Introduction:

The implementation of diagnostic imaging as a means of navigating during surgery has been a focus of interest with recent advances in technology. The impetus for development lies in the potential utility to limit the invasiveness of the actual dissection, to minimize damage to adjacent tissues and to avoid injury to critical structures that are in the vicinity of the area of interest. Although stereotactic biopsy is already in use by interventional radiologists, a surgical tool that can augment an operator’s visual field with radiographic imaging is of obvious utility in complicated operations with high risk of collateral damage.
The DaVinci operator console has a great capacity to incorporate various data inputs and make them available to the operating surgeon. The aim of our experiment was to evaluate current design and technological limitations of the robotic system that need to be overcome in the incorporation of imaging and video modalities.

Method:

The video output of a C-arm portable fluoroscopic machine (OEC 9800, General Electric; Salt Lake City, UT) was spliced into the viewing console of the DaVinci robot (Intuitive Surgical, Sunnyvale, CA) through a video mixer (Panasonic; Japan). It was noted at the initial setup that the robotic camera arm and fluoroscopic collimator unavoidably collide at all times—regardless of the lens angle—and that they could not be used together. Therefore an external live video feed from a 10 mm (0o and 30o) video conventional laparoscope was spliced into the video mixer and subsequently into the robotic console. Once the setup was verified, the video mixer was adjusted to 50% opacity for each input. This image overlay arrangement was then applied to a bench model to evaluate image disparity and distance measurements. This was accomplished by using radiopaque markers of known size and rulers placed in the field

Results:

The initial setup involving the robotic camera and fluoroscope was not possible. The collimator and the robotic arm holding the camera collided in every configuration attempted and this was aborted in favor of a conventional laparoscope. Our first experience employed conventional laparoscopes and the c-arm in a bench model. When a 0o laparoscope and fluoroscope were attempted, the images could be closely overlaid, but only if the laparoscope was in the path of the collimator with an identical focal point. This positioning created a fluoroscopic blind spot that is unacceptable. The use of a 30 degree lens gave a better view, but the part of the lens was still visible within the fluoroscopic image. While observing the overlaid images within the console of the DaVinci robot, the two were superimposed with the aid of radiopaque markers and rulers. After near-perfect superimposition, movement of the instruments in the vertical plane resulted in disparity of the images. Also noted was the fact that as the instruments moved further from the collimator the disparity became greater and there was enlargement of the resultant instrument image. It was clear from this bench model that radiographic superimposition was impractical because alignment could only be achieved in one vertical plane. Our second experience, with a picture-in-picture configuration, involved performing portions of a robotic cholecystectomy in a large animal model. A live cholangiogram was performed, aiding the dissection and allowing visualization of the biliary tree. The common bile duct and duodenum were fluoroscopically evident at all times, preventing injury to these vital structures during dissection. Attention was the turned to the right posterior peritoneal cavity. An intravenous injection of iodinated contrast resulted in a live pyelogram. This was useful in helping quickly locate the ureter and dissect the posterior peritoneum with confidence in an attempt to isolate it. Injury to the ureter was avoided since it was visible at all times.

Conclusion:

The surgical robot has technological hurdles which it must overcome in order to reach its potential for being a truly integrated platform for surgery. Fluoroscopic image overlay is not practical secondary to disparity in multiple planes—it is not possible for both the operative target and the surgical instruments to be in alignment at the same time. This is largely due to the physical differences between visible light and x-rays. Different light wavelengths or ultrasound, both of which are reflected off the object of interest, have the potential to overcome image disparity when combined with video input. Current technology allows integrated fluoroscopic imaging to be practically applied to resection of deep pulmonary nodules normally impalpable or invisible at operation. A picture-in-picture configuration is the most useful for combing such inputs for the time being.

Presented at Minimally Invasive Robotic Association: Rome, Italy. January 2008.