LIVER CONTRAST ENHANCEMENT IN PRIMATES USING IOPROMIDE LIPOSOMES

Rationale and Objectives. We studied the feasibility of using iodinate d liposomes as computed tomography (CT) liver contrast agents in nonhu man primates. Methods. Iopromide-containing liposomes were investigate d as reticuloendothelial (RES) contrast agents for CT scanning of the liver in normal adult baboons. For intravenous (IV) injection, liposom es were resuspended in mannitol solution, filtered under sterile condi tions, and injected TV at doses of 200 and 400 mg I/kg to each of five anesthetized adult baboons. Results. Animals tolerated the injections without measurable electrocardiographic changes and recovered unevent fully from anesthesia. Sequential CT scans of the baboons' upper abdom en acquired up to 60 min postinjection showed persistent enhancement o f 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 mi n with the 200-mg/kg dose and 10 min with the 400-mg/kg dose. The grea test splenic enhancements were 181 and 301 Delta H after the 200- and 400-mg/kg doses, respectively. Conclusion. Iopromide liposomes are eff ective as RES contrast agents in primates.