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Proceedings Paper

Motorized photoacoustic tomography probe for label-free improvement in image quality
Author(s): Gurneet S. Sangha; Nick H. Hale; Craig J. Goergen
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Paper Abstract

One of the challenges in high-resolution in vivo lipid-based photoacoustic tomography (PAT) is improving penetration depth and signal-to-noise ratio (SNR) past subcutaneous fat absorbers. A potential solution is to create optical manipulation techniques to maximize the photon density within a region of interest. Here, we present a motorized PAT probe that is capable of tuning the depth in which light is focused, as well as substantially reducing probe-skin artifacts that can obscure image interpretation. Our PAT system consists of a Nd:YAG laser (Surelite EX, Continuum) coupled with a 40 MHz central frequency ultrasound transducer (Vevo2100, FUJIFILM Visual Sonics). This system allows us to deliver 10 Hz, 5 ns light pulses with fluence of 40 mJ/cm2 to the tissue interest and reconstruct PAT and ultrasound images with axial resolutions of 125 µm and 40 µm, respectively. The motorized PAT holder was validated by imaging a polyethylene-50 tubing embedded polyvinyl alcohol phantom and periaortic fat on apolipoprotein-E deficient mice. We used 1210 nm light for this study, as this wavelength generates PAT signal for both lipids and polyethylene-50 tubes. Ex vivo results showed a 2 mm improvement in penetration depth and in vivo experiments showed an increase in lipid SNR of at least 62%. Our PAT probe also utilizes a 7 μm aluminum filter to prevent in vivo probe-skin reflection artifacts that have been previously resolved using image post-processing techniques. Using this optimized PAT probe, we can direct light to various depths within tissue to improve image quality and prevent reflection artifacts.

Paper Details

Date Published: 19 February 2018
PDF: 9 pages
Proc. SPIE 10486, Design and Quality for Biomedical Technologies XI, 1048604 (19 February 2018);
Show Author Affiliations
Gurneet S. Sangha, Purdue Univ. (United States)
Nick H. Hale, Purdue Univ. (United States)
Craig J. Goergen, Purdue Univ. (United States)

Published in SPIE Proceedings Vol. 10486:
Design and Quality for Biomedical Technologies XI
Ramesh Raghavachari; Rongguang Liang, Editor(s)

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