Study of rat skeletal muscle activation by PET/CT and [11C]acetate

Purpose: The purpose of the present study is to apply kinetic analysis to investigate exercise-related changes in the skeletal muscle of the rat hind limb by [¹¹C]acetate PET/CT. Methods: One-leg contractions were induced in Wistar rats by electrostimulation of the VL muscle motor point. After 15 minutes of muscle contractions [¹¹C]acetate was injected and PET/CT of the rat hind limbs was acquired. The resting leg was used as a control reference. The perfusion index F was calculated for the target muscles (exercised and control) and correlated to the corresponding SUVs. For both F and the SUV, the ratio of the value extracted for the active muscle to the one derived for the muscle at rest was computed (respectively, F_E/F_R and SUV_E/SUV_R). Results: For the experimental dataset, a strong correlation (R² = 0.97, P = 0.01) between F_E/F_R and SUV_E/SUV_R was observed. The ratio F_E/F_R resulted to be higher than the ratio SUV_E/SUV_R (average values: 2.1 ± 0.7 and 1.19 ± 0.08, respectively). Conclusion: Preliminary results indicate that both kinetic modeling and the SUV can detect changes in muscles between rest and exercise conditions, when associated to [¹¹C]acetate PET/CT.