1. A, Plots showing the signal-intensity behavior as a function of flip angle for gray matter (GM) and white matter (WM) at field strengths 1.5T and 3T.
A, Plots showing the signal-intensity behavior as a function of flip angle for gray matter (GM) and white matter (WM) at field strengths 1.5T and 3T. B, Plots showing the corresponding contrast between GM-WM and GM-CSF. These curves are calculated taking into consideration the higher signal intensity available at 3T and assuming that bandwidth is correspondingly increased at 3T to ensure equivalent geometric distortion. Tissue parameters are given in Table 1. Note that the GM/WM contrast is highest around 20° at 3T and there is a minimum or reversal of contrast around 5° (where GM is now brighter than WM; ie, it is a high-contrast spin echo-weighted image).
E.M. Haacke et al. AJNR Am J Neuroradiol 2009;30:19-30
©2009 by American Society of Neuroradiology