University of Houston

Intravascular ultrasound (IVUS) is an invasive imaging modality capable of providing high-resolution, cross-sectional images of the interior of human blood vessels. While IVUS excels at structural imaging, its uses for functional imaging remain less advanced. However, modern ultrasound contrast agents present the potential to improve IVUS imaging in this respect. These agents consist of solutions of suspended microbubbles or other particles designed to be efficient reflectors of acoustic energy. Due to their small scale they may be used to track blood perfusion under ultrasound, providing useful indicators of flow and vascular anatomy.

Unfortunately, a wide variety of confounding factors with respect to microbubble detection have so far prevented IVUS imaging from taking full advantage of these applications. Some of these problems include eliminating the severe motion artifacts caused by the beating heart, isolating the contrast effect, and reliably tracking the elastic tissues imaged by IVUS. This thesis proposes computational methods which systematically address these problems. Also presented are the first published in vivo IVUS analyses of plaque perfusion. The use of contrast-enhanced IVUS for the detection of inflamed atherosclerotic plaques is also discussed. This application in particular shows potential for the early detection of so-called vulnerable plaques: the fatty, unstable lesions responsible for heart attacks and strokes.