Characterization of mechanical tissue properties in post-mortem human brain using magnetic resonance elastography

Area of Science:

• Biomechanics
• Neuroscience
• Medical Imaging

Background:

• Traumatic brain injury (TBI) research often uses post-mortem human subjects (PMHS) due to ethical constraints on living subjects.
• Understanding the mechanical properties of PMHS brains is vital for accurate TBI biomechanical modeling, as tissue properties change post-mortem.

Purpose of the Study:

• To quantify the material properties of cadaveric brain tissue using magnetic resonance elastography (MRE).
• To investigate the changes in brain mechanical properties over time post-mortem.
• To compare the mechanical properties of PMHS brains with in vivo data.

Main Methods:

• Magnetic Resonance Elastography (MRE) was performed on three post-mortem human subjects (PMHS).
• Material properties including storage modulus, loss modulus, shear stiffness, and damping ratio were estimated.
• Longitudinal MRE scans were conducted over two months to track degradation-related property changes.

Main Results:

• PMHS brains exhibited significantly higher stiffness (mean: 5.96 kPa) and lower damping ratios (mean: 0.09) compared to in vivo subjects (age 70-75).
• Shear stiffness increased up to post-mortem day seven, then decreased by day fifty-eight.
• Damping ratio showed an inverse trend to shear stiffness, with changes being heterogeneous across brain regions.

Conclusions:

• The study provides crucial data on the evolving mechanical properties of post-mortem human brain tissue.
• These findings are essential for developing and validating more accurate computational models for traumatic brain injury (TBI) research.
• Characterizing post-mortem brain mechanics enhances the reliability of TBI simulations using PMHS data.