1FMRIB Centre, University of Oxford, Oxford, Oxon, United Kingdom; 2Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, Singapore, Singapore
The orientation dependence of non-linear GRE phase evolution in white matter (WM) was investigated in this study. GRE phase time course was obtained from in-vivo experiments and correlated to WM fiber orientation information obtained from DTI. A realistic geometric magnetic susceptibility model of WM microstructure was then used to predict the dependence of the non-linear phase evolution on orientation of WM fibers to B0. The striking similarity between simulation and experimental results showed that susceptibility compartmentalization is the driving force of this higher order signal characteristic.