Abstract
BACKGROUND: Positron emission tomography (PET) using the tracer (18)F-fluorodeoxyglucose ((18)F-FDG) and [(18)F] 9-fluoropropyl-(+)-dihydrotetrabenazine ((18)F-FP-DTBZ) is widely utilized to measure metabolic activity and dopaminergic integrity in neurodegenerative diseases such as Parkinson's disease (PD). Previous studies employing (18)F-FDG PET have primarily focused on motor or non-motor symptoms, rather than the severity of PD. This study aimed to measure the glucose metabolism of (18)F-FDG and the dopaminergic function of (18)F-FP-DTBZ across various Hoehn-Yahr (H&Y) stages, analyzing the correlation between metabolic activity, dopaminergic function, and H&Y stages to monitor the severity of PD. METHODS: The cross-sectional study recruited 78 PD patients in 3 groups of H&Y stages I, II, and III-V and 18 healthy control (HC) participants to undergo (18)F-FDG and (18)F-FP-DTBZ PET scans. Differences in cerebral metabolism and dopaminergic function between groups were evaluated using Student's t-test and Mann-Whitney U test. Moreover, Pearson correlation analysis was used to explore the association between cerebral metabolism, dopaminergic function, and H&Y stages in all patients. RESULTS: Patients with PD exhibited significant hypometabolic activity in the frontal cortex and relative hypermetabolic activity in the putamen, globus pallidus, thalamus, and cerebellum when compared to HC individuals (P<0.05). Further imaging-clinical correlation research depicted the negative correlation between the metabolic activity in the frontal and putamen regions with H&Y stage. Furthermore, the (18)F-FP-DTBZ binding reductions were 18.6%, 46.6%, and 56.9% for the caudate, anterior putamen, and posterior putamen at H&Y stages I; 36.0%, 56.9%, and 65.9% at H&Y stages II; and 41.2%, 61.9%, and 68.5% at H&Y stages III-V, respectively. The (18)F-FP-DTBZ binding of caudate, anterior putamen, and posterior putamen exhibited significantly negative correlations to H&Y stage. CONCLUSIONS: In PD, (18)F-FDG and (18)F-FP-DTBZ PET imaging represent potential biomarkers for tracking metabolic activity and dopaminergic degeneration, offering valuable insights into estimating the severity of disease.