Development of real-time three-dimensional ultrasound system without reconstruction and its clinical application in cardiac surgery.

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Three-dimensional (3-D) reconstruction of the heart using consecutive 2-D echo images is associated with several problems. The processing from data acquisition to 3-D display is generally time consuming. These problems limits clinical use of 3-D Echocardiography in cardiovascular surgical fields. The purpose of this research was to develop a new 3-D ultrasound system which delineates spatially the boundaries of intracardiac structure in real time and to evaluate its clinical feasibility in mainly valvular heart diseases. The newly developed real-time 3-D ultrasound system by the present research can acquire volumetric data from mechanical scanning of the phased array transducer (3.5MHz) and display the volume rendered images without storage of the image data and reconstruction process. This system allows not only real-time data acquisition but 3-D display. In the first research year (1998), 3-D images of the intracardiac structure intcluding left ventricle and mitral valve were clearly … More and correctly obtained in 16 of 20 patients (pts.) using the new system by transthoracic approach. In 4 pts.of this series, the penetration of ultrasound beam was disturbed by the chest wall resulting in suboptimal imaging caused by the large size of a probe. In the 2nd research year (1999), the frame rate of 3-D imaging was increased up to 8 f/sec using digital parallel processing. This device offered the improved image quality of real-time 3-D imaging by transthoracic approach. 24 pts. (10 ; normal heart, 14 ; mitral heart disease) were examined using the improved system by transthoracic approach. In all 10 normal hearts, the cavity of left ventricle and mitral valve structure was clearly visualized. In 11 of 14 pts.with mitral disease, pathologies of mitral valve were imaged correctly in real-time. In 3ts.of this series, penetration of ultrasound was insufficient causing poor 3-D imaging. In conclusion, the newly developed real-time 3-D ultrasound system without reconstruction process was shown to be clinically feasible for imaging of spatial anatomy of the mitral, valve and the cavity of the left ventricle in real time. With further technological improvement, this new system, used by direct epicardial approach, has the potential usefulness in increasing the accuracy of repairing procedures in cardiac surgery. Less