Dynamic ¹⁸F-FPCIT PET: Quantification of Parkinson Disease Metabolic Networks and Nigrostriatal Dopaminergic...

Previous multicenter imaging studies with ¹⁸F-FDG PET have established the presence of motor-related and cognition-related metabolic patterns of Parkinson disease (PD), termed the PD-related pattern (PDRP) and the PD cognition-related pattern (PDCP), respectively, 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-N-(3-fluoropropyl)-2β-carboxymethoxy-3β-(4-iodophenyl)nortropane (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 y 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 were compared with analogous measures computed on the basis of the 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 was reduced in PD versus healthy subjects. The PDRP scores from ¹⁸F-FPCIT correlated with clinical motor ratings, disease duration, and 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 or anterior putamen. PDRP and PDCP subject scores using either method rose over 4 y, whereas striatal DAT binding declined over the same 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 a single scanning session.