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JU INSIGHT Limitations of Parenchymal Volume Analysis for Estimating New Baseline GFR After Radical Nephrectomy

By: Kieran Lewis, BS, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Eran N. Maina, BA, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Carlos Munoz Lopez, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Nityam Rathi, BS, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Worapat Attawettayanon, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio, Songklanagarind Hospital, Prince of Songkla University, Songkhla, Thailand; Akira Kazama, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio, Graduate School of Medical and Dental Sciences, Niigata University, Japan; Jihad Kaouk, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Georges-Pascal Haber, MD, PhD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Mohamad Eltemamy, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Venkatesh Krishnamurthi, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Robert Abouassaly, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Christopher J. Weight, MD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio; Steven C. Campbell, MD, PhD, Glickman Urological and Kidney Institute, Cleveland Clinic, Ohio | Posted on: 18 Jun 2024

Lewis K, Maina EN, Lopez CM, et al. Limitations of parenchymal volume analysis for estimating split renal function and new baseline glomerular filtration rate after radical nephrectomy. J Urol. 2024;211(6):775-783. doi:10.1097/JU.0000000000003903

Study Need and Importance

Accurate estimation of new baseline glomerular filtration rate (NBGFR) following radical nephrectomy (RN) can be an important component of preoperative surgical decision-making. Recently, split renal function (SRF)–based models utilizing parenchymal volume analysis (PVA) have proven to be more accurate than traditional nuclear renal scans (NRSs) for the prediction of NBGFR. While the use of PVA in kidney cancer management has continued to increase, there has been little study of its potential limitations. Our study sought to evaluate patient and tumor factors associated with PVA inaccuracy.

What We Found

PVA was highly accurate for predicting NBGFR following RN and outperformed NRSs (Figure). However, the accuracy of PVA-based predictions was reduced in individuals with conditions that distort the renal volume/function relationship (hydronephrosis, pyelonephritis), alter renal functional compensation (increased age), or make accurate discrimination of renal parenchyma difficult (infiltrative tumor features). Importantly, NRSs were not more accurate than PVA even in cohorts where PVA-based predictions tended to be less accurate.

IMAGE

Figure. Accuracy of predicting new baseline glomerular filtration rate (NBGFR) after radical nephrectomy utilizing split renal function–based models. A, Software-derived measurements of parenchymal volume (PV) in the contralateral kidney, tumor plus PV in the ipsilateral kidney, and tumor alone were determined, and the relative amounts of normal parenchyma on each side were used to estimate split renal function. B, Accuracy of nuclear renal scan (NRS)–based predictions for estimation of NBGFR. Dotted lines represent accuracy within 15% of the observed NBGFR. C, Accuracy of PV analysis (PVA)–based predictions for estimating NBGFR. Dotted lines represent accuracy within 15% of the observed NBGFR.

Limitations

This study’s limitations include its retrospective design within a single tertiary center, which may affect generalizability.

Interpretation for Patient Care

Our current practice is to determine SRF utilizing PVA in almost all patients for whom the decision between RN and partial nephrectomy is complex, albeit with a few caveats. In patients with severely altered renal architecture or gross distortion of the parenchymal volume/function relationship, such as polycystic kidney disease or acute pyelonephritis, PVA should not be performed. However, these patients were rare in our cohort. In most patients, including those in cohorts where PVA tends to demonstrate reduced accuracy, PVA remains the superior choice for estimating SRF and NBGFR after RN.

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