Particulate contrast media for computed tomographic scanning of the liver.

A contrast agent that is selectively accumulated in the liver should greatly improve the diagnostic value of contrast enhanced CT scanning. The advantages and disadvantages of different classes of hepatographic agents are briefly reviewed. Experimental results obtained with the particulate contrast agents, iothalamate ethyl ester and iodipamide ethyl ester, are presented in more detail. Following intravenous infusion of iodipamide ethyl ester, approximately 60% of the injected dose is accumulated in the rat liver. CT scanning experiments involving iothalamate ethyl ester infusions in New Zealand White rabbits demonstrate significantly higher liver contrast enhancement at 10-30 minutes postinfusion than is observed with diatrizoate at a sixfold greater iodine dose. The selective accumulation of a particulate contrast agent in hepatic reticuloendothelial cells compared to virtually no accumulation in implanted VX2 carcinoma demonstrates the important potential value of these agents in improving detection of liver metastases.