1Brain Imaging and Analysis Center, Duke University, Durham, NC, United States; 2Radiology, Duke University, Durham, NC, United States
We propose a susceptibility tensor imaging (STI) technique to measure and quantify anisotropy of magnetic susceptibility. This technique relies on the measurement of resonance frequency offset at different orientations. We propose to characterize the orientation variation of susceptibility using an apparent susceptibility tensor. The susceptibility tensor can be decomposed into three eigenvalues (principle susceptibilities) and associated eigenvectors that are coordinate-system independent. We show that the principle susceptibilities offer strong contrast between gray and white matter while the eigenvectors provide orientation information of an underlying magnetic network. We believe that this network may further offer information of white matter fiber orientation.