Assessment of dynamic shear strain in the brain caused by mechanical transients using multi-scale MR elastography

To study how the human brain moves and deforms under a sub-injury level transient impact, we tested the feasibility of measuring in-vivo brain transient motion resulting from a small amplitude impact using the multi-scale MR Elastography technique. Transient motion was encoded by wavelet-based motion encoding gradients at two wavelet scales plus a scaling function, and displacement was calculated using the inverse Haar transform. Brain motion over a wide frequency range was detected and was found to be consistent with previous results from a much higher impact.