Objective, real-time, intraoperative assessment of renal perfusion using infrared imaging

Allograft ischemia induces delayed graft function and is correlated with increasing rates of rejection. There is not currently a way to objectively measure the effects of ischemia in real-time, nor to relate therapies combating reperfusion injury with their intended effects. An infrared (IR) method utilizing a focal plane array detector camera was developed for real-time intraoperative IR imaging of renal allografts, and evaluated in a pilot trial to quantify perfusion in recipients of live (n=8) and cadaveric donor (n=5) allografts. Digital images were taken for 3-8 min postreperfusion. Image data were compared to ischemic time and allograft function to assess potential clinical relevance. Cold ischemic time ranged from 0.5 to 29h and was bimodally distributed between living and cadaveric donors. Renal rewarming time (RT) as determined by IR imaging correlated with cold ischemic time (p < 0.001, R-2=0.81), and predicted the subsequent return of renal function with FIT negatively correlated to the regression slopes of creatinine (p = 0.02, R-2 = 0.38) and BUN (p = 0.07, R-2 = 0.26). Intraoperative IR imaging noninvasively provides clinically relevant real-time whole kidney assessment of reperfusion. This technology may aide in the objective assessment of therapies designed to limit reperfusion injury, and allow for quantitative assessment of allograft ischemic damage.