FOCUS : Echocardiography Three - Dimensional Echocardiography State - of - the - art 1999

Three-dimensional echocardiography depicts the heart and its structures in their realistic forms. This capability decreases variability both in the quality and the interpretation of complex pathology, among investigators. Therefore, it is likely that the method will become the standard echocardiography examination in the future. The availability and versatility of the volumetric data set obtained allows retrieval of an infinite number of cardiac cross-sections. The technique, by obviating geometric assumptions, is more accurate and reproducible for measurements of valve areas, masses and cavity volumes. In the future, additional information will be provided by new physiologic parameters, which may provide answers to new clinical questions. Three-dimensional imaging to objectively view the heart and its structures is already " state-of-the-art. " However, progress in three-dimensional echocardiography has been rather slow since the first attempts were made in the early 1970s. In its early stage, three-dimensional echocardiography was applied mainly in volume measurement of the ventricles using multiple cross-sectional images that employ laborious manual tracing of the cardiac borders. 1-8 Reconstruction of those tracings into static wire-frame pictures demonstrated the shape of the ventricular cavity, but did not provide tissue-depicting information. 9-11 Recently, along with the rapid evolution in computer technology, three-dimensional echocardiography has grown into a well-developed imaging modality, able to display dynamic images of cardiac structures in their realistic forms that depict depth and contain tissue information. 12-16 Many clinical and experimental studies have demonstrated that the method is now ready for clinical application. A. Real-time three-dimensional echocardiography The ideal, but technically the most challenging direction, is real-time three-dimensional imaging when the ultrasound examination is performed. A real-time volumetric ultrasound imaging system has been developed by Von Ramm et al. of Duke University, 16,23 and is based on novel matrix phased-array transducer technology. The elements are arranged in a two-dimensional grid. Using parallel processing techniques, the matrix array offers steering in both the beam's azimuth and elevation, which compensates for the fundamental limitation of speed of ultrasound in tissue. This permits scan of a pyramidal volume at the same time. This mode of three-dimensional echocardiography has great potential in improving anatomical visualization, fast diagnosis of morphological cardiac disorders, left ventricular function assessment, and regional or global wall motion analysis in various situations, including stress or exercise tests. Due to a short image acquisition time, this method is optimal for myocardial perfusion study in combination with myocardial contrast agents. So far, this method …