V1269: A novel use of ICG-NIRF for identification of sentinel lymph nodes and enhanced nerve sparing during robotic radical prostatectomy

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Introduction and Objectives
Indocyanine green (ICG) has been previously been described in the urologic literature using an intravenous technique during robotic partial nephrectomy. There are now pilot series describing interstitial injection during prostatectomy using the dye as an agent to perform real-time fluorescence lymphangiography. Previousy described methods employ conjugated ICG in which the dye is mixed with a radio-isotope and carrier protein. These methods have demonstrated safety and feasibility but are rather cumbersome and costly in that they require several additional hours per patient to prepare, administer, and perform pre-operative scintigraphy. We present out initial clinical series using a simplified approach with injection of free ICG at the time of prostatectomy which we have found also allows for pelvic lympangiography as well as enhanced visualization of pelvic nerves including the neruovacular bundles.

Methods
We utilize percutaneous injection of 0.5 ml of ICG dye with a concentration of 2.5mg/ml into the lateral lobes of the prostate using a spinal needle to perform a real- time fluorescence lymphangiography to identify sentinel drainage from the prostate. We then also evaluate the effects of tissue diffusion of ICG within the prostate to help differentiate the neurovascular bundles.

Results
In all ten patients, we were able to visualize the lymphatic drainage of each prostate identifying the potential sentinel lymph nodes. In all ten patients the neurovascular bundles were hypofluorescent relative to the prostate allowing us to easily differentiate them and perform a successful sparing procedure.

Conclusions
In conclusion, we describe a technique of interstitial injection of ICG dye during robotic prostatectomy which is simple, quick, reproducible, may lead to more accurate pathologic staging of prostate cancer, improved oncologic outcomes, and may also allow more precise nerve sparring with subsequent improvements in sexual and urinary function.

Funding: None