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University of Southern California
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Purpose: Variations in the mechanical properties of soft tissues may be a sign of a disease. Sinc... more Purpose: Variations in the mechanical properties of soft tissues may be a sign of a disease. Since some disease like fibrosis or cancer change the stiffness of related tissues, we can assess the disease of a soft tissue with its elasticity. The elastic stiffness properties of soft tissues can be estimated using locally induced displacements and shear waves. Materials and Methods: A two-dimensional plane finite element model has been created as soft tissue. The soft tissue has been exposed to two Amplitude Modulated High Intensity Focused Ultrasound transducer (AMHIFU), hence shear wave interference patterns which can be captured by lower frame rate imaging are generated. The acoustic radiation force created by a self-focusing ultrasound transducer has been determined from an ultrasound pressure field simulation. A Gaussian function was fitted to the resulting Acoustic Radiation Force (ARF) field and implemented in the form of a body force in the finite element model. Results: The ef...
Elastography as one of the most promising non-invasive methods in the diagnosis of liver diseases... more Elastography as one of the most promising non-invasive methods in the diagnosis of liver diseases is attracting much attention. An interesting technique which is independent of imaging rate uses shear wave interference patterns induced by two external stimulation sources. In this article a 3D finite element model of liver tissue with superficial mechanical stimulation is presented through which, the possibility of using shear wave interference patterns to determine the type of liver fibrosis is investigated. In addition, the effect of various stimulation characteristics on the propagation of elastic waves and formation of shear wave interference patterns can be measured. Besides, ultrasound imaging and methods based on cross correlation are used to find target displacements caused by interference of shear waves. According to the results, the type of fibrosis was determined at all stages without error, and the mean elasticity estimation error of 4.98% was obtained for the finite elem...
Purpose: Variations in the mechanical properties of soft tissues may be a sign of a disease. Sinc... more Purpose: Variations in the mechanical properties of soft tissues may be a sign of a disease. Since some disease like fibrosis or cancer change the stiffness of related tissues, we can assess the disease of a soft tissue with its elasticity. The elastic stiffness properties of soft tissues can be estimated using locally induced displacements and shear waves. Materials and Methods: A two-dimensional plane finite element model has been created as soft tissue. The soft tissue has been exposed to two Amplitude Modulated High Intensity Focused Ultrasound transducer (AMHIFU), hence shear wave interference patterns which can be captured by lower frame rate imaging are generated. The acoustic radiation force created by a self-focusing ultrasound transducer has been determined from an ultrasound pressure field simulation. A Gaussian function was fitted to the resulting Acoustic Radiation Force (ARF) field and implemented in the form of a body force in the finite element model. Results: The ef...
Elastography as one of the most promising non-invasive methods in the diagnosis of liver diseases... more Elastography as one of the most promising non-invasive methods in the diagnosis of liver diseases is attracting much attention. An interesting technique which is independent of imaging rate uses shear wave interference patterns induced by two external stimulation sources. In this article a 3D finite element model of liver tissue with superficial mechanical stimulation is presented through which, the possibility of using shear wave interference patterns to determine the type of liver fibrosis is investigated. In addition, the effect of various stimulation characteristics on the propagation of elastic waves and formation of shear wave interference patterns can be measured. Besides, ultrasound imaging and methods based on cross correlation are used to find target displacements caused by interference of shear waves. According to the results, the type of fibrosis was determined at all stages without error, and the mean elasticity estimation error of 4.98% was obtained for the finite elem...