Evaluating preoperative split renal function (SRF) is vital for donor assessment in living donor kidney transplantation (LDKT). With growing use of volume-based pre-operative assessments, reliance on nuclear-based studies is decreasing. Our study aims to show that volume-based pre-operative assessments are equivalent to nuclear-based methods for assessing living kidney donors with regards to predicting post-operative new baseline glomerular renal function (NBGFR).

58 consecutive donors (mean age 49 ±14, 47% males, BMI 24.3 ±4.3) underwent nephrectomy at our institution (84% left nephrectomy). All donors had CT volumetry and DMSA-based studies for pre-operative evaluation. Split renal volume, by CT volumetry (SRV-eGFR) was calculated by multiplying the remnant kidney's volume (normalized to total kidney volume) with baseline eGFR (51.5 ±2.7%,48.7 ±7.8 ml/min/1.73m²). Split renal function, by DMSA (DMSA-eGFR) was determined using the product of baseline eGFR and the percentage kidney function of remnant kidney from DMSA studies (50.4 ±2.6%, 49.9 ±8.4 ml/min/1.73m²). Post-donation eGFR was measured at 6 months (65.5 ±15.8 ml/min/1.73m²) up to 5 years (70.6 ±16.6ml/min/1.73m²). Pearson’s correlation and Lin’s concordance were used to assess the relationship between preoperative and post-donation eGFR (CKD-EPI), with further analysis using Fisher’s R-to-Z and Steiger’s Z tests.

Pre-operative CT volumetry and DMSA show moderate correlation (r=0.563) in estimating SRF. SRF of the left kidney differed between modalities (51.8 ±2.51% vs 50.6 ±2.56, p <0.05). Agreement between modalities in identifying larger kidney was 82.8%. Both SRV-eGFR and DMSA-eGFR strongly correlated with 6-month GFR (r =0.647, 0.666), without significant difference (z =0.208, p >0.05). Accounting for 25% hyperfiltration improved concordance for SRV (0.301 to 0.580, z =1.66, p =0.048) and DMSA (0.273 to 0.559, z=1.69, p=0.045) assessments. No difference in concordance was found between SRV-eGFR and DMSA-eGFR with 6-month eGFR after adjusting for hyperfiltration (z =-0.135, p =0.45).

CT-based SRV is equivalent to nuclear-based methods in predicting 6-month post-donation eGFR, and adjusting for renal hyperfiltration further enhances the predictive accuracy of these methods. Strong correlation and concordance between volume-based assessments with postoperative 6-month eGFR support their use as a viable alternative in LDKT pre-operative assessments, particularly with emerging automated methods for volumetry using AI and computer vision.