The introduction of the drop-in gamma probe has advanced intraoperative molecular imaging during prostate cancer surgery. We have been able to convert the sensor's numeric readout to tomographic images, so-called robotic-SPECT (RoboSPECT) and investigate how this is impacted by radiopharmaceutical avidities and drop-in scan metrics.
The gamma sensor readout was registered with its 3D position and orientation, allowing a custom reconstruction algorithm to generate RoboSPECT images. Evaluations occurred in 21 patients; 10 sentinel node procedures (SN; primary prostate cancer) and 11 PSMA-radioguided surgery (recurrent prostate cancer). RoboSPECT findings were related to respective pre- and intra-operative controls, including preoperative PSMA-PET/CT and/or SPECT/CT images and fluorescence detection (SN only).
RoboSPECT proved to be safe and applicable in a range of conditions. In the SN-group, 26 SN-SPECT/CT lesions were successfully identified with SN-RoboSPECT (100%); 3 were tumor positive (sensitivity 100%). Only 73% of SNs were surgically visible with fluorescence imaging. For the PSMA guided group, the 14 lesions identified on PSMA-PET/CT were all visualized with PSMA-RoboSPECT (100%); 18 specimens were tumor positive (sensitivity 78% for both PSMA-PET/CT and PSMA-RoboSPECT). Preoperative PSMA-SPECT/CT only identified 4 PSMA-lesions (29%). No false positives were seen for roboSPECT and all final resection margins were clean. At 6-months 0% of the SN-patients and 20% of PSMA-patients showed biochemical recurrence.
RoboSPECT provides 3D context that extends the utility of drop-in gamma tracing and assists the alignment between pre- and intra-operative target perception. Here SN-RoboSPECT clearly outperformed fluorescence SN imaging and PSMA-RoboSPECT outperformed preoperative PSMA-SPECT/CT imaging.
European journal of nuclear medicine and molecular imaging. 2026 Jul 01 [Epub ahead of print]
A C Berrens, K Pirkovets, S Azargoshasb, L J Slof, B A Cakal, P J van Leeuwen, E M K Wit, M Sinaasappel, T Wendler, H G van der Poel, M N van Oosterom, F W B van Leeuwen
Interventional Molecular Imaging Laboratory, Leiden University Medical Center, Leiden, The Netherlands., Department of Urology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands., Department of Clinical Physics and Instrumentation, Netherlands Cancer Institute, Amsterdam, The Netherlands., Diagnostic and Interventional Radiology, Faculty of Medicine, University of Augsburg, Augsburg, Germany., Interventional Molecular Imaging Laboratory, Leiden University Medical Center, Leiden, The Netherlands. .