3-Dimensional Echocardiographic Measurement Of Left-Ventricular Volume In-Vitro - Comparison With 2-Dimensional Echocardiography And Cineventriculography

Objectives. This study was designed to compare three dimensional echocardiography, two dimensional echocardiography and cineventriculography for the purpose of measuring left ventricular volume in vitro. Background. Three dimensional echocardiographic systems have been shown to be highly accurate in measuring the volumes of balloon phantoms. However, three-dimensional techniques have not been compared with standard two dimensional echocardiography in vitro or with cineventriculography, the clinical standard for left ventricular volume measurement. Methods. Excised porcine hearts were prepared with an internal latex sheath that could be filled and maintained with a known (''true'') volume of liquid. Each heart was then imaged by cineventriculography, standard two dimensional echocardiography and three dimensional echocardiography. Left ventricular volumes were calculated from 15 hearts at 25 volumes ranging from 50 to 280 ml by the following methods: 1) biplane cineventriculography using the area length method; 2) two dimensional echocardiography by the apical biplane method using a summation of discs algorithm in 15 cases and the single plane, four-chamber method using a summation of discs algorithm in 10 cases; and 3) three dimensional echocardiography using a polyhedral surface reconstruction volume computation algorithm based on multiple nonparallel, nonevenly spaced short axis cross sections. Results. Results were compared with true volume, and a nonparametric analysis of variance was performed. Both measurement bias (systematic error) and imprecision (random error) were assessed. Ah methods tended to underestimate the true volume (two dimensional echocardiography -6.1 +/- 17.6%, three dimensional echocardiography -4.7 +/- 5.0% and biplane cineventriculography -3.9 +/- 8.2%), although differences were not significant. Although there was a significant correlation between the magnitude of measurement bias and the size of the volume being measured for two dimensional echocardiography and cineventriculography, the bias of three dimensional echocardiography was fairly constant over the range of volumes. When bias was accounted for, two dimensional echocardiography was significantly less precise than cineventriculography and three-dimensional echocardiography in terms of percent error (15.3 +/- 11.9%, 5.6 +/- 5.7% and 3.9 +/- 3.4%, respectively). Conclusions. Three dimensional echocardiography using a polyhedral surface reconstruction algorithm for volume computation provides accuracy comparable to that of biplane cineventriculography in this in vitro model. Standard two-dimensional echocardiographic volume computation is significantly less accurate than the other two methods.