Robotic surgery using a DROP-IN beta probe – feasibility study with 68Ga-PSMA in prostate cancer specimens

Abstract

Background: Recently, a flexible DROP-IN gamma-probe was introduced for robot-assisted radioguided surgery, using traditional low-energy SPECT-isotopes. This study explores the use of a novel DROP-IN beta-particle (DROP-IN b ) detection probe to support the implementation of the large number of PET-tracers available during robot-assisted tumor-receptor-targeted resections. Methods: Following engineering of the DROP-IN b probe, robotic implementation was investigated using surgical specimens. Seven prostate cancer patients with PSMA-PET positive tumors received an intraoperative injection of ~100 MBq 68 Ga-PSMA-11, followed by prostatectomy and extended pelvic lymph node dissection. Results: The probe was able to identify the position of the tumor in the prostate specimens: S/B was > 5 when pathology confirmed that the tumor was located <1 mm below the specimen surface. PSMA-PET positive lymph nodes, as found in two patients, could be identified with the DROP-IN b probe (S/B>3). Conclusions: This ex vivo study underlines the potential to use a DROP-IN b probe for intraoperative tumor identification on the prostate surface and confirmation of PSMA-PET positive lymph nodes.