Metabolite T1 and T2 relaxation times in the macaque brain at 11.7T with local B1+ shimming

Motivation: Knowledge of metabolite T1 and T2 relaxation times is needed for optimal pulse sequence parameterization and to account for partial T1 saturation and T2 decay during metabolite quantification. Goal(s): To measure metabolite relaxation times in the macaque brain at 11.7T with a 6Tx/6Rx surface coil. Approach: Multi-echo and inversion-recovery acquisitions with STEAM combined with a B1+-shimming configuration optimized for the MRS voxel. Results: Performing voxel-specific B1+-shimming reduced the required RF power by 40% (±11%) . Measured T1 values were in agreement with the literature while T2 values were lower than those measured with LASER in the rat brain at 11.7T. Impact: Increased accuracy for metabolite concentration estimation and optimal acquisition parameters to maximize temporal SNR at 11.7T. Parallel transmission elicited a large reduction in the required RF power for a 2.25 mL cortical voxel using a dedicated 6Tx/6Rx surface coil.