Measurement of striatal and extrastriatal dopamine transporter binding with high-resolution PET and [11C]PE2I: quantitative modeling and test-retest reproducibility

J Cereb Blood Flow Metab. 2008 May;28(5):1059-69. doi: 10.1038/sj.jcbfm.9600607. Epub 2008 Jan 9.

Abstract

[(11)C]PE2I is a novel positron emission tomography (PET) radiotracer for the dopamine transporter (DAT). The reproducibility and reliability of [(11)C]PE2I measurements, especially in the small DAT-rich brain regions, is unknown and of critical importance to the interpretation of the data. Five healthy volunteers were scanned twice during the same day using [(11)C]PE2I and the HRRT PET scanner. Methods based on metabolite-corrected arterial plasma curve and reference region were used to estimate distribution volumes (V(T)) and binding potential (BP). Within-subject and between-subject variabilities were compared. [(11)C]PE2I accumulated in the DAT-rich striatum and the midbrain. Equilibrium of specific binding appeared late in the striatum, whereas it was reached earlier in the midbrain. Plasma metabolite analysis showed that the potentially brain-penetrant 4-hydroxymethyl metabolite represented 15% to 20% of total plasma radioactivity. V(T) and BP measurements were associated with low within-subject variability. Measurement of DAT binding in small brain regions, including the substantia nigra, is reproducible and reliable using [(11)C]PE2I and high-resolution research tomograph. A scanning time of more than 70 mins is required for the striatum, while less is sufficient for DAT quantification in the midbrain. The previously suggested involvement of the potentially brain-penetrant radioactive metabolite in the quantification should be further studied.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adult
  • Carbon Radioisotopes / pharmacokinetics
  • Cerebellum / diagnostic imaging
  • Cerebellum / metabolism
  • Cerebral Cortex / diagnostic imaging
  • Cerebral Cortex / metabolism
  • Corpus Striatum / diagnostic imaging*
  • Corpus Striatum / metabolism
  • Dopamine Plasma Membrane Transport Proteins / metabolism*
  • Humans
  • Male
  • Nortropanes* / pharmacokinetics
  • Positron-Emission Tomography / methods*
  • Positron-Emission Tomography / standards*
  • Reproducibility of Results

Substances

  • Carbon Radioisotopes
  • Dopamine Plasma Membrane Transport Proteins
  • N-(3-iodoprop-2-enyl)-2-beta-carbomethoxy-3-(4-methylphenyl)nortropane
  • Nortropanes