ENHANCEMENT OF COMPUTED-TOMOGRAPHY LIVER CONTRAST USING IOMEPROL-CONTAINING LIPOSOMES AND DETECTION OF SMALL LIVER-TUMORS IN RATS

Rationale and Objectives. We evaluated iomeprol-containing liposomes ( Lipiom), a new contrast medium for computed tomography (CT) liver scan ning, in an animal model of chemically induced hepatocellular carcinom as and other liver tumors in rats. Methods. Liver tumors were induced by administration of carcinogens to rats, either 0.55% (w/w) 1'-hydrox ysafrole in the diet or induction by 3'-methyl-4-diethylaminoazobenzen e followed by promotion with carbon tetrachloride. CT scanning was per formed 1-3 hr after intravenous injection of iomeprol-containing lipos omes. Results. After injection of iomeprol-containing liposomes at a d ose of 70 mg of liposome-entrapped iodine per kilogram of body weight, the normal liver parenchyma showed a contrast enhancement, in Hounsfi eld units, of more than 60% over the control value before bolus. Liver tumors with no or few Kupffer cells were not enhanced and appeared as dark areas within the normal parenchyma. Tumors and pretumoral lesion s devoid of Kupffer cells, as small as 3 mm in diameter, could be dist inguished using this noninvasive method. Conclusion. CT liver scanning after injection of iomeprol-containing liposomes appears to be a prom ising method for detecting liver tumors and focal liver lesions.