The most commonly used PET ligands aiming to characterize neuroinflammation target the 18 kDa translocator protein (TSPO), which is overexpressed in the outer mitochondrial membrane of microglia.11 Several TSPO radioligands have been implemented in neurodegenerative diseases,12 including the first-generation [11C]-PK11195.13 In PSP, [11C]-PK11195 PET shows increased signals in subcortical regions,14,15 co-localizing with tau pathology,16 and associates with clinical decline.17 The gene discussed is TSPO; the disease is supranuclear palsy, progressive, 1.