Static and dynamic liver stiffness: An ex vivo porcine liver study using MR elastography.

Magnetic resonance elastography (MRE) is an MRI-based noninvasive technique for quantitatively assessing tissue stiffness. The hypothesis of this study is that stiffness increases with portal pressure. We further hypothesized that the rate of stiffness change with pressure would be larger in liver tissue treated to simulate the stiffening effects of fibrosis. In agreement with our hypothesis, the formalin-treated livers were stiffer than the untreated livers, and in both groups the liver stiffness increased with portal venous pressure. The rate of stiffness change with portal pressure was significantly greater after formalin treatment. In this study, we have developed an ex vivo liver model incorporating portal venous pressure variations and observed significant changes in liver stiffness due to portal pressure. This model could be useful for understanding and investigating the changes in the static and dynamic components of liver stiffness.