Spectroscopic Doppler analysis for visible-light optical coherence tomography

Xiao Shu; Wenzhong Liu; Lian Duan; Hao  F. Zhang

doi:10.1117/1.JBO.22.12.121702

17 October 2017 Spectroscopic Doppler analysis for visible-light optical coherence tomography

Xiao Shu, Wenzhong Liu, Lian Duan, Hao F. Zhang

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Journal of Biomedical Optics, Vol. 22, Issue 12, 121702 (October 2017). https://doi.org/10.1117/1.JBO.22.12.121702

Abstract

Retinal oxygen metabolic rate can be effectively measured by visible-light optical coherence tomography (vis-OCT), which simultaneously quantifies oxygen saturation and blood flow rate in retinal vessels through spectroscopic analysis and Doppler measurement, respectively. Doppler OCT relates phase variation between sequential A-lines to the axial flow velocity of the scattering medium. The detectable phase shift is between −π and π due to its periodicity, which limits the maximum measurable unambiguous velocity without phase unwrapping. Using shorter wavelengths, vis-OCT is more vulnerable to phase ambiguity since flow induced phase variation is linearly related to the center wavenumber of the probing light. We eliminated the need for phase unwrapping using spectroscopic Doppler analysis. We split the whole vis-OCT spectrum into a series of narrow subbands and reconstructed vis-OCT images to extract corresponding Doppler phase shifts in all the subbands. Then, we quantified flow velocity by analyzing subband-dependent phase shift using linear regression. In the phantom experiment, we showed that spectroscopic Doppler analysis extended the measurable absolute phase shift range without conducting phase unwrapping. We also tested this method to quantify retinal blood flow in rodents in vivo.

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Xiao Shu, Wenzhong Liu, Lian Duan, and Hao F. Zhang "Spectroscopic Doppler analysis for visible-light optical coherence tomography," Journal of Biomedical Optics 22(12), 121702 (17 October 2017). https://doi.org/10.1117/1.JBO.22.12.121702

Received: 3 May 2017; Accepted: 18 August 2017; Published: 17 October 2017

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