One TSPO-targeting radioligand, 1-(2-chlorophenyl)-N-[11C]methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide ([11C]PK11195), is lipophilic and exhibits non-specific binding but its R-enantiomer binds TSPO with 2x greater affinity [139] and demonstrates comparable levels in amyloid load in the brains of AD patients [140]. Here, TSPO is linked to Alzheimer disease.