Age dependency of neurometabolite T₁ relaxation times

PURPOSE: To measure T₁ relaxation times of metabolites at 3 T in a healthy aging population and investigate age dependence. METHODS: A cohort of 101 healthy adults was recruited with approximately 10 male and 10 female participants in each "decade" band: 18 to 29, 30 to 39, 40 to 49, 50 to 59, and 60+ years old. Inversion-recovery PRESS data (TE/TR: 30/2000 ms) were acquired at 8 inversion times (TIs) (300, 400, 511, 637, 780, 947, 1148, and 1400 ms) from voxels in white-matter-rich centrum semiovale (CSO) and gray-matter-rich posterior cingulate cortex (PCC). Modeling of TI-series spectra was performed in Osprey 2.5.0. Quantified metabolite amplitudes for total N-acetylaspartate (tNAA2.0), total creatine at 3.0 ppm (tCr3.0), and 3.9 ppm (tCr3.9), total choline (tCho), myo-inositol (mI), and the sum of glutamine and glutamate (Glx) were modeled to calculate T₁ relaxation times of metabolites. RESULTS: T₁ relaxation times of tNAA2.0 in CSO and tNAA2.0, tCr3.0, mI, and Glx in PCC decreased with age. These correlations remained significant when controlling for cortical atrophy. T₁ relaxation times were significantly different between PCC and CSO for all metabolites except tCr3.0. We also propose linear models for predicting metabolite T₁s at 3 T to be used in future aging studies. CONCLUSION: Metabolite T₁ relaxation times change significantly with age, an effect that will be important to consider for accurate quantitative MRS, particularly in studies of aging.