ATRX and neoplasm: Indeed, this series refers to tumours that had their histological diagnosis before publication of the new WHO 2016 and 2021 CNS tumour classifications [2,60], preventing us from analysing possible associations between MET-PET data and some of the currently known biomolecular prognostic factors, as IDH status, 1p/19q co-deletion and MGMT promoter metilation, ATRX mutation.