Laparoscopic Photoacoustic Imaging System Based on Side-Illumination Diffusing Fibers

Objective: To develop a flexible miniaturized photoacoustic (PA) imaging probe for detecting anatomical structures during laparoscopic surgery. The proposed probe aimed to facilitate intraoperative detection of blood vessels and nerve bundles embedded in tissue not directly visible to the operating physician to preserve these delicate and vital structures. Methods: We modified a commercially available ultrasound laparoscopic probe by incorporating custom-fabricated side-illumination diffusing fibers that illuminate the probe's field of view. The probe geometry, including the position and orientation of the fibers and the emission angle, was determined using computational models of light propagation in the simulation and subsequently validated through experimental studies. Results: In wire phantom studies within an optical scattering medium, the probe achieved an imaging resolution of 0.43 +/- 0.09 mm and a signal-to-noise ratio of 31.2 +/- 1.84 dB. We also conducted an ex vivo study using a rat model, demonstrating the successful detection of blood vessels and nerves.Conclusion: Our results indicate the viability of a side-illumination diffusing fiber PA imaging system for guidance during laparoscopic surgery. Significance: The potential clinical translation of this technology could enhance the preservation of critical vascular structures and nerves, thereby minimizing post-operative complications.