Measuring Amino Acid and Glucose Metabolism in Healthy Volunteers and NAFLD Patients Using Total-body PET

Condition(s) studied

Investigational drug(s) / intervention(s)

18F-FDG (oral): Oral administration of 18F-fluorodeoxyglucose (\^18F-FDG) for total-body PET/CT to assess gastrointestinal absorption, systemic biodistribution, and whole-body glucose metabolism.

18F-FDG (intravenous): Intravenous bolus administration of 18F-fluorodeoxyglucose (18F-FDG) for total-body PET/CT to measure systemic biodistribution and whole-body glucose metabolism.

18F-FET (oral): Oral administration of O-(2-\[18F\]fluoroethyl)-L-tyrosine (18F-FET) for total-body PET/CT to assess gastrointestinal amino acid absorption and whole-body amino acid metabolism.

18F-FET (intravenous): Intravenous bolus administration of O-(2-\[18F\]fluoroethyl)-L-tyrosine (18F-FET) for total-body PET/CT to measure systemic amino acid biodistribution and dynamic metabolic kinetics.

Glucagon: Continuous intravenous glucagon infusion to stimulate hepatic amino acid metabolism during a pancreatic clamp.

Somatostatin: Continuous intravenous somatostatin infusion to suppress endogenous pancreatic hormone secretion during the pancreatic clamp.

Sodium chloride (placebo): Intravenous infusion of isotonic sodium chloride solution used as placebo during crossover comparison with glucagon infusion.

Oral Glucose Tolerance Test: Standard oral glucose load (75 g in 250 mL water) to assess glucose-stimulated metabolic responses during PET/CT.

Study summary

This observational study aims to quantify whole-body amino acid and glucose metabolism in healthy adults and in patients with non-alcoholic fatty liver disease (NAFLD) using total-body PET/CT. The study investigates how orally and intravenously administered PET tracers (18F-FDG and 18F-FET) are absorbed in the gastrointestinal tract, distributed across major organs, and metabolized in different physiological and pathological states. A further objective is to examine how glucagon, during a pancreatic clamp using somatostatin, influences amino acid metabolism in healthy individuals and whether this response is altered in patients with NAFLD.

Participants will be healthy volunteers or patients with NAFLD, aged 18-70 years. Depending on study group, participants will undergo one or more total-body PET/CT scans following oral or intravenous tracer administration, and in some cases receive glucagon or placebo infusion. Blood samples will be collected during scanning to assess hormone levels and metabolic responses. Data from these imaging sessions will be used to characterize nutrient metabolism, compare oral and intravenous tracer kinetics, and explore glucagon-induced metabolic changes across study groups.

Eligibility

Primary outcome measure(s)

• Whole-body tracer uptake (SUVmean) assessed using total-body PET/CT — 0-180 minutes after tracer administration

Trial sites (1)

More Copenhagen University Hospital, Rigshospitalet trials in Denmark

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