difference mapping (FDM) is a recently developed phase-based
technique that takes advantage of the non-linear temporal evolution of the
phase in GE sequences to produce images that are sensitive to white matter
microstructure. Images can be produced simply from raw phase data, with minimal
post-processing. In this study 10 subjects underwent six repeats of a
single-slice, sagittal multi-echo GE scan on the mid-line. Frequency difference maps reproducibly
depicted white matter tracts oriented perpendicular to the applied field.
Fitting the FD and magnitude data to a three-pool model provided insight into
the variation of microstructure along the corpus callosum.