Can parenchymal volume analysis replace nuclear renal scans for split renal function before and after partial nephrectomy with warm ischemia?

Abstract

Background: The assessment of split renal function (SRF) before and after partial nephrectomy (PN) is crucial. While nuclear renal scan (NRS) is a traditional method for evaluating SRF, its extensive use is hindered by concerns regarding radioactivity. Parenchymal volume analysis (PVA) has been employed to assess SRF for kidney donors. Nonetheless, the efficacy of PVA in evaluating SRF in kidneys with renal masses before and after PN with warm ischemia remains uncertain.

Aim: The current study probed into the potential of PVA as a substitute for NRS in assessing SRF before and after PN with warm ischemia.

Methods: This study included 318 patients who underwent unilateral PN with warm ischemia at Sun Yat-Sen University Cancer Center (SYSUCC) and had a functional contralateral kidney. All patients underwent PVA and NRS assessments both pre-PN and at 1-12 months post-PN. PVA was analyzed using Mimics software in the venous phase. The estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2021 equation. The correlation between ipsilateral eGFR values derived from SRF assessed via PVA and NRS was examined using Pearson correlation. Concordance between different methods of SRF estimation was analyzed using the Friedman test, Bland-Altman plots, and Kendall's consistency coefficient. Similar study was conducted on a comparable cohort from Sun Yat-Sen Memorial Hospital.

Results: The median tumor size was 3.5cm, and the median warm ischemia time was 25min. Preoperatively, ipsilateral SRF values based on PVA were notably consistent with those derived from NRS (49.4% vs 50.0%, P = .501). A strong correlation was observed between preoperative ipsilateral eGFR based on SRF from PVA and NRS (r = 0.89, P < .0001). Bland-Altman plots indicated minimal bias (-0.36%) between PVA and NRS in assessing SRF. However, post-PN, the median ipsilateral SRF based on PVA was slightly higher than that based on NRS (45.6% vs. 43.6%, P < .0001). Although there was still a strong correlation between post-PN ipsilateral eGFR based on SRF from PVA and NRS (r = 0.87, P < .0001), Bland-Altman plots revealed a non-negligible bias between the 2 methods (2.19 %). External study supported our findings.

Conclusions: PVA shows promise as a substitute for NRS in assessing SRF before PN with warm ischemia. However, this substitution may result in an overestimation of ipsilateral renal function in the post-PN phase.