New photoacoustic imaging helps robotic surgeons avoid hidden anatomical hazards

Surgery is a complicated endeavor. Even a successful surgery can lead to complications, and even the best surgeons sometimes have unsuccessful surgeries. A surgeon must rely on visual cues and their own experience to avoid hitting a nerve or a blood vessel, mistakes that can turn a simple surgery into a much more challenging one.

Unfortunately, many of these potential hazards lurk beneath the surface of the tissue, hidden from the surgeon unless a modern imaging technique reveals them.

Kai Zhang, an associate professor at Worcester Polytechnic Institute, will present his work integrating photoacoustic (PA) imaging into robot-assisted surgeries Monday, May 11, at 8:40 a.m. ET as part of the 190th Meeting of the Acoustical Society of America, running May 11-15.

Robot-assisted laparoscopic surgeries are abdominal or pelvic surgeries that use a small camera, called a laparoscope, inserted through a small incision. Small incisions mean reduced pain and shorter recovery times for patients, and robot assistance means more control and precision for surgeons. Unfortunately, the danger of damaging anatomical structures under the surface remains.

Accidentally severing a hidden blood vessel during robot-assisted laparoscopy occurred in 1%-2% of cases depending on the procedure. Furthermore, such incidents can result in a range of complications, including hemorrhage, paralysis, and, in the worst cases, fatal outcomes."

Kai Zhang, associate professor, Worcester Polytechnic Institute

One emerging solution is PA imaging. This technique directs lasers deep into the tissue, which absorbs the light and produces sound waves. These sound waves can be picked up by ultrasensitive microphones and used to pinpoint subsurface structures like blood vessels and nerve bundles.

"This capability enables visualization of embedded anatomical structures and their depth locations, which is highly valuable for surgical planning and intraoperative monitoring," said Zhang.

Zhang incorporated PA imaging into a laparoscopic surgery workflow to help guide surgeons during operations. He analyzed data from the PA probe and used it to create 3D representations of neurovascular bundles, which are clusters of nerves and blood vessels surgeons desperately want to avoid. Then, these representations were overlaid on video from the laparoscopic camera, providing a real-time augmented reality video feed.

Zhang tested this technique during radical prostatectomies - a surgery to remove prostate cancer - but PA imaging has applications broader than this one surgery.

"We anticipate that this imaging instrumentation will be readily translatable to not only other laparoscopic procedures but also other image-guided procedures," said Zhang.