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Proceedings Paper

Nonlinear acoustic enhancement in photoacoustic imaging with wideband absorptive nanoemulsion beads
Author(s): Chen-wei Wei; Michael Lombardo; Jinjun Xia; Ivan Pelivanov; Camilo Perez; Kjersta Larson-Smith; Thomas J. Matula; Danilo Pozzo; Matthew O’Donnell
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Paper Abstract

A nanoemulsion contrast agent with a perfluorohexane core and optically absorptive gold nanospheres (GNSs) assembled on the surface, is presented to improve the specificity of photoacoustic (PA) molecular imaging in differentiating targeted cells or aberrant regions from heterogeneous background signals. Compared to distributed GNSs, clustered GNSs at the emulsion oil-water interface produce a red-shifted and broadened absorption spectrum, exhibiting fairly high absorption in the near-infrared region commonly used for deep tissue imaging. Above a certain laser irradiation fluence threshold, a phase transition creating a microbubble in the emulsion core leads to more than 10 times stronger PA signals compared with conventional thermal-expansion-induced PA signals. These signals are also strongly non-linear, as verified by a differential scheme using recorded PA images at different laser fluences. Assuming a linear relation between laser fluence and the PA signal amplitude, differential processing results in nearly perfect suppression of linear sources, but retains a significant residue for the non-linear nanoemulsion with more than 35 dB enhancement. This result demonstrates that contrast specificity can be improved using the nanoemulsion as a targeting agent in PA molecular imaging by suppressing all background signals related to a linear PA response. Furthermore, combined with a system providing simultaneous laser/ultrasound excitation, cavitation-generated bubbles have the potential to be a highly specific contrast agent for ultrasound molecular imaging and harmonic imaging, as well as a targeted means for noninvasive ultrasound-based therapies.

Paper Details

Date Published: 3 March 2014
PDF: 6 pages
Proc. SPIE 8943, Photons Plus Ultrasound: Imaging and Sensing 2014, 894325 (3 March 2014); doi: 10.1117/12.2042312
Show Author Affiliations
Chen-wei Wei, Univ. of Washington (United States)
Michael Lombardo, Univ. of Washington (United States)
Jinjun Xia, Univ. of Washington (United States)
Ivan Pelivanov, Univ. of Washington (United States)
Moscow State Univ. (Russian Federation)
Camilo Perez, Univ. of Washington (United States)
Kjersta Larson-Smith, Univ. of Washington (United States)
Thomas J. Matula, Univ. of Washington (United States)
Danilo Pozzo, Univ. of Washington (United States)
Matthew O’Donnell, Univ. of Washington (United States)

Published in SPIE Proceedings Vol. 8943:
Photons Plus Ultrasound: Imaging and Sensing 2014
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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