Copper [⁶⁴Cu] Nuclide
Positron emission tomography (PET) can observe physiological and ecological changes of metabolites or drugs into the body non-invasively, dynamically and quantitatively at the molecular level, and obtain whole-body tomographic images. It is the most advanced method and a hotspot in diagnosis and research of nuclear medicine.
Not only detecting primary, metastatic, and recurrent lesions of the tumor earlier, PET also differentiates tumor and scar necrotic tissue, which also makes significantly differences in terms of tumor stage, malignancy grade, and efficacy judgment.
The diagnostic accuracy of PET is all above 90% over lung cancer, breast cancer, head and neck neoplasm, colon cancer, ovarian cancer, lymphoma, and melanoma.
As to the influence on determining the biological characteristics of lesions, monitoring and adjustment of treatment, PET also reduces treatment errors, individualizes and integrates programs, and positively impacts on the prognosis of patients.
Recently, characterized by high resolution and dynamic metabolic imaging at molecular level, PET imaging has drawn increasing public attention, and has become a research hotspot in the field of nuclear medicine around the world.
Currently, the nuclides used for PET imaging mainly are 11C, 13N, 15O, 18F and other short half-life positron emitters. The short-life positron radioactive drugs are required to be labeled as quickly as possible, and the time of imaging should be short, which limit the application of such drugs in basic research and clinical medicine. Therefore, it is urgent to develop long half-life positron radioactive drugs to meet the research and clinical needs.
With the rapid development of PET technology, the research on positron nuclides and positron medicine has attracted more and more attention from foreign scholars and the development of positron emissive drugs compatible with PET imaging technology has become a hot topic and development trend in the field of radiopharmaceutical chemistry. In recent years, there are successively longer half-life positron nuclides such as 64Cu(T1/2=12.7h), 76Br(T1/2=16.2h), 62Zn(T1/2=9.2h), 73Se(T1/2=7.1h) which are used for the research of positron medicine.
Among many transition metals, copper which has good coordination properties is the essential microelement for human body, and its coordination complex has good photocracking activity. Therefore, many researchers take Cu coordination complex as the research object.
64Cu is an important medical radionuclide with the half-life of 12.7 hours and is undergoing not only the β+decay (17.86 %) but also the β-decay (39.0 %) and electron capture (43.1%). β+ray can be used for PET imaging and β-ray can be used for radiotherapy including blood pool and myocardial imaging, hypoxic imaging, inflammatory imaging, tumor imaging and treatment. 64Cu can be easily obtained, either produced by a nuclear reactor or prepared by an accelerator. In recent years, researchers have found that 64Cu can be produced by 64Ni(p,n)64Cu nuclear reaction on a small low-energy biomedical cyclotron.
Research has shown that in the diagnostic application, the PET imaging map of 64Cu(0.65MeV) can be comparable to that of 18F(0.64MeV), and PET imaging with 64Cu label can also obtain high-resolution 3D image; in the treatment application, the treatment effect of 64Cu is comparable to that of the radionuclide 67Cu which are widely used in the field of nuclear medicine and show good treatment prospect today, and the research result shows that there is no significant difference between 64Cu and 67Cu in inhibiting the proliferation and growth of tumor.
Compared with other medical copper radionuclides, 64Cu has excellent physical properties which make it an important role in the research of metallic radiopharmaceuticals especially the radiopharmaceuticals for PET.