Gynecologic surgery accounts for 75% of all intraoperative injuries to the ureters, due to the close proximityof the ureter to the uterine artery. We propose dual-wavelength photoacoustic imaging in order to distinguish theureter from the uterine artery, identify the position of the surgical tool in proximity to these critical structures,and assist with guidance of hysterectomy procedures. Experiments were preformed in a pilot human cadaverstudy and a dual-wavelength approach was introduced to visualize the uterine artery and a ureter filled withurine and methylene blue. The ureter location was identified with low contrast at a wavelength of 750 nm andhigher contrast at a wavelength of 690 nm, resulting in a 5.8 dB contrast difference in photoacoustic signalsfrom the ureter at these two different wavelengths. The uterine artery was identified at laser wavelengths ofboth 690 nm and 750 nm, with similarly high contrasts of 17.4 dB and 16.0 dB, respectively. By using a dual-wavelength display, both the ureter and the uterine artery were identified and their position was estimated inthe photoacoustic image. The proximity of a surgical tool tip to the ureter was additionally estimated basedon the information provided in the dual-wavelength photoacoustic display and mapped to an auditory signal.This auditory information can be provided as either an alternative or an addition to photoacoustic images thatinform surgeons of the risk of injury. Results highlight the promise of dual-wavelength photoacoustic imagingto achieve our ultimate goal of avoiding accidental ureteral injuries during hysterectomies and possibly othersimilar gynecologic surgeries and procedures.
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