Guangdong Key Laboratory of Liver Disease Research, Department of Medical Ultrasound, The Third Affiliated Hospital of Sun Yat-sen University

The accuracy of ultrasound elastography for assessing liver fibrosis by measuring liver stiffness (elastic modulus) is better than traditional method. Elastography has certain advantage such as non-invasive, simple, real-time and it has been recommended by clinical guidelines.

However, some chanllenging scientific problems showed up with further research and clinical practice. Firstly, present elastography machines can only calculate liver stiffness from shear wave speed or elastic modulus but ignore other physical characteristics such as tissue viscosity. So far, present technique simply assume liver as an idealized model with isotropic elasticity to assess liver fibrosis while liver is actually anisotropic and viscoelastic. What's more, theoretically, there are not only different solid state structures such as cell organization and vessel but also flowing liquid such as blood and bile. Thus, ignoring viscosity and evaluating elasticity only is unreasonable. In the other hand, a number of confounding factors have been found to influence liver stiffness measurement by elastography. Different pathological chang of liver including inflammation, necrosis, cholestasis and inhomogeneity among the individuals such as obesity, ascites, et,al. will decrease the accuracy of liver stiffness measurement and liver fibrosis staging by elastography.

In fact, liver fibrosis is a dynamic process. Liver fibrosis is a reaction of compensation and repair for inflammation and necrosis as well as a contributing factor for liver damage. This dynamic process constitutes the common characteristic of chronic liver disease and result in the complicated biological mechanical characteristics of liver. In consequence, how to measure liver viscosity and elasticity respectively, and to evaluate liver fibrosis stage and Inflammation degree accurately during the complicated and dynamic pathological process is the key scientific problem demanding solution, which is also the urgent requirement of related fundamental research and clinical practice.

Therefore, this project plan to apply LOGIQ E viscoelastography machine as research tool, rat liver fibrosis model and rat liver failure model as research object to investigate the correlation between liver viscoelastography measurement and liver fibrosis stage and Inflammation degree. The investigators also aim to assess the feasibility of using ulstrasound viscoelastography to evaluate liver fibrosis stage and Inflammation degree dynamically.