Relationship of F-18 FP-CIT dopamine transporter loss & cardiac I-123 MIBG uptake is different between the subtypes of Parkinson's diseases

Abstract

Objectives: It is increasingly evident that Parkinson’s disease (PD) is not a single entity but rather a heterogeneous neurodegenerative disorder with a broad spectrum of motor and non-motor features. Dopamine transporter imaging by 18F-FP-CIT and cardiac sympathetic imaging using 123I-MIBG scintigraphy are widely used to access these features of PD. However, the relationships between nigrostriatal degeneration and cardiac sympathetic denervation in different subtypes of PD are not well known. Therefore, we investigated the striatal dopamine transporter (DAT) binding and cardiac MIBG uptake in akinetic-rigid type PD (ART-PD) and tremor dominant type PD (TDT-PD) subtypes. Methods: We reviewed 18F-FP-CIT PET and 123I-MIBG cardiac scintigraphy in the PD patients (20 with ART and 20 with TDT). Region of interest (ROI) was placed on both caudate nuclei, whole putamen, anterior and posterior putamen and occipital cortex in 18F-FP-CIT image and striatal DAT binding activity were evaluated. The heart/mediastinal ratio (H/M ratio) in early and delayed chest 123I-MIBG image were also acquired. The Spearman’s correlation was used to assess a relationship among striatal DAT binding, cardiac 123I-MIBG uptake and UPDRS-III clinical motor scale in each PD subtypes. Results: There was statistically significant correlation between 123I-MIBG cardiac uptake and striatal DAT binding on the more affected and less affected side of whole putamen, anterior putamen, and posterior putamen in ART-PD (all, p<0.05). However, there was no significant correlation in TDT-PD. On the contrary, only in TDT-PD, striatal DAT binding on the more affected and less affected side of whole putamen, anterior putamen, and posterior putamen had significant correlation with UPDRS-III score (all, p<0.05) Conclusion: In our study, ART-PD and TDT-PD represented different relationship between striatal DAT binding and cardiac sympathetic denervation. Putaminal DAT loss was correlated with the sympathetic denervation in ART-PD and with clinical motor score in TDT-PD. Knowledge of difference about these subtypes may lead to further insights into mechanisms of disease and pathogenesis-targeted and symptomatic treatments.