Observation of shear wave dispersion using anharmonic MR elastography
Rump J, Klatt D, Braun J, Sack I, Papazoglou S, Hamhaber U
Institute of Radiology
MR Elastography (MRE) is capable to test mechanical properties of soft tissue using harmonic shear vibrations. Here, the use of anharmonic vibrations is proposed for analyzing the wave propagation in dispersive media at multiple frequencies. The bandwidth of the motion sensitive gradient in our MRE sequence was adjusted to encode multiple frequencies simultaneously. Experiments on tissue specimens were conducted using ramp-shaped actuator vibrations. Comparison to sinusoidal wave excitation revealed non-linear elastic material properties. Initial in vivo studies clearly showed 50Hz- and 100Hz-vibrations in the human liver, which could be used to estimate the viscosity according to Voigts dispersion relation.