Adenosine-induced myocardial flow reactivity in pig as assessed with O-15 water PET

Objectives: This study was intended to evaluate the feasibility and applicability of assessing absolute myocardial blood flow (MBF) using O-15 water and PET 14 times for various doses of vasodilator challenges in miniature pigs. Methods and results: MBFs were quantitated following intravenous injection of O-15 water during various administration doses of adenosine (25-800 μg/kg/min) and A2A-selective CGS-21680 (0.5-20 μg/kg) in six miniature pigs. A low dose of adenosine increased MBF but reached to a maximum, and gradually decreased MBF with reduced heart rate (HR), reduced systolic blood pressure (SBP), and thus decreased RPP, together with prolonged PR interval. Reduction in HR, SBP and RPP were also observed with CGS-21680, but were significantly less, and the maximum MBF was greater with CGS-21680. These findings were consistent and reproducible among all the six subjects. Discussion and conclusion: The technique of assessing MBF with O-15 water and PET appeared to be reproducible and useful for quantitative evaluation of the vascular reactivity for various pharmacological/physiological stresses. The ability of accurately correcting for the partial volume effect, and recent advances of generating functional parametric images from the dynamic O-15 water alone, would be the most important factors in clinical usage of this methodology.