Characterization of polymer ultrasound contrast agents.

Abstract

Ultrasound contrast agents are encapsulated microbubbles with unique acoustic scattering signatures. Polymer shelled agents have been shown to be advantageous for tissue perfusion studies and also more recently high‐frequency ultrasound applications. The thickness and material of the polymer shell can be more finely adjusted for the specific application in the production process. Only recently have independent measurements of the shell material parameters been attempted. We present a series of elastic shell parameter measurements made using two complementary techniques: high‐frequency acoustic microscopy and nano‐indentation (Hysitron device). The elastic properties of the thin films of the polymer material (Philips agents) were measured using both methods. Also variations of these techniques were applied to the full spherical shells to examine curvature effects. Acoustic microscopy measurements indicate values for acoustic impedance of 1.73 MRayl. Simulations are highlighted. [Work supported by NIH EB006372 and 2G12RR003016121.]