Phosphorylated metabolite T1 relaxation times measured in the macaque brain using 31P MRS at 11.7T

Motivation: Knowledge of phosphorylated metabolite T1 relaxation times is needed for optimal pulse sequence parameterization, magnetization transfer experiments and for partial T1 saturation correction during quantification. Goal(s): To measure metabolite relaxation times in the macaque brain at 11.7T without muscle signal contamination. Approach: Perform inversion-recovery acquisitions with semi-LASER and short-TE STEAM sequences. Results: T1 relaxation times between 2.6 to 3.0 s were found for phosphodiesters and Pi, ~2.4 s for PCr, 3.6 s for PE, while the T1 values for the ATP-Γ and ATP-α resonances were within the 0.8 to 1.0 s range. Impact: Knowledge of the T1 relaxation times will play a key role in 31P metabolite quantification and in determining the optimal acquisition parameters for 31P MRSI measurements in the macaque brain at 11.7T.