Three-dimensional echocardiography: in-vitro validation of a new, voxel-based method for rapid quantification of ventricular volume in normal and aneurysmal left ventricles.

BACKGROUND: Previous approaches to ventricular volume calculations by 3-dimensional echocardiography (3-DE) required multiple transverse tomographic sectioning and summation of the volumes of parallel disks. These methods were time consuming and beared the risk of missing the apical volume.
METHODS: We investigated the accuracy of a new, rapid method of 3-DE volume measurements in normal (LV) and aneurysmal (aneurLV) left ventricles in fixed pig hearts. 3-D data sets of 12 LV and 8 experimentally created aneurLV were obtained using a TomTec 3-DE system. For 3-DE volume calculations, a rotational axis in the center of the left ventricle (apical-basal orientation) was defined and 3, 6 and 12 equi-angular rotational planes were created. In each plane the endocardial border was traced and the volume of the corresponding wedge was automatically calculated. The measurements were performed by 2 independent investigators blinded to the anatomic volume and were analyzed for inter- and intraobserver variability.
RESULTS: The anatomic volumes ranged from 5 to 150 ml and 9 to 40 ml in LV and aneurLV, respectively. The correlation between 3-DE and anatomic volume was excellent for LV and aneurLV traced in 3, 6 and 12 planes (r = 0.94-0.99). Ventricular volume was well predicted by 3-DE reconstruction: SEE 5.5-7.1 ml (LV), 3.0-3.2 ml (aneurLV). The correlation for interobserver measurements was good in both, LV (r = 0.99) and aneurLV (r = 0.94-0.99) even in 3 planes. The intra- and interobserver variabilities were 1.6-3.0 ml (<7%) and 7.2-7.3 ml (<15%) in LV and 1.1-1.6 (<6%) and 2.1-3.3 ml (<14%) in aneurLV respectively.
CONCLUSION: This new 3-DE method of ventricular volume measurements using a rotational approach provides rapid, accurate and reproducible volume measurements in LV and aneurLV.