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Background: Positron emission tomography (PET) is a valuable tool for the characterization of brain tumors in vivo. However, few studies have investigated the correlation between carbon-11-methionine (11C-METH) PET metrics and the clinical, radiological, histological, and molecular features of patients affected by lower grade gliomas (LGGs). The present observational study evaluated the relationships between 11C-METH PET metrics and structural magnetic resonance imaging (MRI) findings with the histomolecular biomarkers in patients with LGGs who were candidates for surgery., Methods: We enrolled 96 patients with pathologically proven LGG (51 men, 45 women; age 44.1 ± 13.7 years; 45 with grade II, 51 with grade III), who had been referred from March 2012 to January 2015 for tumor resection and had undergone preoperative 11C-METH PET. The semiquantitative metrics for 11C-METH PET included maximum standardized uptake value (SUVmax), SUV ratio to normal brain, and metabolic tumor burden (MTB). The PET semiquantitative metrics were analyzed and compared with the MRI features, histological diagnosis, isocitrate dehydrogenase-1/2 status, and 1p/19q codeletion., Results: Histological grade was associated with SUVmax (P = 0.002), SUV ratio (P = 0.011), and MTB (P = 0.001), with grade III lesions showing higher values. Among the nonenhancing lesions on MRI, SUVmax (P = 0.001), SUV ratio (P = 0.003) and MTB (P < 0.001) were significantly different statistically for grade II versus grade III. The MRI lesion volume correlated poorly with MTB (r 2  = 0.13). The SUVmax and SUV ratio were greater (P < 0.05) in isocitrate dehydrogenase-1/2 wild-type lesions, and the SUV ratio was associated with the presence of the 1p19q codeletion., Conclusions: The 11C-METH PET metrics correlated significantly with histological grade and the molecular profile. Semiquantitative PET metrics can improve the preoperative evaluation of LGGs and thus support clinical decision-making., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Purpose: We evaluated the relationship between 11 C-methionine PET ( 11 C-METH PET) findings and molecular biomarkers in patients with supratentorial glioma who underwent surgery., Methods: A consecutive series of 109 patients with pathologically proven glioma (64 men, 45 women; median age 43 years) referred to our Institution from March 2012 to January 2015 for tumour resection and who underwent preoperative 11 C-METH PET were analysed. Semiquantitative evaluation of the 11 C-METH PET images included SUVmax, region of interest-to-normal brain SUV ratio (SUVratio) and metabolic tumour volume (MTV). Imaging findings were correlated with disease outcome in terms of progression-free survival (PFS), and compared with other clinical biological data, including IDH1 mutation status, 1p/19q codeletion and MGMT promoter methylation. The patients were monitored for a mean period of 16.7 months (median 13 months)., Results: In all patients, the tumour was identified on 11 C-METH PET. Significant differences in SUVmax, SUVratio and MTV were observed in relation to tumour grade (p < 0.001). IDH1 mutation was found in 49 patients, 1p/19q codeletion in 58 patients and MGMT promoter methylation in 74 patients. SUVmax and SUVratio were significantly inversely correlated with the presence of IDH1 mutation (p < 0.001). Using the 2016 WHO classification, SUVmax and SUVratio were significantly higher in patients with primary glioblastoma (IDH1-negative) than in those with other diffuse gliomas (p < 0.001). Relapse or progression was documented in 48 patients (median PFS 8.7 months). Cox regression analysis showed that SUVmax and SUVratio, tumour grade, tumour type on 2016 WHO classification, IDH1 mutation status, 1p/19q codeletion and MGMT promoter methylation were significantly associated with PFS. None of these factors was found to be an independent prognostic factor in multivariate analysis., Conclusion: 11 C-METH PET parameters are significantly correlated with histological grade and IDH1 mutation status in patients with glioma. Grade, pathological classification, molecular biomarkers, SUVmax and SUVratio were prognostic factors for PFS in this cohort of patients. The trial was registered with ClinicalTrials.gov (registration: NCT02518061).