3-DIMENSIONAL AND 4-DIMENSIONAL ECHOCARDIOGRAPHY

Since its introduction in 1974, 3-D reconstruction of the heart has undergone significant technological refinements in image acquisition, processing and display techniques. Image acquisition for transthoracic 3-D reconstruction utilizes the parasternal or apical windows, or combinations of the two, The parasternal approach allows better endocardial border detection, while the apical approach allows a more complete visualization of the left ventricular apex. Computer algorithms are used to process images with various display techniques incorporated into the algorithm. Transesophageal image acquisition overcomes a significant limitation of the transthoracic approach, which is variable and sometimes poor image quality. Both a multiplane approach and a computerized tomographic approach have been successfully used by several investigators. Potential applications of 3-D echocardiography include reconstruction of the mitral annulus, dynamic cardiac anatomy and function and volume calculations. A major limitation is the need for considerable computer time for image processing and display; furthermore, errors may be introduced by the various smoothing and contouring algorithms. Despite these limitations, 3-D echocardiography has considerable potential for clinical utility, particularly in the areas of reconstructive cardiac surgery and congenital heart disease.