Fig. 2
From: Centiloid cut-off values for optimal agreement between PET and CSF core AD biomarkers
Derivation of amyloid PET Centiloid cut-offs using Aβ42 CSF biomarker. Upper row shows a scatterplot of PET quantitative measures in Centiloids against CSF Aβ42 biomarker values for both ALFA+ (blue) and ADNI (red) participants. Vertical lines depict previously published CSF threshold (Aβ42 1098 pg/ml [22, 30]), and horizontal lines depict optimal cut-offs derived in this study (YI derived: green, OPA derived: yellow). Two outliers were excluded of this picture for having CL value higher than 200. Second row shows this cut-offs derivation by the maximization of YI (left) and OPA (right). The YI (green) was calculated from PPA (blue) and NPA (red) values. The OPA (green) was calculated from PPV (blue) and NPV (red) values. Derivation was done with participants of both cohorts merged. Aβ, amyloid; CSF, cerebrospinal fluid; YI, Youden’s J index; PPA, positive percentage agreement; NPA, negative percentage agreement; CL, Centiloids