Metabolite T₂ relaxation times decrease across the adult lifespan in a large multi-site cohort

Area of Science:

• Neuroimaging
• Biophysics
• Metabolomics

Background:

• Accurate in vivo Magnetic Resonance Spectroscopy (MRS) quantification relies on precise relaxation correction.
• Current MRS protocols often assume constant metabolite T2 values throughout life, neglecting age-related changes.
• Previous studies indicate T2 variations with aging for key metabolites, necessitating a comprehensive investigation.

Purpose of the Study:

• To investigate the correlation between metabolite T2 values and participant age in a large, multi-site cohort.
• To determine if age-related T2 changes impact metabolite quantification in different brain regions.
• To provide age-specific T2 estimation equations for improved MRS accuracy.

Main Methods:

• Recruited 101 participants across five age decades (18-60+ years).
• Acquired PRESS MRS data at eight echo times (TEs) from centrum semiovale (CSO) and posterior cingulate cortex (PCC).
• Quantified metabolite amplitudes using Osprey and estimated T2 by fitting exponential decay curves.

Main Results:

• Older age correlated with shorter T2 for tNAA, tCr, tCho, tissue water, mI, and Glx (p < 0.05, FDR-corrected).
• These associations persisted even after controlling for cortical atrophy.
• Regional differences in T2 values were observed, with longer T2 in CSO for some metabolites and in PCC for others.

Conclusions:

• Metabolite T2 values significantly change with aging, impacting MRS quantification accuracy.
• Age-specific T2 estimation is crucial for reliable metabolite concentration measurements.
• The study provides equations for age-specific T2 values to enhance future 3T MRS research.