Four‐Dimensional Reconstruction of Two‐Dimensional Echocardiographic Images

Real-time two-dimensional echocardiography represents a simple, relatively inexpensive noninvasive technique that has been used extensively to assess left ventricular function, which is a major determinant of prognosis in patients with cardiac disease.ls2 A major drawback of two-dimensional echocardiography is that the left ventricle is assumed to have a known geometric shape, and thus, it cannot be used to accurately quantify left ventricular function, especially in those patients with coronary artery disease in whom the left ventricular shape may be markedly distorted due to the presence of a large dyskinetic area or frank aneurysm formation.'-' As a result, there have been several attempts using the computer to reconstruct the left ventricle, in three dimensions using multiple serial two-dimensional echocardiographic planes obtained as transverse scans'' or by rotating the transducer from the cardiac apex."-13 Because the presence of intervening ribs makes it impossible to obtain serial multiple contiguous transverse slices through the left ventricle, the apical approach, which is free from these limitations, is preferred." With this method, however, the left ventricular endocardium is interrogated in a parallel rather than a perpendicular orientation, often leading to loss of resolution and incomplete delineation of the endocardial boundary. Therefore, a digital processing method needs to be developed that would enhance the left ventricular endocardia1 boundary. Interest has also been evinced in producing and displaying a three-dimensional echocardiogra-