ABSTRACT
The aim of the present study was to preoperatively predict renal function following partial nephrectomy (PN) using an imaging-based approach and to examine the correlation between preoperatively predicted and postoperatively observed renal function in the study cohort. A total of 128 consecutive patients who underwent PN between May 2015 and March 2018 and had available clinical data were included in this study. A hand-scripting method was used to estimate the defected volume (Vdef) from preoperative computerized tomography scans, whereas a cylindrical method was used to obtain preoperative renal volume (Vpre). The function index (FI) was proposed as a new term to estimate preserved parenchyma percentage following PN. The FI was defined as f=(Vpre-Vdef)/Vpre for the operated kidney and adjusted as FI=0.5 × (f + 1) for the bilateral kidneys. The estimated glomerular filtration rates (GFRs) before surgery, one day after surgery and ~12 months after surgery were calculated using the Modification of Diet in Renal Disease Study equation. The GFR rate after PN was predicted by multiplying the preoperative GFR by the FI. The predictive role of the FI was further tested using multiple linear regression and correlation analyses. The median FI in the present study was 94% for unilateral kidney surgery and adjusted to 97% for bilateral kidneys. Linear correlation analysis revealed that the predicted GFR significantly correlated with the observed immediate postoperative GFR (R2, 0.594) and observed late postoperative GFR (R2, 0.828). In multivariate regression analysis, preoperative GFR (P<0.01) and warm ischemic time (P<0.01) were identified as independent determinants of the immediate postoperative renal function, whereas only FI (P<0.01) and preoperative GFR (P<0.01) were identified as independent determinants of late renal function after PN. The preoperatively predicted renal function using an imaging-based approach had a significant positive correlation with the postoperatively observed renal function. The FI estimated from the preoperative diagnostic images in the present study was identified as an independent determinant of long-term renal function after PN.
ABSTRACT
PURPOSE: Several nephrometry scoring systems have been developed based on two-dimensional computerized tomography images to quantify anatomical features of renal tumors. We have developed an accurate three-dimensional nephrometry scoring system to respond to the urgent need for advanced systems based on three-dimensional images. MATERIALS AND METHODS: We retrospectively reviewed 135 patients who underwent partial nephrectomy in our institution. Stereoscopic models were reconstructed from preoperative computerized tomography images and three-dimensional scores were assigned directly on stereoscopic models. All tumors were analyzed for following features: tumor volume; endophytic tumor proportion; renal vascular variations; tumor's relationships with urinary collecting system or renal sinus; longitudinal distance from tumor to equatorial plane. Correlation between three-dimensional score and warm ischemic time was calculated compared with existing classical nephrometry scoring systems. The value of nephrometry scoring systems predicting longer warm ischemic time was explored by receiver operating characteristic curves. RESULTS: Mean tumor volume was 31.25 ml; endophytic volume was less than 50% in 42 cases, more than 50% in 79 cases, and 100% in 14 cases; mean longitudinal distance from tumor to equatorial plane was 1.41 cm; 30 patients (22.2%) presented renal vascular variations; 18 cases (13.3%) involved both urinary collecting system and sinus. Mean three-dimensional score was 8.3. Variance analysis and covariance analysis revealed warm ischemic time a significant association with all evaluated tumor features. Furthermore, three-dimensional scores most highly correlated with warm ischemic time (rs = 0.64, p < 0.001), followed by R.E.N.A.L. scores (rs = 0.21, p = 0.012), centrality index (rs = - 0.20, p = 0.019) and Preoperative Aspects and Dimensions Used for Anatomy score (rs = 0.20, p = 0.019). Area under curve of above nephrometry scoring systems was 0.91, 0.67, 0.68 and 0.67 respectively (p < 0.05). CONCLUSIONS: The three-dimensional scoring system developed in this study was a highly-accurate system to quantify the anatomical features of renal tumors. It was identified to have a value in predicting duration of warm ischemic time.