Distribution of 95Zr and 181Hf in tumor-bearing animals and mechanism for accumulation in tumor and liver.

Tumor uptake rates, concentrations in the mitochondrial fraction (containing lysosome) of liver and tumors, avid accumulations in connective tissue (especially inflammatory tissue) and binding substances in these tissues of 95Zr and 181Hf were essentially similar to those for 67Ga, 111In, 169Yb and 167Tm. However, the main binding substance of the above elements in group IV in tumor and liver was acid mucopolysaccharide whose molecular weight exceeded 40,000, although the above elements in group III were bound mainly to the acid mucopolysaccharide with a molecular weight of about 10,000.