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Proceedings Paper

Photoacoustic and ultrasound imaging to guide photothermal therapy: ex vivo study
Author(s): Jignesh Shah; Suhyun Park; Salavat Aglyamov; Timothy Larson; Li Ma; Konstantin Sokolov; Keith Johnston; Thomas Milner; Stanislav Emelianov
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Paper Abstract

In photothermal therapy, a localized temperature increase is achieved by using a continuous wave laser and optically tuned metal nanoparticles. However, the successful outcome of therapy depends on identifying the presence of nanoparticles in the tumor before therapy and monitoring temperature rise during the photothermal procedure. In this paper, we investigate the utility of photoacoustic and ultrasound imaging to guide photothermal therapy. Differences in the optical properties of tissue, enhanced by the presence of nanoparticles, provide a contrast for photoacoustic imaging. Thus, an uptake of nanoparticles in the tumor can be detected by monitoring a photoacoustic image over time. A temperature rise causes the photoacoustic signal amplitude to increase. In addition, a temperature change also leads to time shifts in an ultrasound signal, primarily due to the change in speed of sound. Therefore, by measuring the change in the photoacoustic signal, and differential motion of ultrasound speckle, the temperature rise during photothermal therapy can be computed. Combined imaging was performed with a tunable pulsed laser and an array-based ultrasound transducer. Experiments were carried out on ex-vivo animal tissue injected with composite and broadly absorbing gold nanoparticles. The photoacoustic imaging identified the presence of nanoparticles in tissue. In addition, a localized temperature increase, obtained during therapy, was monitored using photoacoustic and ultrasound imaging. The temperature profiles, obtained by both imaging techniques, were spatially and temporally co-registered. Therefore, the experimental results suggest that photoacoustic and ultrasound imaging can be used to guide and monitor photothermal therapy.

Paper Details

Date Published: 4 March 2008
PDF: 7 pages
Proc. SPIE 6856, Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics, 68560U (4 March 2008); doi: 10.1117/12.763802
Show Author Affiliations
Jignesh Shah, Univ. of Texas at Austin (United States)
Suhyun Park, Univ. of Texas at Austin (United States)
Salavat Aglyamov, Univ. of Texas at Austin (United States)
Timothy Larson, Univ. of Texas at Austin (United States)
Li Ma, Univ. of Texas at Austin (United States)
Konstantin Sokolov, Univ. of Texas at Austin (United States)
MD Anderson Cancer Ctr. (United States)
Keith Johnston, Univ. of Texas at Austin (United States)
Thomas Milner, Univ. of Texas at Austin (United States)
Stanislav Emelianov, Univ. of Texas at Austin (United States)


Published in SPIE Proceedings Vol. 6856:
Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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