Login to Access Video or Poster Abstract: MP59-13
Sources of Funding: none

Introduction

To investigate the impact of tumor size and the usefulness of the ellipsoid formula for assessing compensatory hypertrophy of the contralateral kidney on preoperative and postoperative computed tomography in renal cell carcinoma(RCC) patients.

Methods

We retrospectively identified 389 patients who had radical nephrectomy for RCC between 2011 and 2015. Contrast-enhanced CT was performed within three months preoperative and at 1 year postoperative. The kidney volumes were calculated from CT images using the ellipsoid formula(volume = length x thickness x width x π/6). We subdivided patients into three groups based on tumor size(A: ?4cm, B: 4-7cm, C: >7cm). Volumetric renal parameters were compared and multivariate linear regression analyses were performed to determine predictors associated with preoperative and postoperative compensatory hypertrophy.

Results

Kidney volume measurements using the ellipsoid method took a median of 51 seconds. Group C had a significantly larger median preoperative contralateral renal volume than groups A and B(A: 140.4, B: 141.6, C: 166.7mL, p<0.05). However, the median ratio of postoperative contralateral renal volume change was significantly higher in groups A and B than in group C(A:0.36, B:0.23, C:0.12, p<0.001)(Table1). On multivariate analysis, tumor size revealed the strongest positive association with preoperative contralateral kidney volume (β=30.8, >7cm) and ratio of postoperative contralateral kidney volume change(β=0.214, A vs. C; β=0.168, B vs. C)(Table2).

Conclusions

Kidney volume measurements for assessing preoperative and postoperative compensatory hypertrophy of the contralateral kidney in RCC patients can be easily and rapidly performed from CT images using the ellipsoid formula. Additionally, tumor size is the strongest factor associated with compensatory hypertrophy in the contralateral kidney before (>7cm) and after (?4 or 4–7 cm) radical nephrectomy.

Funding

none