Ultrasound contrast agent microbubbles are composed of a variety of gases and stabilizing shell materials. FDA-approved applications of ultrasound contrast agents are currently limited to cardiography, and while their diagnostic utility is well-established, significant improvements could lead to increased clinical applications. In addition, the potential of cavitation-related bioeffects for therapeutic applications is exciting, and has received considerable recent attention; e.g., to facilitate targeted drug delivery or to enhance gene therapy, where changes in the vascular endothelium or cell membrane permeability are thought to be critical. The diagnostic and therapeutic effects of ultrasound contrast agents depend on the dynamical responses to the applied acoustic fields insonifying these microbubbles, either contained within the stabilizing shell, or in the form of free gas bubbles liberated from the contrast agent. The long-range objective of this project is to understand those responses and the permeabilizing effects they have on the vascular endothelium, so as to permit a rational exploitation of ultrasound-contrast-agent-enhanced cavitation. We propose to study bubble responses of ultrasound contrast agents in unconstrained media in-vitro, and in in-vivo intestinal mesentery blood vessels and ear veins. Bubble dynamics will be measured with laser light scattering and high-speed imaging, while cavitation will be measured with passive and active cavitation detectors. The biological effects of cavitation on the vascular endothelium will be examined through histology. Accordingly, the three specific aims of this project are as follows: (1) To image and to analyze the interaction of imaging and therapeutic ultrasound pulses with individual and clustered UCA microbubbles in vitro; (2) to assess cavitation in response to acoustic parameters for imaging and therapeutic applications; and (3) to determine how the constrained intravascular environment affects microbubble response ex vivo, and to determine its association with vascular permeabilization in vivo. This research is relevant to public health because understanding the interaction of ultrasound with designer bubbles will lead to improvements in medicine. These improvements will include a better diagnosis of medical problems, and therapeutic applications, such as delivery of drugs and medicine. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Type
Research Project (R01)
Project #
5R01EB000350-06
Application #
7475159
Study Section
Biomedical Imaging Technology Study Section (BMIT)
Program Officer
Zhang, Yantian
Project Start
2001-05-11
Project End
2010-07-31
Budget Start
2008-08-01
Budget End
2009-07-31
Support Year
6
Fiscal Year
2008
Total Cost
$459,611
Indirect Cost
Name
University of Washington
Department
Type
Schools of Earth Sciences/Natur
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
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Gur, David; Bandos, Andriy I; Klym, Amy H et al. (2008) Agreement of the order of overall performance levels under different reading paradigms. Acad Radiol 15:1567-73
Hwang, Joo Ha; Brayman, Andrew A; Reidy, Michael A et al. (2005) Vascular effects induced by combined 1-MHz ultrasound and microbubble contrast agent treatments in vivo. Ultrasound Med Biol 31:553-64
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Porter, Tyrone M; Crum, Lawrence A; Stayton, Patrick S et al. (2004) Effect of polymer surface activity on cavitation nuclei stability against dissolution. J Acoust Soc Am 116:721-8

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