Utilizing computed tomography-based renal parenchymal volumes to calculate split renal function in patients with ureteral stricture disease.

Purpose: Evaluation of split renal function (SRF) is critical for guiding surgical treatment decisions for patients with ureteral stricture disease (USD). We aimed to determine whether computed tomography (CT)-based renal parenchymal volumes may be used to predict SRF in patients with USD.

Methods: We retrospectively reviewed all patients undergoing surgical management for USD at a single institution from October 2021 to January 2024. Patients who had preoperative nuclear medicine scan (NMS) and CT scan with intravenous contrast that were obtained within six weeks of each other were included. Interval between NMS and CT could be longer if the affected renal unit was drained with ureteral stent and/or percutaneous nephrostomy. Volume measurements were obtained using the 3D Region of Interest (ROI) Tool on Visage7 Enterprise Imaging Platform (Visage Inc., San Diego, USA) by two investigators that were blinded to NMS derived SRF. Intraclass correlation coefficient (ICC) was used to assess consistency between investigators. Predictive accuracy was assessed using Pearson correlation coefficient (r) and linear regression.

Results: 40 of 160 patients met inclusion criteria. There was excellent reliability in calculating renal parenchymal volume between raters (ICC = 0.990). There was a strong linear correlation between estimated CT SRF and NMS SRF (r = 0.912, p < 0.00001). A linear regression model found R = -0.013 + 1.015(R), with r = 0.832.

Conclusion: CT-derived parenchymal volume analysis may be used to estimate SRF in patients with USD. This may obviate the need to obtain preoperative renal scans for SRF measurement in selected patients when assessing surgical management options.