Detection of echoes from adherent targeted microbubbles

A challenging task in ultrasonic molecular imaging is to detect the echoes from microbubbles that are tethered to a vessel wall by targeting ligands, and distinguish them from echoes from flowing agents and tissue. By combining optical and acoustical experimental systems, a protocol was developed to force targeted microbubbles to bind to a phantom vessel wall with the binding verified optically and the echo recorded acoustically. Differences in the acoustical response between free and bound contrast agents were observed and mechanisms for these differences were proposed. The observed acoustical difference can be utilized for a new selective detection method for adherent microbubbles.