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The recent advent of real-time 3-D ultrasound (3DUS) imaging enables a variety of surgical procedures to be performed within the beating heart. Implementation of these procedures is hampered by the difficulty of manipulating tissue guided by the distorted, low resolution 3DUS images and the dexterity constraints imposed by the confined intracardiac space. This paper investigates the use of surgical robotics in conjunction with 3DUS to overcome these limitations. In addition, it describes the development of a graphics processor based volume renderer for real-time stereo visualization of the ultrasound data. Stereo displayed 3DUS was compared to 2D- displayed 3DUS and endoscopic guidance with a user study. Five subjects performed in vitro surgical tasks using a surgical robot. Results indicate that subjects were able to complete surgical tasks 35% faster with stereo-displayed 3DUS images compared to conventional two dimensional display of 3DUS.

New 3D ultrasound visualization has enabled minimally invasive, beating-heart intracardiac procedures. However, rapid motion of internal heart structures limits the realization of these new procedures. This paper investigates the concept of using a single actuator to compensate for tissue motions which occur largely in one direction. We characterize mitral valve annulus motion and show that it is well approximated by a ID model. The subsequent development of a motion-compensating tool (MCT) is described. The resulting instrument was tested in user trials under a series of positional error and tracking delay conditions. Results indicate that the MCT provides an approximately 50% increase in dexterity and 50% decrease in applied force in comparison to a solid tool. The study also shows that MCT tracking efficacy is highly dependent on tracking delays, indicating the importance of predictive, cyclical control algorithms.

Background The recent advent of real-time 3D ultrasound (3DUS) imaging enables a variety of new surgical procedures. These procedures are hampered by the difficulty of manipulating tissue guided by the distorted, low-resolution 3DUS images. To lessen the effects of these limitations, we investigated stereo displays and surgical robots for 3DUS-guided procedures. Methods By integrating real-time stereo rendering of 3DUS with the binocular display of a surgical robot, we compared stereo-displayed 3DUS with normally displayed 3DUS. To test the efficacy of stereo-displayed 3DUS, eight surgeons and eight non-surgeons performed in vitro tasks with the surgical robot. Results Error rates dropped by 50% with a stereo display. In addition, subjects completed tasks faster with the stereo-displayed 3DUS as compared to normal-displayed 3DUS. A 28% decrease in task time was seen across all subjects. Conclusions The results highlight the importance of using a stereo display. By reducing errors and increasing speed, it is an important enhancement to 3DUS-guided robotics procedures. Copyright © 2006 John Wiley & Sons, Ltd.