Xiaoping Wu1, Dinesh Kumar Deelchand1, Vasily L. Yarnykh2, Kmil Ugurbil1, Pierre-Franois Van de Moortele1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA; 2Department of Radiology, University of Washington, Seattle, WA, USA
Recently, actual flip angle imaging (AFI) has been introduced as an efficient, fast 3D flip angle (FA) mapping technique. In some circumstance, a 2D version would be preferable (e.g., 2D Parallel Transmission) since it would require a significantly shorter acquisition time. Although in the original 3D version the FA calculation in AFI does not need to take into consideration the impact of slice profiles, this is however not the case when a 2D slice selective version of the same approach is considered, especially with regard to T1 sensitivity. Therefore, the purpose of this study was to evaluate the properties and feasibility of 2D AFI FA mapping where 2D (instead of 3D) image signals are used for FA calculations, using the equation that was derived for the 3D AFI FA mapping. For this purpose, we performed phantom experiments at 9.4 T, together with simulations, to study the relationship between 2D and 3D AFI FA values for different T1's.