Improved quantification of left ventricular mass based on endo- and epicardial surface detection using real-time three-dimensional echocardiography

Objective: Our goal was to develop a technique for volumetric analysis of real-time three-dimensional echocardiography (RT3DE) data aimed at quantification of LV mass and validate it against magnetic resonance (MR) assumed as “gold standard”. Design: RT3DE, which has recently become widely available, provides dynamic pyramidal data structures that encompass the entire heart and allows four-dimensional assessment of cardiac anatomy and function. However, analysis techniques for the quantification of left ventricular (LV) mass from RT3DE data are fundamentally twodimensional, rely on geometric modelling and do not fully exploit the volumetric information contained in RT3DE datasets. Twenty-one patients underwent 2D echocardiography (2DE), RT3DE and cardiac MR. LV mass was measured from 2DE and MR images using conventional techniques. RT3DE data were analyzed to semiautomatically detect endocardial and epicardial LV surfaces using the level-set approach. From the detected surfaces, LV mass was computed directly in the 3D space as voxel counts. Results: RT3DE measurements were feasible in 19/21 patients and resulted in higher correlation with MR (r=0.96) than 2DE (r=0.79). RT3DE measurements also had a significantly smaller bias (-2.1g) and tighter limits of agreement (2SD:±23g) with MR than the 2DE values (bias (2SD):-34.9 (50) g). Additionally, interobserver variability of RT3DE (12.5%) was significantly lower than that of 2DE (24.1%). Conclusions: Direct 3D model-independent LV mass measurements from RT3DE images are feasible in the clinical setting and provide fast and accurate assessment of LV mass, superior to the 2D analysis techniques.