TSPO and neoplasm: In another study Perrone et al. synthetized, by nucleophilic aliphatic substitution in a single-step radiolabeling procedure, a new fluorine-substituted ligand, named [18F]CB251 (Figure 1), with high affinity and selectivity for the TSPO, which is suitable for the diagnosis of neuroinflammation, neurodegeneration, and tumor progression [17].