Production and therapeutic use of rhenium-186, 188--the future of radionuclides

Abstract

In contemporary nuclear medicine, alpha, pure beta or beta-gamma emitters are used for targeted therapy. Use of pure and combined alpha/beta emitters in oncology, endocrinology, rheumatology and, a short while ago, interventional cardiology, has refined as an important alternative to more common therapeutic regimens. Two radioisotopes of rhenium, rhenium-186 and rhenium-188, are of particular interest. PRODUCTION OF RHENIUM-186 AND RHENIUM-188: Rhenium-186 is routinely produced in nuclear reactors by direct neutron activation of metallic rhenium enriched with 185Re via 185Re(n,) 186Re nuclear reaction. For production of 188Re the target is 186W. 188W is produced by double neutron capture which gives 188Re due to beta decay. Separation of 188Re is performed in generators by column chromatography, extraction or by gel technology. The best results are obtained using chromatographic 188W/188Re generator in which 188W is adsorbed on aluminium. Rhenium-188 is eluted in saline solution. There are several fields of applications of radiopharmaceuticals labeled with 186,188Re. For bone pain palliation the most often used are 186Re-HEDP and 188Re-DMSA. For synovectomy, 186Re-sulphide in kit form is already commercially available. Endovascular radiation therapy is performed by using 188Re-perrhenate or 188Re-MAG3. Labeling of peptides and antibodies with 188Re is also reported. Application of rhenium radiosotopes depends on their specific activity. Rhenium-186,188 of low specific activity can be used only for labeling of particles or diphosphonates. However, labeling of peptides or antibodies can be performed only by using 188Re of high specific activity. 188Re is expected to have wide applications after development of a chromatographic 188W/188Re generator. One of the advantages of rhenium is tis chemical similarity with technetium. So technetium analogues labeled with 186,188Re can be developed for several specific applications.