Tissue-mimicking phantom for the design and optimization of fluorescence depth imaging in nerve-sparing prostatectomy

Iatrogenic injury to critical neurovascular structures during nerve-sparing robotic-assisted radical prostatectomy (RARP) surgery can result in severe complications and long-term morbidity. Fluorescence imaging has the potential to enhance visualization of these critical structures. In addition, multi-excitation ratiometric fluorescence imaging is capable of quantitative measurement of nerves and blood vessel depth in tissue. To this end, we developed a flexible, benchtop fluorescence imaging system using a super continuum laser source, enabling multi-excitation ratiometric fluorescence imaging using a wide range of excitation wavelengths. We formulated gelatin-based tissue phantoms to mimic different tissue types and designed phantom molds with fluorescent inclusions embedded in turbid media at precise depths to test our multi-excitation, fluorescence-based depth estimation technique, validating phantom mold as semi-infinite medium which is required by the proposed depth recovery method. Initial depth estimates in prostate-mimicking demonstrated the potential of this technique. The progress reported herein will inform the future development of a clinical laparoscope capable of fluorescence-based measurement of nerves and blood vessels at depth for guidance during RARP procedures.