Correlation between F-18 FDG FP-CIT and clinical findings in patients with Parkinson’s disease

Objectives The aim of this study was to examine the relationship among F-18 FP-CIT parameters and the clinical findings of patients with Parkinson’s disease.

Methods We retrospectively reviewed the F-18 FP-CIT studies performed in patients with Parkinson’s disease at a single institution from March 2009 to June 2015. Patients with no prior history of stroke or medication for treatment of Parkinson’s disease were evaluated by neurologist using the unified Parkinson's disease rating scale (UPDRS). The interval between the patient reported symptom onset time and F-18 FP-CIT scan was documented. Segmentation of striatum was automatically perfomed (MIRADA Medical, UK) using following SUV cut-off thresholds: (1) 1.5 x maximum standardized uptake value (SUVmax) of 3 cm sized sphere from right occipital lobe; (2) 50%, 60% and 70% of the SUVmax of bilateral striata; and (3) 50%, 60% and 70% of the the SUVmax of symptom correlated side striatum (contralateral to the side of dominant motor symptom). Correlation among the PET volumes, SUVmax, symptom duration, and UPDRS was determined using Pearson correlation coefficient.

Results Using threshold of 1.5 x occipital lobe SUVmax, symptom duration and striatum volume on PET (bilateral striata, and unilateral striatum) show weak correlation (R^2=0.041, p<0.05). The other PET parameters did not show statistically significant association with symptom duration. There was no statistically significant correlation between the PET parameters and UPDRS (R^2=0.017, p=0.11).

Conclusions Though striatal volume computed from F-18 FP-CIT PET using occipital lobe as a reference area decreased as the duration of Parkinson’s disease increased, the degree of correlation was weak. There was no statistically significant correlation between the PET parameters and UPDRS. Further studies are needed to determine how to best utilize quantitative F-18 FP-CIT PET in Parkinson’s disease.