PSMA Radio-Guided Surgery to Detect Nodal Metastases in Prostate Cancer Patients Undergoing Robot-assisted Radical Prostatectomy

Description

PSMA radioguided surgery (PSMA-RGS) was performed at the time of robot-assisted radical prostatectomy (RARP) in prostate cancer (PCa) patients with a risk of lymph node invasion (LNI) >5%. After ethical committee approval, 99mTc-PSMA-I&S (piCHEM, Raaba-Grambach, Austria) was prepared and administered intravenously (median activity: 735 MBq) the day before surgery. All procedures were performed through a trans-peritoneal approach with the Da Vinci Xi (Intuitive Surgical, Sunnyvale, CA, USA) robotic system by two surgeons. After incision of the peritoneum and release of the bladder, a sterilizable, CE-marked Drop-In gamma probe (Crystal Photonics, Berlin, Germany) inserted through a 15-mm assistant port was used for in vivo intraoperative measurements to identify metastatic lesions in the internal iliac, external iliac, obturatory, and common iliac stations. Intraoperative measurements with the Drop-In gamma probe were performed at the common iliac above ureteric crossing presacral, and retroperitoneal stations. A positive finding was defined as the presence of a count rate of at least twice as compared to the background reference (namely, the homolateral fatty tissue of each patient). All positive lesions (a count rate of at least twice as compared to the background reference) were excised. Ex vivo gamma measurements were performed to confirm the removal of the radioactive lesion or to prompt further search in case of a missing signal. All the removed tissue was collected separately according to the anatomical site of resection. An anatomically defined extended pelvic lymph node dissection which included the common, external, internal iliac and obturatory stations was performed.