Nonlinear elasticity phantom containing spherical inclusions undergoing large deformations

Most biological tissues demonstrate nonlinear stress strain relationships for sufficiently large deformations. A useful approach to characterizing and "optimizing" methodologies for studying nonlinear tissue elasticity is through experiments with tissue-mimicking phantoms. This work reports a phantom containing spherical inclusions created using information about the nonlinear behavior of agar-gelatin mixtures and agar-gelatin with oil emulsification. In this study, we demonstrated that the small strain shear modulus and the nonlinear behavior affect the strain image contrast as the material deforms. These observations are consistent with realistic Finite Element Analysis (FEA) simulations. The clinical relevance of this work is that nonlinear elasticity of the object being imaged may not only affect the image quality during strain imaging but might also provide information that can be used to differentiate tissues based on their nonlinear behaviors.