The reversible transverse relaxation rate, R
2
,
is sensitive to mesoscopic magnetic field inhomogeneity
resulting from subvoxel differences in magnetic
susceptibility. This sensitivity has been exploited to
measure tissue iron concentration, resting oxygen
extraction fraction (qBOLD) and changes in oxygen
metabolism (calibrated BOLD). However, R
2
is
also sensitive to macroscopic magnetic field
inhomogeneity that left uncorrected will reduce the
specificity of these applications. In this work we
combined an echo planar Asymmetric Spin Echo (ASE) pulse
sequence with the Gradient Echo Slice Excitation Profile
Imaging (GESEPI) technique to provide compensation for
through-slice magnetic field gradients during image
acquisition.