MRI estimation of total renal volume demonstrates significant association with healthy donor weight

Purpose: The purpose of this study was to correlate total renal volume (TRV) calculations, obtained through the voxel-count method and ellipsoid formula with various physical characteristics. Materials and methods: MRI reports and physical examination from 210 healthy kidney donors (420 kidneys), on whom renal volumes were obtained using the voxel-count method, were retrospectively reviewed. These values along with ones obtained through a more traditional method (ellipsoid formula) were correlated with subject height, body weight, body mass index (BMI), and age. Results: TRV correlated strongly with body weight (r = 0.7) and to a lesser degree with height, age, or BMI (r = 0.5, -0.2, 0.3, respectively). The left kidney volume was greater than the right, on average (p < 0.001). The ellipsoid formula method over-estimated renal volume by 17% on average which was significant (p < 0.001). Conclusions: Body weight was the physical characteristic which demonstrated the strongest correlation with renal volume in healthy subjects. Given this finding, a formula was derived for estimating the TRV for a given patient based on the his or her weight: TRV = 2.96 × weight (kg) + 113 ± 64.