Exciting new imaging-based technologies including volumetric reconstruction, 3D printing, digital simulation and augmented reality (AR) are changing the way urologic oncologists address solid malignancies. Across all urologic oncologic surgery, advanced imaging plays a key role in staging and therapeutic planning, although applications vary across the 3 most common sites–prostate, bladder and kidney. Although applied mostly in preoperative planning today, surgeons have long desired to bring image guidance into real-time usage for decision making in the operating room. During our plenary session at the 2021 Annual Meeting of the AUA, we will discuss the use of innovative imaging-based technologies in the context of the partial nephrectomy model.

Richard Link from the Baylor College of Medicine will present applications of volumetric reconstruction and 3D printing to partial nephrectomy. These technologies are the most accessible and least costly approach to integrating image guidance into surgical planning. Moreover, this approach can be made patient-specific quite easily without lengthy and expensive custom software development or capital equipment costs. Soft tissue-like models derived from this approach allow presurgical rehearsal of tumor resection and have been shown to have construct validity.¹ As this approach results in a tangible physical model, it can also be very valuable for teaching partial nephrectomy to residents and fellows, and for counseling patients who may not be highly technologically adept.

Ahmed Ghazi from the University of Rochester will take this a step further and demonstrate the transformation of 3D imaging into a patient-specific hydrogel model with the primary aim of replicating the entire operative experience with complete anatomical and pathological details (fig. 1). These models take the 3D virtual reality (VR) and give the surgeon a tangible model to plan. Compared to virtual and 3D-printed models, patient-specific rehearsals (PSR) have the unique ability to optimize the real intervention through genuine practice that addresses potential problems related to a specific patient.² In a prospective study, 19 patients with complex renal masses (RENAL [radius, exophytic/endophytic, nearness of tumor to collecting system, anterior/posterior, location relative to polar line] scores >9) randomized to preoperative patient-specific simulations (PSS) (virtual vs PSR) were propensity-matched to a standard imaging group (38). The PSS group demonstrated lower rates of blood loss, positive margins, mean hematocrit/glomerular filtration rate change and complications translating to a 2-day reduction in hospital stay demonstrating the superiority of PSS.³

Figure 1. Workflow for fabrication of PSS in surgical management of renal masses. Left to right: DICOM® files of patient axial imaging are exported and each kidney component (tumor, kidney, vasculature, etc.) is segmented to develop a 3D computer assisted design (CAD) → Optimization functions smooth CAD to remove any artifacts → CAD is converted into several PSSs including Virtual Reality (3D anatomical modeling software allowing functional manipulation), 3D printing and hydrogel molding (hydrogel replica of patient’s kidney fabricated from 3D printed injection molds is anatomically positioned into abdominal torso and perfused for surgical rehearsal), and Augmented Reality (overlapping digital and real images to help identify hidden anatomical features, tumor location and vascular variations).

Virtual and augmented reality technologies take this approach a step further (fig. 2). Marc Bjurlin from the University of North Carolina will review 3D virtual reality models, which when reviewed by surgeons during partial nephrectomy have been shown to improve understanding of patient anatomy and consequently influence surgical plans and outcomes.⁴ In a randomized clinical trial of 92 patients using an easily accessible 3D format on a smartphone and in VR with an off-the-shelf Google Cardboard-compatible VR headset, patients whose surgical planning involved 3D VR models had reduced operative time, estimated blood loss, clamp time, and length of hospital stay.⁵ Additionally, 3D VR models have been associated with improved parenchyma preservation, which may contribute to improvement in postoperative renal function.⁶

Figure 2. Example of PSR using 3D printing and hydrogel molding applications. Left to right: operative setup for surgical rehearsals with da Vinci® surgical robot docked onto simulated abdominal torso containing anatomical hydrogel kidney; side-to-side comparison of simulated perfused surgical rehearsal and live surgery during tumor resection; post-rehearsal autopsy of patient-specific model to review outcomes (surgical debrief).

Francesco Porpiglia from the University of Turin (Italy) will demonstrate his methods of intraoperative navigation using a mixed reality (AR) platform. This application overlaps digital and real images to help identify hidden anatomical features, tumor location and vascular variations.⁷ Since 2009, AR-3D model applications have been shown to be safe, feasible, and able to influence surgical planning.^8,9 A recent prospective study compared the AR-3D technology with the standard intraoperative ultrasound guidance during robot-assisted partial nephrectomy performed for complex renal tumors (PADUA score ≥10).¹⁰ The AR-3D technology provided a more accurate intraoperative guidance than the standard ultrasound one, able to identify the position of renal vessels (facilitating the selective clamping procedures) and of endophytic and posterior tumors.

In summary, we will have a lively set of presentations moderated by John W. Davis from MD Anderson Cancer Center. The content will interest all surgeons looking for future improvements in image-guided surgery and those intrigued by how these new technologies will change future practice in urologic oncology. We will challenge each speaker to present their best case for why their technology works well, evidence for improvements in partial nephrectomy outcomes, practical considerations, and best arguments for picking one technology over another.