Dual radiolabeled liposomes: Biodistribution studies and localization of focal sites of infection in rats

Liposomes encapsulating both glutathione and deferoxamine were labeled with Tc-99m-HMPAO and In-111-oxine at the same time. These dual radiolabeled liposomes were intravenously injected in rats with S. aureus infection in thigh. The target-to background ratio (T/BG) increased from 2.9 at 2 h to 4.4 at 8 h in Tc-99m images, In In-111 images, T/BG of 5.5 at 8 h increased to 10.5 by 48 h. The 24-h spleen uptake of In-111- and Tc-99m-liposomes was 24.14%ID and 8.91%ID. In femur, Tc-99m-liposomes remained at similar to 10.5%ID, but In-111-liposomes increased from similar to 11%ID at 4 h to similar to 25.5%ID at 24 h. The simultaneous presence of Tc-99m and In-111 in the liposomes resulted in good early (2-8 h) as well as delayed (24-48 h) images delineating the infection site. (C) 1998 Elsevier Science Inc.