This is a systematic review and critical analysis of the current evidence on the applications of near-infrared fluorescence (NIRF) in robotic urologic surgery. It uses indocyanine green (ICG), a sterile water-soluble dye which has been tested in various fields. In urology, it is most studied in robotic partial nephrectomy (RPN). Its favourable features are (1) confined to the vascular compartments, (2) plasma life of three to five minutes, (3) low toxicity, and (4) can be detected with an NIRF camera. ICG dye is cleared by hepatic metabolism and is not nephrotoxic. Fourteen studies published since 2011 were included in this review. Renal tumours demonstrate reduced expression of bilitranslocase, a carrier protein for ICG present in normal proximal tubule cells. This process leads to a reduction in NIRF of these tumours, allowing visual differentiation of tumour and complex renal vascular branching. Tumours, cysts, and fat necrosis were mostly hypofluorescent. During RPN, the NIRF scope inserted separately displayed images on a separate monitor. Malignant masses were hypofluorescent, whereas the benign lesions were all isofluorescent or hyperfluorescent. However, opposite conclusions were drawn in a subsequent study. They could not reliably correlate hypofluorescence with malignancy. The only two reliable patterns of fluorescence involved angiomyolypomas and cystic lesions that were all non-fluorescent. Tumour differentiation could also be influenced by the ICG dose, as underdosing gives inadequate fluorescence of normal parenchyma surrounding the tumour, whereas overdosing could cause all tissues to fluoresce. This technology is also used in adrenal surgery, ureteric surgery, nodal metastasis – to differentiate masses / abnormal tissue, and also to ensure bowel vascularity and anastomotic blood flow. 

Current applications of near-infrared fluorescence imaging in robotic urologic surgery: a systematic review and critical analysis of the literature.
Autorino R, Zargar H, et al.
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Gokul Vignesh Kanda Swamy

ABM University Health Board, Swansea, UK.

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