Magnetic resonance elastography of the brain

Magnetic resonance elastography (MRE) allows noninvasive measurement of the mechanical properties of the living, intact brain. Quantitative measurements of the brain’s material properties and structure are critical to understanding traumatic brain injury. In addition, mechanical properties of brain tissue change due to development, disease, and degeneration; such changes may lead to new methods for diagnosis or therapy. MRE studies have been performed recently in the human brain and in the brains of mice and other animals. In this chapter, we review the experimental methods used in these studies and the techniques to estimate mechanical properties from MRE data. We discuss the assumptions, technical choices, and limitations specific to MRE of the mammalian brain. Particular attention is given to safe and effective actuation; the relationships among frequency, sampling, and length scale; and the choice of an appropriate material model of brain tissue, which in general is nonlinear, dissipative, anisotropic, and heterogeneous.