MR Elastography of Complex Brain Mechanical Properties

Abstract 

The mechanical properties of brain tissue reflect its underlying microstructure and are sensitive markers of neurological health, but the brain is a mechanically complex organ. Its white matter is organized into aligned fiber tracts that give rise to direction-dependent stiffness, and the brain sits within the skull, suspended by meninges and cerebrospinal fluid that govern how it moves in response to external loading. Magnetic resonance elastography (MRE) measures tissue viscoelasticity in vivo by imaging shear wave propagation, yet conventional approaches typically make several simplifying assumptions not appropriate for the complex mechanical behavior of the brain. In this talk I will discuss the work of my group in developing MRE methods that capture this mechanical complexity. This includes approaches for estimating anisotropic properties of white matter using multiple wave excitations and transversely isotropic inversion, enabling measurement of mechanical anisotropy along major fiber pathways. I will also present our work characterizing the skull-brain interface through measurements of relative motion and mechanical coupling, and how these properties inform models of traumatic brain injury biomechanics. Finally, I will describe how these advances in MRE acquisition and inversion extend our ability to relate brain mechanics to structure and function across the lifespan.

About the Speaker 

Curtis L Johnson, PhD, is an Associate Professor in the Department of Biomedical Engineering at the University of Delaware, and the Director of the Center for Biomedical and Brain Imaging. He received his PhD in Mechanical Engineering in 2013 from the University of Illinois at Urbana-Champaign. His research group develops and uses magnetic resonance elastography (MRE) to measure the integrity of the human brain through tissue mechanical properties. Dr. Johnson uses these methods to understand the structure, function, and health of the brain in different populations. He has received several awards including the Early Career Researcher Award from the Journal of the Mechanical Behavior of Biomedical Materials and the Gerard Mangone Young Scholar Award from the University of Delaware.

Host: Professor Callan Luetkemeyer