Simple Synthesis of [18F] AV-45 and its Clinical Application in the Diagnosis of Alzheimer's Disease.

OBJECTIVE: [18F] AV-45 can be produced in a simple, stable, and repeatable manner on the Tracerlab FXF-N platform using a self-editing synthetic procedure and solid-phase extraction purification method. This technique is applied to positron emission tomography (PET) imaging of Alzheimer's disease (AD) to observe its distribution and characteristics in various brain regions and its diagnostic efficiency for the disease. METHODS: The precursor was subjected to nucleophilic radiofluorination at 120°C in anhydrous dimethyl sulfoxide, followed by acid hydrolysis of the protecting groups. The neutralized reaction mixture was purified by solid phase extraction to obtain a relatively pure [18F] AV-45 product with a high specific activity. A total of 10 participants who were diagnosed with Alzheimer's disease (AD group) and 10 healthy controls (HC group) were included retrospectively. All of them underwent [18F] AV-45 brain PET/CT imaging. The distribution of [18F] AV-45 in the AD group was analyzed visually and semi-quantitatively. RESULTS: Six consecutive radiochemical syntheses were performed in this experiment. The average production time of [18F] AV-45 was 52 minutes, the radiochemical yield was 14.2 % ± 2.7% (n = 6), and the radiochemical purity was greater than 95%. When used with PET/CT imaging, the results of the visual analysis indicated increased [18F] AV-45 radioactivity uptake in the frontal, temporal, and parietal lobes in AD patients. Semiquantitative analysis showed the highest diagnostic efficacy in the posterior cingulate gyrus compared with other brain regions (P < 0.001). CONCLUSION: Intravenous [18F] AV-45 was successfully prepared on the Tracerlab FXF-N platform by solid-phase extraction of crude product and automated radiochemical synthesis. PET/CT imaging can be used to diagnose and evaluate AD patients and provide a more robust basis for clinicians to diagnose AD.

Optimization of Automatic Synthesis and Separation of [18F] AV-45 and Quality Control.

Objective: Based on the Tracerlab FXF-N platform, a synthesis program and preparative high-performance liquid chromatography (HPLC) purification program edited by us can stably and repeatedly produce [18F] AV-45 without changing the process. The [18F] AV-45 produced meets the main indexes of radiopharmaceutical intravenous preparations. Methods: The O-toluene sulfonated precursor (1 mg) was subjected to nucleophilic radiofluorination at 115°C in anhydrous dimethyl sulfoxide (DMSO), then the protective group was hydrolyzed by acid. The neutralized reaction mixture was purified through a preparative HPLC then formulated for injection using a C18 purification cartridge. This method yielded a relatively pure [18F] AV-45 product with high specific activity. Results: Four consecutive radiochemical synthesis operations were carried out in this experiment; the average production time of [18F] AV-45 preparation was 60 min, the radiochemical yield was 14.8 ± 2.1% (n = 4), the radiochemical purity was greater than 95%, and the other important quality control indexes met the requirements of radioactive drugs for intravenous administration. Conclusion: This experiment was based on the Tracerlab FXF-N platform with the synthesis program and preparative HPLC purification program edited by us. Through screening and optimization of the separation and purification system and the separation and analysis system, as well as automatic radiochemical synthesis and preparation quality control, intravenous [18F] AV-45 was successfully prepared.