Flow measurement using speckle in optical coherence tomography images

Jennifer Kehlet Barton; Steven Stromski

doi:10.1117/12.589632

13 April 2005 Flow measurement using speckle in optical coherence tomography images

Jennifer Kehlet Barton, Steven Stromski

Proceedings Volume 5690, Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine IX; (2005) https://doi.org/10.1117/12.589632
Event: SPIE BiOS, 2005, San Jose, CA, United States

Abstract

Doppler optical coherence tomography (DOCT) is a valuable tool for depth-resolved flow measurements in tissue. However, DOCT suffers from two disadvantages: it is insensitive to flow in the direction normal to the imaging beam, and it requires knowledge of the phase of the demodulated signal. We present an alternative method of extracting flow information, using speckle of conventional amplitude optical coherence tomography images. The two techniques can be shown to be essentially equivalent, with the distinction that speckle methods are sensitive to flow in all directions but do not provide information on the direction of flow. It is well known in other imaging modalities that moving scatterers cause a time-varying speckle pattern. Due to the pixel-by-pixel acquisition scheme of conventional OCT, time-varying speckle is manifested as a change of OCT image spatial speckle frequencies. We tested the ability of speckle to provide quantitative flow information using a flow phantom (a tube filled with Intralipid flowing at a constant volumetric flow rate). Initially, m-scans were taken at over the center of the tube. Images were averaged to reduce noise and the region corresponding to the center one-quarter of the tube lumen was selected. Sequential a-scans were concatenated, the Fourier transform performed, and a ratio of high to low spatial frequencies computed. We found that, over a range of velocities, this ratio bore a linear relation to flow velocity. For two-dimensional imaging, the program was modified to use a sliding window. Parabolic flow profile was visualized inside the tube. This study shows the feasibility of extracting quantitative flow data in all directions without phase information.

Citation Download Citation

Jennifer Kehlet Barton and Steven Stromski "Flow measurement using speckle in optical coherence tomography images", Proc. SPIE 5690, Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine IX, (13 April 2005); https://doi.org/10.1117/12.589632

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