Measuring volumetric segmentation changes in the ipsilateral and contralateral kidney postpartial nephrectomy

Objective: To analyze the volumetric changes of the ipsilateral and contralateral kidneys and their effect on functional outcome post partial nephrectomy using segmentation analysis. Patients and methods: We have analyzed the data of 119 patients from a single surgeon series of partial nephrectomy patients. Median follow-up was 11.40 months. Patients with bilateral tumors, and solitary kidney were excluded from analysis. Volumetric measurements were performed using a semiautomated tissue segmentation tool. A simple linear regression model to assess the predictors for parenchymal volume loss (PVL). A multivariable linear regression model was used to evaluate the association between PVL and warm ischemia time (WIT), controlling for other factors. Results: Mean WIT was 12.09 ± 4.40 minutes and the mean percentage decrease in the volume of the operated kidney was 16.99 ± 13.49%. WIT (β = 1.24, P < 0.001) and tumor complexity (simple vs. intermediate, β = 0.06, P = 0.984; simple vs. high, β = 11.62, P = 0.007) were associated with PVL. A 1 minute increase in WIT was associated with an increase in the percentage volume loss in the operated kidney by 1.38% (β = 1.20, P < 0.001). Patients with high tumor complexity (β = 11.17, P = 0.009) had a significantly higher percentage volume loss compared to patients with simple tumor complexity. Ipsilateral PVL (β = −0.35, P = 0.015) and male gender (β = −9.89, P = 0.021) were associated with change in eGFR. After adjusting for confounders, % volume loss (β = −0.32, P < 0.001) remained a significant predictor for contralateral hypertrophy. Conclusion: Tumor complexity results in higher WIT and increased PVL as measured by volumetric segmentation. PVL is a key factor associated with functional outcome, and is directly linked to WIT. Increased PVL is also associated with decreased contralateral hypertrophy. Prospective studies with larger samples sizes will be required to validate our findings.