Age dependence of regional proton metabolites T₂ relaxation times in the human brain at 3 T

Although recent studies indicate that use of a single global transverse relaxation time, T₂, per metabolite is sufficient for better than ±10% quantification precision at intermediate and short echo-time spectroscopy in young adults, the age-dependence of this finding is unknown. Consequently, the age effect on regional brain choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) T₂s was examined in four age groups using 3D (four slices, 80 voxels 1 cm³ each) proton MR spectroscopy in an optimized two-point protocol. Metabolite T₂s were estimated in each voxel and in 10 gray and white matter (GM, WM) structures in 20 healthy subjects: four adolescents (13 ± 1 years old), eight young adults (26 ± 1); two middle-aged (51 ± 6), and six elderly (74 ± 3). The results reveal that T₂s in GM (average ± standard error of the mean) of adolescents (NAA: 301 ± 30, Cr: 162 ± 7, Cho: 263 ± 7 ms), young adults (NAA: 269 ± 7, Cr: 156 ± 7, Cho: 226 ± 9 ms), and elderly (NAA: 259 ± 13, Cr: 154 ± 8, Cho: 229 ± 14 ms), were 30%, 16%, and 10% shorter than in WM, yielding mean global T₂s of NAA: 343, Cr: 172, and Cho: 248 ms. The elderly NAA, Cr, and Cho T₂s were 12%, 6%, and 10% shorter than the adolescents, a change of under 1 ms/year assuming a linear decline with age. Formulae for T ₂ age-correction for higher quantification precision are provided.