Elastography using torsional wave motion in transverse isotropic material

Abstract

An experimental configuration for driving and measuring torsional wave motion is designed, fabricated and experimentally tested using magnetic resonance elastography (MRE) in both a ultra-high field preclinical MRI system and in a cryogen-free low-field tabletop MRI system. Cylindrically-shaped isotropic and transversely isotropic phantoms, as well as the excised cat soleus muscle are statically stretched along their main axis to specific prestrain levels while simultaneously conducting MRE measurements with torsional waves. In the case of the excised cat soleus, diffusion tensor imaging is also performed to enable a co-registered mapping of fiber structure. The potential advantage of torsional wave excitation to drive shear wave motion over a large volume with uniform amplitude, and hence SNR, is tested by comparison to excitation of shear waves using other methods.