The use of near-infrared wavelengths for photoacoustic (PA) imaging takes advantage of the relatively low inherent absorption of tissues and has encouraged the development of agents which show high contrast in this range. Here, we describe the modification of a commercially available PA imaging system (Vevo LAZR, VisualSonics, Toronto) to take advantage of the 532nm and 1064nm wavelengths inherent in the generation of the currently tuneable range of 680 to 970nm and in the use of these two wavelengths to assess contrast agents. The photoacoustic imaging system generated light from a Nd/YAG laser modified to extract the 532 and 1064nm wavelengths in addition to its OPO-derived tuneable range (680 - 970 nm) and deliver this light through a fiber integrated into a linear array transducer (LZ400, VisualSonics). Gold nanorods (UT Austin), carbon nanotubes (Stanford U), DyLight 550 (Thermo Fisher) and blood were imaged in a phantom (PE20 tubing) and in a hindlimb subcutaneous tumor in vivo to determine their photoacoustic signal intensity at all wavelengths. In the phantom and in vivo, all agents caused an enhancement of the photoacoustic signal at their respective peak absorbance wavelengths. These results show that the 532nm and 1064nm wavelengths could prove useful in biomedical imaging due to the contrast agents customized for them. The 1064nm wavelength in particular has the advantage of having very low generation of endogenous signal in vivo, making agents tuned to this wavelength ideal for targeted contrast imaging.

Date Published: 4 March 2013
PDF: 7 pages
Proc. SPIE 8581, Photons Plus Ultrasound: Imaging and Sensing 2013, 85813O (4 March 2013); doi: 10.1117/12.2004804

Published in SPIE Proceedings Vol. 8581:
Photons Plus Ultrasound: Imaging and Sensing 2013
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)