Florent Eggenschwiler1, Arthur William
Magill1,2, Tobias Kober1, Rolf Gruetter1,3,
Jos Pedro Marques1,2
1EPFL, Laboratory for
Functional & Metabolic Imaging, Lausanne, Vaud, Switzerland; 2University
of Lausanne, Department of Radiology, Lausanne, Vaud, Switzerland; 3Universities
of Geneva & Lausanne, Department of Radiology, Switzerland
The accuracy of the recently proposed B1+-mapping sequence: Saturation prepared with 2 RApid Gradient Echoes (Sa2RAGE) was improved in terms of T1-insensitivity by considering partial Fourier encoding as well as a parallel imaging technique (GRAPPA). This sequence was then used to map the B1+ field distribution obtained when performing in-vivo brain RF-shimming at 7 Tesla. Shimming was performed by solving the Magnitude Least Squares (MLS) problem and the B1+ homogeneity improvement throughout the brain was demonstrated by showing that the distribution of the B1+ values after shimming is more centered on the mean B1+, illustrating the validity of the Sa2RAGE sequence as well.