Effect of A-scan rate and interscan interval on optical coherence angiography

Ting-Hao Chen; Yi-Chun Wu; Ting-Yen Tsai; Chuan-Bor Chueh; Bo-Huei Huang; Yin-Peng Huang; Meng-Tsan Tsai; Yoshiaki Yasuno; Hsiang-Chieh Lee

doi:10.1364/BOE.409636

Effect of A-scan rate and interscan interval on optical coherence angiography

Biomed Opt Express. 2021 Jan 6;12(2):722-736. doi: 10.1364/BOE.409636. eCollection 2021 Feb 1.

Authors

Ting-Hao Chen¹, Yi-Chun Wu¹, Ting-Yen Tsai¹, Chuan-Bor Chueh¹, Bo-Huei Huang², Yin-Peng Huang³, Meng-Tsan Tsai^{2

4}, Yoshiaki Yasuno⁵, Hsiang-Chieh Lee^{1

6

7}

Affiliations

¹ Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
² Department of Electrical Engineering, Chang Gung University, Taoyuan 33302, Taiwan.
³ Graduate Institute of Networking and Multimedia, National Taiwan University, Taipei 10617, Taiwan.
⁴ Department of Neurosurgery, Chang Gung Memorial Hospital, Linkou, Taoyuan 33306, Taiwan.
⁵ Computational Optics Group, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8573, Japan.
⁶ Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan.
⁷ Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan.

Abstract

Optical coherence tomography angiography (OCTA) can provide rapid, volumetric, and noninvasive imaging of tissue microvasculature without the requirement of exogenous contrast agents. To investigate how A-scan rate and interscan time affected the contrast and dynamic range of OCTA, we developed a 1.06-µm swept-source OCT system enabling 100-kHz or 200-kHz OCT using two light sources. After system settings were carefully adjusted, almost the same detection sensitivity was achieved between the 100-kHz and 200-kHz modalities. OCTA of ear skin was performed on five mice. We used the variable interscan time analysis algorithm (VISTA) and the designated scanning protocol with OCTA images reconstructed through the correlation mapping method. With a relatively long interscan time (e.g., 12.5 ms vs. 6.25 ms for 200-kHz OCT), OCTA can identify more intricate microvascular networks. OCTA image sets with the same interscan time (e.g., 12.5 ms) were compared. OCTA images acquired with a 100-kHz A-scan rate showed finer microvasculature than did other imaging modalities. We performed quantitative analysis on the contrast from OCTA images reconstructed with different A-scan rates and interscan time intervals in terms of vessel area, total vessel length, and junction density.