 grade II → IV (*n* = 00) (C). Deviation in quantified mean metabolite levels of grade II → III and II → IV glioma relative to grade II → II glioma; reported levels are unitless owing to the *T*~0~ dependence of the CPMG acquisition (D). Significant increases or decreases in the metabolite levels displayed as residuals are highlighted in red and green, respectively. Statistical significance was defined as *p* \< 0.00 for the comparative analysis among subtypes using the proportional odds logistic regression analysis. MeOH and EtOH are contaminants resulting from surgical sterilization procedures. 0HG, [d]{.smallcaps}-0-hydroxyglutarate; Ace, acetate; Ala, alanine; Asp, aspartate; Bet, betaine; Cho, free choline; Cr, PCr, creatine, phosphocreatine; Eth, ethanolamine; EtOH, ethanol; GABA, γ-aminobutyric acid; Glc, glucose; Gln, glutamine; Glu, glutamate; Gly, glycine; GPC, glycerophosphocholine; GSH, glutathione; GSSG, glutathione disulfide; hTau, hypotaurine; Ile, isoleucine; Lac, lactate; Leu, leucine; Lip, lipid; Lys, lysine; MCI, myo-inositol to total choline index; MeOH, methanol; MI, myo-inositol; NAA, *N*-acetylaspartate; PC, phosphocholine; PE, phosphoethanolamine; SI, scyllo-inositol; Suc, succinate; Tau, taurine; tCho, total choline (\[Cho\] + \[PC\] + \[GPC\]); tGSH, total glutathione (\[GSH\] + \[GSSG\]); Thr, threonine; Val, valine.](nbm0000-0000-f0){#fig00}  ######   Metabolite levels of primary *versus* secondary glioblastoma multiforme (GBM). Relative metabolite levels for each subtype of glioma, displayed as mean ± standard error of the mean (SEM); no units are expressed owing to the *T*~0~ dependence of the Carr--Purcell--Meiboom--Gill (CPMG) acquisition                 Grade I