Abstract
Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism. The volume is probed from two distinct illumination directions with variable controlled incidence plane, allowing for reconstruction of the true flow velocity at arbitrary vessel orientations. The principle is implemented with Swept Source OCT at 1060nm with 100,000 A-Scans/s. We apply the system to resolve pulsatile retinal absolute blood velocity by performing segment scans around the optic nerve head and circumpapillary scan time series.
Highlights
Phase resolved Doppler optical coherence tomography (DOCT) has the unique ability to provide depth resolved blood flow velocity information with high spatial resolution and noninvasively
Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle
We measured the velocity in the capillary with varying tilt angles (α) and rotation angles (β) for two preset velocities, using circular scan generated by the galvo scanners and the following two configurations: firstly, when the illuminating beams are static (Δβ = 90°-β) with the Dove prism at rest, and secondly, when the beams are rotated by the Dove prism synchronously with the circular scan (Δβ~0°)
Summary
Phase resolved Doppler optical coherence tomography (DOCT) has the unique ability to provide depth resolved blood flow velocity information with high spatial resolution and noninvasively. Measurement of tissue blood flow might lead to a better understanding of vascular diseases and might provide beneficial information for treatment monitoring [1,2]. High-speed OCT allows for example following flow dynamics over time within individual tissue vessels. DOCT allows a selective assessment of blood flow and flow velocity in retinal and choroidal vessels and is a promising candidate for early diagnosis of major eye’s posterior segment diseases. Standard DOCT has the drawback of being sensitive to motion along the optical axis only, requiring information on the blood vessel orientation to calculate the absolute velocity and to quantitatively extract the blood flow. The absolute flow velocity v and the axial velocity va are related to the phase difference ∆φ between two A-Scans
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