Tumor detection by radioimaging of hepatic radiozinc--correlation with metallothionein content.

In order to determine if the radioimaging of the level of hepatic metallothionein (MT) is able to detect malignancy, we performed, using 45Zn, a trial to measure MT levels in the liver of experimental tumor-bearing mice and rats. The distribution of 65Zn in the livers of the mice and rats increased with s.c. transplantation of Ehrlich carcinoma and ascites hepatoma 7974F, respectively. A Sephadex G-75 elution profile of the cytosol fraction of the liver showed that the elevation of 65Zn level was due to elevation of the MT level. At 2 days after tumor transplantation in mice, the 65Zn-image demonstrated elevation of the hepatic MT level, while 67Ga-citrate, which is currently utilized, could not image the tumor at such an early period of growth. These results suggest that hepatic MT is a useful marker for the detection of malignancy at the early stage.