Imaging may change how urologists view laparoscopy

August 15, 2007

Developments in laparoscopy, robotics, and other minimally invasive urologic techniques continue to evolve at a rapid pace.

Developments in imaging technology may significantly enhance the surgeon's visual capacity during minimally invasive surgery.

Researchers at the National Cancer Institute, Bethesda, MD, reported on infrared imaging to assess segmental renal profusion and visual enhancement with a three-charge-coupled device (3-CCD camera) for laparoscopic partial nephrectomy. Infrared imaging was used with specialized cameras sensitive to changes of heat content in the tissue as small as 0.02°C. Utilizing segmental artery occlusion of the kidney in a porcine model, researchers were able to demonstrate that the intraoperative infrared imaging consistently identified regional ischemic deficits in renal profusion. This technology may have the ability to help surgeons identify renal profusion deficits in real time and correlate this with potential threats to renal viability. Its application could extend to renal transplantation and nephron-sparing surgery.

Researchers from the University of Virginia, Charlottesville, also presented a new technology designed to enhance surgeons' visualization of delicate structures during challenging tissue dissections. They injected fluorescein nerve tracer into the corporus cavernosum of rats. The tracer, a non-toxic B subunit of cholera toxin conjugated to Alexa Flour 488, can be picked up by a fiber optic confocal fluorescent imaging device to provided real-time images of the tracer in vivo.

Toxicity experiments demonstrated no increased apoptosis in the cavernous tissue in the group receiving the fluorescein tracer, and the procedure did not generate reactive oxygen species in the corporus cavernosum. This novel method permitted sensitive detection of the cavernous nerves without functional impairment of the nerves. The potential application of this new technology is for use during pelvic surgery to improve preservation of cavernous nerves and to decrease the risk of erectile dysfunction postoperatively. This technology will require further animal investigation.

Equipment malfunction is a rare occurrence during robot-assisted radical prostatectomy.

A multi-institutional study from Ohio State University, Columbus, and a single-center study from the University of Chicago showed similar results regarding the incidence of malfunction of the robotic equipment during robot-assisted radical prostatectomy. In the two studies, the incidence of critical malfunction rate of the robot was 0.3% and 0.5%, respectively. Both research teams noted that less obtrusive technical problems occur more commonly, but appear not to affect the satisfactory completion of the surgical procedure. As new technologies are applied clinically, information on malfunction will be important to appropriately advise patients preoperatively.

Use of a hemostatic hydrodissector and bipolar vessel coagulation appears to be a safe technique during laparoscopic partial nephrectomy.

This interesting study from Naples, FL, provided a prospective analysis of five partial nephrectomies for small exophytic renal masses using a hemostatic hydrodissector and bipolar vessel coagulation. Although the renal hilar vessels were dissected in all cases, none required vascular control or clamping during the excision of the renal mass. Mean renal mass size was 2.2 cm and mean estimated blood loss was 130 cc. The mean operative time was 180 minutes, and all resection margins were negative for malignancy.

No delayed complications have occurred in these five preliminary patients. While this is an interesting technology, it will require the more challenging application in endophytic renal masses before it can be considered a breakthrough in laparoscopic partial nephrectomy.