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. Author manuscript; available in PMC: 2020 Jun 11.
Published in final edited form as: Phys Med Biol. 2020 Jan 13;65(1):015014. doi: 10.1088/1361-6560/ab5c2d

Figure 1.

Figure 1.

(a) Experimental configuration commonly used for investigations of shear wave propagation in an incompressible, TI material (see, also, figure 2 of Chatelin et al 2014). The left side shows a sketch of a linear ultrasound transducer and transversely isotropic material with the material symmetry indicated by the gray lines respresenting, for example, skeletal muscle fibers. The transducer can rotate about a vertical axis to observe shear waves for a range of propagation directions. The experimental X, Y, Z coordinate system shows the ARFI excitation force F→ along the Z axis and the material symmetry axis A^ and propagation direction n^ in the X − Y (Z = 0) plane. Polarization vectors for the SH (slow shear), SV (fast shear), and P (longitudinal) propagation modes are defined relative to the A^ − n^ plane shown in gray. Ultrasonic tracking measures the Z component of the shear wave displacement signal and is sensitive only to the SH propagation mode. (b) A more complicated experimental configuration in which the material symmetry axis A^ and propagation direction n^ are not restricted to the X − Y plane. Measurements of the Z component of shear wave displacement are sensitive to both the SH and SV propagation modes.