The uniquely structured diphytanoylphosphatidylcholine (DphPC) forms liposomes more stable than conventional straight chain phospholipids. In this study DphPC and pegylated DphPC (DphPC-PEG) liposomes were radiolabelled and evaluated in vitro and in vivo. (99)mTc-DphPC liposomes were found to be nontoxic to human white blood cells in vitro. In addition Tc-99m labelled DphPC-PEG liposomes were evaluated as a nonspecific infection imaging agent in a mouse model. Infection sites were imaged within 30 min postinjection, and the radiopharmaceutical exhibited a remarkable in vivo stability. As their biodistribution and pharmacokinetic patterns can be size-modulated, DphPC-based lipsomes are excellent candidates for diagnostic and therapeutic applications.