Florent Eggenschwiler1, Arthur Magill1,2,
Rolf Gruetter1,3, Jos P. Marques1,2
1EPFL, Laboratory for Functional and
Metabolic Imaging, Lausanne, Vaud, Switzerland; 2University of
Lausanne, Department of Radiology, Lausanne, Vaud, Switzerland; 3Universities
of Geneva and Lausanne, Department of Radiology, Switzerland
Sa2RAGE
is based on the rapid acquisition of two images with low flip angles just
before and after a saturation pulse. The ratio of the signals from the images
can be linked to a specific B1+. Optimization of the
sequence parameters allowed the derivation of a protocol that performs 3D B1+-mapping
in ~30s (matrix size 64x64x16) with limited T1 dependence.
Experimental work showed the accuracy of the B1+-mapping
over a 10 fold range of B1+. In-vitro and in-vivo B1+
maps were performed to demonstrate the applicability of the method on the
context of parallel transmission.