Preferential loss of striatal DAT is different among PD, PSP & MSA

Objectives Parkinson’s disease (PD), progressive supranuclear palsy (PSP), & multiple system atrophy (MSA) have known to affect the striatal presynaptic dopaminergic neurons with different preferential subregional involvement. We investigated the difference of the striatal subregional dopamine transporter (DAT) loss among PD, PSP & MSA, and the diagnostic value of F-18 FP-CIT PET in differentiating PSP & MSA from PD.

Methods Thirty four PD (63±11y; H&Y 2.2±1.1), 19 PSP (68±8y; H&Y 3.2±1.5), 24 MSA-parkinson type (62±12y; H&Y 3.8±1.4) patients, & 13 normals (55±9y) underwent PET scan 3hr after injection of F-18 FP-CIT. Binding potential (BP) & inter-regional uptake ratio of subgregional VOIs were calculated using a predefined 12 striatal subregional (bilateral ventral striatum, VS; anterior caudate, AC; posterior caudate, PC; anterior putamen, AP; posterior putamen, PP, ventral putamen, VP) & 1 occipital VOIs set after spatial normalization of PET images.

Results BPs of all VOIs in PD,MSA & PSP groups were significantly lower than those of normals (P<0.05). BPs of AC & AC/VS ratio in PSP were significantly lower than those in PD. BPs of VP & VP/PP ratio in MSA were significantly lower than those in PD. AC/VS ratio & VP/PP ratio were not related to H&Y stage and duration of symptom in PSP & MSA, respectively (P>0.05) but not in PD. By cut-off value of AC/VS ratio < 0.8, sensitivity & specificity for differentiating PSP from PD were 83% & 85%, respectively. By cut-off value of VP/PP ratio < 1.3, those for differentiating MSA from PD were 100% & 60%, respectively. By visual analysis, the diagnostic accuracy for differentiating PSP or MSA from PD was 85% with high inter-observer agreement (kappa = 0.77).

Conclusions PD,PSP & MSA showed significantly decreased striatal BP & the different patterns of preferential striatal subregional DAT loss on F-18 FP-CIT PET. Subregional analysis of striatal DAT binding on F-18 FP-CIT PET could be useful in differentiating PSP & MSA from PD