3D Tracking of Magnetic Pathways in White Matter Based on Magnetic Susceptibility Anisotropy

INTRODUCTION : Mapping white matter fiber pathways in central nervous system (CNS) is important for the understanding of neural transmission and brain organization in general. In this study, we propose a non-diffusion based method for tracking a magnetic network existing in brain white matter. The proposed method utilizes a previously unexplored magnetic property of white matter fibers. We found that the magnetic moment of white matter varies significantly when measured at different brain orientations with respect to the external field. This orientation dependence is modeled by an apparent susceptibly tensor which is experimentally determined by the susceptibility tensor imaging (STI) technique. Decomposing this tensor into its eigensystem revealed a spatially coherent network. Following the orientation of the major eigenvector, we were able to map distinctive magnetic pathways in 3D. The relationship between the magnetic network and fiber pathways is discussed.