Figure 1:

PRISMA flow charts that show the database selection and inclusion process of the (A) concentration and (B) T₂ relaxation publications. Records “Removed Before Screening” were duplicates (identified from more than one database), reviews, meta-analyses, textbooks, or re-analyses. Conference abstracts were generally excluded, with exceptions made when information for a given metabolite/disease was scarce. “Records Excluded” were those identified as the wrong field of study, non-¹H MRS, non-spectroscopy MR methods, nonbrain regions, or animal studies (for Concentration study only). “Reports Excluded” during the “Assessed for Eligibility” did not include metabolite concentrations nor relaxation values.