Volumetric microvascular imaging of human retina using optical coherence tomography with a novel motion contrast technique

California Institute of Technology, Pasadena, California 91125, USA.
Optics Express (Impact Factor: 3.49). 11/2009; 17(24):22190-200. DOI: 10.1364/OE.17.022190
Source: PubMed

ABSTRACT Phase variance-based motion contrast imaging is demonstrated using a spectral domain optical coherence tomography system for the in vivo human retina. This contrast technique spatially identifies locations of motion within the retina primarily associated with vasculature. Histogram-based noise analysis of the motion contrast images was used to reduce the motion noise created by transverse eye motion. En face summation images created from the 3D motion contrast data are presented with segmentation of selected retinal layers to provide non-invasive vascular visualization comparable to currently used invasive angiographic imaging. This motion contrast technique has demonstrated the ability to visualize resolution-limited vasculature independent of vessel orientation and flow velocity.

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Available from: Robert J Zawadzki, Sep 26, 2015
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    • "Once the scan was completed, one OCT data cube (256 (X) × 2048 (Y) × 4096 (Z) voxels) was produced over the region of interest within 20 s. After the analytical OCT data cube was converted to an amplitude form using a fast Fourier transformation (FFT), a cross-correlation based image registration method was applied for the adjacent B-frames in the 3D amplitude data set to compensate axial displacement induced by possible tissue bulk motion [50]. Then, subtraction between the adjacent B-frames was operated with the consecutive 8 B-frames obtained at the same location to suppress the stationary signals and extract the moving blood flow signals, and thus the resulting 7 images were averaged to enhance flow signal sensitivity, yielding one cross-sectional blood flow intensity image. "
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    • "One uses the absolute value of the phase difference [10]. Another adopts the variance of several adjacent A-line phase differences [11,12]. The physical principle behind the phase-resolved methods is the Doppler effect. "
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    • "For in-vivo human patient imaging especially when using the IF-IBDV method, there may be strong axial movement induced by involuntarily motion of the imaging subject and axial direction movement may degrade the performance of the IBDV method. Axial movement induced displacement can be compensated by cross-correlating the amplitude values of neighboring A-lines used in the algorithm [16]. Both OCT and IBDV images were then obtained from the compensated A-line amplitudes. "
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