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


MATERIALS AND METHODS
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.


RESULTS
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).


CONCLUSIONS
IVIM MRI shows great potential in noninvasive assessment of renal fibrosis induced by UUO. J. Magn. Reson. Imaging 2016;44:698-706.
['Cai|Xiang-Ran|XR|', 'Yu|Juan|J|', 'Zhou|Qing-Chun|QC|', 'Du|Bin|B|', 'Feng|You-Zhen|YZ|', 'Liu|Xiao-Ling|XL|']
D000465:Algorithms D000818:Animals D005260:Female D005355:Fibrosis D007089:Image Enhancement D007090:Image Interpretation, Computer-Assisted D021621:Imaging, Three-Dimensional D007668:Kidney D008279:Magnetic Resonance Imaging D008297:Male D009038:Motion D051381:Rats D017207:Rats, Sprague-Dawley D015203:Reproducibility of Results D012680:Sensitivity and Specificity D014517:Ureteral Obstruction
intravoxel incoherent motion unilateral ureteral obstruction diffusion-weighted imaging hydronephrosis renal interstitial fibrosis