An illustration of magnetic resonance elastography (MRE). MRE is a non-invasive technique used to measure the mechanical properties of biological tissue. This technique was used to palpate tissue (in this case the brain) by sending shear waves through that tissue and measuring their displacement. Wave displacement can then be reconstructed into stiffness maps providing a quantitative measure of the health and organization of the underlying cellular architecture. Source: Dr. Aron K. Barbey, University of Illinois at Urbana-Champaign