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Abstract #3271

Evaluating the Static Dephasing Regime Assumption for Gradient Echo Signal in Brain Cells

Asli Alpman1 and Chunlei Liu1,2
1Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, United States, 2Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States

Synopsis

Keywords: Susceptibility/QSM, Susceptibility

Motivation: The static dephasing regime, which neglects diffusion effects, is typically assumed for modeling magnetic susceptibility effects within a voxel. Given the complexity of brain microstructure, this assumption warrants further investigation.

Goal(s): This work aims to assess the validity of the static dephasing regime under varying diffusion conditions within two brain cell types.

Approach: Monte Carlo simulations were performed to model spin diffusion around myelinated axons and astrocytes under different diffusion conditions.

Results: Spin phase accumulation and decay rates around astrocytes and axons show significant deviations from the static dephasing assumption, particularly in regions with restricted/hindered diffusion and high axonal volume fractions.

Impact: The static dephasing assumption, commonly used to model magnetic susceptibility effect within a voxel, may fail in brain microstructure, particularly in regions with restricted/hindered diffusion and high axonal volume fraction, highlighting the necessity of incorporating diffusion effects.

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Keywords