The consistent, on-demand production of carbon-11 radiopharmaceuticals is critical for continued research using positron emission tomography (PET) imaging. Currently, radiopharmaceuticals for PET are typically synthesized using fixed-tube synthesis modules (e.g., GE TRACERLab) requiring extensive cleaning, custom module configurations, and extensive day-of-synthesis setup. Synthesis of radiopharmaceuticals using a cassette-based module (e.g., GE FASTLab) offers a possible solution for complexities associated with fixed-tube modules and increased production consistency, but many imaging agents are labeled with carbon-11 and there are limited reports of cassette-based radiochemistry with this radionuclide. To address this gap, 14 11C-labeled radiopharmaceuticals with applications in functional PET imaging currently synthesized on TRACERLab were translated to the FASTLab using a variety of radiochemistry approaches (resin-based, reactor-based, and loop-based labeling) and various carbon-11 synthons (11CCH3I, 11CCH3OTf, 11CCO2, 11CCO, and 11CHCN). To demonstrate feasibility for routine radiopharmaceutical production, a selection of common radiopharmaceuticals with application in PET imaging (11Ccholine, 11CPE2i, 11Ccarfentanil, 11Cmethionine, 11Csarcosine, 11Craclopride, 11Cdihydrotetrabenazine, 11Cflumazenil, 11Cbutyrate, 11Cbutanol, 11Cacetate, 11Cacetylacetate, 1-11Cglycine, and 11CPittsburgh compound B) were translated to the FASTLab platform. Radiochemical yields ranged from 2.8 to 38%, radiochemical purities were >90%, and molar activity ranged from 1800 to 14,400 Ci/mmol. These yields and radiochemical purities were comparable to those of previously reported TRACERLab syntheses, demonstrating the versatility of this new cassette-based approach. Additionally, a novel solid phase extraction purification of 11Craclopride was developed to streamline translation to cassette-based systems. Although further validation studies are required prior to routine use for clinical production, this initial proof of concept demonstrates general compatibility of the FASTLab with carbon-11, opens up 11C radiochemistry to smaller sites that only have cassette-based synthesis modules, and future-proofs the production of 11C-labeled radiopharmaceuticals for PET imaging.
Wang et al. (Tue,) studied this question.