The Naval Research Laboratory (NRL) has developed a non-invasive method to evaluate anisotropic viscoelastic properties of fibrous structures, such as neuronal pathways in the human brain and muscle, using sound, for diagnostic purposes. Injury and disease in brain matter and muscle effect material parameters like stiffness and velocity, and the causes of these alterations are currently poorly understood. As methods of diagnosis are often based on purely symptomatic indicators, NRL provides a methodology for the noninvasive evaluation and diagnosis of these conditions. This is the first procedure that provides in-vivo analysis of the anisotropic material models and elastic coefficients of white matter.
Previous methods for evaluation were limited for anisotropic materials. This invention applied measurements of Magnetic Resonance Elastography (MRE), which is a method to quantitatively measure elastic displacements throughout biological materials, and Diffusion Tensor Imaging (DTI), which is a method to quantitatively measure the diffusion of water (protons) along fibrous pathways. These measurements are used in the Adaptive Anisotropic Inversion Algorithm, evaluates an Orthotropic model (consisting of nine independent coefficients), and allows for lower order models to present themselves as valid by exposing redundancies in the elastic coefficients. The algorithm outputs stiffness values and velocities, or the square root of the stiffness divided by density.
When the algorithm was applied to the Corticospinal Tracts in the detection of Amyotrophic Lateral Sclerosis (ALS), NRL correctly differentiated between the control group and patients (P
- Innovative: The first noninvasive method to evaluate the anisotropic material models of white matter
- Noninvasive: The first noninvasive method to work for anisotropic materials
- Painless and Non-harmful: Does not require X-ray measurement technologies
- Visual: Advanced spatial-spectral filtering procedures reduce noise and improve inversion results
- Rapid scans: Complete in minutes
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