Medical ultrasound with microbubbles

Abstract

In the medical ultrasound applications, microbubbles are closely tied to the diagnostic/therapeutic uses. For diagnostic applications, their sound scattering properties yield improved imaging, when the microbubbles are used as contrast agents. The harmonics and subharmonics responses from the bubbles assist in distinguishing the acoustic scattering of blood from that of the surrounding tissue. The therapeutic use of microbubbles has recently been the subject of much interest. In a HIFU treatment, the heat generated by the bubble motion contributes an enhanced localized heating effect from the ultrasound. In the lithotripsy of renal calculi, the acoustic cloud cavitation contributes to the comminution of the renal stones. In all these applications, it is essential to understand the microbubbles and bubble cloud dynamics. The bubble motion and bubble cloud behavior are strongly influenced by the internal phenomena of the bubbles, such as thermal diffusion, mist formation, mass diffusion and heat and mass transfer through the bubble wall. In our research, bubble and bubble cloud dynamics in the medical ultrasound field have been examined. In this paper numerical results and the new techniques of medical ultrasound applications with microbubbles, microbubble enhanced HIFU and Cavitation Control Lithotripsy (CCL), are highlighted.