Novel prediction model of renal function after nephrectomy from automated renal volumetry with preoperative multidetector computed tomography (MDCT)

Background and purpose The predictive model of postoperative renal function may impact on planning nephrectomy. To develop the novel predictive model using combination of clinical indices with computer volumetry to measure the preserved renal cortex volume (RCV) using multidetector computed tomography (MDCT), and to prospectively validate performance of the model. Patients and methods Total 60 patients undergoing radical nephrectomy from 2011 to 2013 participated, including a development cohort of 39 patients and an external validation cohort of 21 patients. RCV was calculated by voxel count using software (Vincent, FUJIFILM). Renal function before and after radical nephrectomy was assessed via the estimated glomerular filtration rate (eGFR). Factors affecting postoperative eGFR were examined by regression analysis to develop the novel model for predicting postoperative eGFR with a backward elimination method. The predictive model was externally validated and the performance of the model was compared with that of the previously reported models. Results The postoperative eGFR value was associated with age, preoperative eGFR, preserved renal parenchymal volume (RPV), preserved RCV, % of RPV alteration, and % of RCV alteration ( p < 0.01). The significant correlated variables for %eGFR alteration were %RCV preservation ( r = 0.58, p < 0.01) and %RPV preservation ( r = 0.54, p < 0.01). We developed our regression model as follows: postoperative eGFR = 57.87 − 0.55(age) − 15.01(body surface area) + 0.30(preoperative eGFR) + 52.92(%RCV preservation). Strong correlation was seen between postoperative eGFR and the calculated estimation model ( r = 0.83; p < 0.001). The external validation cohort ( n = 21) showed our model outperformed previously reported models. Conclusions Combining MDCT renal volumetry and clinical indices might yield an important tool for predicting postoperative renal function.