Assessment of the relationship between renal volume and renal function after minimally-invasive partial nephrectomy: the role of computed tomography and nuclear renal scan.

BACKGROUND: To evaluate the correlation between the loss of renal function as assessed by Tc99MAG-3 renal scan and the loss of renal volume as calculated by volumetric assessment on CT-scan in patients who underwent minimally-invasive partial nephrectomy (PN).

METHODS: PN prospectively-maintained database was retrospectively queried for patients who underwent minimally-invasive PN (2012-2017) for renal mass ≤cT2 and had complete data on renal scan and contrast-enhanced CT-scan (both performed in our Institution) both at preoperative assessment and at the third postoperative month follow-up. Tc99MAG-3 renal scan was performed to get renal functional data; renal volume was calculated by dedicated software from CT-scan with a semiautomated method. Statistical analysis aimed to identify relationships between loss of renal volume and loss of renal function and other patients' and surgical variables, particularly regarding lesion complexity (assessed by PADUA Score).

RESULTS: Fifty-seven patients were analyzed. Both at univariate and multivariate analysis, the percentage of loss of renal function was significantly correlated to the loss of renal volume (P<0.001). Warm ischemia significantly correlated with the loss of renal volume (P=0.003). After stratification according to PADUA score categories, higher surgical complexity renal masses had stronger correlation between the loss of renal volume and the loss of renal function.

CONCLUSIONS: The use of the semiautomated method for the 3D segmentation of the kidney to get the volumetric assessment could be a valid tool to support the future use of CT-scan as the tool to pair the oncological and the functional follow-up after PN.