A Simplified Approach for Anisotropic Susceptibility Map Calculation

Sam Wharton¹, Richard Bowtell¹

Recently, it was shown that the magnetic susceptibility of white matter has measurable anisotropy, but calculation of the full anisotropic susceptibility tensor requires a 6-parameter fit, using phase maps acquired at multiple orientations to B0. Here, we present a method for reducing the parameters in the fitting process to two, based on the assumption of cylindrical symmetry and a priori knowledge of the orientation of the principal axis of the susceptibility tensor. The 2-parameter method is demonstrated on simulated data and shown to require less sampling orientations and a smaller range of rotation angles compared to the 6-parameter method.