Optimisation of synthesis, purification and reformulation of (R)-[N-Methyl-11C]PK11195 for in vivo PET imaging studies

Neurodegenerative, inflammatory and neoplastic disorders involve neuroinflammatory reactions in the central nervous system that isolate the damaged tissue and promote im-mune responses by the activation of resident cells of the mono-cytes lineage (microglia). This process involves an overexpression of the 18 kDa translocator protein receptor (TSPO). PK11195 is an isoquinoline carboxamide which binds selectively to this re-ceptor. The (R)-enantiomer radiolabelled with carbon-11 is the most widely used radiotracer for in vivo TSPO imaging with Posi-tron Emission Tomography (PET).