Department of Advanced Molecular Imaging, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Ibaraki, Japan.
Jpn J Radiol. 2020 Apr;38(4):343-357. doi: 10.1007/s11604-019-00901-8. Epub 2020 Feb 10.
Radiolabeled tracers allow visualization of not only perfusion, but receptors, function, and metabolism as well. Although spatial resolution is lower than that of computed tomography and magnetic resonance imaging, positron emission tomography (PET) and single photon emission computed tomography (SPECT) have great potential for target-specific imaging. In this review, we discuss several SPECT and PET tracers used in brain imaging, specifically focusing on tracers currently available, or developed, in Japan. Several important and sophisticated methods exist for analysis of brain PET and SPECT images. Two of them, quantitative cerebral blood flow measurement and voxel-based statistical analysis are discussed in this review. The former method, which employs acetazolamide loading, is useful for evaluation of the brain perfusion reserve for ischemic brain diseases. The latter is useful in diagnosing dementing diseases. Additionally, great strides have been made in the development of the technology used in the scanners. New SPECT systems based on cadmium-zinc-telluride, PET/MRI, and semiconductor PET/CT may provide higher spatial resolution with an acquisition time shorter than ever before. Such developments of both tracers and scanners can be integrated for unprecedented imagery of the brain, providing valuable insight into underlying causes of some fatal brain disorders.
放射性示踪剂不仅可以可视化灌注，还可以可视化受体、功能和代谢。虽然与计算机断层扫描和磁共振成像相比，其空间分辨率较低，但正电子发射断层扫描（PET）和单光子发射计算机断层扫描（SPECT）在靶向成像方面具有巨大潜力。在这篇综述中，我们讨论了几种用于脑成像的 SPECT 和 PET 示踪剂，特别是目前在日本可用或开发的示踪剂。存在几种用于分析脑 PET 和 SPECT 图像的重要和复杂方法。本文讨论了其中两种，即定量脑血流测量和基于体素的统计分析。前者方法，即使用乙酰唑胺负荷，可用于评估缺血性脑疾病的脑灌注储备。后者在诊断痴呆症方面很有用。此外，在扫描仪技术的开发方面也取得了重大进展。基于碲化镉锌的新型 SPECT 系统、PET/MRI 和半导体 PET/CT 可提供比以往更高的空间分辨率和更短的采集时间。示踪剂和扫描仪的这种发展可以整合在一起，对大脑进行前所未有的成像，深入了解一些致命性脑疾病的潜在原因。
