Identification of Recurrent Anatomical Clusters Using Three-dimensional Virtual Models for Complex Renal Tumors with an Imperative Indication for Nephron-sparing Surgery: New Technological Tools for Driving Decision-making.

Background: Some renal tumors have an imperative indication for nephron-sparing surgery (NSS), such as in cases of chronic kidney disease and bilateral complex tumors. Objective: To demonstrate the degree to which three-dimensional virtual model (3DVM) assistance can be helpful in planning the surgical strategy for high-complexity renal masses with an imperative indication for NSS. Design setting and participants: Three patients with high-complexity renal masses with unusual anatomy and an imperative indication for NSS were prospectively selected across 2020 and 2021 at our institution. All patients underwent contrast-enhanced computed tomography from which a 3DVM was obtained. Surgical procedure: Robot-assisted partial nephrectomy with 3DVM augmented reality guidance. Measurements: Demographics and tumor-related features were recorded. Data for intraoperative, pathological, and functional assessments were collected for all three patients. Results and limitations: Two of the three patients harbored bilateral renal tumors. The third patient presented with a renal mass in the left kidney and contralateral renal hypoplasia (right-split renal function of 25%). All of the patients demonstrated similar anatomical and tumor features on 3DVMs, with potentially independent vascularization and drainage for the lower pole. In one patient the upper pole of the kidney was spared, exiting in a functionally excluded hydrocalyx, while in the other two cases the upper pole was removed together with the lesion. The spared portion of the kidney retained vascularization, as demonstrated by intraoperative ultrasound and indocyanine green injection. The small sample size and short follow-up are the main limitations of the study. Conclusions: 3DVMs, especially for complex renal masses with an imperative indication for NSS, allow planning of the surgical strategy on the basis of the anatomical characteristics of the organ in which the tumor is growing. Patient summary: Three-dimensional models help in defining the best surgical strategy for kidney tumors, especially for complex tumors that require surgery to spare as much of the kidney as possible.