Department of Basic & Clinical Neuroscience, Neurodegeneration Imaging Group, King's College London, London, United Kingdom.
Department of Neurosciences, Reproductive Sciences and Odontostomatology, Federico II University of Naples, Naples, Italy.
Int Rev Neurobiol. 2019;144:211-257. doi: 10.1016/bs.irn.2018.10.003. Epub 2018 Nov 8.
Even before the success of combined positron emission tomography and computed tomography (PET/CT), the neuroimaging community was conceiving the idea to integrate the positron emission tomography (PET), with very high molecular quantitative data but low spatial resolution, and magnetic resonance imaging (MRI), with high spatial resolution. Several technical limitations have delayed the use of a hybrid scanner in neuroimaging studies, including the full integration of the PET detector ring within the MRI system, the optimization of data acquisition, and the implementation of reliable methods for PET attenuation, motion correction, and joint image reconstruction. To be valid and useful in clinical and research settings, this instrument should be able to simultaneously acquire PET and MRI, and generate quantitative parametric PET images comparable to PET-CT. While post hoc co-registration of combined PET and MRI data acquired separately became the most reliable technique for the generation of "fused" PET-MRI images, only hybrid PET-MRI approach allows merging these measurements naturally and correlating them in a temporal manner. Furthermore, hybrid PET-MRI represents the most accurate tool to investigate in vivo the interplay between molecular and functional aspects of brain pathophysiology. Hybrid PET-MRI technology is still in the early stages in the movement disorders field, due to the limited availability of scanners with integrated optimized methodological models. This technology is ideally suited to investigate interactions between resting-state functional/arterial spin labeling MRI and [F]FDG PET glucose metabolism in the evaluation of the brain "hubs" particularly vulnerable to neurodegeneration, areas with a high degree of connectivity and associated with an efficient synaptic neurotransmission. In Parkinson's disease, hybrid PET-MRI is also the ideal instrument to deeper explore the relationship between resting-state functional MRI and dopamine release at [C]raclopride PET challenge, in the identification of early drug-naïve Parkinson's disease patients at higher risk of motor complications and in the evaluation of the efficacy of novel neuroprotective treatment able to restore at the same time the altered resting state and the release of dopamine. In this chapter, we discuss the key methodological aspects of hybrid PET-MRI; the evidence in movement disorders of the key resting-state functional and perfusion MRI; [F]FDG PET and [C]raclopride PET challenge studies; the potential advantages of using hybrid PET-MRI to investigate the pathophysiology of movement disorders and neurodegenerative diseases. Future directions of hybrid PET-MRI will be discussed alongside with up-to-date technological innovations on hybrid systems.
即使在正电子发射断层扫描和计算机断层扫描（PET/CT）联合成功之前，神经影像学界就已经在构想将具有非常高的分子定量数据但空间分辨率较低的正电子发射断层扫描（PET）与具有高空间分辨率的磁共振成像（MRI）结合起来。几项技术限制延迟了在神经影像学研究中使用混合扫描仪，包括将 PET 探测器环完全集成到 MRI 系统中、优化数据采集以及实施可靠的 PET 衰减、运动校正和联合图像重建方法。为了在临床和研究环境中有效和有用，该仪器应能够同时采集 PET 和 MRI，并生成与 PET-CT 相当的定量参数 PET 图像。虽然事后分别采集的联合 PET 和 MRI 数据的配准成为生成“融合”PET-MRI 图像的最可靠技术，但只有混合 PET-MRI 方法允许以自然的方式合并这些测量值并以时间方式对其进行关联。此外，混合 PET-MRI 是研究脑病理生理学的分子和功能方面相互作用的最准确工具。由于具有集成优化方法模型的扫描仪有限，混合 PET-MRI 技术在运动障碍领域仍处于早期阶段。该技术非常适合研究静息状态功能/动脉自旋标记 MRI 与 [F]FDG PET 葡萄糖代谢之间的相互作用，以评估对神经退行性变特别敏感的大脑“枢纽”，这些区域具有高度的连通性，并与有效的突触神经传递相关。在帕金森病中，混合 PET-MRI 也是深入探索静息状态功能 MRI 与 [C]raclopride PET 挑战时多巴胺释放之间关系的理想工具，可在识别处于更高运动并发症风险的早期未经药物治疗的帕金森病患者方面，以及评估能够同时恢复改变的静息状态和多巴胺释放的新型神经保护治疗的疗效方面。在本章中，我们讨论了混合 PET-MRI 的关键方法学方面；运动障碍中关键的静息状态功能和灌注 MRI 的证据；[F]FDG PET 和 [C]raclopride PET 挑战研究；使用混合 PET-MRI 研究运动障碍和神经退行性疾病的病理生理学的潜在优势。还将讨论混合 PET-MRI 的未来方向以及混合系统的最新技术创新。
