Frequency Difference Mapping at 7 T Using Two- And Three-Echo Approaches

Samuel J. Wharton¹, Richard W. Bowtell¹

Frequency difference mapping is a recently proposed gradient-echo-based MRI technique for creating image contrast that is sensitive to the orientation of myelinated nerve fibers in white matter. Frequency difference maps (FDM) are created by calculating the difference in phase-based frequency maps acquired at short and long echo times. In this study, we use simulations to determine the optimum TE values for creating in vivo FDM at 7T using two- and three-echo acquisition schemes. Both approaches yield high quality FDM in a 6 minute scan time. The two-echo scheme yields higher SNR, but requires the use of a high-pass filtering step.