Non-invasive imaging of skeletal metastases by Positron Emission Tomography (PET) for cancer prognosis, staging and treatment monitoring is one of the prominent fields of radiopharmaceutical research. Among the radionuclides suitable for PET imaging, 64Cu T1/2 = 12. 7 h. , EC = 45%, β− =37. 1%, β+ =17. 9%, Eβ+ (max) = 0. 65 MeV is a versatile candidate due to its attractive decay properties. In the present article, we have investigated the potential of 64Cu-labeled 4- (bis (phosphonomethyl) ) carbamoyl methyl-7, 10-bis (carboxymethyl) -1, 4, 7, 10-tetraazacyclododec-1-yl) acetic acid (BPAMD), prepared using low specific activity 64Cu produced in research reactor toward skeletal imaging by PET. An optimized protocol for the radiolabeling of 64Cu (~ 150 MBq) with the BPAMD in high radiochemical purity (> 95%) and excellent in vitro stability was achieved. Comparative hydroxyapatite binding affinity analysis showed that 64CuCu-BPAMD demonstrated significantly higher affinity compared to the 64CuCu-complex of corresponding polyaza macrocyclic ligand DOTMP (1, 4, 7, 10-tetraazacyclododecane-1′, 4′, 7′, 10′-tetramethylenephosphic acid). In vivo evaluation of 64CuCu-BPAMD in healthy Wistar rats showed selective bone uptake with good contrast and rapid clearance from non-target organs. Overall, the approach of using low specific activity reactor produced 64Cu presents a cost-effective, cyclotron independent alternative to 68Ga/18F based PET agents for detection of skeletal lesions.
Shetty et al. (Sat,) studied this question.