Evaluation of Radioactive Compounds for the External Detection of Cerebral Tumors

Abstract

Summary Studies of the distribution in the organs and body fluids of various radioactive compounds in a pure strain of tumor-bearing mice indicated the potential value of serum albumin-I 131 , Cholografin-I 131 , Neohydrin-Hg 203 , and cobaltous-Co 57 tetraphenylporphinesulfonate for brain tumor localization in man. For serum albumin-I 131 , the tumor concentration was higher than for several substances tested, and the optimum tumor-to-brain concentration ratio was 33 to 1. A persistently high blood level and a relatively long biological half-life were its chief disadvantages. Neohydrin-Hg 203 and Cholografin-I 131 were removed from the blood stream more quickly than albumin-I 131 , and their total-body biological half-lives were considerably shorter; tumor-to-brain concentration ratios in mice were 22 to 1 and 80 to 1, respectively. The absolute tumor concentrations were lower than for serum albumin and were especially low for Cholografin-I 131 . Cobaltous-Co 57 tetraphenylporphinesulfonate produced absolute tumor concentrations as high as did albumin-I 131 , and the tumor-to-brain concentration ratios were 60 to 1. Moreover, the blood levels after 24 hours were considerably lower than for albumin-I 131 . All substances evaluated which produced high tumor-to-brain concentration ratios were protein-bound in the plasma. Free radioactive ions and positron-emitting compounds which have been used for clinical studies to date gave tumor-to-brain concentration ratios inferior to protein-bound substances.