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Objectives: Cognitive impairment is a common non-motor feature of Parkinson's disease (PD). However, the underlying pathophysiology of cognitive decline is unclear. We investigated the association of striatal dopamine transporter (DAT) loss with cognitive function and cerebral cortical metabolism in PD., Methods: Twenty-eight patients (63.1 ± 7.1 yrs, M:F = 15:13) with advanced stage of PD were enrolled, including 15 (53.6%) diagnosed with mild cognitive impairment (MCI). All patients underwent FP-CIT PET/CT, neuropsychological tests, and FDG PET/CT within a 2-week interval. We calculated the specific to non-specific binding ratio on FP-CIT PET images in 12 striatal subregional VOIs, using one occipital VOI template as a reference. Age-adjusted normalized specific to non-specific binding ratios (%BRs) of striatal subregions were compared in two groups: PD with MCI versus PD (without cognitive impairment)., Results: There were no statistical differences in age, age at onset, disease duration, motor symptoms, or level of education between the two groups. The PD with MCI had lower %BRs in all striatal subregions (P < 0.05) except the posterior putamen, compared with the PD. Striatal DAT availability correlated with frontal/executive function (r = 0.567, P = 0.003) and visuospatial function (r = 0.614, P = 0.001) but not with memory function. Dopamine transporter binding of striatal subregions also correlated with posterior cortical metabolism., Conclusion: This study suggest that DAT loss in the striatum, except in the posterior putamen, is associated with cognitive dysfunction, specifically frontal/executive function and visuospatial function in PD subjects.

Delayed phase 18F-FP-CIT PET (dCIT) can assess the striatal dopamine transporter binding to detect degenerative parkinsonism (DP). Early phase 18F-FP-CIT (eCIT) can assess the regional brain activity for differential diagnosis among parkinsonism similar with 18F-FDG PET. We evaluated the diagnostic performance of dual phase 18F-FP-CIT PET (dual CIT) and 18F-FDG PET compared with clinical diagnosis in 141 subjects [36 with idiopathic Parkinson's disease (IPD), 77 with multiple system atrophy (MSA), 18 with progressive supranuclear palsy (PSP), and 10 with non-DP)]. Visual assessment of eCIT, dCIT, dual CIT, 18F-FDG and 18F-FDG PET with dCIT was in agreement with the clinical diagnosis in 61.7%, 69.5%, 95.7%, 81.6%, and 97.2% of cases, respectively. ECIT showed about 90% concordance with non-DP and MSA, and 8.3% and 27.8% with IPD and PSP, respectively. DCIT showed ≥ 88% concordance with non-DP, IPD, and PSP, and 49.4% concordance with MSA. Dual CIT showed ≥ 90% concordance in all groups. 18F-FDG PET showed ≥ 90% concordance with non-DP, MSA, and PSP, but only 33.3% concordance with IPD. The combination of 18F-FDG and dCIT yielded ≥ 90% concordance in all groups. Dual CIT may represent a powerful alternative to the combination of 18F-FDG PET and dCIT for differential diagnosis of parkinsonian disorders. [ABSTRACT FROM AUTHOR]

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]