Progress of PET imaging tracers for Alzheimer's disease diagnosis
Alzheimer's disease(AD)is the most common form of irreversible dementia.In addition to assessing of patients'memory abilities,positron emission tomography(PET),as a non-invasive diagnostic modality with high sensitivity and qualitative or quantitative imaging of the target sites,can qualitatively and quantitatively evaluate β-amyloid(Aβ),tau proteins,synaptic proteins,and other related biomarkers,which is of great significance in the diagnosis of AD.As PET imaging approved by FDA,[18F]-flutemetamol,a derivative of 18F labelled thioflavin-T,and[18F]-florbetaben,[18F]-florbetapir,which are phenylpyridine derivates,have high specificity in their affinity for Aβ plaque binding.Other radionuclides such as 68Ga and 64Cu labeled radiotracers also showed high affinity with Aβ plaques.Quinoline derivatives[18F]-THK5351,[18F]-PPQ8,benzimidazolopyrimidine and pyridine-indole derivatives[18F]-T807,and lansoprazole derivatives[11C]-NML as PET imaging agents,can quantify tau protein tangles.And the structural derivatives of levetiracetam[11C]-UCB-J and[18F]-SDM-8 can measure synaptic density,while the structural derivatives[18F]-FPEB of 3-fluoro-4-acetylidene-benzylnitrile can assist in the diagnosis of AD by binding with mGluR5.The fluorobenzoyl derivative[18F]-altanserin,with ketoserin as its structural parent,acts on 5-hydroxytryptamine to study the molecular changes of early AD.