Human imaging at 9.4 T using T2*-, phase-, and susceptibility-weighted contrast

Abstract

The effect of susceptibility differences on an MR image is known to increase with field strength. Magnetic field inhomogeneities within the voxels influence the apparent transverse relaxation time T2*, while effects due to different precession frequencies between voxels caused by local field variations are evident in the image phase, and susceptibility-weighted imaging highlights the veins and deep brain structures. Here, these three contrast mechanisms are examined at a field strength of 9.4 T. The T2* maps generated allow the identification of white matter structures not visible in conventional images. Phase images with in-plane resolutions down to 130 μm were obtained, showing high gray/white matter contrast and allowing the identification of internal cortical structures. The susceptibility-weighted images yield excellent visibility of small venous structures and attain an in-plane resolution of 175 μm. © 2010 Wiley-Liss, Inc.