Objectives: This study aimed to investigate whether the amino acid PET tracer cis-4-[F]fluoro-D-proline [D-cis-[F]FPro] shows increased uptake in the basal ganglia of patients with neurodegenerative akinetic-rigid parkinsonism. D-Cis-[F]FPro is a sensitive PET tracer for inflammation-associated neurodegeneration in animal models. We hypothesized that D-cis-[F]FPro might also be a sensitive marker of alterations of the basal ganglia in parkinsonian syndromes.
Participants and methods: Ten patients with neurodegenerative akinetic-rigid parkinsonism (five with idiopathic Parkinson's disease and five with atypical parkinsonian syndromes) were imaged with D-cis-[F]FPro and compared with 13 patients with brain tumors who had no basal ganglia involvement. PET images 20-50 min after injection were evaluated and tracer uptake in the basal ganglia was quantified using volume-of-interest analysis with basal ganglia to background ratios. The severity of disease was assessed with unified Parkinson's disease rating scale III and correlated with D-cis-[F]FPro uptake.
Results: In patients with parkinsonism, volume-of-interest analysis showed mild, but significantly increased D-cis-[F]FPro uptake in the basal ganglia, pronounced in the lenticular nucleus. Disease severity correlated with D-cis-[F]FPro uptake in the right pallidum (r=-0.687, P=0.041).
Conclusion: Data suggest that D-cis-[F]FPro is a sensitive marker of inflammation-associated degenerative processes in parkinsonian syndromes.