Understanding the Orientation Dependent T2* Contrast of the Cingulum in Ultra High Fields

Andreas Schfer¹, Christopher J. Wiggins^2,3, Robert Turner¹

It was shown recently that high resolution T2*-weighted images display T2* heterogeneity in white matter and an unexpected signal dependence in the cingulum bundles on head orientation to the main magnetic field. The signal change with orientation is still poorly explained. Here we used, in addition, phase images arising from high resolution spoiled gradient echo sequences, because such images are more sensitive to susceptibility effects. We also obtained TSE images to determine whether the orientation dependence of the signal appears in that sequence as well. Furthermore we compared the measurements with simulations using the forward field calculation.