Dynamic 18F-FPCIT PET: Quantification of Parkinson Disease Metabolic Networks and Nigrostriatal Dopaminergic Dysfunction in a Single Imaging Session

Previous multi-center imaging studies with ¹⁸F-FDG PET have established the presence of Parkinson’s disease motor- and cognition-related metabolic patterns termed PDRP and PDCP in patients with this disorder. Given that in PD cerebral perfusion and glucose metabolism are typically coupled in the absence of medication, we determined whether subject expression of these disease networks can be quantified in early-phase images from dynamic ¹⁸F-FPCIT PET scans acquired to assess striatal dopamine transporter (DAT) binding. Methods: We studied a cohort of early-stage PD patients and age-matched healthy control subjects who underwent ¹⁸F-FPCIT at baseline; scans were repeated 4 years later in a smaller subset of patients. The early ¹⁸F-FPCIT frames, which reflect cerebral perfusion, were used to compute PDRP and PDCP expression (subject scores) in each subject, and compared to analogous measures computed based on ¹⁸F-FDG PET scan when additionally available. The late ¹⁸F-FPCIT frames were used to measure caudate and putamen DAT binding in the same individuals. Results: PDRP subject scores from early-phase ¹⁸F-FPCIT and ¹⁸F-FDG scans were elevated and striatal DAT binding reduced in PD versus healthy subjects. The PDRP scores from ¹⁸F-FPCIT correlated with clinical motor ratings, disease duration, and with corresponding measures from ¹⁸F-FDG PET. In addition to correlating with disease duration and analogous ¹⁸F-FDG PET values, PDCP scores correlated with DAT binding in the caudate/anterior putamen. PDRP and PDCP subject scores using either method rose over 4 years whereas striatal DAT binding declined over the same time period. Conclusion: Early-phase images obtained with ¹⁸F-FPCIT PET can provide an alternative to ¹⁸F-FDG PET for PD network quantification. This technique therefore allows PDRP/PDCP expression and caudate/putamen DAT binding to be evaluated with a single tracer in one scanning session.