Age dependency of neurometabolite T1relaxation times

Purpose To measure T 1 relaxation times of metabolites at 3T in a healthy aging population and investigate age dependence. Methods A cohort of 101 healthy adults were recruited with approximately 10 male and 10 female participants in each ‘decade’ band: 18-29, 30-39, 40-49, 50-59, 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 3T 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.