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Purpose: The aim of this study was to evaluate whether striatal dopamine transporter (DAT) loss as measured by F-fluorinated- N-3-fluoropropyl-2-b-carboxymethoxy-3-b-(4-iodophenyl) nortropane ([F]FP-CIT) PET differs according to the metabolic subtype of multiple system atrophy (MSA) as assessed by [F]FDG PET. Methods: This retrospective study included 50 patients with clinically diagnosed MSA who underwent [F]FP-CIT and [F]FDG brain PET scans. The PET images were analysed using 12 striatal subregional volume-of-interest templates (bilateral ventral striatum, anterior caudate, posterior caudate, anterior putamen, posterior putamen, and ventral putamen). The patients were classified into three metabolic subtypes according to the [F]FDG PET findings: MSA-P (striatal hypometabolism only), MSA-mixed (both striatal and cerebellar hypometabolism), and MSA-C (cerebellar hypometabolism only). The subregional glucose metabolic ratio (MR), subregional DAT binding ratio (BR), and intersubregional ratio (ISR; defined as the BR ratio of one striatal subregion to that of another striatal subregion) were compared according to metabolic subtype. Results: Of the 50 patients, 13 presented with MSA-P, 16 presented with MSA-mixed, and 21 presented with MSA-C. The BR of all striatal subregions in the MSA-P and MSA-mixed groups were significantly lower than those in the MSA-C group. The posterior putamen/anterior putamen ISR and anterior putamen/ventral striatum ISR in the MSA-P and MSA-mixed groups were significantly lower than those in the MSA-C group. Conclusion: Patients with MSA-P and MSA-mixed showed more severe DAT loss in the striatum than patients with MSA-C. Patients with MSA-C had more diffuse DAT loss than patients with MSA-P and MSA-mixed. [ABSTRACT FROM AUTHOR]

Background: The characteristics of clinical features and nigrostriatal dopaminergic dysfunction in patients with combined postural and resting tremors have been less clearly reported. Methods: The present study examined 43 patients with a visible persistent bilateral postural tremor and a unilateral/bilateral resting tremor involving the hands and forearms. The patients had experienced tremors for more than 3 years, with no evidence of Parkinson's disease or other parkinsonian disorders. Visual and quantitative analyses of [18F] N-(3-fluoropropyl)-2beta-carbon ethoxy-3beta-(4-iodophenyl) nortropane (FP-CIT) PET in 36 patients were performed. Seventeen age-matched normal controls were also studied. Results: On visual analysis, 28 patients (78%) showed normal [18F] FP-CIT uptake and eight (22%) showed significantly reduced uptake, suggesting nigrostriatal dopaminergic neuronal degeneration. The reduced [18F] FP-CIT uptake was significantly associated with earlier age-at-onset of tremor and asymmetric presentation of resting tremor. On quantitative analysis, there were statistically significant differences in the [18F] FP-CIT uptake ratio in the posterior putamen between patients with reduced uptake (2.37 ± 1.83) and patients with normal uptake (6.39 ± 1.35) (P < 0.001). However, posterior putamen uptake levels in patients with normal [18F] FP-CIT uptake on visual analysis were similar to those in normal controls (7.22 ± 1.29) (P = 0.291). Conclusion: The nigrostriatal dopaminergic dysfunction in patients with combined postural and resting tremors may be associated with earlier age-at-onset of tremor and asymmetric pattern of resting tremor, which might help to correctly diagnose patients with mixed tremors. [ABSTRACT FROM AUTHOR]