On the Enhancement of Ultrasound Backscatter from Microbubbles for Optimal Particle Image Velocimetry

We have developed a non-invasive ultrasound-based method for performing particle image velocimetry in vivo. This method provides high resolution multi-component blood flow data with high temporal resolution. The method takes advantage of the non-linear ultrasound backscatter characteristics of small gas-filled microbubbles (ultrasound contrast) that are seeded into the blood stream [1]. Preliminary data under in vitro and in vivo conditions are highly promising [2,3]. The method now needs to be developed further in order to be used in a wide range of physiological flow conditions. As part of this, significant optimization needs to be performed. While part of the optimization involves signal and image processing manipulation of the ultrasound signals to maximize parameters such as signal-to-noise ratio, an equally important component involves further understanding of the fundamentals of the backscatter process, as it applies to our method. This report documents the development of the theoretical model describing ultrasound backscatter from microbubbles.