Intraoperative fluorescence vascular imaging using indocyanine green for assessment of transplanted kidney perfusion

Indocyanine green (ICG) emits infrared light with exposure to laser light. When intravenously injected, it binds to plasma proteins and predominantly persists in the vasculature, which is very useful for definition of the vascular network. The HyperEye Medical System (HEMS; Mizuho Ikakogyo Co., LTD, Tokyo, Japan) is a new device able to identify both near-infrared and visible rays "in situ" without needing to dim the operation room lighting. We speculated that intraoperative ICG imaging would be applicable for kidney transplantation, by providing "in situ" determination of successful vascular anastomosis.

Four patients underwent intraoperative ICG imaging following intravenous administration of 1 mL of a solution containing 0.25% ICG. After performing vascular anastomosis, the allograft was examined using the HEMS light source device. Fluorescent signals were transmitted to a digital video processor connected to a television monitor and evaluated in real time.

In all 4 patients, intraoperative ICG imaging provided excellent resolution of blood flow at each step in real time, namely, coming from the recipient's artery to the allograft renal artery, circulating throughout the whole grafted kidney, and draining through the allograft renal vein to the recipient's vein. HEMS provides ICG fluorescence image in color, allowing surgeons to clearly discriminate the positional relationship between the target tissue and the surrounding tissue. No complications associated with ICG injection were noted.

Our preliminary results indicate that HEMS is a feasible and safe ICG imaging system that helps prevent technical failure during vascular anastomosis, and also demonstrates blood supply to the grafted kidney.