Bubble Destruction

Abstract

Microbubbles are promising ultrasound contrast agents with potentially important clinical applications in cardiovascular and body imaging. Although other ultrasound contrast agents have been proposed (Mattrey et al. 1982; Violante et al. 1988), microbubbles are most promising because of their high effectiveness at very small dosages (Mattrey et al. 1996). They typically consist of a free gas bubble, or gas contained within an elastic, semirigid, or rigid shell. Microbubbles are effective scatterers owing to the large impedance difference between the surrounding fluid (e.g., blood) and the encapsulated gas, as well as their resonance in the ultrasound beam. The amplitude of the reflected signal is linearly related to bubble concentration and to the bubble’s radius raised to the sixth power (Powsner et al. 1986; Morse and Ingard 1968; Vuille et al. 1994; Vandenberg and Melton 1994; Wiencek et al. 1993). The bubbles in plasma have similar rheology as red blood cells and can traverse the pulmonary and systemic circulation (Goldberg et al. 1994; Powsner et al. 1986; Wiencek et al. 1993).