Unlabelled: (18)F-(E)-N-(3-iodoprop-2E-enyl)-2β-carbofluoroethoxy-3β-(4-methylphenyl)nortropane ((18)F-FE-PE2I) is a new PET radioligand with a high affinity and selectivity for the dopamine transporter (DAT). In nonhuman primates, (18)F-FE-PE2I showed faster kinetics and less production of radiometabolites that could potentially permeate the blood-brain barrier than did (11)C-PE2I. The aims of this study were to examine the quantification of DAT using (18)F-FE-PE2I and to assess the effect of radiometabolites of (18)F-FE-PE2I on the quantification in healthy humans.
Methods: A 90-min dynamic PET scan was obtained for 10 healthy men after intravenous injection of (18)F-FE-PE2I. Kinetic compartment model analysis with a metabolite-corrected arterial input function was performed. The effect of radiometabolites on the quantification was evaluated by time-stability analyses. The simplified reference tissue model (SRTM) method with the cerebellum as a reference region was evaluated as a noninvasive method of quantification.
Results: After the injection of (18)F-FE-PE2I, the whole-brain radioactivity showed a high peak (∼3-5 standardized uptake value) and fast washout. The radioactive uptake of (18)F-FE-PE2I in the brain was according to the relative density of the DAT (striatum > midbrain > thalamus). The cerebellum showed the lowest uptake. Tissue time-activity curves were well described by the 2-tissue-compartment model (TCM), as compared with the 1-TCM, for all subjects in all regions. Time stability analysis showed stable estimation of total distribution volume with 60-min or longer scan durations, indicating the small effect of radiometabolites. Binding potentials in the striatum and midbrain were well estimated by the SRTM method, with modest intersubject variability. Although the SRTM method yielded a slight underestimation and overestimation in regions with high and low DAT densities, respectively, binding potentials by the SRTM method were well correlated to the estimates by the indirect kinetic method with 2-TCM.
Conclusion: (18)F-FE-PE2I is a promising PET radioligand for quantifying DAT. The binding potentials could be reliably estimated in both the striatum and midbrain using both the indirect kinetic and SRTM methods with a scan duration of 60 min. Although radiometabolites of (18)F-FE-PE2I in plasma possibly introduced some effects on the radioactivity in the brain, the effects on estimated binding potential were likely to be small.
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http://dx.doi.org/10.2967/jnumed.111.101626 | DOI Listing |
Environ Monit Assess
January 2025
School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, 2000, South Africa.
The grassland ecosystem forms a critical part of the natural ecosystem, covering up to 15-26% of the Earth's land surface. Grassland significantly impacts the carbon cycle and climate regulation by storing carbon dioxide. The organic matter found in grassland biomass, which acts as a carbon source, greatly expands the carbon stock in terrestrial ecosystems.
View Article and Find Full Text PDFEnviron Monit Assess
December 2024
ICAR - Directorate of Coldwater Fisheries Research, Bhimtal, Nainital, Uttarakhand- 263136, India.
In regions characterized by mountainous landscapes, such as watersheds with high elevations, steep inclines, and rugged terrains, there exists an inherent susceptibility to water-induced soil erosion. This susceptibility underscores the importance of identifying areas prone to erosion to mitigate the loss of valuable natural resources and ensure their preservation over time. In response to this need, the current research employed a combination of four multi-criteria decision-making (MCDM) models, namely TOPSIS-AHP, VIKOR-AHP, ARAS-AHP, and CODAS-AHP, for the identification of areas susceptible to soil erosion within the Himalayan River basin of Nandakini, Uttarakhand, India.
View Article and Find Full Text PDFEnviron Sci Pollut Res Int
December 2024
Wadia Institute of Himalayan Geology, Dehradun, 248001, India.
Our understanding of identifying and monitoring surge-type glacier distribution patterns, fluctuations, periodicities, and occurrence mechanism under the changing climate is challenging and scarce due to small numbers, limitations on the spatiotemporal coverage of remote sensing observations, and insufficient field-based glaciological data from the High Mountain Asia. The surging glaciers have caused major hazards, and their movement can destroy peripheral and downstream areas like roads, connecting bridges, villages, and hydropower stations and trigger a glacial lake outburst flood or form a dammed (moraine or ice) lake in High Mountain Asia (HMA) in the recent past. Many glaciers have experienced a mass loss and retreat due to ongoing climate change in HMA in recent decades, whereas studies conducted in the Karakorum, Pamir, Tien Shan, and Kunlun Shan regions have reported the surging of the glaciers.
View Article and Find Full Text PDFTrials
October 2024
Clinical Neuroscience, Max-Planck-Institute of Experimental Medicine, City Campus, Göttingen, Germany.
Eur J Nucl Med Mol Imaging
December 2024
Department of Radiology and Biomedical Imaging, Yale School of Medicine, 801 Howard Avenue, PO Box 208048, New Haven, CT, 06520- 8048, USA.
Purpose: [F]SynVesT-1, a positron emission tomography (PET) radiotracer for the synaptic vesicle glycoprotein 2A (SV2A), demonstrates kinetics similar to [C]UCB-J, with high brain uptake, fast kinetics fitting well with the one-tissue compartment (1TC) model, and excellent test-retest reproducibility. Challenges arise due to the similarity between k and [Formula: see text] (efflux rate of the reference region), when applying the simplified reference tissue model (SRTM) and related methods in [C]UCB-J studies to accurately estimate [Formula: see text]. This study evaluated the suitability of these methods to estimate [F]SynVesT-1 binding using centrum semiovale (CS) or cerebellum (CER) as reference regions.
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