Estimating the amount of FDG uptake in physiological tissues

Nucl Med Biol. 2014 Oct;41(9):717-20. doi: 10.1016/j.nucmedbio.2014.06.003. Epub 2014 Jun 24.

Abstract

Introduction: It is known that for a fixed amount of injected tracer, the amount available for a tissue of interest will be less if other tissues show intense uptake. The aim of this study was to estimate the magnitude of 2-deoxy-2-[(18)F]fluoro-D-glucose (18FDG) uptake amount in physiological tissues that may show an intense uptake in current clinical practice.

Methods: A formula was established providing an estimate of the percentage of injected 18FDG molecules (P; in %) that are irreversibly trapped in an 18FDG-positive tissue during a PET examination.

Results: P ≅ 0.17*exp(-λt(acq))*TLG/W, where λ is the (18)F physical decay constant, t(acq) is the injection-acquisition time delay, TLG is total lesion glycolysis (g) and W is the patient weight (kg). The magnitude of P was calculated in two patients showing an intense uptake in brown fat, myocardium and bowels: 0.5, 3.5, and 4.2% respectively.

Conclusions: A formula is available to quickly estimate the amount of 18FDG uptake in tissues. We suggest that the accumulation of different physiological uptakes may actually affect SUV quantification in a tissue of interest.

Keywords: 18FDG PET; Biologic factor; Physiological tissue uptake; SUV; TLG.

MeSH terms

  • Adult
  • Algorithms*
  • Body Burden
  • Body Weight*
  • Fluorodeoxyglucose F18 / pharmacokinetics*
  • Humans
  • Image Interpretation, Computer-Assisted / methods*
  • Male
  • Metabolic Clearance Rate
  • Middle Aged
  • Models, Biological*
  • Organ Specificity
  • Positron-Emission Tomography / methods*
  • Radiopharmaceuticals / pharmacokinetics
  • Tissue Distribution

Substances

  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18