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Abstract #4409

T1-Nonlinearity Corrections for Fast Transmit-Array B1+-Mapping of the Human Brain in the Small-Tip-Angle Regime

Martijn Anton Cloos1,2, Nicolas Boulant1, Guillaume Ferrand2, Michel Luong2, Christopher J. Wiggins1, Denis Le Bihan1, Alexis Amadon1

1LRMN, CEA, DSV, I2BM, NeuroSpin, Gif-Sur-Yvette, ile-de-France, France; 2CEA, DSM, IRFU, Gif-Sur-Yvette, ile-de-France, France

Currently, B1+-mapping is particularly difficult due to the combination of time and conservative specific absorption rate (SAR) constraints applicable to parallel transmission studies involving human subjects. Measuring relative B1+-maps in the low-tip-angle regime provides a low SAR solution. Inherently, this method requires a relatively long TR (0.2-1.0s) to remain in the domain where the signal intensity is linearly dependent for a large range of flip-angles. Considering 3D tailored excitation pulses, such TR values require too much time for transmit-array B1+-mapping and pulse validation. To tackle the aforementioned problems, an optimized version of this method for the quantification of non-selective excitation pulses is presented.