Presentation Authors: Nina Harke*, Christopher Darr, Essen, Germany, Maarten Grootendorst, Chesham, United Kingdom, Ina Binse, Pedro Fragoso Costa, Ken Herrmann, Boris Hadaschik, Essen, Germany
Introduction: Cerenkov Luminescence Imaging (CLI) is a molecular imaging technique that detects light emitted by Positron Emission Tomography (PET) radiopharmaceuticals.This first-in-men study evaluates 68Ga-PSMA for intraoperative assessment of tumor margins at time of robot-assisted radical prostatectomy following preoperative PSMA-PET/CT.
Methods: 3-4 hours prior to surgery, PSMA-PET/CT was performed after intravenous injection of 68Ga-PSMA with varying doses. Scan results were assessed by the specialists of nuclear medicine and urology. Radical prostatectomy was performed robotically and the prostate specimen was imaged with a CLI imager (Lightpoint Medical Ltd, UK) intraoperatively immediately after excision. Mean radiance (photons/s/cm2/sr) was measured as well as the agreement in margin distance on histopatholgy and CLI.
Results: CLI was used in five patients after preoperative injection of 144 mBq 68Ga-PSMA (mean, range 95-202). Intraprostatic lesions were detected by PSMA-PET/CT in 100%, positive lymph nodes could be seen in 3 of 5 patients. CLI was performed intraoperatively after a mean of 329 minutes after tracer injection. Mean background radiance of the prostate was 1441 photons/s/cm2/sr. Positive surgical margins were found in two patients based on histopathology (patient 1: pT3b, pN1, Gleason score 5+3=8, patient 2: pT3a, pN1, Gleason score 4+5=9). In these patients, elevated radiance levels were found in the tumor positive areas (mean radiance: 4254 photons/s/cm2/sr).
Conclusions: Intraoperative 68Ga-PSMA CLI seems to be a promising technique for intraoperative assessment of surgical margins in robot-assisted radical prostatectomy. A prospective trial is planned to elucidate further results concerning sensitivity and specificity.