Three-dimensional echocardiography: In vitro and in vivo validation of left ventricular mass and comparison with conventional echocardiographic methods

Abstract

OBJECTIVES: This study aimed to validate a method for mass computation in vitro and in vivo and to compare it with conventional methods. BACKGROUND: Conventional echocardiographic methods of determining left ventricular mass are limited by assumptions of ventricular geometry and image plane positioning. To improve accuracy, we developed a three-dimensional echocardiographic method that uses nonparallel, nonintersecting short-axis planes and a polyhedral surface reconstruction algorithm for mass computation. METHODS: Eleven fixed hearts were imaged by three-dimensional echocardiography, and mass was determined in vitro by multiplying the myocardial volume by the density of each heart and comparing it with the true mass. Mass at diastole and systole by three-dimensional echocardiography and magnetic resonance imaging (MRI) was compared in vivo in 15 normal subjects. Ten subjects also underwent imaging by one- and two-dimensional echocardiography, and mass was determined by Penn convention, area-length and truncated ellipsoid algorithms. RESULTS: In vitro results were r = 0.995, SEE 2.91 g, accuracy 3.47%. In vivo interobserver variability for systole and diastole was 16.7% to 27%, 14% to 18.1% and 6.3% to 12.8%, respectively, for one-, two- and three-dimensional echocardiography and was 7.5% for MRI at end-diastole. The latter two agreed closely with regard to diastolic mass (r = 0.895, SEE 11.1 g) and systolic mass (r = 0.926, SEE 9.2 g). These results were significantly better than correlations between MRI and the Penn convention (r = 0.725, SEE 25.6 g for diastole; r = 0.788, SEE 28.7 g for systole), area-length (r = 0.694, SEE 24.2 g for diastole; r = 0.717, SEE 28.2 g for systole) and truncated ellipsoid algorithms (r = 0.687, SEE 21.8 g for diastole; r = 0.710, SEE 24.5 g for systole). CONCLUSIONS: Image plane positioning guidance and elimination of geometric assumptions by three-dimensional echocardiography achieve high accuracy for left ventricular mass determination in vitro. It is associated with higher correlations and lower standard errors than conventional methods in vivo.