We present images from a 71-year-old prostate cancer patient who underwent a robot-assisted radical prostatectomy and extended pelvic lymph node dissection (ePLND) complemented with experimental sentinel node (SN) resection [1]. Additional intraoperative lymphangiography was performed to highlight lymphatic structures that should ideally be spared. This concept is part of a prospective trial wherein we aim to use the presented approach to reduce the 20% complication rate associated with ePLND procedures [2].

For SN identification, the bimodal/hybrid tracer ICG-99mTc-nanoscan (218 MBq in 2 ml) was used, which has replaced the well-known ICG-99mTc-nanocolloid [3]. Preoperative (lymphoscintigraphy and SPECT/CT) and intraoperative SN imaging (gamma and fluorescence imaging) were performed after intraprostatic tracer injection. Previous work indicates that the hybrid tracer and the visible-dye fluorescein both stain lymphatic structures, but with different kinetics [4]. It is also known that multi-color fluorescence imaging can be used to differentiate between lymphatics of different organs [5, 6]. With this first-in-human implementation (see Scheme), we underscore that lymphatic ducts draining the left upper leg can be made visible using fluorescein (80 mg in 4 ml; yellow, dotted triangle) and that this drainage can be distinguished from the SNs visualized with ICG-99mTc-nanoscan (blue, dotted circle). With that, the former can act as “red-flag” to highlight tissues that should be spared, while the latter provides a ”green-flag” for tissues that should be resected. As such, the presented three-way multiplexing approach may help preserve the oncological benefit of ePLND + SN [3], while providing a handle to reduce complication rates.

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