Estimated functional renal parenchymal volume predicts the split renal function following renal surgery

The change in functional renal volume (FRV) has an absolute influence on renal function after nephrectomy (Nx) or nephron-sparing surgery (NSS). In this study, we prospectively examined whether the postoperative renal function following Nx and NSS could be accurately predicted and assessed the reproducibility of our newly developed 3-D image reconstruction system (Kashihara) to measure the FRV.

We enrolled 98 patients who underwent Nx and 41 patients who underwent NSS from April 2006 to September 2009 to predict postoperative FRV and renal function. FRV was measured before and after (1 month and 1 year) renal surgery. The postoperative estimated glomerular filtration rate (eGFR) was predicted from the preoperative eGFR calculated from the serum creatinine (sCr) level and the ratio of the postoperative/preoperative FRV. To assess the reproducibility and accuracy of our newly developed 3-dimensional (3-D) image reconstruction system, FRV was measured by five examiners using images obtained by CT (five cases) and MRI (five cases).

Significant correlation was found both for FRV and for renal function between the predictive values and the actually measured values at 1 month and 1 year after surgery, not only in the Nx group, but also in the NSS group. The accuracy and reproducibility could be confirmed both with CT and MRI studies.

The postoperative FRV and renal function could be predicted preoperatively using a 3-D image reconstructive system, preoperative routine diagnostic imaging, and preoperative sCr level.