Virtual reality tumor navigated robotic radical prostatectomy by using three‐dimensional reconstructed multiparametric prostate MRI and 68Ga‐PSMA PET/CT images: A useful tool to guide the robotic surgery?

Abstract Objectives To evaluate the use and benefits of tumor navigation during performing robotic assisted radical prostatectomy (RARP). Patients and Methods Borders of the visible tumor(s) was/were and surrounding structures marked on multiparametric prostate magnetic resonance imaging (mpMRI) and 68Ga‐labeled prostate‐specific membrane antigen ligand using positron emission computed tomography (Ga68 PSMA‐PET/CT). Three dimensional (3D) reconstruction of the images were done that were transferred to virtual reality (VR) headsets and Da Vinci surgical robot via TilePro. Images were used as a guide during RARP procedures in five cases. Indocyanine green (ICG) guided pelvic lymph node dissection (n = 2) and Martini Klinik Neurosafe technique (n = 2) were also applied. Results Mean patient age was 60.6 ± 3.7 years (range, 56‐66). All VR models were finalized with the agreement of radiologist, urologist, nuclear physician, and engineer. Surgeon examined images before the surgery. All VR models were found very useful particularly in pT3 diseases. Pathological stages included pT2N0 (n = 1), pT3aN0 (n = 1), pT3aN1 (n = 2), and pT3bN1 (n = 1). Positive surgical margins (SMs) occurred in two patients with extensive disease (pT3aN1 and pT3bN1) and tumor occupied 30% and 50% of the prostate volumes. Mean estimated blood loss was 150 ± 86.6 cc (range, 100‐300). Mean follow‐up was 3.4 ± 1.7 months (range, 2‐6). No complication occurred during perioperative (0‐30 days) and postoperative (30‐90 days) periods in any patient. Conclusions 3D reconstructed VR models by using mpMRI and Ga68 PSMA‐PET/CT images can be accurately prepared and effectively applied during RARP that might be a useful tool for tumor navigation. Images show prostate tumors and anatomy and might be a guide for the console surgeon. This is promising new technology that needs further study and validation.

computed tomography (Ga68 PSMA-PET/CT). Three dimensional (3D) reconstruction of the images were done that were transferred to virtual reality (VR) headsets and Da Vinci surgical robot via TilePro. Images were used as a guide during RARP procedures in five cases. Indocyanine green (ICG) guided pelvic lymph node dissection (n = 2) and Martini Klinik Neurosafe technique (n = 2) were also applied.
Results: Mean patient age was 60.6 ± 3.7 years (range, 56-66). All VR models were finalized with the agreement of radiologist, urologist, nuclear physician, and engineer.
Conclusions: 3D reconstructed VR models by using mpMRI and Ga68 PSMA-PET/CT images can be accurately prepared and effectively applied during RARP that might be a useful tool for tumor navigation. Images show prostate tumors and anatomy

| INTRODUC TI ON
Prostate cancer (PCa) is the most common malignant disease in men leading to cancer-related deaths in the United States. 1 With rapid dissemination of robotic platform worldwide, robotic assisted radical prostatectomy (RARP) has become the most commonly applied surgical method in PCa surgery. 2

| PATIENTS AND ME THODS
Overall, five patients with the diagnosis of prostatic adenocarcinoma underwent RARP and bilateral pelvic lymph node dissection (BPLND) were included in this study (Table 1). All five patients were operated by the same surgeon (AEC) with previously published technique. 5    The images were interpreted in AW work station of GE by a nuclear medicine physician. Any focal 68Ga-PSMA uptake higher than surrounding activity not associated with a known site of physiological uptake and with a corresponding morphological abnormality on CT was considered pathological and suspicious for malignancy. All pathological uptakes were analyzed with regard to their location and their maximum standardized uptake value (SUVmax).

| 3D image reconstruction of the prostate
Axial T2W 3D-TSE sequence was used in mpMRI. Borders of the tumor(s) were marked by our uro-radiologist. Ga68 PSMA-PET/CT images were evaluated by nuclear medicine physician. 3D images of the prostate were created by engineer. In order to obtain the and might be a guide for the console surgeon. This is promising new technology that needs further study and validation.

K E Y W O R D S
3D reconstruction, augmented reality, radical prostatectomy, robotic, training, virtual reality TA B L E 1 Preoperative patient characteristics, preoperative findings, and robotic assisted radical prostatectomy outcomes

| D ISCUSS I ON
In our study, we were able to successfully reconstruct 3D VR models by using mpMRI and Ga68 PSMA-PET/CT images and transfer them to the surgical robot.
Initially 3D printed virtual prostate models were designed, 10  Currently, mpMRI is probably the most important imaging modality in showing cancerous foci in the prostate. 13 In addition, Ga68 PSMA-PET/CT is increasingly used in PCa imaging. 14 Therefore, currently these two imaging modalities seem to be the most important F I G U R E 1 A, mpMRI image. Axial T2-weighted space sequence shows a 3.5 cm PI-RADS 5 lesion in the left posterior peripheral zone at the level of midgland-basis. There is suspicion of left seminal vesicle and NVB involvement. Borders of the lesion which was pathologically known to be adenocarcinoma was drawn. B, Ga68 PSMA-PET/CT: PSMA uptakes were seen in left lateral-medial sides of mid-gland and left medial side of apex with 3.21 SUVmax. C, 3D reconstructed image of the prostate. Left up (yx axis): appearance from the top, left down (zx axis): appearance from front, right down (zy axis): appearance from right, right up (xyz axis, perspective). Green: tumor on MRI, yellow: peripheral zone, purple: anterior-transition zone, red: bladder. D, 3D reconstructed image of the prostate (maximized perspective, xyz axis). Green: tumor on MRI, yellow: peripheral zone, purple: anterior-transition zone, red: bladder. Tumor involving almost the entire left half of the prostate gland with obvious extraprostatic extension is visible (green). E, 3D reconstructed image of the prostate with tumor on Ga68 PSMA-PET/CT overlap in addition to mpMRI (maximized perspective, xyz axis). Orange: 68Ga-PSMA uptake area, Green: tumor on MRI, yellow: peripheral zone, purple: anterior-transition zone, red: bladder. F, Real time use of 3D reconstructed image of the prostate during RARP and intraoperative surgical appearance. Due to the possible involvement of left seminal vesicle and NVB by the tumor that also appears in the 3D images, console surgeon did not preserve left NVB and did a careful dissection at the level of left seminal vesicle. G, ICG guided pelvic LN dissection (left side). Please note ICG(+) LN that was excised and sent for intraoperative pathological frozen evaluation that was reported as metastatic. H, Postoperative pathology mapping of the prostate ones in PCa work-up. To the best of our knowledge, our study is the first that used 3D VR reconstructed images of the prostate combining mpMRI and Ga68 PSMA-PET/CT images.
Growing evidence of the importance of performing radical prostatectomy (RP) in high-risk PCa draws particular attention on this subject. Very recently, in a systematic review and meta-analysis, RP was shown to have significantly more survival benefits than radiotherapy on cancer-specific survival (P = .003) and overall survival (P = .002) in patients with high-risk PCa disease. 15  Other previously published studies on VR models were useful to identify NVBs, capsular involvement and accessory pudendal arteries to achieve negative SMs. 4,10,[16][17][18][19][20][21] Researchers from National Cancer Institute (NCI), USA applied a mpMRI-based VR tool at RARP and suggested as useful in deciding to perform a wider excision to reduce (+) SMs in locally advanced PCa. 22 We previously demonstrated that coexistence of T2 WI signs provide higher diagnostic value in predicting the grade of EPE in locally advanced PCa. 23 A European

Association of Urology (EAU) Robotic Urology Section (ERUS) survey
showed that most of the participants believed that there could be a role for AR navigated tool particularly for training in robotic surgery. 24 The limitations of our study include being a preliminary study with a small sample size without a control group. Only visible lesions on mpMRI were included. Manual data segmentation was done. An experienced radiologist, nuclear medicine physician, urologist, and engineer were required. The 3D VR reconstructed images need to be controlled by an assistant surgeon or by the console surgeon during the RARP procedure in order to present the area of interest.
In conclusion, 3D reconstructed VR models by using mpMRI and Ga68 PSMA-PET/CT images can be accurately prepared and effectively applied during RARP that might be a useful tool for tumor navigation. Images show prostate tumors and anatomy and might be a guide for the console surgeon. They might be particularly useful in patients with locally advanced PCa that needs further study and validation.

ACK N OWLED G M ENT
We would like to thank to our uropathologists Prof. Dilek Ertoy Baydar, Dr. Ayşe Armutlu, and Dr. İbrahim Kulaç for histopathological evaluation of the prostate biopsies, intraoperative frozen section, final pathology results, and tumor mapping of the prostates.