Detection of tau spatial extent using MK6240 and flortaucipir PET

MK6240 tau PET measured greater tau spatial extent than Flortaucipir across the AD continuum, with higher TSE in CU Aβ+ MTL (42% vs 25%) and dementia Aβ+ late neocortical (55% vs 42%).

• Why it matters: Cross-tracer comparability of tau spatial extent is unclear, limiting whether TSE can be used consistently when switching between flortaucipir and MK6240.
• What they did: In 682 individuals across the AD continuum, TSE was quantified as the percentage of regional voxels exceeding tracer-specific abnormality thresholds and compared head-to-head with SUVR.
• The result: TSE showed higher associations than SUVR with memory, Aβ PET, and plasma pTau217, but raw TSE was not interchangeable across tracers (MTL Deming slope: TSE 1.29; SUVR 2.69).