Moreover, some tumors are non-FDG-avid and, thus, can hardly be imaged by it ( 16).
However, because of its mechanism of action, -FDG lacks specificity and cannot differentiate between a tumor-associated high metabolic rate and one due to infection or inflammation. This tracer has found wide applications, taking advantage of increased glucose metabolic rates under several conditions, especially most cancers ( 2, 15).
Positron emission tomography (PET) imaging is currently dominated by 18F-fluorinated radiotracers, and particularly the glucose analog 18F-fluorodeoxyglucose (-FDG), covering about 90% of PET scans in oncology, neurology, and cardiology.
PET imaging and its hybrid derivatives PET/CT and the more recent PET/MR have had a tremendous impact on patient management, and have now become the new standard for functional imaging, both in oncology and non-oncological setting ( 9– 14). This type of examination allows for functional exploration of biological processes in order to obtain a diagnosis, prognosis, follow-up, or preselection for targeted therapy depending on the drug used ( 6– 8). Among available modalities, PET imaging has the advantage of unlimited depth penetration, very high sensitivity, capability to detect early changes at cellular or even molecular level, and superior resolution and quantification compared to SPECT ( 2– 5). In particular, molecular imaging, always making use of more precise contrast agents, enables the visualization, characterization, and measurement of biological processes at molecular and cellular levels in humans and other living systems ( 1). Today, medicine makes an extensive use of various imaging modalities based on different physical properties, including CT, ultrasonography, MRI, optical imaging or radionuclide-based single-photon emission computed tomography (SPECT), and PET, alone or in combination, to get anatomical and/or functional information in a non-invasive way. This article discusses the development of 68Ga cold kit radiopharmacy, including technical issues, and regulatory aspects. Already available commercial kits for the production of 68Ga radiopharmaceuticals have demonstrated the feasibility of using such an approach, thus paving the way for more kit-based 68Ga radiopharmaceuticals to be developed. To make them technically and economically accessible to the medical community and its patients, it appears mandatory to develop a procedure similar to the well-established kit-based 99mTc chemistry. However, the widespread use of these radiopharmaceuticals may rely on simple and efficient radiolabeling methods, undemanding in terms of equipment and infrastructure. Increasing clinical demand and regulatory issues have led to the development of automated procedures for the production of 68Ga radiopharmaceuticals. Beside those, a bunch of new 68Ga-labeled molecules are in the preclinical and clinical pipelines, with some of them showing great promise for patient care. It represents a major clinical impact, particularly in the context of theranostics, coupled with their 177Lu-labeled counterparts. It has gained routine use, with successful radiopharmaceuticals such as somatostatin analogs (Ga-DOTATOC and GaDOTATATE) for neuroendocrine tumors, and PSMA ligands for prostate cancer. Over the last couple of decades, gallium-68 ( 68Ga) has gained a formidable interest for PET molecular imaging of various conditions, from cancer to infection, through cardiac pathologies or neuropathies.
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