br Besides the limited number
Besides the limited number of patients included and the
rather short follow-up, our study is also limited by the fact that Iberiotoxin the administered dose of 99mTc-PSMA-I&S, and the time interval between application and surgery have been chosen empirically and were not evaluated in detail.
However, the clinical introduction of PSMA-targeted RGS approaches might open the field for further innovations and technical refinements. The recent development of small drop-in gamma probes that can be utilized during robotic surgery could enable minimally invasive targeted salvage surgery procedures in PC patients . Modifications of PSMA-targeted agents employing optical-dye conjugates for fluorescence imaging [24,25] as well as development of specialized camera systems  might enable multifunc-tional image guidance during surgical procedures and thus improve the efficacy of salvage dissections. In general, complete follow-up of patients undergoing these individual salvage surgery procedures, preferentially in registries, is mandatory to identify clinical predictors of favorable outcome to further define the role of salvage surgery or intraoperative guidance by labeled PSMA ligands.
We demonstrate the feasibility of 99mTc-PSMA-RGS to guide intraoperative identification and surgical removal of metastatic LN in PC patients scheduled for salvage surgery. The surgical technique complemented by ex vivo gamma
probe measurement with immediate feedback about successful removal of tumor deposits is highly useful to identify and excise small or atypically localized lesions, as seen on preoperative PSMA PET. However, caution is advised as both the procedure of 99mTc-PSMA-RGS and PSMA PET as an initial tool to stratify patients for salvage lymphadenectomy are not capable of detecting microscopic disease. Our short-term follow-up data indicate a high potential to positively influence disease progression and delay further systemic treatment, which has to be validated in prospective clinical trials.
Author contributions: Tobias Maurer had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Maurer, Robu, Schottelius, van den Berg, van Leeuwen, Gschwend, Schwaiger, Wester, Eiber.
Acquisition of data: Maurer, Robu, Schwamborn, Rauscher, van den Berg, Horn, Heck, Eiber. Analysis and interpretation of data: Maurer, Robu, Schwamborn, Rauscher, van den Berg, van Leeuwen, Haller, Horn, Eiber.
Drafting of the manuscript: Maurer, Robu, van den Berg, van Leeuwen, Eiber.
Critical revision of the manuscript for important intellectual content:
Schottelius, Rauscher, Horn, Heck, Gschwend, Schwaiger, Wester.
Statistical analysis: Maurer, Haller.
Obtaining funding: None.
Administrative, technical, or material support: Maurer, Robu, Schottelius, van den Berg, van Leeuwen, Gschwend, Schwaiger, Wester, Eiber. Supervision: Gschwend, Schwaiger, Wester.
Financial disclosures: Tobias Maurer certifies that all conflicts of interest, including specific financial interests and relationships and affiliations relevant to the subject matter or materials discussed in the manuscript (eg, employment/affiliation, grants or funding, consultancies, honoraria, stock ownership or options, expert testimony, royalties, or patents filed, received, or pending), are the following: H.-J. Wester is CEO of Scintomics GmbH and owns stock or options at the company. Scintomics is the distributor of the automated module used for the synthesis of the 68Ga-PSMA HBED-CC ligand.
Funding/Support and role of the sponsor: None.
Appendix A. Supplementary data
The Surgery in Motion video accompanying this article can be found in the online version at https://doi.org/10. 1016/j.eururo.2018.03.013 and via www.europeanurology. com.