The Age Dependence of Regional Proton Metabolites T2 Relaxation Times in the Human Brain at 3 Tesla

摘要

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 (4 slices, 80 voxels 1 cm³ each) proton MR spectroscopy in an optimized two-point protocol. Metabolite T2s were estimated in each voxel and in ten 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 T2 age-correction for higher quantification precision are provided.