Photoacoustic-Guided Laparoscopic and Open Hysterectomy Procedures Demonstrated with Human Cadavers

Hysterectomy (i.e., surgical removal of the uterus) requires severing the main blood supply to the uterus (i.e., the uterine arteries) while preserving the nearby, often overlapping, ureters. In this paper, we investigate dual-wavelength and audiovisual photoacoustic imaging-based approaches to visualize and differentiate the ureter from the uterine artery and to provide the real-time information needed to avoid accidental ureteral injuries during hysterectomies. Dual-wavelength 690/750 nm photoacoustic imaging was implemented during laparoscopic and open hysterectomies performed on human cadavers, with a custom display approach designed to visualize the ureter and uterine artery. The proximity of the surgical tool to the ureter was calculated and conveyed by tracking the surgical tool in photoacoustic images and mapping distance to auditory signals. The dual-wavelength display showed up to 10 dB contrast differences between the ureter and uterine artery at three separation distances (i.e., 4 mm, 5 mm, and 6 mm) during the open hysterectomy. During the laparoscopic hysterectomy, the ureter and uterine artery were visualized in the dual-wavelength image with up to 24 dB contrast differences. Distances between the ureter and the surgical tool ranged from 2.47 to 7.31 mm. These results are promising for the introduction of dual-wavelength photoacoustic imaging to differentiate the ureter from the uterine artery, estimate the position of the ureter relative to a surgical tool tip, map photoacoustic-based distance measurements to auditory signals, and ultimately guide hysterectomy procedures to reduce the risk of accidental ureteral injuries.