A Comparison of Excisional Volume Loss Calculation Methods to Predict Functional Outcome After Partial Nephrectomy

Area of Science:

• Nephrology
• Urology
• Radiology

Background:

• Functional volume loss (FVL) is a key predictor of kidney function decline post-partial nephrectomy (PN).
• Accurate quantification of FVL is crucial for predicting post-PN outcomes.
• Two methods for FVL quantification exist: imaging-based tissue segmentation (TS) and pathological analysis.

Purpose of the Study:

• To compare the accuracy of imaging-based TS and pathological analysis in quantifying FVL post-PN.
• To determine the association of each quantification method with estimated glomerular filtration rate (eGFR) decline.

Main Methods:

• Retrospective analysis of 42 patients undergoing PN for cT1 renal mass.
• FVL calculated using TS (preoperative imaging) and pathological analysis (specimen dimensions).
• Spearman's correlation and multivariable linear mixed-effects models used to assess associations.

Main Results:

• eGFR significantly decreased by -5.1 mL/min/1.73 m² at 6 months post-PN (p=0.004).
• Pathological analysis underestimated FVL (5.76 mL) compared to TS (32.2 mL) (p<0.001).
• TS analysis was significantly associated with eGFR decline (β=0.084, p=0.012), while pathological analysis was not (β=0.02, p=0.87).

Conclusions:

• Pathological analysis underestimates parenchymal volume loss post-PN.
• Imaging-based TS is the only method significantly associated with changes in eGFR after PN.
• TS is a more reliable method for assessing FVL and predicting kidney function post-PN.