Estimation of left ventricular volume based on real-time 3D echocardiography: An in vitro validation study

Accurate evaluation of left ventricular (LV) volume and ejection fraction (EF) has important diagnostic and therapeutic implications; therefore a reproducible, rapid and exact method of calculating these indices is important. In this study a computerized semi-automatic method for LV chamber segmentation is proposed. Left ventricle is imaged by real-time three dimensional echocardiography (RT3DE). This method allows to evolve a three-dimensional surface in an accurate and numerically stable way. The initial condition is manually established on a small subset of data slices for the entire volume and the solution obtained is the surface between LV cavity and LV endocardium. Thirteen phantoms filled with water (volume range 68-256 ml) have been acquired by RT3DE system and processed to obtain volume estimates. An excellent relationship was found between volume measured by the level set method and the actual volume (r = 0.99, y = 1.01x - 3.65, Delta = -2.45 +/- 7.47 ml, n = 14, p < 0.0001). The intraobserver variability was -1 +/- 5 %. Our hi vitro study demonstrated the accuracy of level set method for semi-automatically quantifying LV volume.