Introduction: In the recent years, PSMA-based diagnostics and therapy has become increasingly established with the addition of radioguided surgery (RGS) and the intraoperative detection of radioactively labeled lymph nodes. We present the first results of a new robotic drop-in gamma probe (SENSEI®; Lightpoint Medical) for the detection of 99mTc-PSMA in robot-assisted radical prostatectomy (RARP). Methods: The data of nine patients with prostate cancer undergoing RGS were evaluated retrospectively. After preoperative administration of 99mTc-PSMA, a SPECT-CT was conducted and a robotic radical prostatectomy was performed the following day including intraoperative measurement of the lymph node stations using SENSEI®. This was followed by a robotic extended pelvic lymph node dissection with ex vivo control measurement using SENSEI® and a conventional gamma probe. Results: With a mean PSA value of 12.2 ng/ml, seven patients had high-risk and two patients had intermediate-risk prostate cancer. The SPECT-CT examination carried out preoperatively showed no findings suspicious for metastases in eight patients. The in- and ex-vivo lymph node measurements did not show a count rate that was significantly higher than the background. In one patient, intra- and postoperative measurement confirmed the positive signal found on SPECT-CT with lymph node metastases in the final histopathology results. Overall, a mean of 22 lymph nodes were dissected. No postoperative complications related to 99mTc-PSMA RGS or extended pelvic lymph node dissection occurred. Conclusions: 99mTc-PSMA RGS with SENSEI® allows for safe and easy lymph node measurements during surgery with no false-negative nor false-positive findings so far. Data from further patients will have to confirm these initial results. SOURCE OF Funding: None
