Metabolite T1relaxation times differ across the adult lifespan

Abstract

AbstractPurposeTo investigate the age-dependence of metaboliteT1relaxation times at 3T in both gray- and white-matter-rich voxels.MethodsThis manuscript analyzes publicly available metabolite and metabolite-nulled (single inversion recovery TI = 600 ms) spectra acquired at 3T using PRESS localization. Voxels were placed in posterior cingulate cortex and centrum semiovale in 102 healthy volunteers across 5 decades of life (20s to 60s). All spectra were analyzed in Osprey v2.4.0. To estimateT1relaxation times for tNAA2.0and tCr3.0, the ratio of modeled metabolite residual amplitudes in the metabolite-nulled spectrum to the full metabolite signal was calculated using the single inversion recovery signal equation. Correlations betweenT1and subject age were evaluated.ResultsSpearman correlations revealed that estimated T1relaxation times of tNAA2.0(rs= −0.43; p < 0.001) and tCr3.0(rs= −0.23; p = 0.021) decreased significantly with age in white-matter-rich CSO, and less steeply (and not significantly) for tNAA2.0(rs= −0.15; p = 0.136) and tCr3.0(rs= −0.10; p = 0.319) in gray-matter-rich PCC.ConclusionThe analysis harnessed a large publicly available cross-sectional dataset to test an important hypothesis, that metabolite T1relaxation times change with age. This preliminary study stresses the importance of further work to measure age-normed metabolite T1relaxation times for accurate quantification of metabolite levels in studies of aging.