geometry compared with two-dimensional echocardiography using magnetic resonance imaging as a standard. Background: Two-dimensional echocardiographic methods for estimating left ventricular volume and mass in clinical use today are limited by inaccuracies and variations caused by use of geometric assumptions and errors in image plane posit ioning. Freehand three-dimensional echocardiography with operator guid ance by a ''line of intersection'' display eliminates these assumption s and errors. This method of volume and mass computation has been vali dated as highly accurate and reproducible in healthy subjects. Methods : Left ventricular end-systolic and end-diastolic volumes and myocardi al mass were determined by freehand three-dimensional echocardiography , by conventional two-dimensional echocardiography using the apical bi plane summation of discs method (volume) and the truncated ellipsoid m ethod (mass), by M-mode echocardiography using the Penn method (mass), and by magnetic resonance imaging in 30 patients selected only for th e presence of an abnormal ventricle. Results were compared by means of linear regression and the Bland-Altman method of analysis. Results: T here was excellent correlation, low bias, and low variability between three-dimensional echocardiography and magnetic resonance imaging for end-diastolic volume (r = 0.90, standard error of the estimate = 31.8 ml, bias = -28.4 ml), end-systolic volume (r = 0.93, standard error of the estimate = 24.1 ml, bias = -13.1 ml), and mass (r = 0.90, standar d error of the estimate = 27.3 gm, bias = -22.6 ml). Two-dimensional e chocardiography was less accurate and more variable as follows: end-di astolic volume (r = 0.70, standard error of the estimate = 39.8 ml, bi as = -33.5 ml), end-systolic volume (r = 0.78, standard error of the e stimate = 31.2 ml, bias = -26.7 ml), and mass (r = 0.80, standard erro r of the estimate = 37.3 gm, bias = 28.9 ml). M-mode echocardiography mass determination (Penn method) was least accurate and most variable (r = 0.075, standard error of the estimate = 78.3 gm, bias = 78.3 gm). Conclusions: Freehand three-dimensional echocardiography is a method of high accuracy and low variability for computing left ventricular vo lume and mass in clinical patients with abnormal ventricles. It is sup erior to conventional one-and two-dimensional echocardiography. The im provement achieved is attributed to elimination of geometric assumptio ns and image plane positioning errors and additional sampling of the v entricle.