Quantification of PET studies with the very high-affinity dopamine D 2/D3 receptor ligand [11C]FLB 457: Re-evaluation of the validity of using a cerebellar reference region

Marie-Claude Asselin, Andrew J. Montgomery, Paul M. Grasby, Susan P. Hume

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The very high-affinity position emission tomography (PET) radioligand [11C]FLB 457 was developed in order to study extrastriatal tissues, where the density of dopamine D2/D3 receptors is one to two orders of magnitude lower than in the striatum. The present study investigated the validity of using the cerebellum as a reference region. Ten healthy volunteers underwent a 90-min dynamic PET study after the bolus injection of [11C]FLB 457. The total volume of distribution (VD t) was estimated for the thalamus, hippocampus, frontal cortex, and cerebellum using a two-tissue compartmental model with a metabolite-corrected arterial plasma input function. VDt was sensitive to co-injected stable FLB 457 in all regions, including the cerebellum. Ex vivo saturation studies were also conducted in 17 rats where the dose of stable ligand was varied over five orders of magnitude. Specific binding was estimated to account for more than half of the rat cerebellar uptake of [11C]FLB 457, questioning the latter as an estimate of nonspecific binding in human PET studies. To check whether the cerebellum is a reference region, the binding potential (BP) was calculated either from the VDt ratio or using the simplified reference tissue model (SRTM). A non-negligible density of D 2/D3 receptors in the cerebellum was shown to lead to underestimation of BP as well as erroneous estimation of differential occupancies. Binging potential estimates from the SRTM were found to be sensitive to changes in cerebral blood flow, providing further evidence for caution in the use of the cerebellum as a reference region in measures of [ 11C]FLB 457 binding. © 2007 ISCBFM All rights reserved.
    Original languageEnglish
    Pages (from-to)378-392
    Number of pages14
    JournalJournal of Cerebral Blood Flow and Metabolism
    Volume27
    Issue number2
    DOIs
    Publication statusPublished - Feb 2007

    Keywords

    • [11C]FLB 457
    • Cerebellar reference region
    • Dopamine D 2/D3 receptors
    • Extrastriatal tissues
    • Positron emission tomography (PET)

    Fingerprint

    Dive into the research topics of 'Quantification of PET studies with the very high-affinity dopamine D 2/D3 receptor ligand [11C]FLB 457: Re-evaluation of the validity of using a cerebellar reference region'. Together they form a unique fingerprint.

    Cite this