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Proceedings Paper

In vivo imaging of inducible tyrosinase gene expression with an ultrasound array-based photoacoustic system
Author(s): Tyler Harrison; Robert J. Paproski; Roger J. Zemp
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Paper Abstract

Tyrosinase, a key enzyme in the production of melanin, has shown promise as a reporter of genetic activity. While green fluorescent protein has been used extensively in this capacity, it is limited in its ability to provide information deep in tissue at a reasonable resolution. As melanin is a strong absorber of light, it is possible to image gene expression using tyrosinase with photoacoustic imaging technologies, resulting in excellent resolutions at multiple-centimeter depths. While our previous work has focused on creating and imaging MCF-7 cells with doxycycline-controlled tyrosinase expression, we have now established the viability of these cells in a murine model. Using an array-based photoacoustic imaging system with 5 MHz center frequency, we capture interleaved ultrasound and photoacoustic images of tyrosinase-expressing MCF-7 tumors both in a tissue mimicking phantom, and in vivo. Images of both the tyrosinase-expressing tumor and a control tumor are presented as both coregistered ultrasound-photoacoustic B-scan images and 3-dimensional photoacoustic volumes created by mechanically scanning the transducer. We find that the tyrosinase-expressing tumor is visible with a signal level 12dB greater than that of the control tumor in vivo. Phantom studies with excised tumors show that the tyrosinase-expressing tumor is visible at depths in excess of 2cm, and have suggested that our imaging system is sensitive to a transfection rate of less than 1%.

Paper Details

Date Published: 23 February 2012
PDF: 7 pages
Proc. SPIE 8223, Photons Plus Ultrasound: Imaging and Sensing 2012, 82230S (23 February 2012); doi: 10.1117/12.908987
Show Author Affiliations
Tyler Harrison, Univ. of Alberta (Canada)
Robert J. Paproski, Univ. of Alberta (Canada)
Roger J. Zemp, Univ. of Alberta (Canada)

Published in SPIE Proceedings Vol. 8223:
Photons Plus Ultrasound: Imaging and Sensing 2012
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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