Rationale and objectives: We studied the feasibility of using iodinated liposomes as computed tomography (CT) liver contrast agents in nonhuman primates.
Methods: Iopromide-containing liposomes were investigated as reticuloendothelial (RES) contrast agents for CT scanning of the liver in normal adult baboons. For intravenous (i.v.) injection, liposomes were resuspended in mannitol solution, filtered under sterile conditions, and injected i.v. at doses of 200 and 400 mg l/kg to each of five anesthetized adult baboons.
Results: Animals tolerated the injections without measurable electrocardiographic changes and recovered uneventfully from anesthesia. Sequential CT scans of the baboons' upper abdomen acquired up to 60 min postinjection showed persistent enhancement of the liver 10-60 min after injection. Maximum enhancement levels were 36 and 61 delta Hounsfield units (delta H) after the 200- and 400-mg/kg doses, respectively. The mean time to plateau enhancement was 20 min with the 200-mg/kg dose and 10 min with the 400-mg/kg dose. The greatest splenic enhancements were 181 and 301 delta H after the 200- and 400-mg/kg doses, respectively.
Conclusion: Iopromide liposomes are effective as RES contrast agents in primates.