Magnetic Resonance Elastography With Incremental Compressive Prestrain as a Method for Mapping Ex Vivo Brain Tissue...

Area of Science:

• Biomechanics
• Biomaterials
• Neuroscience

Background:

• Traumatic brain injury (TBI) affects millions annually, necessitating accurate biomechanical models for safety and treatment.
• Current TBI models often lack precise mechanical input parameters, especially under large deformation conditions relevant to injury.
• Magnetic Resonance Elastography (MRE) quantifies tissue viscoelasticity but struggles with nonlinear behavior.

Purpose of the Study:

• To characterize the nonlinear mechanical properties of brain tissue under large deformations.
• To provide novel, strain-dependent material data for enhancing computational TBI models.
• To extend the application of MRE for quantifying complex tissue mechanics.

Main Methods:

• Coupled ex vivo MRE with incremental compression using a custom MR-compatible device.
• Applied controlled axial pre-strain to fresh brain tissue-agar phantoms.
• Fit experimental data (storage modulus, pre-strain) to a phenomenological equation.

Main Results:

• Demonstrated a 73.6% increase in storage modulus with approximately 6.4% applied strain.
• Successfully extracted material parameters, including a nonlinearity metric.
• Generated novel, strain-dependent mechanical data for brain tissue beyond small-strain assumptions.

Conclusions:

• The study provides critical, injury-relevant mechanical input parameters for computational TBI models.
• Characterizing nonlinear brain tissue mechanics is essential for improving TBI prediction and prevention.
• This approach advances MRE's capability in quantifying complex soft tissue behavior.