Metabolite T2relaxation times decrease across the adult lifespan in a large multi-site cohort

Abstract

AbstractPurposeRelaxation correction is crucial for accurately estimating metabolite concentrations measured usingin vivomagnetic resonance spectroscopy (MRS). However, the majority of MRS quantification routines assume that relaxation values remain constant across the lifespan, despite prior evidence of T2changes with aging for multiple of the major metabolites. Here, we comprehensively investigate correlations between T2and age in a large, multi-site cohort.MethodsWe recruited approximately 10 male and 10 female participants from each decade of life: 18-29, 30-39, 40-49, 50-59, and 60+ years old (n=101 total). We collected PRESS data at 8 TEs (30, 50, 74, 101, 135, 179, 241, and 350 ms) from voxels placed in white-matter-rich centrum semiovale (CSO) and gray-matter-rich posterior cingulate cortex (PCC). We quantified metabolite amplitudes using Osprey and fit exponential decay curves to estimate T2.ResultsOlder age was correlated with shorter T2for tNAA, tCr3.0, tCr3.9, tCho, Glx, and tissue water in CSO and PCC; rs= −0.21 to −0.65, allp<0.05, FDR-corrected for multiple comparisons. These associations remained statistically significant when controlling for cortical atrophy. T2values did not differ across the adult lifespan for mI. By region, T2values were longer in the CSO for tNAA, tCr3.0, tCr3.9, Glx, and tissue water and longer in the PCC for tCho and mI.ConclusionThese findings underscore the importance of considering metabolite T2changes with aging in MRS quantification. We suggest that future 3T work utilize the equations presented here to estimate age-specific T2values instead of relying on uniform default values.