6-(18)F-fluorodopa PET depicts the striatal dopaminergic lesion characterizing Parkinson disease (PD); however, striatal uptake of 6-(18)F-fluorodopa-derived radioactivity can be normal. Supine hypertension (SH) might increase 6-(18)F-fluorodopa uptake.
Methods: We measured putamen, caudate, and occipital cortex 6-(18)F-fluorodopa-derived radioactivity and supine blood pressure in patients with PD + SH (systolic pressure >/= 180 mm Hg, n = 8), patients with PD without SH (PD - SH, n = 19), patients with pure autonomic failure (n = 8), and controls (n = 16).
Results: Peak putamen radioactivity correlated with supine systolic pressure across all subjects and among PD patients and was higher in PD + SH than in PD - SH (P = 0.01). Both subgroups had rapid fractional declines in radioactivity between the peak and late values (P < 0.0001, compared with controls). Arterial 6-(18)F-fluorodopa concentrations were similar in the compared groups.
Conclusion: In PD, SH is associated with augmented striatal 6-(18)F-fluorodopa-derived radioactivity. Regardless of SH, retention of 6-(18)F-fluorodopa-derived radioactivity is markedly reduced. A model-independent approach can identify striatal dopaminergic denervation in PD.