Quantification of Left Ventricular Linear, Areal and Volumetric Dimensions: A Phantom and in Vivo Comparison of 2-D and Real-Time 3-D Echocardiography with Cardiovascular Magnetic Resonance.

Two-dimensional echocardiography and real-time 3-D echocardiography have been reported to underestimate human left ventricular volumes significantly compared with cardiovascular magnetic resonance. We investigated the ability of 2-D echocardiography, real-time 3-D echocardiography and cardiovascular magnetic resonance to delineate dimensions of increasing complexity (diameter-area-volume) in a multimodality phantom model and in vivo, with the aim of elucidating the main cause of underestimation. All modalities were able to delineate phantom dimensions with high precision. In vivo, 2-D and real-time 3-D echocardiography underestimated short-axis end-diastolic linear and areal and all left ventricular volumetric dimensions significantly compared with cardiovascular magnetic resonance, but not short-axis end-systolic linear and areal dimensions. Underestimation increased successively from linear to volumetric left ventricular dimensions. When analyzed according to the same principles, 2-D and real-time 3-DE echocardiography provided similar left ventricular volumes. In conclusion, echocardiographic underestimation of left ventricular dimensions is due mainly to inherent technical differences in the ability to differentiate trabeculated from compact myocardium. Identical endocardial border definition criteria are needed to minimize differences between the modalities and to ensure better comparability in clinical practice.