Partial nephrectomy (PN) is one of the surgical treatment options for renal tumors. Small renal tumors can be challenging in targeting during operation. Therefore, the aim of this study was to compare the surgical outcomes of retroperitoneal PN for small renal tumors using indocyanine green (ICG) fluorescence imaging.

We enrolled 100 patients with renal tumors detected on abdominal computed tomography who underwent retroperitoneal robot-assisted partial nephrectomy (RAPN) between January 2021 and December 2024. Tumor size was assessed using preoperative CT, and only small renal tumors (<4 cm) were included. Patients were categorized based on whether they received preoperative ICG fluorescence-guided embolization. A super-selective trans-arterial delivery of an ICG-lipiodol mixture into the terminal arterial branches supplying the renal tumor, followed by placing a pushable coil in the tumor vessels to enhance the efficacy of embolization, was performed 3-hours prior to RAPN. Surgical outcomes were compared between approaches using the chi-squared, Student’s t-tests, logistic regression analysis and stratification analysis.

Of the 100 patients, 40 patients had small renal tumors. 9 (22.5%, ICG group) patients had received pre-operative ICG embolization and 31 (77.5%, non-ICG group) just received robotic-assisted PN straightly. On comparing the surgical results between the two groups, the ICG group had significantly shorter operation time (81 mins vs. 107.9 mins, p = 0.024). Also, the estimated blood loss was also significantly less than non-ICG group (167.8 mL vs. 377.4 mL, p = 0.048). In addition, warm ischemic time during operation had no significantly difference between two groups (17.6 mins vs. 18.2 mins, p = 0.784). The alteration in estimated glomerular filtration rate (eGFR) at post-operative 1st day (p = 0.291), 6th month (p = 0.390) and at post-operative 1st year (p = 0.976) were not significantly different between the two groups. Other surgical outcomes, such as blood transfusion rate, complications, and lengths of stay, also had no significant difference. No post-operative gastrointestinal-related or embolization-related complications were reported.

This study highlights the effectiveness of preoperative ICG embolization in enhancing tumor visualization during surgery, leading to reduced operative time and blood loss. The innovative use of super-selective trans-arterial delivery of the ICG-lipiodol mixture adds a new perspective to the evolving field of RAPN for small renal tumors.