Feasibility of short imaging protocols for [(18)F]PI-2620 tau-PET in progressive supranuclear palsy

PURPOSE: Dynamic 60-min positron emission tomography (PET) imaging with the novel tau radiotracer [(18)F]PI-2620 facilitated accurate discrimination between patients with progressive supranuclear palsy (PSP) and healthy controls (HCs). This study investigated if truncated acquisition and static time windows can be used for [(18)F]PI-2620 tau-PET imaging of PSP. METHODS: Thirty-seven patients with PSP Richardson syndrome (PSP-RS) were evaluated together with ten HCs. [(18)F]PI-2620 PET was performed by a dynamic 60-min scan. Distribution volume ratios (DVRs) were calculated using full and truncated scan durations (0–60, 0–50, 0–40, 0–30, and 0–20 min p.i.). Standardized uptake value ratios (SUVrs) were obtained 20–40, 30–50, and 40–60 min p.i.. All DVR and SUVr data were compared with regard to their potential to discriminate patients with PSP-RS from HCs in predefined subcortical and cortical target regions (effect size, area under the curve (AUC), multi-region classifier). RESULTS: 0–50 and 0–40 DVR showed equivalent effect sizes as 0–60 DVR (averaged Cohen’s d: 1.22 and 1.16 vs. 1.26), whereas the performance dropped for 0–30 or 0–20 DVR. The 20–40 SUVr indicated the best performance of all static acquisition windows (averaged Cohen’s d: 0.99). The globus pallidus internus discriminated patients with PSP-RS and HCs at a similarly high level for 0–60 DVR (AUC: 0.96), 0–40 DVR (AUC: 0.96), and 20–40 SUVr (AUC: 0.94). The multi-region classifier sensitivity of these time windows was consistently 86%. CONCLUSION: Truncated and static imaging windows can be used for [(18)F]PI-2620 PET imaging of PSP. 0–40 min dynamic scanning offers the best balance between accuracy and economic scanning. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00259-021-05391-3.