Azimuth mapping of fibrous tissue in linear dichroism-sensitive photoacoustic microscopy

Eunwoo Park; Yong-Jae Lee; Chulhong Kim; Tae Joong Eom

doi:10.1016/j.pacs.2023.100510

Azimuth mapping of fibrous tissue in linear dichroism-sensitive photoacoustic microscopy

Photoacoustics. 2023 May 10:31:100510. doi: 10.1016/j.pacs.2023.100510. eCollection 2023 Jun.

Authors

Eunwoo Park¹, Yong-Jae Lee², Chulhong Kim¹, Tae Joong Eom^{2

3}

Affiliations

¹ Department of Convergence IT Engineering, Electrical Engineering, Mechanical Engineering, Medical Science and Engineering, Graduate School of Artificial Intelligence, and Medical Device Innovation Center, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673, the Republic of Korea.
² Engineering Research Center for Color-Modulated Extra-Sensory Perception Technology, Pusan National University, Busan 46241, the Republic of Korea.
³ Department of Congo-Mechatronics Engineering, Pusan National University, Busan 46241, Republic of Korea.

Abstract

Photoacoustic imaging (PAI) has emerged as a molecular-selective imaging technology based on optical absorption contrast. Dichroism-sensitive photoacoustic (DS-PA) imaging has been reported, where the absorption coefficient has a vector characteristic, featuring dimensions of contrast in polarization and wavelength. Herein, we present a DS-PA microscopy (DS-PAM) system that implements optical anisotropy contrast and molecular selectivity. Moreover, we propose mathematical solutions to fully derive dichroic properties. A wavelength for the PAI of collagenous tissue was used, and the proposed algorithms were validated using linear dichroic materials. We successfully mapped dichroic information in fibrous tissue imaging based on the degree of anisotropy and axis orientation, and also deduced mechanical assessment from the tissue arrangement. The proposed DS-PAM system and algorithms have great potential in various diagnostic fields using polarimetry, such as musculoskeletal and cardiovascular systems.

Keywords: Anisotropy; Dichroism; Optic axis; Photoacoustic microscopy; Polarization; Stokes parameters.