Ma Yan, Kuebler Laura, Haas Sabrina, Maurer Andreas, Herfert Kristina
Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, University of Tuebingen, Tuebingen, Germany.
Max Planck Institute for Biological Cybernetics, Tuebingen, Germany.
Mol Imaging Biol. 2025 May 14. doi: 10.1007/s11307-025-02006-3.
Positron Emission Tomography (PET), a crucial tool in molecular brain imaging, has evolved into a hybrid system through integration with functional MRI (fMRI). This advancement facilitates the simultaneous recording of molecular and functional data in animal models, offering insights into neuroreceptor and neurotransmitter dynamics and their effects on brain function. While mechanical ventilation is often used in small animal fMRI to stabilize physiological blood gas levels, its effects on PET tracer kinetics remain underexplored.
This study examines the kinetics of [C]raclopride, a dopamine-sensitive PET tracer targeting D2/D3 receptors, under various respiratory conditions and anesthesia protocols frequently used in small animal fMRI and PET.
Results indicate significant variations in tracer kinetics: increased peak levels, a shorter time to peak, and a faster tracer equilibrium in standard uptake value ratio were observed in spontaneously breathing animals versus those under mechanical ventilation. The anesthesia type also strongly influenced the tracer kinetics: α-chloralose anesthesia reduced brain uptake, whereas isoflurane led to a more rapid equilibrium.
These findings underscore the profound impact of mechanical ventilation and anesthesia selection on PET tracer kinetics in hybrid PET/fMRI studies. The study highlights that those protocols established for fMRI are not directly transferable to PET imaging in small animals, emphasizing the necessity for a careful investigation of the influence of anesthesia and ventilation techniques on tracer kinetics.
正电子发射断层扫描（PET）是分子脑成像中的一项关键工具，通过与功能磁共振成像（fMRI）集成已发展成为一种混合系统。这一进展有助于在动物模型中同时记录分子和功能数据，从而深入了解神经受体和神经递质动力学及其对脑功能的影响。虽然在小动物功能磁共振成像中常使用机械通气来稳定生理血气水平，但其对PET示踪剂动力学的影响仍未得到充分研究。
本研究考察了[C]雷氯必利（一种靶向D2/D3受体的多巴胺敏感性PET示踪剂）在小动物功能磁共振成像和PET中常用的各种呼吸条件和麻醉方案下的动力学。
结果表明示踪剂动力学存在显著差异：与机械通气的动物相比，自主呼吸的动物在标准摄取值比率中观察到峰值水平升高、达到峰值的时间缩短以及示踪剂平衡更快。麻醉类型也对示踪剂动力学有强烈影响：α-氯醛糖麻醉降低了脑摄取，而异氟烷导致平衡更快。
这些发现强调了在PET/fMRI混合研究中机械通气和麻醉选择对PET示踪剂动力学的深远影响。该研究强调，为功能磁共振成像建立的那些方案不能直接转移到小动物PET成像中，强调了仔细研究麻醉和通气技术对示踪剂动力学影响的必要性。
