Proton T 1 relaxation times of metabolites in human occipital white and gray matter at 7 T

Proton T 1 relaxation times of metabolites in the human brain have not previously been published at 7 T. In this study, T 1 values of CH 3 and CH 2 group of N ‐acetylaspartate and total creatine as well as nine other brain metabolites were measured in occipital white matter and gray matter at 7 T using an inversion‐recovery technique combined with a newly implemented semi‐adiabatic spin‐echo full‐intensity acquired localized spectroscopy sequence (echo time = 12 ms). The mean T 1 values of metabolites in occipital white matter and gray matter ranged from 0.9 to 2.2 s. Among them, the T 1 of glutathione, scyllo‐inositol, taurine, phosphorylethanolamine, and N ‐acetylaspartylglutamate were determined for the first time in the human brain. Significant differences in T 1 between white matter and gray matter were found for water (−28%), total choline (−14%), N ‐acetylaspartylglutamate (−29%), N ‐acetylaspartate (+4%), and glutamate (+8%). An increasing trend in T 1 was observed when compared with previously reported values of N ‐acetylaspartate (CH 3 ), total creatine (CH 3 ), and total choline at 3 T. However, for N ‐acetylaspartate (CH 3 ), total creatine, and total choline, no substantial differences compared to previously reported values at 9.4 T were discernible. The T 1 values reported here will be useful for the quantification of metabolites and signal‐to‐noise optimization in human brain at 7 T. Magn Reson Med 69:931–936, 2013. © 2012 Wiley Periodicals, Inc.