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Abstract #4423

Sa2RAGE Sequence Improvements & In-Vivo Brain RF-Shimming at 7 Tesla

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.