title: Constitutive modeling of human liver based on in vivo measurements.
abstract: In vivo aspiration experiments on human livers are analyzed and material parameters for a non-linear-viscoelastic constitutive model are determined. A novel procedure is applied for the inverse analysis that accounts for the initial tissue deformation in the experiment and for the non-homogeneity of liver tissue. A numerical model is used consisting of a surface layer (capsule) and an underlying non-linear-viscoelastic solid (parenchyma). The capsule is modeled as hyperelastic membrane using data from measurements on bovine and human tissue. In a two step optimization procedure the set of constitutive model parameters for the "average" response of liver parenchyma is obtained. The proposed model is in line with literature values of high strain rate elastic modulus obtained from dynamic elastography. The model can be used to predict the nonlinear, time dependent behavior of human liver in computer simulations related to surgery training and planning.
authors.affiliation: Institute of Mechanical Systems, Department of Mechanical and Process Engineering, ETH, 8092 Zurich, Switzerland. Edoardo.Mazza@imes.mavt.ethz.ch
authors.forename: Edoardo
authors.initials: E
authors.lastname: Mazza
authors.forename: Patrick
authors.initials: P
authors.lastname: Grau
authors.forename: Marc
authors.initials: M
authors.lastname: Hollenstein
authors.forename: Michael
authors.initials: M
authors.lastname: Bajka
mesh_terms: D019245:Compressive Strength / Q000502:physiology; D003198:Computer Simulation; D004548:Elasticity; D006244:Hardness; D006801:Humans; D008099:Liver / Q000502:physiology*; D008954:Models, Biological; D013314:Stress, Mechanical; D014783:Viscosity