In the past, given the dynamic nature of the heart, real-time 3D ultrasound imaging of this organ has not been technically feasible. Echocardiographic evaluations in everyday clinical practice have tended to use 2D datasets. But Siemens ACUSON SC2000^TM volume imaging ultrasound system uses technological innovations such as In Focus technology, which allows each transducer to collect data from overlapping scan lines enabling focal zones at all depths generating real-time 3D datasets. Moreover, the frame rate is high enough that, for the first time, full volume 90 by 90 degree 3D images of the heart can be generated without the need to stitch subvolumes together. Cardiologists, accustomed as they are to two-dimensionality, are only just beginning to understand the full potential of this high-speed 3D imaging.

Many echocardiographic parameters that are estimated from 2D datasets are based on assumptions that are not necessarily true. For example, in mitral regurgitation, 2D color Doppler measurements require an assumption of sphericity of flow for the calculation of effective regurgitant orifice (ERO) area using Proximal Isovelocity Surface Area (PISA). In many situations, the flow convergence area of mitral regurgitation is not a perfect sphere, preventing accurate calculations of ERO. Another example is the calculation of left-ventricular ejection fraction. Once again, certain assumptions are made concerning ventricular symmetry that – in certain instances such as patients with aneurysm – are unlikely to hold true.

In both the examples above, 3D imaging can be applied to obtain an answer that is free from assumptions. In the case of left ventricular ejection fraction, functionality is already available with the ACUSON SC2000 system for automatic measurement of the parameter. For mitral regurgitation, investigators at the Hospital Clínico San Carlos in Madrid, Spain, are working on validating the use of 3D datasets for calculating this parameter.