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, T(2), 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) T(2)s was examined in four age groups using 3D (four slices, 80 voxels 1 cm(3) each) proton MR spectroscopy in an optimized two-point protocol. Metabolite T(2)s 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 T(2)s 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 T(2)s of NAA: 343, Cr: 172, and Cho: 248 ms. The elderly NAA, Cr, and Cho T(2)s 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. (c) 2008 Wiley-Liss, Inc.