ICG-99mTc-nanocolloid vs. 99mTc-nanocolloid en een intraoperatieve injectie van ICG voor de schildwachtklierprocedure van prostaat kanker.

Recently fluorescent dyes such as indocyanine green (ICG) have been introduced into clinical practice for fluorescence-based sentinel node (SN) biopsy in a variety of malignancies, amongst others prostate cancer. A study by Jeschke et al. [Jeschke et al., Urology 2012] showed that intraoperative fluorescence imaging allowed SN and lymphatic duct visualization in prostate cancer. However, it did not allow for preoperative SN mapping; the limited tissue penetration of the fluorescence signal prohibits this. With the introduction of a hybrid tracer, in which ICG is coupled to the conventional radiocolloid 99mTc-nanocolloid, our group showed that with this tracer preoperative SN mapping was possible. In addition, intraoperatively, the fluorescence signature allowed for optical SN identification [van der Poel et al., Eur Urol 2012]. Logistical reasons, but also the fact that not every medical center has a highly skilled nuclear medicine department, lead to the suggestion that intraoperative fluorescence imaging can possibly replace the preoperatively radiocolloid-based method.

Intraoperative fluorescence imaging alone is sufficient to identify the sentinel nodes of the prostate as seen with preoperative radiocolloid-based sentinel node mapping

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On the morning of surgery patients will receive an transrectal-ultrasound guided intraprostatic or intratumoral injection with the hybrid tracer ICG-99mTc-nanocolloid (ARM 1) or 99mTc-nanocolloid (ARM 2). Thereafter, preoperative imaging will be performed: static lymphoscintigraphy (15min and 2hrs p.i.) and SPECT-CT imaging (2hrs p.i.). The nuclear medicine physician will evaluate the images and determine the number and location of the sentinel node(s).

Prior to the start of the operation, the patients in ARM 2 will receive an intraprostatic ICG injection. Then SN biopsy is performed. Intraoperatively, SNs will be initially pursued via fluorescence imaging alone. After identification of all fluorescent SNs the urologist will evaluate the preoperative images (lymphoscintigraphy and SPECT/CT) to confirm removal of all preoperatively defined SNs. Thereafter, with the conventional gamma probe the area of resection will be checked for any remaining hot nodes. If there are any remaining SNs left in situ, these SNs will also be removed. After removal and documentation of all preoperatively defined SNs the subsequent extensive nodal dissection will be performed followed by the prostatectomy.