Iodinated starch particles: new contrast material for computed tomography of the liver.

An iodinated starch suspension was used as a model particulate hepatic contrast agent for computed tomography (CT). The material, synthesized from starch and triiodobenzoic acid, formed a stable concentrated suspension, containing particles smaller than 4 micrometer. Following intravenous administration of 0.16 gI/kg to rabbits, approximately 85% of the injected dose was present in the liver, resulting in a 180 to 200 Hounsfield unit (1,000 scale) increase in liver CT value. The material produced marked and sustained normal liver opacification but no hepatic tumor enhancement. Lesions as small as 2 mm in diameter were detected. The approximate LD50 of the suspension in mice was 0.9 g I/kg. There were no signs of toxicity at sublethal doses. This suspension produces greater, more sustained, and more selective liver opacification than conventional biliary and urographic contrast materials.