Effects of flow changes on radiotracer binding: Simultaneous measurement of neuroreceptor binding and cerebral blood flow modulation

J Cereb Blood Flow Metab. 2019 Jan;39(1):131-146. doi: 10.1177/0271678X17725418. Epub 2017 Aug 17.


The potential effects of changes in blood flow on the delivery and washout of radiotracers has been an ongoing question in PET bolus injection studies. This study provides practical insight into this topic by experimentally measuring cerebral blood flow (CBF) and neuroreceptor binding using simultaneous PET/MRI. Hypercapnic challenges (7% CO2) were administered to non-human primates in order to induce controlled increases in CBF, measured with pseudo-continuous arterial spin labeling. Simultaneously, dopamine D2/D3 receptor binding of [11C]raclopride or [18F]fallypride was monitored with dynamic PET. Experiments showed that neither time activity curves nor quantification of binding through binding potentials ( BPND) were measurably affected by CBF increases, which were larger than two-fold. Simulations of experimental procedures showed that even large changes in CBF should have little effect on the time activity curves of radiotracers, given a set of realistic assumptions. The proposed method can be applied to experimentally assess the flow sensitivity of other radiotracers. Results demonstrate that CBF changes, which often occur due to behavioral tasks or pharmacological challenges, do not affect PET [11C]raclopride or [18F]fallypride binding studies and their quantification. The results from this study suggest flow effects may have limited impact on many PET neuroreceptor tracers with similar properties.

Keywords: Cerebral blood flow; dopamine receptor imaging; functional magnetic resonance imaging; pharmacokinetic modeling; positron emission tomography.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Behavior, Animal / physiology
  • Benzamides / pharmacokinetics
  • Cerebrovascular Circulation / physiology*
  • Computer Simulation
  • Female
  • Magnetic Resonance Imaging
  • Male
  • Multimodal Imaging
  • Papio / physiology*
  • Positron-Emission Tomography
  • Psychomotor Performance / physiology
  • Raclopride / pharmacokinetics
  • Radiopharmaceuticals / pharmacokinetics*
  • Receptors, Dopamine D2 / metabolism
  • Receptors, Dopamine D3 / metabolism
  • Sensory Receptor Cells / metabolism*
  • Spin Labels


  • Benzamides
  • Radiopharmaceuticals
  • Receptors, Dopamine D2
  • Receptors, Dopamine D3
  • Spin Labels
  • Raclopride
  • fallypride