Abstract
PURPOSE: To measure T(1) 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 (tNAA(2.0)), total creatine at 3.0 ppm (tCr(3.0)), and 3.9 ppm (tCr(3.9)), total choline (tCho), myo-inositol (mI), and the sum of glutamine and glutamate (Glx) were modeled to calculate T(1) relaxation times of metabolites. RESULTS: T(1) relaxation times of tNAA(2.0) in CSO and tNAA(2.0), tCr(3.0), mI, and Glx in PCC decreased with age. These correlations remained significant when controlling for cortical atrophy. T(1) relaxation times were significantly different between PCC and CSO for all metabolites except tCr(3.0). We also propose linear models for predicting metabolite T(1)s at 3 T to be used in future aging studies. CONCLUSION: Metabolite T(1) relaxation times change significantly with age, an effect that will be important to consider for accurate quantitative MRS, particularly in studies of aging.