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Published April 2018 | Published + Supplemental Material
Journal Article Open

Dichroism-sensitive photoacoustic computed tomography


Photoacoustic computed tomography (PACT), a fast-developing modality for deep tissue imaging, images the spatial distribution of optical absorption. PACT usually treats the absorption coefficient as a scalar. However, the absorption coefficients of many biological tissues exhibit an anisotropic property, known as dichroism or diattenuation, which depends on molecular conformation and structural alignment. Here, we present a novel imaging method called dichroism-sensitive PACT (DS-PACT), which measures both the amplitude of tissue's dichroism and the orientation of the optic axis of uniaxial dichroic tissue. By modulating the polarization of linearly polarized light and measuring the alternating signals through lock-in detection, DS-PACT can boost dichroic signals from biological tissues. To validate the proposed approach, we experimentally demonstrated the performance of DS-PACT by imaging plastic polarizers and ex vivo bovine tendons deep inside scattering media. We successfully detected the orientation of the optic axis of uniaxial dichroic materials, even at a depth of 4.5 transport mean free paths. We anticipate that the proposed method will extend the capability of PACT to imaging tissue absorption anisotropy.

Additional Information

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. Received 16 March 2018; accepted 28 March 2018 (Doc. ID 325859); published 18 April 2018. We thank Yan Liu and Liang Gao for helpful discussions and sharing data. We thank Jinyang Liang, Yang Li, Hun He, and Bin Rao for their support in the experiment. We thank Professor James Ballard, Utku Baran, and Sandra Matteucci for proofreading the paper. This project is supported in part by the March of Dimes Prematurity Research Center. K. Maslov has a financial interest in Microphotoacoustics, Inc. L. V. Wang has a financial interest in Microphotoacoustics, Inc., CalPACT, LLC, and Union Photoacoustic Technologies, Ltd., which, however, did not support this work. Funding: National Institutes of Health (NIH) (DP1 EB016986, R01 CA186567, R01 EB016963, U01 NS090579, U01 NS099717); March of Dimes Foundation (3125-17303A).

Attached Files

Published - optica-5-4-495.pdf

Supplemental Material - 3325287.pdf

Supplemental Material - Visualization1.mp4


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August 19, 2023
October 18, 2023