Autoradiography allows to identify radioligands with suitable imaging contrast for further in vivo studies. As Tzs do not possess a native target within the brain, direct autoradiography cannot be carried out. In light of that, we developed an autoradiography protocol based on pretargeting (Figure , SI Section S8). In short, brain slices from Tg-ArcSwe mice -a mouse strain with high content of beta-amyloid (Abeta) fibrils in the cortex -were first incubated with TCO-modified 3D6 (anti-Abeta) mAbs. Excess of mAbs was then washed away. In a second step, these slices were incubated with 18 F-Tzs. Structures clicked subsequently to Abeta-bound TCO-3D6. This strategy enabled us to visualize the binding of the mAb to Abeta, but more importantly it also allowed us to study the binding properties of applied 18 F-Tzs, e.g., with respect to their displaceable binding component. In order to mimic the in vivo situation as close as possible, so called "nowash" autoradiographic experiments were carried out. The uptake values in cortex (Cor, high binding region) and in cerebellum (Cer, low binding region) were determined. Cor/Cer ratios were used to rank 18 F-Tzs -the higher the ratio the better the contrast (Figure ). [ 18 F]12 possessed the best ratio, whereas [ 18 F]1 the worst (Figure ). Cor/Cer ratios inversely correlated with clogP (SI Figure ) and showed -as expected -that more lipophilic Tzs possess a higher non-displaceable component.