Investigating the acoustic response of microbubbles attached to surfaces

Contrast agents in medical imaging are specifically designed for each imaging modality. For ultrasound imaging contrast agents are in the form of gas filled microbubbles. These microbubbles expand and contract when exposed to the ultrasound wave and their echoes can be distinguished from echoes from surrounding tissue. Clinically they are currently used for imaging the liver. A potential application is targeting the microbubbles to bind to specific markers for selective imaging or delivery of material to specific targets. In order to develop this application more detailed understanding of the response of microbubbles when they are attached to a surface are required. We have developed an experimental set up for the investigation of attached, individual microbubbles in order to determine differences in echoes from microbubbles attached to a surface and those free flowing in blood vessels. An understanding of the differences in the microbubble responses will help to optimise the ultrasound settings used in different imaging situations.