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Journal of Biomedical Optics

Characterization of multiphoton photoacoustic spectroscopy for subsurface brain tissue diagnosis and imaging
Author(s): Sudhir Dahal; Brian M. Cullum
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Paper Abstract

The development and demonstration of a multiphoton photoacoustic imaging technique capable of providing high spatial resolution chemical images of subsurface tissue components as deep as 1.4 cm below the tissue surface is described. By combining multiphoton excitation in the diagnostic window (650 to 1100 nm), with ultrasonic detection of nonradiative relaxation events, it is possible to rapidly reconstruct three-dimensional, chemical specific, images of samples underneath overlying structures as well as chemical species of the same material. Demonstration of this technique for subsurface tissue differentiation is shown, with the ability to distinguish between grade III astrocytoma tissue and adjacent healthy tissue in blind studies. By employing photoacoustic signal detection, the high nonradiative relaxation rates of most biological tissue components (>90%) and the minimal signal attenuation of the resulting ultrasound compensate for excitation efficiency losses associated with two-photon absorption. Furthermore, the two-photon absorption process results in a highly localized excitation volume (ca., 60  μm). Characterization of the probing depth, spatial resolution, and ability to image through overlying structures is also demonstrated in this paper using tissue phantoms with well-characterized optical scattering properties, mimicking those of tissues.

Paper Details

Date Published: 18 April 2016
PDF: 10 pages
J. Biomed. Opt. 21(4) 047001 doi: 10.1117/1.JBO.21.4.047001
Published in: Journal of Biomedical Optics Volume 21, Issue 4
Show Author Affiliations
Sudhir Dahal, Univ. of Maryland, Baltimore County (United States)
Brian M. Cullum, Univ. of Maryland, Baltimore County (United States)

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