Reproducibility of H-1-MRS in vivo

The current study sought to investigate the reproducibility of a quantitati ve spectroscopic examination, using rigorous positioning guidelines and aut omated spectral fitting for measuring the cerebral metabolites N-acetylaspa rtate (NAA), creatine (Cre), choline (Cho), and myo-inositol (ml). Ten subj ects were studied in three sessions to determine the variability associated with measurement of metabolites in normal-appearing occipitoparietal white matter, using short echo STEAM spectroscopy. A careful relocalization prot ocol based on local landmarks identified on thin-slice images was used. No changes in mean metabolite concentrations for each subject between sessions were found, confirming relocalization. Mean coefficients of variation in m easurement of NAA, Cre, Cho, and ml were 3.30, 4.33, 5.30, and 8.10, respec tively. These data suggest that changes in metabolite concentrations as sma ll as 12% can be confidently discerned in an individual subject over time. The implication of these results to study design is discussed. Magn Reson M ed 41:193-197, 1999. (C) 1999 Wiley-Liss, Inc.