Contrast enhancement and stimulated acoustic emission

Simple resonance phenomena producing strong backscatter are generally regarded as the major mechanism of echo enhancement, but a number of non-linear processes such as microbubble destruction and stimulated acoustic emission (SAE) also occur. A novel agent, SHU563A is known to be particularly effective at producing such signals when insonated but other microbubbles also produce this type of response. We describe a characteristic color Doppler effect withing the livers after Levovist, characterised by (i) a mosaic like appearance (ii) transience and (iii) a parenchymal location, particularly within the liver and spleen some time (>5 mins) after conventional Doppler enhancement is complete. We have observed this effect prospectively in over 90 patients who have received Levovist and describe a number of studies investigating reproducibility, duration, biodistribution technical properties and effects on lesion conspicuity. Using this mode of imaging, Levovist is seen to have a liver specific phase after the blood pool phase. Metastases and other liver lesions are seen as non-enhancing areas and conspicuity is greatly increased.