Comparison of brain viscoelasticity and brain volumetry in healthy volunteers

Introduction: Mechanical properties of human soft tissues can be investigated in vivo with dynamic magnetic resonance elastography (MRE) by applying low frequency shear waves and measuring the resulting tissue deflections [1]. From these data, elastic and viscoelastic modules are commonly calculated using the algebraic Helmholtz inversion [2,3]. So far, MRE is the only method for a noninvasive determination of the viscoelastic behavior of living brain tissue [4-7]. The brain’s stiffness and internal friction can change significantly since some central nervous system pathologies are associated with a loss of brain volume [8-9]. To ensure an accurate differentiation and staging of such neurodegenerative diseases with MRE, the influence of changing but usually not in inversion algorithms included boundary conditions, e.g. the brain volume, has to be clarified. The objective of this study was therefore to investigate whether MRE based viscoelastic modules depend on atrophy related changes of the brain.