Last, 18F-FDG is a nonspecific substrate for neuroendocrine tumors, but a few AA PET tracers are substrates of the enzyme aromatic AA decarboxylase (AADC), which are specific for neuroendocrine tumors imaging, such as 3,4-dihydroxy-6-18F-fluoro-L-phenylalanine (18F-FDOPA) and 5-hydroxy-L-[β-11C] tryptophan (11C-HTP) (Jager et al., 2008; Oberg and Castellano, 2011). Here, DDC is linked to neuroendocrine neoplasm.