Tissue Elasticity Reconstruction Based on 3-Dimensional Finite-Element Model

We describe a method of estimating the elasticity distribution in tissue based on the 3-D finite-element model. Generally, the elastic modulus is calculated from the strain and the stress. The strain field can be estimated from the RF signals measured for pre- and postcompressed tissue, while it is impossible to directly measure the stress field within the tissue. Therefore, we reconstruct the tissue elasticity distribution by solving the inverse problem, that is, by estimating the elasticity modulus from the axial strain field and the external pressure distribution at the surface of the tissue. We have performed a simulation and a phantom experiment to demonstrate the ability of the proposed method. The results verified that the method is able to detect tumors more quantitatively than the conventional method based on the 2-D model, even for lesions invisible in a B-mode image.