LAUSR

BACKGROUND The relationship between uptake of amino acid tracer with PET and glioma subtypes/gene status is still unclear. OBJECTIVE To assess the relationship between uptake of 11C-methionine using PET and pathology, IDH mutation, 1p/19q codeletion, and TERT promoter status in gliomas. METHODS The participants were 68 patients with newly diagnosed and untreated glioma who underwent surgical excision and preoperative 11C-methionine PET examination at Osaka City University Hospital between July 2011 and March 2018. Clinical and imaging studies were reviewed retrospectively based on the medical records at our institution. RESULTS The mean L/N ratio of diffuse astrocytomas were significantly lower than those of anaplastic astrocytomas (p=.00155), glioblastoma (p<.001) and oligodendrogliomas (p=.0157). The mean L/N ratio of IDH mutant gliomas was significantly lower than that of IDH wild-type gliomas (median 1.75 vs 2.61; p = .00162). A mean L/N ratio of 2.05 provided the best sensitivity and specificity for distinguishing between IDH mutant and IDH wild-type gliomas, 69.2% and 76.2%, respectively. The mean L/N ratio of TERT promoter mutant gliomas was significantly higher than that of TERT promoter wild-type gliomas (p=.0147). Multiple regression analysis revealed that pathological diagnosis was the only influential factor on L/N ratio. CONCLUSIONS Distinguishing glioma subtypes based on the revised 2016 WHO classification of the central nervous system tumors on the basis of 11C-methionine PET alone appears to be difficult. However, 11C-methionine PET might be useful for predicting the IDH mutation status in newly diagnosed and untreated gliomas noninvasively prior to tumor resection.