Objective: We aim to evaluate the differences in striatal subregional dopamine transporter loss between Parkinson disease (PD) and progressive supranuclear palsy (PSP) of any stage with [18F] PR04.MZ PET, and to assess the results with [18F] PI-2620 PET quantification of tau deposits

Background: PSP is a neurodegenerative disease characterized by the accumulation of tau protein in the brain, leading to progressive motor and cognitive impairment. Differentiation of PSP from PD can be problematic in the early stages. Both affect dopaminergic neurons of the brain stem and striatum with different preferential involvement.  PET imaging with [18F] PI-2620, a marker for tau deposition, has shown promising results in detecting tau pathology in PSP patients—additionally, [18F] PR04.MZ PET, a marker for dopamine transporter loss, has been used to evaluate the striatal subregional dopamine transporter loss in patients with PD and PSP.

Method: Ten patients with PSP (mean age 69.8±7.5 years) and 11 healthy individuals (mean age 63.6 ± 7 years) underwent PET scans to evaluate DAT ([18F]PR04.MZ PET) and tau ([18F] PI- 2620 PET). The results were complemented by a previous study conducted in 2016, which evaluated seven patients with PSP and seven patients with PD using [18F]PR04.MZ PET. Scans were co-registered with CT images and normalized to a standardized brain template. PSP diagnosis was made by movement disorder subspecialists using both NINDS and MDS criteria. Data analysis results are expressed as mean and range plus or minus standard deviation.

Results: Regardless of disease stage, a significant decrease in the PR04.MZ uptake is seen in the posterior putamen in patients with PSP. These patients had more prominent and earlier DAT loss in the posterior putamen than PD. Regarding the results of [18F] PI-2620 PET, a difference in TAU uptake was observed, varying according to the evaluated region, with greater uptake observed in basal ganglia.

Conclusion: Both examinations show differences among PSP, PD, and healthy individuals. In addition, an earlier and more prominent loss of DAT in the posterior putamen associated with higher TAU uptake was observed in patients with PSP compared to patients with PD or healthy individuals. The results may aid in the accuracy of early diagnosis of PSP and the differentiation from PD.

References: Kramer V, Juri C, Riss PJ, Pruzzo R, Soza-Ried C, Flores J, Hurtado A, Rösch F, Chana-Cuevas P, Amaral H. Pharmacokinetic evaluation of [18F]PR04.MZ for PET/CT imaging and quantification of dopamine transporters in the human brain. Eur J Nucl Med Mol Imaging. 2020 Jul;47(8):1927-1937 Epub 2019 Dec 1.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/quantification-of-striatal-and-extrastriatal-dopamine-transporters-with-18fpr04-mz-and-18f-pi-2620-pet-in-patients-with-progressive-supranuclear-palsy/