Finding the optimal cutoff value for amyloid ? positivity using the iterative outlier method and concordance rate

Purpose The purpose of this study was to calculate the cutoff value for amyloid β (Aβ) positron emission tomography (PET) positivity using iterative outlier method and evaluate its validity based on concordance rate. Methods We performed 373 cognitively unimpaired (CU) subjects calculated optimal Aβ positivity. validation independent dataset, comprising 83 (27 CU, 27 amnestic mild cognitive impairment, 29 Alzheimerâ??s dementia). evaluated by calculating rate with visual assessment between two different tracers in same subject. Results values ranged from 84.3% 91.5%, depending reference regions. 90.3% 97.5%, all which were higher than that (86.7%). Conclusion demonstrated could identify PET Keywords: Alzheimer disease; Amyloid; Positron-emission