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19 February 2009 Velocity-resolved single-pass volumetric retinal flow imaging spectral domain optical coherence tomography
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Advances in Doppler spectral domain optical coherence tomography (SDOCT) have demonstrated several image acquisition schemes that enable real-time, high-resolution, volumetric display of blood flow maps. Current generation Doppler SDOCT systems use phase differences between sequential A-scans acquired at a single spatial position to calculate the velocity of moving scatterers. Recently, several methods for optical angiography have been developed which resolve moving scatterers by imposing a spatial frequency modulation across a lateral scan dimension. The carrier frequency is generated by adding a reference phase delay using a moving reference arm or an off-pivot scanning beam. The resulting data is spatial frequency windowed such that all moving scatterers (flow) modulating the carrier frequency can be separated from non-moving scatterers (structure). However, spatial frequency modulation requires precise synchronization of the reference arm delay with B-scan acquisition and multiple B-scans are required to image bidirectional flow into and out-of the A-scan axis. Here we demonstrate single-pass volumetric bidirectional blood flow imaging (SPFI) SDOCT using a modified Hilbert transform without the use of spatial frequency modulation. By windowing low-spatial frequency scatterers across a B-scan, bidirectionally moving scatterers centered at Doppler frequencies outside of the frequency window are resolved. Additionally, 3D velocimetry maps can be constructed by setting the spatial frequency window to a corresponding velocity range and shifting it across all spatial frequencies to image scatterers moving within a particular velocity range. We show that SPFI SDOCT allows for 3D imaging of in vivo human retinal microvasculature down to 20μm, thus providing information about vessel morphology and dynamics.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yuankai K. Tao, Kristen M. Kennedy, and Joseph A. Izatt "Velocity-resolved single-pass volumetric retinal flow imaging spectral domain optical coherence tomography", Proc. SPIE 7168, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIII, 716809 (19 February 2009);

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