(18)F-FET and (18)F-choline PET-CT in patients with MRI-suspected low-grade gliomas: a pilot study

AIM: To investigate the diagnostic accuracy of O-(2-[(18)F]-fluoroethyl)-L-tyrosine ((18)F-FET) and fluoromethyl-((18)F)-dimethyl-2-hydroxyethyl-ammonium chloride ((18)F-FCH) computed tomography (CT) in patients with primary low-grade gliomas (LGG). METHODS: The study enrolled patients with magnetic resonance imaging (MRI)-suspected LGG. Patients underwent both (18)F-FET and (18)F-FCH positron emission tomography (PET)-CT. Brain PET-CT was performed according to standard protocol – 20 minutes after intravenous injection of 185 MBq of (18)F-FET and 185 MBq of (18)F-FCH PET. Surgery and pathohistological diagnosis were performed in the next two weeks. RESULTS: We observed significantly better concordance between tumor histology and (18)F-FET PET (weighted Kappa 0.74) compared with both (18)F-FCH (weighted Kappa 0.15) and MRI (weighted Kappa 0.00). Tumor histology was significantly associated with (18)F-FET (odds ratio 12.87; 95% confidence interval [CI], 0.49-333.70; P = 0.013, logistic regression analysis). Receiver operating characteristic curve analysis comparing (18)F-FCH (area under the curve [AUC] 0.625, 95% CI 0.298-0.884) and (18)F-FET (AUC 0.833, 95% CI 0.499-0.982) showed better diagnostic properties of (18)F-FET (AUC difference 0.208, 95% CI -0.145 to 0.562, P = 0.248). CONCLUSION: Performing PET-CT in patients with newly diagnosed LGG should be preceded by a selection of an appropriate radiopharmaceutical. (18)F-FET seems to be more accurate than (18)F-FCH in the LGG diagnosis.