Effects of flow changes on radiotracer binding: Simultaneousmeasurement of neuroreceptor binding and cerebral blood flowmodulation

摘要

The potential effects of changes in blood flow on the delivery and washout ofradiotracers has been an ongoing question in PET bolus injection studies. Thisstudy provides practical insight into this topic by experimentally measuringcerebral blood flow (CBF) and neuroreceptor binding using simultaneous PET/MRI.Hypercapnic challenges (7% CO ) were administered to non-humanprimates in order to induce controlled increases in CBF, measured withpseudo-continuous arterial spin labeling. Simultaneously, dopamineD /D receptor binding of [ C]racloprideor [ F]fallypride was monitored with dynamic PET. Experiments showedthat neither time activity curves nor quantification of binding through bindingpotentials ( ) were measurably affected by CBFincreases, which were larger than two-fold. Simulations of experimentalprocedures showed that even large changes in CBF should have little effect onthe time activity curves of radiotracers, given a set of realistic assumptions.The proposed method can be applied to experimentally assess the flow sensitivityof other radiotracers. Results demonstrate that CBF changes, which often occurdue to behavioral tasks or pharmacological challenges, do not affect PET[ C]raclopride or [ F]fallypride binding studies andtheir quantification. The results from this study suggest flow effects may havelimited impact on many PET neuroreceptor tracers with similar properties.