in or relating to contrast agents improvements.

Some agents ultrasound contrast comprising microbubbles of a gas biocompatible, FOR EXAMPLE, a halide of sulfur or a perfluorocarbon, STABILIZED BY MATERIAL amphiphilic OPSONIZABLE, FOR EXAMPLE, a lipid membrane forming, as a phospholipid, especially a negatively charged phospholipid , as phosphatidylserine, may show a prolonged period of permanence, GENERATING contrast, in the liver after intravenous administration.