Experimental study on tumor affinity of 201T1-chloride.

The tumor affinity of 201T1 was studied with normal and VX-2 cancer-bearing rabbits. 201T1 distribution in normal rabbit tissues was greatest in the kidney and heart muscle, followed by thyroid gland small intestine, spleen, lung, liver, bone marrow, bone, skeletal muscle, and blood, respectively. Accumulation into the thyroid varied greatly according to individuals. Generally, the taller the height of follicular cells, the greater was the affinity. Accumulation of 201T1 into the tumor transplanted into femoral muscle reached its maximum within 1 h after administration, and thereafter decreased gradually. When the tumor affinity was compared with that of 67Ga, the ratio of 67Ga accumulation to tissues (except blood) was greater than that of 201T1. Accumulation of 201T1 is significantly correlated to that of 42K, and the mechanism of 201T1-tumor affinity seems to be triggered by the acceleration of the potassium metabolism of a tumor. Accumulation into the inflammatory focus was greater with 67Ga as a ratio to muscle, while the ratio to blood was greater with 201T1.