Assessment of left ventricular function by three-dimensional echocardiography

Accurate quantification of left ventricular (LV) volume and function is important in clinical decision-making and follow-up assessment. Although various other techniques including invasive angiography, radionuclide angiography and magnetic resonance imaging are used, echocardiography is currently the most commonly applied modality in the practice of cardiology.M-mode echocardiography, a one dimensional ultrasound scanning of the cardiac structures, was developed in the early 1970s and immediately applied in practice for left ventricular function assessment because of its simple algorithm and non-invasiveness. Ejection fraction was estimated as a percentage derived from the mid left ventricular diameters in end-systole and end-diastole and expressed as fractional shortening. However, serious problems were raised especially in patients with myocardial infarction and asymmetric ventricles.Two-dimensional sectional echocardiography, with the ability of imaging of the heart in tomographic views, considerably improved the accuracy of left ventricular volume measurement. Of the different mathematical models, modified biplane Simpson's rule provided more accurate data in both symmetric and asymmetric left ventricles. Software-based algorithms for automatic endocardial border detection and on-line calculation of left ventricular volume and ejection fraction have been developed. As a result, two-dimensional echocardiography has become a routine examination for left ventricular volume and function assessment but the assumptions about LV geometry remain a limitation.In the past decade, three-dimensional echocardiography has emerged as a more accurate and reproducible approach to LV quantitation mainly by avoiding the use of geometric assumptions of the LV shape. Three methods have been proposed for the acquisition of temporal and positional image data: the use of positional locators (free-hand scanning), rotational systems and real-time volumetric scanning. Reconstruction metho