Therapeutic radionuclides / 핵의학분자영상

Since the development of sophisticated molecular carriers such as octereotides for peptide receptor targeting and monoclonal antibodies against various antigens associated with specific tumor types, radionuclide therapy (RNT) employing open sources of therapeutic agents is promising modality for treatment of tumors. Furthermore, the emerging of new therapeutic regimes and new approaches for tumor treatment using radionuclide are anticipated in near future. In targeted radiotherapy using peptides and other receptor based carrier molecules, the use of radionuclide with high specific activity in formulating the radiopharmaceutical is essential in order to deliver sufficient number of radionuclides to the target site without saturating the target. In order to develop effective radiopharmaceuticals for therapeutic applications, it is crucial to carefully consider the choice of appropriate radionuclides as well as the carrier moiety with suitable pharmacokinetic properties that could result in good in vivo localization and desired excretion. Up to date, only a limited number of radionuclides have been applied in radiopharmaceutical development due to the constraints in compliance with their physical half-life, decay characteristics, cost and availability in therapeutic applications. In this review article, we intend to provide with the improved understanding of the factors of importance of appropriate radionuclide for therapy with respect to their physical properties and therapeutic applications.

The Effects of (66)Ho-Loaded Radioactive Stent in a Porcine Model

BACKGROUND AND OBJECTIVES: Vascular brachytherpy known to be an effective method in the prevention of restenosis following percutaneous coronary intervention (PCI). In this study we observed the effects of a radioisotope-loaded stent in a porcine model. MATERIALS AND METHODS: Holmium-166 ((166)Ho) was loaded onto the stent surface using impregnated polyurethane, and placed the stents into 7 porcine coronary arteries. Four weeks after stent overdilation injury, histopathological examination was performed. RESULTS: The absorbed dose of (166)Ho to the coronary artery, from the 158.5+/-140.9 microCi (166)Ho stent, was about 141 Gy at a depth of 0.5 mm, which was calculated by Monte Carlo EGS 4 Code. The mean external, and internal elastic lamina areas, the luminal and neointimal areas and the histopathological area stenosis in the 7 porcine coronary arteries were 7.6+/-2.8 mm2, 4.7+/-1.6 mm2, 2.4+/-1.4 mm2, 2.3+/-1.6 mm2 and 49.4+/-24.9%, respectively. The histopathological findings revealed remarkable inflammatory reactions and thrombosis in two of the porcine coronary arteries. CONCLUSION: (166)Ho radioactive loaded stents, using impregnated polyurethane, may inhibit neointimal hyperplasia, but the problems of stent thrombosis and inflammation should be solved.