MAPT and Alzheimer disease: This has led to the development of [18F]T807 ([18F]AV-1451) [11, 12], [18F]T808 ([18F]AV-680) [13, 14], [11C]PBB3 [15], [18F]THK5105 [16, 17], [18F]THK523 [18–20], [18F]THK5117 [16, 21], [18F]THK5351 ([18F]GE-216) [22], [18F]RO6958548, [11C]RO6931643, [11C]RO6924963 [23–27] and most recently, [18F]MK-6240 [28] and [18F]PI-2620 [29] as tau imaging agents for clinical studies of AD pathophysiology.