Browsing by Author "Sun, L. Z."

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    Elastography Method for Reconstruction of Nonlinear Breast Tissue Properties
    Wang, Z. G.; Liu, Y.; Wang, G.; Sun, L. Z. (Hindawi, 2009-07-09)
    Elastography is developed as a quantitative approach to imaging linear elastic properties of tissues to detect suspicious tumors. In this paper a nonlinear elastography method is introduced for reconstruction of complex breast tissue properties. The elastic parameters are estimated by optimally minimizing the difference between the computed forces and experimental measures. A nonlinear adjoint method is derived to calculate the gradient of the objective function, which significantly enhances the numerical efficiency and stability. Simulations are conducted on a three-dimensional heterogeneous breast phantom extracting from real imaging including fatty tissue, glandular tissue, and tumors. Anexponential-form of nonlinear material model is applied. The effect of noise is taken into account.Results demonstrate that the proposed nonlinear method opens the door toward nonlinear elastographyand provides guidelines for future development and clinical application in breast cancer study.
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    Nonlinear Elasto-Mammography for Characterization of Breast Tissue Properties
    Wang, Z. G.; Liu, Y.; Wang, G.; Sun, L. Z. (Hindawi, 2011-12-22)
    Quantification of the mechanical behavior of normal and cancerous tissues has important implication in the diagnosis of breast tumor. The present work extends the authors' nonlinear elastography framework to incorporate the conventional X-ray mammography, where the projection of displacement information is acquired instead of full three-dimensional (3D) vector. The elastic parameters of normal and cancerous breast tissues are identified by minimizing the difference between the measurement and the corresponding computational prediction. An adjoint method is derived to calculate the gradient of the objective function. Simulations are conducted on a 3D breast phantom consisting of the fatty tissue, glandular tissue, and cancerous tumor, whose mechanical responses are hyperelastic in nature. The material parameters are identified with consideration of measurement error. The results demonstrate that the projective displacements acquired in X-ray mammography provide sufficient constitutive information of the tumor and prove the usability and robustness of the proposed method and algorithm.