Which Better Determines the Renal Function and Glomerular Filtration Rate: Renal Parenchymal Thickness or Renal Resistive Index?

Abstract

Resistive index (RI) could provide more useful diagnostic and prognostic information for kidney disease than parenchymal thickness (PT) only. The aims of this study were to find the association between PT, glomerular filtration rate (GFR), and RI and their determination of renal function. B-mode and Doppler ultrasonography and standard biochemical laboratory testing (urea and creatinine) were performed among 75 participants (57.1 ± 10.6 years). We measured PT and RI and calculated GFR. The mean and standard deviation were 0.671 ± 0.041, 12.24 ± 1.98 mm, and 86.38 ± 15.96 mL/min/1.73 m2 for RI, PT, and GFR, respectively. The mean RI in two subgroups with PT smaller or greater than 12.5 mm was RI1 = 0.692 ± 0.038 or RI2 = 0.648 ± 0.03 (P <0.0001). Strong inverse correlation between RI (y) and PT (x) presented by the linear regression equation: y = 0.744 + (-0.005932 x). By multiple regression, we show GFR and PT as predictors for increasing of RI (R2 = 0.2063, βst = -0.0009176, P = 0.0012 and βst = -0.006003, P = 0.0078), respectively. Renal RI inversely strongly correlates with the PT and GFR. Renal PT and GFR are independent predictors for increasing of RI in general population.