Differential uptake of gallium-67-labeled liposomes between tumors and inflammatory lesions in rats.

The differential gallium-67 (67Ga) accumulation in tumors and inflammatory lesions in rats after i.v. injection of liposome encapsulated 67Ga ([67Ga]liposomes) was studied. The 67Ga accumulation in the tumor was much greater than that in the granulation tissue regardless of the surface charge of liposomes; however, the difference between the two tissues was the greatest when using positive charged liposomes. Gallium-67 delivery to tumors by liposomes was greater than that to granulation tissue in all stages of growth. After i.v. injection, the accumulation of 67Ga in the tumor reached a maximum at 12 hr, whereas in the granulation tissue it was delayed to 24 hr postinjection. In the study of tissue distribution of 67Ga in rats bearing both tumor and granulation tissue, positively charged liposomes preferentially delivered 67Ga to the tumor than to the granulation tissue. These results suggest that [67Ga]liposomes are able to discriminate between the tumor and the inflammatory lesion.