Parking sensor-inspired approach to photoacoustic-guided hysterectomy demonstrated with human cadavers
Similar to the parking-assist sensors on modern automobiles, which alert drivers of impending impact to an object, we are developing an auditory photoacoustic-based guidance system to assist with avoidance of impending injuries to ureters during hysterectomy procedures. The contribution described in this paper considers international standards for medical alarms. The system was demonstrated during both open and laparoscopic hysterectomy procedures on two human cadavers. Using methylene blue to enhance ureter contrast, the proximity of a surgical tool tip to the ureter was measured using the visual information provided in photoacoustic images. Distance measurements were then successfully mapped to auditory signals, which increased in auditory frequency as the tool-to-ureter distance decreased to convey surgical tool proximity to the ureter. Fundamental frequencies increased from 150 Hz to 866 Hz for tool-to-ureter distances of 2.47 mm to 5 mm. These results are promising to assist with the avoidance of accidental ureteral injuries during hysterectomy and other procedures that suffer from similar challenges with regard to iatrogenic ureteral injuries.