Semi-Quantitative Tissue Perfusion Assessment Using Indocyanine Green In Complex Open Urethral Reconstruction.

INTRODUCTION: Current assessment of critical tissue in genitourinary reconstruction, including graft beds and tissue flaps, primarily relies upon qualitative visual and tactile assessment by experienced surgeons. Here we explore the feasibility of using intravenous indocyanine green (ICG) for semi-quantitative assessment of perfusion in complex open urethral reconstruction.

METHOD: A standardized protocol for intravenous use of ICG and near-infrared fluorescence was established. Black and white mode was used for qualitative assessment of perfusion based on signal brightness. Quantitative perfusion mode was used to assess relative perfusion to tissue of interest compared to a control area with similar tissue type outside of the studied area. Real-time perfusion was visualized as percentage of perfusion relative to control.

RESULT: In case 1, the graft bed was assessed during dorsal onlay graft substitution urethroplasty. Perfusion to graft bed was compared to that of erectile bodies proximally. A proposed perfusion cutoff of 60% was noted to correlate with clinical judgment of graft bed quality. In case 2, tissue perfusion of Blandy flap in perineal urethrostomy was assessed before and after mobilization. A cutoff of 40% was proposed based on existing flap-based reconstruction literature with the goal to tailor flap and ultimately avoid tissue ischemia and necrosis. In case 3, in a complex staged substitution urethroplasty after hypospadias repair, the use of ICG facilitated a limited excision and shorter graft inlay in this staged reconstruction.

CONCLUSION: The application of near-infrared fluorescence tools in open genitourinary reconstruction has the potential to advance quantitative assessment of graft, flaps, and other critical tissue planes, and help establish meaningful perfusion threshold and correlate with clinical outcomes.