The present invention refers to an antigen specific echographic contrast medium for diagnostic and/or therapeutic use, a process for the preparation thereof and its uses in ultrasound diagnostic imaging and in therapy. In particular, a contrast medium according to the invention has proven to be useful in selectively carrying drugs and/or other bio-active principles into a diseased tissues and in releasing the same in site, once bond to such tissue and suitably insonated. Moreover, an echographic contrast medium according to the invention allows a differentiation of the diseased tissues from the surrounding (healthy) tissues, by conferring an improved contrastographic enhancement to the diseased tissue alone over an extended period of time.
