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KMID : 1144120120020010052
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Biomedical Engineering Letters
2012 Volume.2 No. 1 p.52 ~ p.61
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A Simulation study on iterative shear velocity image reconstruction for ultrasound transient elastography
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Hossain A. B. M. Aowlad
Cho Min-Hyoung
Lee Soo-Yeol
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Abstract
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Purpose: Ultrasound transient elastography takes images of shear modulus that is strongly associated with pathological and physiological states of biological tissues. Propagating shear wave velocity in the tissue is related to its shear modulus. In this paper, we propose an iterative shear velocity image reconstruction method for ultrasound transient elastography which is robust to the noise and fast in computation.
Methods: We reconstruct shear velocity images by iteratively finding the solution of the forward problem that best matches to the measured displacement data. We solve the forward problem of the shear wave propagation, governed by the Helmholtz equation, using the finite difference time domain (FDTD) method. To reduce the computation time in finding the gradient of the cost function, we use the Born approximation that considers the tissue heterogeneity as secondary virtual sources to cause displacement perturbations. We use the steepest descent method to solve the inverse problem.
Results: For the simulated noisy displacement data, we have reconstructed shear velocity images using the proposed method and the direct inversion technique. The proposed method shows more robust behavior to the noise than the direct inversion method whilst the computation time is about 60∼100 times longer depending on the number of frames used in the direct inversion.
Conclusions: The proposed method can be used as a fast solver of the inverse problem of ultrasound transient elastography with less noise vulnerability than the direct inversion method.
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KEYWORD
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Shear velocity, FDTD method, Born approximation, Optimization, Transient elastography
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