Estimating the amount of FDG uptake in physiological tissues.

Authors :: Laffon E
de Clermont H
Lamare F
Marthan R
Source :: Nuclear medicine and biology [Nucl Med Biol] 2014 Oct; Vol. 41 (9), pp. 717-20. Date of Electronic Publication: 2014 Jun 24.
Publication Year :: 2014
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.<br />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.<br />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.<br />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.<br /> (Copyright © 2014 Elsevier Inc. All rights reserved.)