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.
• Understanding the mechanical properties of cadaveric brain tissue is crucial for accurate TBI modeling, as tissue properties change post-mortem.

Purpose of the Study:

• To characterize the material properties of PMHS brain tissue using magnetic resonance elastography (MRE).
• To investigate the changes in brain tissue mechanical properties over time post-mortem.
• To compare the mechanical properties of PMHS brains with those of living subjects.

Main Methods:

• Magnetic Resonance Elastography (MRE) was performed on three PMHS specimens.
• 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 living subjects (age 70-75).
• Shear stiffness initially increased up to seven days post-mortem before decreasing by day 58; damping ratio showed an inverse relationship.
• These mechanical property changes varied heterogeneously across different brain regions.

Conclusions:

• The study quantifies significant differences in mechanical properties between post-mortem and living brain tissue.
• The findings highlight the temporal evolution of brain tissue properties after death.
• This data is vital for developing and validating computational biomechanical models for TBI research.