1Medical
Biophysics, University of Toronto, Toronto, ON, Canada; 2Imaging
Research, Sunnybrook Research Institute, Toronto, ON, Canada
As resolution increases, so does unwanted diffusion sensitization from imaging and spoiler gradients. Quantitative T2 (qT2) is especially problematic as this effect increases with each echo, decreasing the measured T2 noticeably as voxel size decreases below 0.5x0.5mm2. Measured T2 becomes orientation dependent in the presence of anisotropic diffusion. Fully refocused imaging gradients can mitigate the problem, as can minimizing spoiler gradients and measuring diffusion in order to calculated corrected T2 values. Decreasing spoiler gradient schemes affect qT2 non-linearly and can result in an overestimation of myelin water fraction as well as precluding simple arithmetic correction of T2.