Fig. 4.

Pharmacokinetic models examined in this study. C_p: plasma concentration of [¹¹C]-acetate, also known as the arterial input function or AIF. C₁-C₃: concentration of [¹¹C]-acetate or its metabolites in different physical or biochemical compartments. Tissue compartments are in blue, vascular compartments are in red. K₁: flow constant (mL/g/min); k₂-k₅: rate constants (min⁻¹). All models also include a blood volume parameter (v_b) to account for the vascular [¹¹C]-acetate and metabolite signals. For the four-compartmental models (#5, #6, and #7), the entry and exit rates for the oxidative compartment are set to the same value