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

AIM: To investigate the diagnostic accuracy of O-(2-[18F]-fluoroethyl)-L-tyrosine (18F-FET) and fluoromethyl-(18F)-dimethyl-2-hydroxyethyl-ammonium chloride (18F-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 18F-FET and 18F-FCH positron emission tomography (PET)-CT. Brain PET-CT was performed according to standard protocol - 20 minutes after intravenous injection of 185 MBq of 18F-FET and 185 MBq of 18F-FCH PET. Surgery and pathohistological diagnosis were performed in the next two weeks. RESULTS: We observed significantly better concordance between tumor histology and 18F-FET PET (weighted Kappa 0.74) compared with both 18F-FCH (weighted Kappa 0.15) and MRI (weighted Kappa 0.00). Tumor histology was significantly associated with 18F-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 18F-FCH (area under the curve [AUC] 0.625, 95% CI 0.298-0.884) and 18F-FET (AUC 0.833, 95% CI 0.499-0.982) showed better diagnostic properties of 18F-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. 18F-FET seems to be more accurate than 18F-FCH in the LGG diagnosis.

In vitro release of metal ions from a gold-platinum alloy in saliva-simulated conditions.

The aim of this study was to evaluate the behavior of high-noble gold-platinum alloy samples (18 + 8 Rafinerija plemenitih kovina, Zagreb, Hrvatska), in a phosphate buffer pH 6.0. The aim of the study was to determine the type and amount of released metal ions from the alloy, and to evaluate how the time of exposure to the phosphate buffer pH 6.0 influences the release of metal ions from the alloy. Manufacturer samples 8.0 x 6.5 x 1.0 mm in size, with a surface area of 133 mm2 were used. The release of metal ions from the tested alloy was measured in ten time periods (after 1, 2, 3, 4, 5, 6, 7, 14, 21 and 30 days). Six samples were used (n = 6) for each time period that the alloy was in the solution, which means that a total of 60 samples was analyzed. Solutions, in which the samples were placed, were analyzed with the inductively coupled plasma atomic emission spectrometer (ICP-AES, JY 50P, Jobin-Ywon, France). It was found that four metal ions were released; zinc ions (Zn), chromium ions (Cr), copper ions (Cu) and iron ions (Fe). The most released ions from the gold-platinum alloy were those of zinc (Zn), and the least released were those of iron (Fe) (p < 0.01). The results of the study show that the time the tested alloy spent in the phosphate buffer pH 6.0 solution has an effect on the release of ions (p < 0.01).