Characterizing nearly incompressible transversely isotropic (NITI) biological tissue with MR elastography

Motivation: The anisotropic mechanical properties of fiber-embedded biological tissues are crucial for understanding development, aging, disease progression, and treatment response. Goal(s): Measure mechanical anisotropy in vivo using elastography in a fast and accurate way. Approach: A computational framework using the traveling wave expansion model that exploits the wave characteristics of transversely isotropic materials was proposed. Results: Simulations, ex vivo muscle tissue, and in vivo human brain experiments validate the performance of the proposed method in measuring the anisotropic biomechanical properties, showing its potential for assessing fiber-embedded tissues. Impact: The TWE-NITI method offers an accurate and fast way to measure fiber-reinforced tissues in vivo, showing the potential application of anisotropic MRE. Furthermore, the proposed framework may also help solving the inverse problem in other fields.