IDH1 and glioblastoma: These cystathionine estimates may not be entirely due to the limited ability of the MRS method used given that (1) significant levels of cystathionine were measured in IDH‐wildtype glioma tissues by mass spectrometry in a prior study [25], (2) a high level of cystathionine (4.5 mM) was detected by MRS in one of two IDH‐wildtype gliomas in a prior study [25], and (3) 1p/19q codeletion was observed in one of eight IDH‐wildtype glioblastomas in a prior pathological study [27].