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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]