Application of 18F-DOPA PET imaging in the diagnosis and assessment of early-stage Parkinson′s disease

Objective To investigate the clinical values of L-6-18F-fluoro-3, 4-dihydroxyphenylalanine (18F-DOPA) PET in the diagnosis and severity assessment of early-stage Parkinson′s disease (PD). Methods Thirty-eight patients (24 males, 14 females; age: 34-74 years) with early-stage PD (Hoehn-Yahr (H-Y) staging: 1-2) and 5 age-matched healthy volunteers (all males; age: 45-65 years) from July 2016 to March 2017 were included and underwent 18F-DOPA PET scan in this retrospective study. The striatal-to-occipital ratio (SOR) was calculated and compared between PD patients and healthy volunteers. The unified PD rating scale (UPDRS) Ⅲ score and H-Y staging were used to evaluate the clinical symptoms. Two-sample t test and Pearson correlation analysis were used. Results In the control group, 18F-DOPA SORs in bilateral putamen and caudate nucleus were 2.50±0.24 and 2.61±0.23, respectively. In PD group, the SORs of ipsilateral and contralateral putamen nucleus were 2.02±0.27 and 1.80±0.26 respectively, lower than those in the control group (t values: -4.006, -5.440, both P<0.01). The SORs of ipsilateral and contralateral caudate nucleus were 2.16±0.32 and 2.08±0.28 respectively, lower than those in the control group (t values: -2.990, -4.047, both P<0.01). The SORs of contralateral putamen and caudate nucleus were significantly lower than those of the ipsilateral striatum respectively (t values: -6.431, -3.837, both P<0.01). Furthermore, the SORs in the striatum (putamen and caudate nucleus) were negatively correlated with UPDRS Ⅲ score, H-Y staging, and duration of disease (r values: from -0.526 to -0.369, all P<0.05). Conclusions 18F-DOPA PET can reflect the changes in the striatum neurons, and it may be an important method in the diagnosis and assessment of early-stage PD patients. Key words: Parkinson disease; Positron-emission tomography; Tomography, X-ray computed; Levodopa; Fluorine radioisotopes