A Convenient Radiolabeling of 11C(R)-PK11195 Using Loop Method in Automatic Synthesis Module / 핵의학분자영상

PURPOSE: ((R)-1-(2-chlorophenyl)-N-1-[11C]methyl-N-(1-propyl)-3-isoquinoline carboxamide ((R)-PK11195) is a specific ligand for the peripheral type benzodiazepine receptor and a marker of activated microglia, used to measure inflammation in neurologic disorders. We report here that a direct and simple radiosynthesis of [11C](R)-PK11195 inmild condition using NaH suspension in DMF and one-step loop method. MATERIALS AND METHODS: (R)-NDesmethyl- PK11195 (1 mg) in DMSO (0.1 mL) and NaH suspension in DMF (0.1 mL) were injected into a semi-prep HPLC loop. [11C]methyl iodide was passed through HPLC loop at room temperature. Purification was performed using semi-preparative HPLC. Aliquots eluted at 11.3 min were collected and analyzed by analytical HPLC and mass spectrometer. RESULTS: The labeling efficiency of [11C](R)-PK11195 was 71.8+/-8.5%. The specific activity was 11.8 +/-6.4 GBq/micromol and radiochemical purity was higher than 99.2%. The mass spectrum of the product eluted at 11.3 min showed m/z peaks at 353.1 (M+1), indicating the mass and structure of (R)-PK11195. CONCLUSION: By the one-step loop method with the [11C]CH3I automated synthesis module, [11C](R)-PK11195 could be easily prepared in high radiochemical yield using NaH suspension in DMF.

Radiosynthesis of 11C6-OH-BTA-1 in Different Media and Confirmation of Reaction By-products / 핵의학분자영상

PURPOSE: [11C]6-OH-BTA-1 ([N-methyl-11C]2-(4'-methylaminophenyl)-6-hydroxybenzothiazole, 1), a -amyloid imaging agent for the diagnosis of Alzheimer's disease in PET, can be labeled with higher yield by a simple loop method. During the synthesis of [11C]1, we found the formation of by-products in various solvents, e.g., methylethylketone (MEK), cyclohexanone (CHO), diethylketone (DEK), and dimethylformamide (DMF). MATERIALS AND METHODS: In Automated radiosynthesis module, 1 mg of 4-aminophenyl-6-hydroxybenzothiazole (4) in 100 l of each solvent was reacted with [11C]methyl triflate in HPLC loop at room temperature (RT). The reaction mixture was separated by semi-preparative HPLC. Aliquots eluted at 14.4, 16.3 and 17.6 min were collected and analyzed by analytical HPLC and LC/MS spectrometer. RESULTS: The labeling efficiencies of [11C]1 were 86.0+/-5.5%, 59.7+/-2.4%, 29.9+/-1.8%, and 7.6+/-0.5% in MEK, CHO, DEK and DMF, respectively. The LC/MS spectra of three products eluted at 14.4, 16.3 and 17.6 mins showed m/z peaks at 257.3 (M+1), 257.3 (M+1) and 271.3 (M+1), respectively, indicating their structures as 1, 2-(4'-aminophenyl)-6-methoxybenzothiazole (2) and by-product (3), respectively. Ratios of labeling efficiencies for the three products ([11C]1:[11C]2:[11C]3) were 86.0+/-5.5%:5.0+/-3.4%:1.5+/-1.3% in MEK, 59.7+/-2.4%:4.7+/-3.2%:1.3+/-0.5% in CHO, 9.9+/-1.8%:2.0+/-0.7%:0.3+/-0.1% in DEK and 7.6+/-0.5%:0.0%:0.0% in DMF, respectively. CONCLUSION: The labeling efficiency of [11C]1 was the highest when MEK was used as a reaction solvent. As results of mass spectrometry, 1 and 2 were conformed. 3 was presumed.

Quality Control of Residual Solvents in 18FFDG Preparations by Gas Chromatography / 핵의학분자영상

PURPOSE: Analysis of volatile organic solvents in 2-deoxy-2-[18F] fluoro-D-glucose ([18F]FDG) preparations was performed by gas chromatography (GC), in accordance with USP. MATERIALS AND METHODS: Analyses were carried out on a Hewlett-Packard 6890 gas chromatography equipped with an FID. RESULTS: We determined the amounts of ethanol and acetonitrile on every batch of our routine [18F]FDG preparations, ranging between 5000 ppm and 100 ppm. In our routine preparation of [18F]FDG, the amount of acetonitrile and ethanol in the final product were well below the maximum allowable limit described in the USP. CONCLUSION: Our [18F]FDG preparations were in accordance with the suggested USP maximum allowable levels of the quality control analysis of volatile organic compounds.