RT Journal Article SR Electronic T1 Quantification, Variability, and Reproducibility of Basal Skeletal Muscle Glucose Uptake in Healthy Humans Using 18F-FDG PET/CT JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1520 OP 1526 DO 10.2967/jnumed.115.159715 VO 56 IS 10 A1 Olivier Gheysens A1 Andrey Postnov A1 Christophe M. Deroose A1 Corinne Vandermeulen A1 Jan de Hoon A1 Ruben Declercq A1 Justin Dennie A1 Lori Mixson A1 Inge De Lepeleire A1 Koen Van Laere A1 Michael Klimas A1 Manu V. Chakravarthy YR 2015 UL http://jnm.snmjournals.org/content/56/10/1520.abstract AB The quantification and variability of skeletal muscle glucose utilization (SMGU) in healthy subjects under basal (low insulin) conditions are poorly known. This information is essential early in clinical drug development to effectively interrogate novel pharmacologic interventions that modulate glucose uptake. The aim of this study was to determine test–retest characteristics and variability of SMGU within and between healthy subjects under basal conditions. Furthermore, different kinetic modeling strategies were evaluated to find the best-fitting model to assess SMGU studied by 18F-FDG. Methods: Six healthy male volunteers underwent 2 dynamic 18F-FDG PET/CT scans with an interval of 24 h. Subjects were admitted to the clinical unit to minimize variability in daily activities and food intake and restrict physical activity. 18F-FDG PET/CT scans of gluteal and quadriceps muscle area were obtained with arterial input. Regions of interest were drawn over the muscle area to obtain time–activity curves and standardized uptake values (SUVs) between 60 and 90 min. Spectral analysis of the data and kinetic modeling was performed using 2-tissue-irreversible (2T3K), 2-tissue-reversible, and 3-tissue-sequential-irreversible (3T5KS) models. Reproducibility was assessed by intraclass correlation coefficients (ICCs) and within-subject coefficient of variation (WSCV). Results: SUVs in gluteal and quadriceps areas were 0.56 ± 0.09 and 0.64 ± 0.07. ICCs (with 90% confidence intervals in parentheses) were 0.88 (0.64–0.96) and 0.96 (0.82–0.99), respectively, for gluteal and quadriceps muscles, and WSCV for gluteal and quadriceps muscles was 2.2% and 3.6%, respectively. The rate of glucose uptake into muscle was 0.0016 ± 0.0004 mL/mL⋅min, with an ICC of 0.94 (0.93–0.95) and WSCV of 6.6% for the 3T5KS model, whereas an ICC of 0.98 (0.92–1.00) and WSCV of 2.8% was obtained for the 2T3K model. 3T5KS demonstrated the best fit to the measured experimental points. Conclusion: Minimal variability in skeletal muscle glucose uptake was observed under basal conditions in healthy subjects. SUV measurements and rate of glucose uptake values were reproducible, with an average WSCV of less than 5%. Compared with SUV, the 3-tissue model adds information about kinetics between blood, intra- and intercellular compartments, and phosphorylation that may highlight the exact mechanisms of metabolic changes after pharmacologic intervention.