V11-04: 3D ELASTIC AUGMENTED REALITY ROBOT-ASSITED RADICAL PROSTATECTOMY: FURTHER EVOLUTION OF THE STANDARD PROCEDURE
Recent advances in 3D reconstruction from digitalized images are now allowing to provide intraoperative surgical navigation. Our group already published a preliminary experience of Augmented Reality (AR) Robot assisted Radical Prostatectomy (RARP). Notwithstanding the encouraging results, this first generation static models were not devoid of limitations: their were unable to simulate tissue deformation. The aim of our study was to demonstrate if, with the introduction of the 3D elastic virtual models, prostate’s deformation was correctly simulated during surgery and the location of the lesion was correctly identified, even in a dynamic phase of the intervention.
We enrolled patients with suspicious capsular contact at preoperative mp-MRI. Image processing allowed to obtain 3D high definition virtual models (HA3DTM) of the prostate. Then, the models were loaded by the pViewer application, a specifically developed software using the Unity platform, in order to improve the models navigation. All transformations were applied starting from prostate apex to accurately reproduce movements and rotations of the real prostate. Specifically for this study, non-linear parametric deformations made possible to stretch and bend the prostate simulating the real grasping during the intervention. Finally, the video rendered by the pViewer application was fused with the one taken by the endoscopic camera and then, the obtained images were sent back to Da Vinci console by using the Tile-pro. Thanks to the AR images, the suspicious area of capsular involvement was marked on the prostate by a metallic clip during the nerve-sparing phase of the intervention. Later on, according to the pre-surgical indications, a partial or minimal nerve sparing (NS) procedure was carried out. Finally, after prostate removal, a 3D AR guided selective biopsy was performed at the level of suspicious CI.
We enrolled in our study 15 patients with suspicious capsular involvement at pre-operative MRI. 16 suspicious lesions were identified at the MRI. The mean lesion volume was 4.4 cc. At final pathology, the overall positive surgical margin rate was 26%. At macroscopic evaluation the metallic clip was placed at the level of the tumor in all the cases thanks to the elastic overlapping. In particular, the marker had been placed at the level of suspicious capsule bulging in 100% of the cases. Subsequently the microscopic assessment was performed. It confirmed the cancer presence in 15 (93.7%) cases at the level of the suspicious area. Moreover, the CI was correctly identified in 11/11 patients. The selective biopsies were positive in 40% of the cases
This new technology allowed to correctly simulate prostate’s deformation and identify the location of the lesion. It permitted to perform a 3D Elastic AR-RARP, optimizing the NS tailoring with a subsequent potential reduction of positive surgical margins rate and, in the meantime, a maximization of the functional outcomes.