Fig. 3
From: Centiloid cut-off values for optimal agreement between PET and CSF core AD biomarkers
Derivation of amyloid PET Centiloid cut-offs for CSF pTau/Aβ42. Top row shows scatterplots of PET quantitative measures in Centiloids against CSF pTau/Aβ42 biomarker values for both ALFA+ (blue) and ADNI (red) participants. Vertical line depicts previously published CSF thresholds (pTau/Aβ42 0.022 [22, 30]), and horizontal line depicts optimal cut-offs derived in this study (YI and OPA derived cut-offs are equal). Two outliers were excluded of this picture for having CL value higher than 200. Second row shows this cut-off derivation by 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. pTau, phosphorylated tau; CSF, cerebrospinal fluid; YI, Youden’s J index; PPA, positive percentage agreement; NPA, negative percentage agreement; CL, Centiloids