18F-FDG assessment of glucose disposal and production rates during fasting and insulin stimulation: a validation study.
The glucose analog (18)F-FDG is commonly used to quantify regional glucose uptake in vivo. The aim of this study was to test whether the analysis of plasma (18)F-FDG kinetics could be used to estimate endogenous glucose production (EGP) and the total rate of appearance (Ra), total rate of disappearance (Rd), and the metabolic clearance rate (MCR) of glucose.


METHODS
Fourteen pigs were coinjected with (18)F-FDG and 6,6-(2)H-glucose ((2)H-G) during fasting (n = 6) and during physiologic (1.0 mU.kg(-1).min(-1), n = 4) and supraphysiologic (5.0 mU.kg(-1).min(-1), n = 4) euglycemic hyperinsulinemia. Arterial plasma was sampled for 180 min to quantify the parameters for the 2 tracers.


RESULTS
Fasting Rd((2))(H-G) and Rd(FDG) were 12.3 +/- 2.1 and 13.3 +/- 1.3 micromol.kg(-1).min(-1) (difference not statistically significant [NS]). M values were more than doubled between the 2 clamp studies (P < 0.0001). Rd((2))(H-G) and Rd(FDG) were dose-dependently higher during the hyperinsulinemic state (19.8 +/- 3.7 vs. 18.9 +/- 1.1 and 31.4 +/- 4.1 vs. 31.9 +/- 2.3 in 1.0 and 5.0 mU.kg(-1).min(-1) studies, respectively; difference between tracers NS) than during the fasting state, with a parallel suppression of EGP((2))(H-G) and EGP(FDG). Parameters estimated by (18)F-FDG and (2)H-G were equivalent in all groups; their agreement was confirmed by Bland-Altman examination. Total Rd(FDG) correlated with Rd((2))(H-G) (r = 0.74; P = 0.003), M (r = 0.92; P = 0.001), MCR((2))(H-G) (r = 0.52; P = 0.037), and EGP((2))(H-G) (r = -0.71; P = 0.004). EGP(FDG) correlated with EGP((2))(H-G) (r = 0.62; P = 0.018), Rd((2))(H-G) (r = -0.78; P = 0.001), and MCR((2))(H-G) (r = -0.67; P = 0.008). The (18)F-FDG mean transit time correlated inversely with the M and Rd values and positively with EGP.


CONCLUSIONS
The glucose analog (18)F-FDG can be used in the simultaneous estimation of whole-body glucose turnover and production and regional (18)F-FDG PET measurements under both fasting and insulin-stimulated conditions.
Iozzo
Patricia
P
Turku PET Centre, University of Turku, Turku, Finland. patricia.iozzo@ifc.cnr.it
Gastaldelli
Amalia
A
Järvisalo
Mikko J
MJ
Kiss
Jan
J
Borra
Ronald
R
Buzzigoli
Emma
E
Viljanen
Antti
A
Naum
G
G
Viljanen
Tapio
T
Oikonen
Vesa
V
Knuuti
Juhani
J
Savunen
Timo
T
Salvadori
Piero A
PA
Ferrannini
Ele
E
Nuutila
Pirjo
P
D000818:Animals; D005215:Fasting; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005947:Glucose / Q000378:metabolism*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood*; D008657:Metabolic Clearance Rate / Q000187:drug effects; D019275:Radiopharmaceuticals; D013552:Swine
D007328:Insulin; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose