Abstract
Ultrasonic contrast agents (UCAs) have been used to enhance the acoustic backscattered intensity of blood and thereby assist the assessment of blood perfusion. A unique characteristic of UCAs is that they can be fragmented after suitable acoustic excitation. Characterization of contrast agent destruction provides important information for the design of UCAs destruction/replenishment perfusion imaging. In this paper, we proposed an acoustic measurement procedure to obtain relevant threshold parameters including transmission acoustic pressures, pulse lengths and pulse frequencies for bubble destruction. The procedure not only provides a simple and convenient method to determine the bubble destruction threshold, but observes the destruction phenomenon of a group of microbubbles. The condition is more close to clinical usage of UCAs. Two agents with lipid- and polymer-shelled UCAs are introduced in this study. The results show that lipid-shell UCAs can be destroyed in response to a five-cycle pulse at a pressure approaching 0.6 MPa. The polymer-shelled UCAs are hard to be destroyed due to not significant oscillation in response to ultrasound pulse. Potential applications of this technique include UCAs high resolution destruction/replenishment imaging model, drug delivery and gene therapy.