PURPOSETo study the potential of viscoelastic parameters such as liver stiffness, loss tangent (marker of viscous properties) and viscoelastic dispersion to detect hepatic inflammation by in-vivo and ex-vivo MR elastography (MRE) at low and high vibration frequencies. METHODS15 patients scheduled for liver tumor resection surgery were prospectively enrolled in this IRB-approved study and underwent multifrequency in-vivo MRE (30-60Hz) at 1.5-Tesla prior to surgery. Immediately after liver resection, tumor-free tissue specimens were examined with ex-vivo MRE (0.8-2.8kHz) at 0.5-Tesla and histopathologic analysis including NAFLD activity score (NAS) and inflammation score (I-score) as sum of histological sub-features of inflammation. RESULTSIn-vivo in regions where tissue samples were obtained, the loss tangent correlated with the I-score (R=0.728; p=0.002) and c-dispersion (stiffness dispersion over frequency) correlated with lobular inflammation (R=-0.559; p=0.030). In a subgroup of patients without prior chemotherapy, c-dispersion correlated with I-score also in the whole liver (R=-0.682; p=0.043). ROC analysis of the loss tangent for predicting the I-score showed a high AUC for I≥1 (0.944; p=0.021), I≥2 (0.804; p=0.049) and I≥3 (0.944; p=0.021). Ex-vivo MRE was not sensitive to inflammation, whereas strong correlations were observed between fibrosis and stiffness (R=0.589; p=0.021), penetration rate (R=0.589; p=0.021), loss tangent (R=-0.629; p=0.012), and viscoelastic model parameters (spring-pot powerlaw exponent, R=-0.528; p=0.043; spring-pot shear modulus, R=0.589; p=0.021). CONCLUSIONOur results suggest that c-dispersion of the liver is sensitive to inflammation when measured in-vivo in the low dynamic range (30-60Hz), while at higher frequencies (0.8-2.8kHz) viscoelastic parameters are dominated by fibrosis.