PARENCHYMAL ENHANCEMENT AND TUMOR VISUALIZATION USING A NEW SONOGRAPHIC CONTRAST AGENT

The purpose of this study was to assess the ability of a sonographic c ontrast agent to increase parenchymal echogenicity and improve tumor v isibility. The agent is an emulsion that changes at body temperature f rom nonechogenic submicrometer liquid droplets to echogenic 1 to 5 mu m microbubbles, capable of traversing the pulmonary and capillary circ ulations. Peripheral venous injections (dosages of 0.05 to 0.8 ml/kg) were administered to five woodchucks (three with multiple hepatomas), 12 rabbits (with renal VX-2 tumors), and four dogs. Ultrasonograms wer e acquired from kidney, liver, tumors (including tumor vessels) and no rmal vessels. Uptake and washout curves were generated via videodensit ometry. Finally, Doppler shifts from a cuff transducer around the celi ac trunk were analyzed to provide an in vivo dose-response curve. Vasc ular enhancement, including hepatoma and VX-2 tumor vessels, was seen for 2 to 3 min. Maximum enhancement was 18.7 dB for a 0.6 ml/kg dose. Enhancement of normal liver and kidney parenchyma was observed in all three species for up to 20 min. Small hepatomas became more echogenic centrally, but larger tumors showed no increase in central echogenicit y. In conclusion, improved tumor visibility and parenchymal enhancemen t was demonstrated in animals.