The extent to which robot-assisted surgery has been embraced by the surgical community has been unparalleled, driven by developments in 3-dimensional (3D) visualization, ergonomic design, energy delivery systems, instrument miniaturization, precision and dexterity across 4 generations of the da Vinci® Surgical System (Intuitive Surgical, Inc., Sunnyvale, California) to maximize the full potential of a minimally invasive surgical approach. With the da Vinci robot approaching almost 2 decades of commercial use, a shift in the focus toward advances in software integration are now shaping the future of minimal invasive surgery.¹

This is exemplified in robot-assisted partial nephrectomy (RAPN) where confined working spaces, a lack of haptic sensation, proximity to critical vasculature and other vitally important anatomical structures bestow significant challenges on the surgeon.² Recent advances in the field of surgical image guidance show promise in helping address these issues. In its most advanced form, this combination of technologies results in a fusion of visual information such that the operative field is combined with navigational cues and representations of key anatomical structures through augmented reality alignment, registration and overlay. Intraoperative ultrasound-guided navigation has long been utilized during RAPN as it relays additional information directly into the surgical console revealing otherwise obscured anatomy.³ However, development of a precise radiological guidance technology to specifically address difficulties of this procedure would be a superior technique.⁴ Multi-modal visualization, where 3D anatomical models are layered onto live video feeds, represents the cutting edge of surgical navigation systems, especially for robotic platforms.

IRIS^TM is the first interactive 3D anatomical modeling software that allows functional manipulation of anatomical models for intraoperative navigation during RAPN. The process converts DICOM files of computerized tomography (CT) images to 3D virtual anatomical models, viewed on an iOS device that can be directly relayed and manipulated into the da Vinci surgical system TilePro^TM input for intraoperative navigation (fig. 1).

Figure 1. IRIS 3D virtual anatomical models, viewed on an iOS device and directly relayed and manipulated into da Vinci surgical system TilePro^™.

Figure 2. Intraoperative navigation using IRIS during a partial nephrectomy for a complex renal tumor facilitating hilar dissection (a) defining tumor depth and violation of the urinary system (b).

In an IRIS pre-market study conducted at the University of Rochester, scans of 40 patients with renal masses were reviewed by 6 urologists.⁵ The vast majority reported IRIS to be very intuitive, with accurate representation of the anatomical details of all kidney components and tumor. IRIS improved surgeon confidence in completing the planned procedure compared to 2-dimensional CT alone with a higher tendency to attempt partial vs radical nephrectomy, especially in high nephrometry score complex cases. IRIS was found to be an optimal adjunct that could potentially influence efficiency and outcomes of the procedure.

In the first study to show clinical utility of IRIS, the technology was utilized for preoperative planning and intraoperative navigation via an iOS device and da Vinci surgical system TilePro input in 19 patients scheduled for RAPN at the University of Rochester (fig. 2).⁶ The impact of IRIS on anatomy interpretation and procedure efficiency was evaluated for every case through a 5-point Likert-type scale. The degree of overlap between the preoperative planned clamping technique and the actual clamping performed operatively was evaluated. Mean (±SD) age, body mass index, RENAL (radius, exophytic/endophytic, nearness of tumor to collecting system, anterior/posterior, location relative to polar line) nephrometry score and tumor diameter were 61 (±15), 30 (±5.5), 7.3 (±2.2) and 28.4 (±16.6) years, respectively. Of the tumors 21% were hilar, and 37%, 47% and 16% of patients had a RENAL score of 4–6, 7–9 and 10–12, respectively. Average (±SD) blood loss and ischemia time were 129 (±108.6) ml and 18.1 (±7.7) minutes, respectively. Preoperatively, all surgeons rated (≥4) that IRIS helped achieve good spatial sensation of the anatomy. Ratings reached 100% during preoperative planning for higher renal score cases and during intraoperative navigation for all cases. Intraoperatively, surgeons rated that IRIS improved procedure efficiency in 79% of cases, mainly attributed to ease in interpreting anatomy (95% of cases). The majority of surgeons (63%) spent an average of <5 minutes reviewing IRIS. In 15 of 19 cases, a high degree of overlap was found between preoperative planned clamping techniques to the actual operative clamping technique. In 5 cases, surgeons were able to perform super selective or off-clamp technique.

Figure 3. Touch-based registration method: mapping kidney surface by tracing a section of kidney with robotic instrument that registers it to segmented preoperative imaging displaying a reconstructed kidney relative to modeled da Vinci instruments in TilePro.

Preliminary analysis of 9 CT only arm versus 9 IRIS RAPN arm cases with comparable mean age (62 vs 65), body mass index (28 vs 32), RENAL nephrometry score (9) and tumor diameter (28.1 vs 32.1 mm), respectively, were compared. Preoperatively, all surgeons rated (≥4) that IRIS helped achieve good spatial sensation of the anatomy and only 56% of the surgeons who used CT rated (≥4). Intraoperatively, surgeons rated that IRIS improved procedure efficiency in 100% of cases compared to 0% in the CT arm, mainly attributed to ease in interpreting anatomy in the IRIS arm (100% of cases). In 6 of 9 IRIS cases, a high degree of overlap was found between preoperative planned clamping techniques to the actual operative clamping technique in IRIS arm, and 4 of the 9 cases performed super-selective or off-clamp technique in the IRIS arm compared to none in the CT arm.

Benefits of this intraoperative adjunct are evident, however these technologies can be further enhanced through automated registration that includes a seamless integration into the current surgical workflow. Towards this end, researchers at the Vanderbilt Institute for Surgery and Engineering developed a touch-based registration method that requires no additional hardware. Using data already recorded by the da Vinci Xi regarding an instrument’s tip position in space the topography of the kidney surface is mapped by tracing a section of the renal capsule with the instrument.⁷ A computer algorithm subsequently registers the surface contours from the operative field to those from segmented preoperative imaging and displays a reconstructed kidney relative to modeled da Vinci instruments in TilePro (fig. 3). As the kidney is mobilized during the operation, updates to the registration can be made instantaneously by using virtual fiducials, thus avoiding the need for invasive fiducial placement, intraoperative cross-sectional imaging/segmentation or optical trackers seen with other registration methods. Additionally, bodily fluids and smoke will not interfere with the registration as may be the issue in computer vision-based approaches. Most importantly, an operator does not have to manually align a reconstructed kidney with the operative field. Vanderbilt researchers are currently evaluating the registration error of their touch-based approach in a clinical series.

IRIS offers an interactive and accurate representation of complex anatomy, intraoperatively allowing surgeons to perform the procedure efficiently with consistency. Imminent improvements include manipulating the 3D model using master controls, additional procedures (robotic radical prostatectomy) and 1-step Picture Archiving and Communication System (PACS) integration.

As robotic surgery enters the digital era, further evidence of the impact of this and similar technologies on patient outcomes is required to justify commercialization.