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The purpose of this study was to evaluate the effect of the normal aging process on DAT densities in human-specific brain regions including the substantia nigra and thalamus using positron emission tomography (PET) with [18F]FE-PE2I, a new PET radioligand with high affinity and selectivity for DAT.
 Thirty-six healthy volunteers ranging in age from 22 to 80 years were scanned with PET employing [18F]FE-PE2I for measuring DAT densities. Region of interest (ROI)-based analysis was used, and ROIs were manually defined for the caudate, putamen, substantia nigra, thalamus, and cerebellar cortex. DAT binding was quantified using a simplified reference tissue model, and the cerebellum was used as reference region.
Estimations of binding potential in the caudate, putamen, substantia nigra, and thalamus were individually regressed according to age using simple regression analysis. Estimates of DAT loss per decade were obtained using the values from the regression slopes. There were 7.6, 7.7, and 3.4 % per-decade declines in DAT in the caudate, putamen, and substantia nigra, respectively. By contrast, there was no age-related decline of DAT in the thalamus
. [18F]FE-PE2I allowed reliable quantification of DAT, not only in the caudate and putamen but also in the substantia nigra.....