Targeted delivery of gas-filled microspheres, contrast agents for ultrasound imaging

Gas-filled microbubbles, with the size of several micrometres, are strong s catterers of ultrasound waves used in diagnostic imaging. Application of th ese microbubbles as ultrasound contrast materials is discussed, in view of the design of materials capable of selectively targeting the diseased tissu es/organs. Methods of preparation, mechanisms of action, biodistribution an d stability in vitro and in vivo are reviewed. Targeted microbubbles with v arious ligands (antibodies, peptides) attached to the shells have been prep ared and tested ih vitro and in vivo. Examples of specific application in d iagnostic imaging and possible therapeutic use are discussed. (C) 1999 Else vier Science B.V. All rights reserved.