Quantitative Validation of MRI-Based Motion Estimation for Brain Impact Biomechanics

Area of Science:

• Biomechanics
• Neuroimaging
• Traumatic Brain Injury Research

Background:

• Head impacts can cause traumatic brain injury (TBI) via axonal overstretch or inflammation.
• Understanding head impact biomechanics is crucial for TBI prevention.
• Tagged magnetic resonance imaging (MRI) allows in vivo measurement of brain deformation during mild impacts.

Purpose of the Study:

• To develop and validate a method for quantifying errors in tagged MRI measurements of brain deformation.
• To establish a gold standard for validating in vivo MRI measurements.
• To assess the accuracy of tagged MRI for analyzing brain deformation during impact events.

Main Methods:

• Utilized a calibration phantom compatible with both MRI and high-speed video (gold standard).
• Measured maximum shear strain (MSS) in the phantom during linear acceleration.
• Quantified displacement and MSS errors by comparing MRI data to high-speed video recordings.
• Applied temporal filtering to video data to match MRI resolution.

Main Results:

• Phantom deformation (0-12% MSS) during acceleration mimicked in vivo brain deformation.
• Mean displacement error between MRI and video was 0.3±0.3 mm.
• Mean MSS error was 1.4±0.3%.
• Resolution matching improved MRI-video agreement by 15%.

Conclusions:

• Tagged MRI analysis demonstrates good agreement with high-speed video data when resolutions are matched.
• This validated method is essential for accurate error quantification in TBI research.
• Findings are applicable to validating biomechanical simulations of head impacts.