IMPORTANCE Progressive supranuclear palsy (PSP) is a 4-repeat tauopathy. Region-specific tau aggregates establish the neuropathologic diagnosis of definite PSP post mortem. Future interventional trials against tau in PSP would strongly benefit from biomarkers that support diagnosis.OBJECTIVE To investigate the potential of the novel tau radiotracer 18 F-PI-2620 as a biomarker in patients with clinically diagnosed PSP. DESIGN, SETTING, AND PARTICIPANTSIn this cross-sectional study, participants underwent dynamic 18 F-PI-2620 positron emission tomography (PET) from 0 to 60 minutes after injection at 5 different centers (3 in Germany, 1 in the US, and 1 in Australia). Patients with PSP (including those with Richardson syndrome [RS]) according to Movement Disorder Society PSP criteria were examined together with healthy controls and controls with disease. Four additionally referred individuals with PSP-RS and 2 with PSP-non-RS were excluded from final data analysis owing to incomplete dynamic PET scans.

ObjectivesIn recent years several [18F]-labelled amyloid PET tracers have been developed and have obtained clinical approval. There is accumulating evidence that early (post injection) acquisitions with these tracers are equally informative as conventional blood flow and metabolism studies for diagnosis of Alzheimer's disease, but there have been few side-by-side studies. Therefore, we investigated the performance of early acquisitions of [18F]-florbetaben (FBB) PET compared to [18F]-fluorodeoxyglucose (FDG) PET in a clinical setting.MethodsAll subjects were recruited with clinical suspicion of dementia due to neurodegenerative disease. FDG PET was undertaken by conventional methods, and amyloid PET was performed with FBB, with early recordings for the initial 10 min (early-phase FBB), and late recordings at 90–110 min p.i. (late-phase FBB). Regional SUVR with cerebellar and global mean normalization were calculated for early-phase FBB and FDG PET. Pearson correlation coefficients between FDG and early-phase FBB were calculated for predefined cortical brain regions. Furthermore, a visual interpretation of disease pattern using 3-dimensional stereotactic surface projections (3D-SSP) was performed, with assessment of intra-reader agreement.ResultsAmong a total of 33 patients (mean age 67.5 ± 11.0 years) included in the study, 18 were visually rated amyloid-positive, and 15 amyloid-negative based on late-phase FBB scans. Correlation coefficients for early-phase FBB vs. FDG scans displayed excellent agreement in all target brain regions for global mean normalization. Cerebellar normalization gave strong, but significantly lower correlations. 3D representations of early-phase FBB visually resembled the corresponding FDG PET images, irrespective of the amyloid-status of the late FBB scans.ConclusionsEarly-phase FBB acquisitions correlate on a relative quantitative and visual level with FDG PET scans, irrespective of the amyloid plaque density assessed in late FBB imaging. Thus, early-phase FBB uptake depicts a metabolism-like image, suggesting it as a valid surrogate marker for synaptic dysfunction, which could ultimately circumvent the need for additional FDG PET investigation in diagnosis of dementia.

2-[(18)F]FA-85380 PET appears to be a sensitive and feasible tool for the detection of a reduction in α4β2* nAChRs which seems to be an early event in AD. In addition, 2-[(18)F]FA-85380 PET might give prognostic information about a conversion from MCI to AD.

These results indicate florbetaben to be a safe and efficacious β-amyloid-targeted tracer with favourable brain kinetics. Subjects with AD could be easily differentiated from HCs by both visual and quantitative assessment of the PET data. The operator-independent, voxel-based analysis yielded whole brain β-amyloid load which appeared valuable as a surrogate marker of disease severity.

Background Corticobasal syndrome is associated with cerebral protein aggregates composed of 4‐repeat (~50% of cases) or mixed 3‐repeat/4‐repeat tau isoforms (~25% of cases) or nontauopathies (~25% of cases). Objectives The aim of this single‐center study was to investigate the diagnostic value of the tau PET‐ligand [18F]PI‐2620 in patients with corticobasal syndrome. Methods Forty‐five patients (71.5 ± 7.6 years) with corticobasal syndrome and 14 age‐matched healthy controls underwent [18F]PI‐2620‐PET. Beta‐amyloid status was determined by cerebral β‐amyloid PET and/or CSF analysis. Subcortical and cortical [18F]PI‐2620 binding was quantitatively and visually compared between β‐amyloid‐positive and ‐negative patients and controls. Regional [18F]PI‐2620 binding was correlated with clinical and demographic data. Results Twenty‐four percent (11 of 45) were β‐amyloid‐positive. Significantly elevated [18F]PI‐2620 distribution volume ratios were observed in both β‐amyloid‐positive and β‐amyloid‐negative patients versus controls in the dorsolateral prefrontal cortex and basal ganglia. Cortical [18F]PI‐2620 PET positivity was distinctly higher in β‐amyloid‐positive compared with β‐amyloid‐negative patients with pronounced involvement of the dorsolateral prefrontal cortex. Semiquantitative analysis of [18F]PI‐2620 PET revealed a sensitivity of 91% for β‐amyloid‐positive and of 65% for β‐amyloid‐negative cases, which is in excellent agreement with prior clinicopathological data. Regardless of β‐amyloid status, hemispheric lateralization of [18F]PI‐2620 signal reflected contralateral predominance of clinical disease severity. Conclusions Our data indicate a value of [18F]PI‐2620 for evaluating corticobasal syndrome, providing quantitatively and regionally distinct signals in β‐amyloid‐positive as well as β‐amyloid‐negative corticobasal syndrome. In corticobasal syndrome, [18F]PI‐2620 may potentially serve for a differential diagnosis and for monitoring disease progression. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society