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FIGURE 1. Biochemical pathways of 18F-FDOPA after administration in venous circulation. Metabolite OMFD is produced in blood and liver and in negligible amounts in brain and is transported bidirectionally. Because this metabolite still has 18F label, it cannot be distinguished from injected tracer 18F-FDOPA. In brain, 2 compartments are considered: one with unbound 18F-FDOPA and another with bound (metabolized) tracer. Question mark indicates that role of 18F-FDOPA in third compartment of tumors is not known. FDA = 6-fluorodopamine; FDOPAC = 6-fluoro-3,4-dihydroxyphenylacetic acid; FHVA = 6-fluorohomovanillic acid. Adapted from Huang et al. (16).
