Introduction: Preservation of renal parenchymal volume is one of the major goals of surgeons performing a partial nephrectomy (PN). IRIS anatomical visualization software generates a segmented 3D model, allowing surgeons to better visualize the tumor, renal vasculature, collecting system, and their relationship. We hypothesize that using a segmental 3D model intra-operatively during PN on complex tumors would improve renal parenchymal volume preservation. Methods: We identified 74 non-IRIS and 19 IRIS patients who underwent PN from January 1st, 2019 to January 1st, 2022, with nephrometry scores of 9, 10, 11, and had complete pre and postoperative axial imaging. We completed propensity score matching (PSM) based on nephrometry score, age, BMI, and tumor volume and finalized 18 PS matched pairs. Pre and postoperative imaging (MRI or CT) were obtained from patient charts on Fuji PACS and quality screened by our researchers. Volumes of the preoperative renal tumor mass and whole kidney volume were obtained and used to calculate predicted postoperative volume. Measured postoperative renal volumes were compared to the predicted postoperative volumes. Statistical analysis was performed using a paired one-sided t-test. All analyses were performed using R. Results: The mean predicted postoperative kidney volume in the IRIS and non-IRIS groups were 194.1 cm3 (71.5) and 218.9 cm3 (SD=48.9), and postoperative whole kidney volume was 175.0 cm3 (SD=73.5) and 186.9 cm3 (SD=47.2). Mean difference between predicted and actual postoperative whole kidney volume in the IRIS group was statistically smaller, 19.2 cm3 (SD=20.2), than the non-IRIS group, 32 cm3 (SD=16.1, P=0.0074). Percent difference from predicted kidney volume in the IRIS group was 10.9% vs. 17.1% in the non-IRIS group. There was no significant change in mean GFR from baseline to 6-month postoperative period between IRIS and non-IRIS groups (-6.39, SD=15.8 vs. -9.54, SD=13.3; P=0.374). Additionally, no significant difference in complication rates (0 vs. 1, P=0.235), frequency of patients who experienced worsening GFR staging (5 vs 4, P=1.00) and >25% decrease in GFR levels (3 vs. 4, P=1.00) were found between IRIS and non-IRIS groups respectively. Conclusions: We demonstrated that using a segmental 3D model intra-operatively when performing a partial nephrectomy on complex tumors improves renal parenchymal preservation. The long-term clinical significance of this preservation remains to be determined. SOURCE OF Funding: No Funding
