Department of Chemistry , Stony Brook University , Stony Brook , New York 11794 , United States.
Division of Nuclear Medicine and Molecular Imaging, Department of Radiology , Boston Children's Hospital , Boston , Massachusetts 02115 , United States.
Chem Rev. 2019 Jan 23;119(2):870-901. doi: 10.1021/acs.chemrev.8b00281. Epub 2018 Oct 9.
Nuclear medicine is composed of two complementary areas, imaging and therapy. Positron emission tomography (PET) and single-photon imaging, including single-photon emission computed tomography (SPECT), comprise the imaging component of nuclear medicine. These areas are distinct in that they exploit different nuclear decay processes and also different imaging technologies. In PET, images are created from the 511 keV photons produced when the positron emitted by a radionuclide encounters an electron and is annihilated. In contrast, in single-photon imaging, images are created from the γ rays (and occasionally X-rays) directly emitted by the nucleus. Therapeutic nuclear medicine uses particulate radiation such as Auger or conversion electrons or β or α particles. All three of these technologies are linked by the requirement that the radionuclide must be attached to a suitable vector that can deliver it to its target. It is imperative that the radionuclide remain attached to the vector before it is delivered to its target as well as after it reaches its target or else the resulting image (or therapeutic outcome) will not reflect the biological process of interest. Radiochemistry is at the core of this process, and radiometals offer radiopharmaceutical chemists a tremendous range of options with which to accomplish these goals. They also offer a wide range of options in terms of radionuclide half-lives and emission properties, providing the ability to carefully match the decay properties with the desired outcome. This Review provides an overview of some of the ways this can be accomplished as well as several historical examples of some of the limitations of earlier metalloradiopharmaceuticals and the ways that new technologies, primarily related to radionuclide production, have provided solutions to these problems.
核医学由两个互补的领域组成，即成像和治疗。正电子发射断层扫描（PET）和单光子成像，包括单光子发射计算机断层扫描（SPECT），构成了核医学的成像部分。这些领域的区别在于它们利用了不同的核衰变过程和不同的成像技术。在 PET 中，图像是由放射性核素发射的正电子与电子相遇并湮灭时产生的 511keV 光子创建的。相比之下，在单光子成像中，图像是由原子核直接发射的γ射线（偶尔还有 X 射线）创建的。治疗核医学使用粒子辐射，如俄歇或转换电子或β或α粒子。所有这三种技术都通过要求放射性核素必须附着在合适的载体上，以便将其输送到目标来联系在一起。在将放射性核素输送到目标之前以及到达目标之后，放射性核素必须附着在载体上，否则所得图像（或治疗结果）将不会反映出感兴趣的生物学过程。放射化学是这个过程的核心，放射性金属为放射性药物化学家提供了大量的选择，以实现这些目标。它们还在放射性核素半衰期和发射特性方面提供了广泛的选择，从而能够仔细地将衰变特性与所需的结果相匹配。这篇综述概述了实现这一目标的一些方法，以及一些早期金属放射性药物的局限性的历史实例，以及新技术（主要与放射性核素生产有关）如何为这些问题提供解决方案。
