Purpose: Diagnosis of Parkinson's disease (PD) can be difficult. F-DOPA PET is able to quantify striatal dopa decarboxylase activity and storage capacity of F-dopamine, but is expensive and not generally available. FP-CIT binds to the dopamine transporter, and FP-CIT SPECT is cheaper and more widely available, but has a lower resolution. The aim of this study was to compare these two methods in the same patients with different stages of PD to assess their power in demonstrating deficits of the striatal dopaminergic system.
Methods: Thirteen patients with de novo PD and 17 patients with advanced PD underwent FP-CIT SPECT and static F-DOPA PET. After data transfer to standard stereotactic space, a template with regions of interest was used to sample values of the caudate, putamen and an occipital reference region. The outcome value was striato-occipital ratios. Patients were clinically examined in the "off state" (UPDRS-III and H&Y stage).
Results: Good correlations were found between striatal F-DOPA uptake and striatal FP-CIT uptake (r = 0.78) and between putaminal F-DOPA uptake and putaminal FP-CIT uptake (r = 0.84, both p < 0.0001). Both striatal uptake of FP-CIT and that of F-DOPA correlated moderately with H&Y stage (rho = -0.52 for both techniques), UPDRS-III (rho = -0.38 for F-DOPA; rho = -0.45 for FP-CIT) and disease duration (rho = -0.59 for F-DOPA; rho = -0.49 for FP-CIT, all p < 0.05).
Conclusion: FP-CIT values correlate well with F-DOPA values. Both methods correlate moderately with motor scores and are equally able to distinguish patients with advanced PD from patients with de novo PD.