A Drop-in Gamma Probe for Minimally Invasive Sentinel Lymph Node Dissection in Prostate Cancer

Abstract

Purpose This study evaluated the performance of a drop-in gamma probe for prostate cancer (PCa) sentinel lymph node dissection (SLND) in a pelvic phantom, porcine model, and in PCa patients as part of an ongoing prospective multicenter clinical trial. Methods Two design variants of the drop-in gamma probe (SENSEI; Lightpoint Medical Ltd) were assessed in the pelvic phantom, and the preferred design was evaluated in a porcine model with clinically representative volumes and 99mTc activities. In the clinical trial, radical prostatectomy, SLND, and extended pelvic lymph node dissection were performed the day after 99mTc-nanocolloid injection and imaging. Sentinel lymph nodes (SLNs) were detected with the drop-in probe and a rigid laparoscopic gamma probe (RLGP). An interim analysis was performed after 10 patients were recruited. Results The narrow field of view probe design outperformed the wide field of view design in the pelvic phantom (detection rate, 100% vs 50%). In the porcine model, all activity concentrations could be successfully detected. The drop-in gamma probe successfully detected SLNs in all 10 patients (detection rate, 100%). Two of the SLNs identified by the drop-in gamma probe could not be found with the RLGP. No false-negative cases and no adverse events related to the SLND procedure or the drop-in gamma probe occurred. Conclusion The drop-in gamma probe meets the usability and performance requirements for SLND in PCa and provides performance advantages over the RLGP. The final clinical study results will confirm the performance of the technique across multiple sites.