The human body has a lot of jobs to do, and its mechanical features, such as strength and flexibility, are important to how well it does them. Washington University in St. Louis engineers are now applying a new imaging technique to a model of brain tissue to see how stiff or soft it might be.
Philip Bayly, PhD, the Lilyan and E. Lisle Hughes Professor of Mechanical Engineering and chair the Department of Mechanical Engineering & Materials Science, has received a three-year, $429,222 grant from the National Science Foundation to study directionally dependent mechanical properties in muscle, white matter in the brain or artificial tissue.
In the brain, white matter holds the nerve fibers that wire cells together. Fibers in tissue also determine mechanical stiffness and strength and influence in which direction waves travel during motion. But these fibers also make it difficult to measure the properties without taking invasive measures.
Bayly and Joel Garbow, PhD, research associate professor of radiology at the School of Medicine, plan to use magnetic resonance elastrography (MRE), a non-invasive technique, to view and measure different properties of waves when they travel in different directions in the fibrous materials. There are a variety of factors that come into play.
“The speed of the waves depends on the stiffness of the material,” he says. “The more stiff the material, the faster the waves travel. In fibrous materials, such as muscle and white matter in the brain, stiffness depends on direction. So we plan to use waves propagating in different directions with different polarizations to study the mechanical properties of these tissues.”
What they determine could ultimately lead to new diagnostic tools for nerve and brain disorders and new insight into how artificial tissue degrades over time.
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