Three-dimensional image guidance using instrument tracking facilitates intraoperative resection-line determination during robot-assisted partial nephrectomy.

Resection-line planning during robot-assisted partial nephrectomy (RAPN) requires accurate tumor localization while preserving normal renal parenchyma. We developed a three-dimensional image-guided (3D-IG) system that displays a patient-specific 3D kidney model together with the real-time position of the surgical instrument tip. This retrospective comparative study evaluated the initial clinical implementation of 3D-IG in RAPN. Ten consecutive patients with moderate- to high-complexity renal tumors who underwent RAPN using 3D-IG between February and June 2025 were compared with ten randomly selected historical controls with a matching R.E.N.A.L. (R = tumor radius, E = exophytic/endophytic properties, N = nearness of tumor to the collecting system or sinus, A = anterior/posterior, L = location relative to polar line) nephrometry score range who underwent conventional ultrasound (US)-guided RAPN in 2024. Resection-line marking time was significantly shorter in the 3D-IG group than in the US group (77 vs. 282 s, p < 0.001), as was resection-line localization time (25 vs. 125 s, p < 0.001). Electrocautery activation events during marking were also fewer in the 3D-IG group (16 vs. 39, p < 0.001). Even after including routine US confirmation performed for safety in the 3D-IG group, total planning time remained comparable between groups (207 vs. 282 s, p = 0.226). Pathological margin width did not differ significantly between groups, no positive surgical margins were observed, and perioperative and renal functional outcomes showed no apparent adverse signal. The 3D-IG system improved the efficiency of resection-line marking during RAPN while maintaining acceptable short-term surgical outcomes.