SAR-Reduced Spectroscopic FAST Imaging with Variable Flip Angles

Linda Becker¹, Wolfgang Dreher¹, Dieter Leibfritz¹

A variation of the SSFP-based fast spectroscopic imaging technique spFAST is presented. By flip angle variation the specific absorption rate (SAR) can be reduced considerably with only a minor loss in the signal-to-noise ratio (depending on the relaxation times). Additionally, the oscillating signal intensities can be exploited for k-space weighting in one spatial phase encoding direction which enables better spatial localization. Simulations and experiments at 7T showed that a gaussian flip angle series offers good results for all tested relaxation times.