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An important advantage of transient elastography compared to harmonic elastography techniques is the separation of shear waves and compression waves. [16] The technique can be implemented in 1D [ 17 ] and 2D which required the development of an ultrafast ultrasound scanner.
Magnetic resonance elastography (MRE) is a method for studying the properties of biological materials in living organisms by propagating shear waves at desired frequencies throughout the desired organic tissue. [10] This method uses a vibrator to send the shear waves into the tissue and magnetic resonance imaging to view the response in the ...
MR elastography for detection of liver fibrosis in two patients. The left column shows the anatomy, with the liver outlined. The middle row shows images of propagating shear waves in the liver, captured with the MRE technique. The right column shows elastograms computed from the wave images, with tissue stiffness depicted with on color scale.
Tomoelastography of the abdomen; upper a healthy state, lower with malignancy.. Tomoelastography (from ancient Greek τόμος tomos, “slice” and elastography – imaging of viscoelastic properties) is a medical imaging technique that provides quantitative maps of the mechanical properties of biological soft tissues with high spatial resolution (called elastograms).
The acoustoelastic effect is an effect of finite deformation of non-linear elastic materials. A modern comprehensive account of this can be found in. [1] This book treats the application of the non-linear elasticity theory and the analysis of the mechanical properties of solid materials capable of large elastic deformations.
Shearography uses the test object itself as the known reference; it shears the image so a double image is created. The superposition of the two images, a shear image, represents the surface of the test object at this unloaded state. This makes the method much less sensitive to external vibrations and noise.
In mechanics, strain is defined as relative deformation, compared to a reference position configuration. Different equivalent choices may be made for the expression of a strain field depending on whether it is defined with respect to the initial or the final configuration of the body and on whether the metric tensor or its dual is considered.
In seismology, shear waves are also called secondary waves or S-waves. Transverse waves are contrasted with longitudinal waves , where the oscillations occur in the direction of the wave. The standard example of a longitudinal wave is a sound wave or "pressure wave" in gases, liquids, or solids, whose oscillations cause compression and ...