Diffusion Metrics for Staging Pancreatic Fibrosis and Correlating With Epithelial-Mesenchymal Transition Markers in a Chronic Pancreatitis Rat Model at 11.7T MRI.

Background Chronic pancreatitis (CP) is characterized by pancreatic fibrosis, in which a epithelial-mesenchymal transition (EMT)-like process is observed. However, few noninvasive approaches have been reported to evaluate pancreatic fibrosis and EMT in an animal model based on diffusion imaging. Purpose To evaluate pancreatic fibrosis in CP by conventional diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis imaging (DKI) and then explore the correlation between diffusion parameters and the EMT markers in an animal model. Study Type Prospective controlled imaging histological correlation. Population Forty-five rats with CP induced by injecting dibutyltin dichloride solution and 10 normal rats comprised the control group. Field Strength/Sequence 11.7T MR, diffusion imaging with 10 b-values. Assessment Apparent diffusion coefficient (ADC), IVIM-associated perfusion fraction (f), pseudodiffusion coefficient (D*), diffusion coefficient (D), DKI-associated mean kurtosis (MK), and mean corrected diffusion coefficient (MD) were quantitatively measured and correlated with pancreatic fibrosis stages as well as the EMT markers E-cadherin and alpha-smooth muscle actin (alpha-SMA) expression. The discriminative performance of diffusion parameters for staging fibrosis was compared. Statistical Tests Spearman's correlation, Student's t-test, and a receiver operating characteristic curve was conducted for statistical analysis. Results ADC, D, and MD (r = -0.637, -0.688, and -0.535; P < 0.001) were negatively correlated with pancreatic fibrosis staging, but MK (r = 0.740, P < 0.001) had a positive correlation. ADC, D, MD, and MK were significantly correlated with alpha-SMA (r = -0.684, -0.728, -0.627, and 0.721, all P < 0.001), while MK was significantly correlated with E-cadherin (r = -0.606, P < 0.001). The area under the curve (AUC) was not significantly different (P > 0.05) among ADC (0.797, 0.816, 0.873), D (0.862, 0.810, 0.895), MD (0.767, 0.772, 0.801), and MK (0.836, 0.893, 0.951) for F1 or greater, F2 or greater, and F3 pancreatic fibrosis separately. Data Conclusion ADC, D, MD, and MK were helpful for assessing pancreatic fibrosis staging, and these diffusion parameters were also significantly correlated with the expression of EMT markers in pancreatic fibrosis. Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019.