3-D ultrasound guidance of surgical robotics: a feasibility study.

Laparoscopic ultrasound has seen increased use as a surgical aide in general, gynecological, and urological procedures. The application of real-time, three-dimensional (RT3D) ultrasound to these laparoscopic procedures may increase information available to the surgeon and serve as an additional intraoperative guidance tool. The integration of RT3D with recent advances in robotic surgery also can increase automation and ease of use. In this study, a 1-cm diameter probe for RT3D has been used laparoscopically for in vivo imaging of a canine. The probe, which operates at 5 MHz, was used to image the spleen, liver, and gall bladder as well as to guide surgical instruments. Furthermore, the three-dimensional (3-D) measurement system of the volumetric scanner used with this probe was tested as a guidance mechanism for a robotic linear motion system in order to simulate the feasibility of RT3D/robotic surgery integration. Using images acquired with the 3-D laparoscopic ultrasound device, coordinates were acquired by the scanner and used to direct a robotically controlled needle toward desired in vitro targets as well as targets in a post-mortem canine. The rms error for these measurements was 1.34 mm using optical alignment and 0.76 mm using ultrasound alignment.

Real-time stereo 3D ultrasound.

Real-time 3D ultrasound was developed at Duke University in 1991 and has since been used with a variety of transducers and shown effectiveness in clinical applications and in vivo animal imaging studies. Methods for displaying the 3D pyramid of data acquired by the system include selecting 2D image slices or integrating data into a volume rendered view. A third method, real-time stereo 3D imaging, is discussed here. The clinical commercial 3D system has been modified in our laboratory to display a real-time stereo image pair on the scanner display to be viewed through a stereoscope. This merges the pair into a single image, with a sensation of depth. Stereoscopic displays have previously been demonstrated to provide benefits, including improved depth judgments and increased perception of image quality in other applications. Previously-saved volumes of ultrasound data are shown in stereo 3D using the new system.