Rat liver model for testing intraoperative echo contrast sonography.
The present animal experimental study showed that intraoperative hepatic ultrasonography using an echo contrast medium can visualize small hepatomas (with a diameter of between 3 and 15 mm) induced in the rat liver, although they were not recognizable with plain ultrasonography. A homogeneous increase in the echogenicity of the liver tissue was achieved by using an echo contrast medium (Echovist) based on galactose microparticles. Self-made bubble preparations such as those used in echocardiography were far less effective. When the dosage was optimal (0.01-0.003 ml/g liver weight with concentrations of 200 and 300 mg/ml Echovist), homogeneous contrast enhancement of the liver was achieved for at least 10 min after a single bolus injection via all routes of contrast administration (hepatic artery, portal vein, bile duct). As a result, hepatomas appeared as hypodense formations (portal vein and bile duct) or as hyperdense zones (hepatic artery).