A Simple 3D Susceptibility Model to Simulate Magnetic Field Patterns in White Matter Microstructure

Way Cherng Chen¹, Karla Loreen Miller¹

Recent studies of susceptibility-weighted (GRE) imaging have revealed significant heterogeneity in white matter, including dependence on tract orientation to B0. We have developed a 3D susceptibility model that explicitly simulates field patterns generated by tissue microstructure to study potential sources of the observed signal properties. Axons and myelin are modeled as concentric cylinders and oligodendrocytes are modeled as solid spheres using susceptibility values estimated from literature. The frequency distribution obtained from our model provides estimates of the frequency mean and variance (the source of GRE phase and magnitude signals) and highlights the potential information provided by higher-order distribution statistics.