Research and clinical use of positron emission tomography (PET) as a tool for non-invasive quantitative physiologic imaging has traditionally relied on radiopharmaceuticals labeled with the short-lived cyclotron-produced nuclides: 15O, 13N, 11C, and 18F (half-lives of 2, 10, 20, and 110-minutes, respectively). But, a number of positron-emitting metallic radionuclides also offer attractive nuclear properties for biomedical imaging applications. As decay products of longer-lived nuclides (62Zn and 68Ge), positron-emitting 62Cu2+ (10-minute half-life) and 68Ga3+ (68-minute half-life) can be made available at a clinical site �on-demand� from parent/daughter generator systems, obviating reliance on a nearby cyclotron facility for radionuclide production. Three additional longer-lived cyclotron-produced isotopes of copper also decay with emission of positrons (64Cu, 61Cu, 60Cu; half-lives of 12.8-h, 3.3-h, and 23-minutes, respectively), and can potentially be employed in tailoring the radiopharmaceutical use of a given copper chelate to specific imaging needs. The development of useful radiopharmaceuticals involves definition of chemical agents suitable for detecting clinically relevant aspects of tissue physiology or biochemistry; validation of the robustness of the associated PET measurements; and refinement of the required synthetic and analytical methods to approaches that are both practical and reliable for the clinical setting. As examples, copper(II) bis(thiosemicarbazone) chelates have shown utility for PET mapping of regional tissue perfusion (capillary blood flow) in both animal models and human subjects for a variety of tissues of interest (myocardium, kidney, tumor, brain). In the case of 68Ga, we are routinely labeling macroaggregated human serum albumin (MAA) particles for use in research to predict the fate of 90Y-labeled glass microspheres administered therapeutically for liver tumor radioembolization. For clinical use under an Expanded Access IND, we have also implemented a manual synthetic procedure for delivery of sterile and endotoxin-free 68Ga-DOTA-NOC, a somatostatin-receptor-targeting peptide that shows outstanding performance in detection of neuroendocrine tumors with whole-body PET/CT imaging.

Biomedical imaging with short-lived positron-emitting radiometals

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.