Use of intravoxel incoherent motion MRI to assess renal fibrosis in a rat model of unilateral ureteral obstruction

Abstract

To investigate the potential of intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) in assessment of renal fibrosis using a rat model of unilateral ureteral obstruction (UUO). Thirty-two UUO rats were created by complete ligation of the left ureter. IVIM was performed on a clinical 3.0T whole-body MRI scanner before the ligation (day 0) and on days 1, 3, 5, and 7 after ligation, and followed by histological analysis to examine α-smooth muscle actin (α-SMA) expression and tubulointerstitial lesion (TIL). IVIM parameters of renal cortex and medulla were measured. Changes in each parameter with time were analyzed and correlated with α-SMA expression level and grades of TIL. The apparent diffusion coefficient (ADC), true diffusion (D), and fractional perfusion (f) values between the cortex and inner medulla and between the cortex and outer medulla were found to be significantly different (P < 0.01). The average ADC, D, D*, and f values of renal cortex, outer medulla, and inner medulla on the UUO side significantly decreased over time (P < 0.05), and negatively correlated with both α-SMA expression level and TIL grades (Spearman Correlation Coefficient r: ADC and α-SMA.805, -0.707, -0.805; ADC and TIL: -0.758, -0.761, -0.810; D and α-SMA: -0.782, -0.486, -0.833; D and TIL: -0.518, -0.504, -0.826; D* and α-SMA: -0.707, -0.605, -0.639; D* and TIL: -0.450, -0.670, -0.701; f and α-SMA: -0.866, -0.872, -0.863; and TIL: -0.870, -0.875, -0.863). IVIM MRI shows great potential in noninvasive assessment of renal fibrosis induced by UUO. J. Magn. Reson. Imaging 2016;44:698-706.