Degree of contrast enhancement improves prediction of new baseline glomerular filtration rate following radical nephrectomy.

Abstract

To assess the accuracy of PVA⁺, a model integrating differential degree of enhancement (DOE) with parenchymal volume analysis (PVA), for predicting new baseline glomerular filtration rate (NBGFR) following radical nephrectomy (RN), and to assess PVA⁺ vs PVA alone in patients with hydronephrosis, where disruptions in the parenchymal volume/function relationship may impact prediction accuracy. A total of 485 RN patients (2006-2021) with preoperative contrast-enhanced computed tomography were included. The predicted NBGFR was estimated to be 1.25 (GFR_preRN x split renal function [SRF]_{contralateral}), with 1.25 representing the average renal functional compensation following RN in adults. For PVA, SRF was determined with differential parenchymal volumes, whereas for PVA⁺ the differential DOE was also incorporated. Parenchymal volumes and DOE were measured using semi-automated software from the venous phase vs non-contrast images. The accuracy of predicted vs observed NBGFR was compared using a 15% threshold. Overall, PVA⁺ accurately predicted NBGFR for 76% (r = 0.86) of the cases, compared to 72% for PVA alone (r = 0.84, both P < 0.05). PVA⁺ was particularly advantageous in patients with hydronephrosis or renal vein thrombosis (RVT; 68% vs 50% accuracy for PVA⁺ vs PVA alone; P < 0.01). Similarly, PVA⁺ was superior in patients with infiltrative renal masses (IRMs) compared to PVA alone (55% vs 40%; P < 0.01). Accurate prediction of NBGFR following RN is essential for counselling patients for whom RN is being considered vs partial nephrectomy. PVA⁺ was superior to PVA alone for NBGFR prediction, particularly in patients with hydronephrosis, RVT and IRMs. Requiring only routine contrast-enhanced preoperative imaging, PVA⁺ improves peri-operative decision-making for patients with localised renal masses, particularly in cases where the parenchymal volume/function relationship might be distorted.