1. Articles from Weisong Shi

    1-7 of 7
    1. Real-time en-face Gabor optical coherence tomographic angiography on human skin using CUDA GPU

      Real-time en-face Gabor optical coherence tomographic angiography on human skin using CUDA GPU

      We recently proposed an optical coherence tomographic angiography (OCTA) algorithm, Gabor optical coherence tomographic angiography (GOCTA), which can extract microvascular signals from a spectral domain directly with lower computational complexity compared to other algorithms. In this manuscript, we combine a programmable swept source, an OCT complex signal detecting unit, and graphics process units (GPU) to achieve a real-time en-face GOCTA system for human skin microvascular imaging. The programmable swept source can balance the A-scan rate and the spectral tuning range; the polarization-modulation based complex signal detecting unit can double the imaging depth range, and the GPU can accelerate data processing ...

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    2. Gabor optical coherence tomographic angiography (GOCTA) (Part II): theoretical basis of sensitivity improvement and optimization for processing speed

      Gabor optical coherence tomographic angiography (GOCTA) (Part II): theoretical basis of sensitivity improvement and optimization for processing speed

      We previously proposed a Gabor optical coherence tomography angiography (GOCTA) algorithm for spectral domain optical coherence tomography (SDOCT) to extract microvascular signals from spectral fringes directly, with speed improvement of 4 to 20 times over existing methods. In this manuscript, we explored the theoretical basis of GOCTA with comparison of experimental data using solid and liquid displacement sample targets, demonstrating that the majority of the GOCTA sensitivity advantage over speckle variance based techniques was in the small displacement range (< 10 ∼ 20 µm) of the moving target (such as red blood cells). We further normalized GOCTA signal by root-mean-square (RMS) of ...

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    3. 2D MEMS-based high-speed beam-shifting technique for speckle noise reduction and flow rate measurement in optical coherence tomography

      2D MEMS-based high-speed beam-shifting technique for speckle noise reduction and flow rate measurement in optical coherence tomography

      In this manuscript, a two-dimensional (2D) micro-electro-mechanical system (MEMS)-based, high-speed beam-shifting spectral domain optical coherence tomography (MHB-SDOCT) is proposed for speckle noise reduction and absolute flow rate measurement. By combining a zigzag scanning protocol, the frame rates of 45.2 Hz for speckle reduction and 25.6 Hz for flow rate measurement are achieved for in-vivo tissue imaging. Phantom experimental results have shown that by setting the incident beam angle to ϕ = 4.76° (between optical axis of objective lens and beam axis) and rotating the beam about the optical axis in 17 discrete angular positions, 91% of speckle ...

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    4. Beam-shifting technique for speckle reduction and flow rate measurement in optical coherence tomography

      Beam-shifting technique for speckle reduction and flow rate measurement in optical coherence tomography

      In this Letter, we propose a beam-shifting optical coherence tomography scheme for speckle reduction and blood flow rate calculation, where variations of the speckle pattern and Doppler angle were generated by parallel shifting of the sample beam incident on the objective lens. The resultant optical coherent tomography images could then be averaged for speckle noise reduction and simultaneously analyzed for flow rate measurement. The performance of the proposed technique was verified by both phantom and in vivo experiments.

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    5. Buffer-averaging super-continuum source based spectral domain optical coherence tomography for high speed imaging

      Buffer-averaging super-continuum source based spectral domain optical coherence tomography for high speed imaging

      In super-continuum (SC) source based spectral domain optical coherence tomography (SC-SDOCT), the stability of the power spectral density (PSD) has a significant impact on OCT system sensitivity and image signal to noise ratio (SNR). High speed imaging decreases the camera's exposure time, thus each A-scan contained fewer laser pulse excited SC wideband emissions, resulting in a decrease of SNR. In this manuscript, we present a buffer-averaging SC-SDOCT (BASC-SDOCT) to improve the system's performance without losing imaging speed, taking advantage of the excess output power from typical SC sources. In our proposed technique, the output light from SC was ...

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    6. Differential standard deviation of log-scale intensity based optical coherence tomography angiography

      Differential standard deviation of log-scale intensity based optical coherence tomography angiography

      In this paper, a differential standard deviation of log-scale intensity (DSDLI) based optical coherence tomography angiography (OCTA) is presented for calculating microvascular images of human skin. The DSDLI algorithm calculates the variance in difference images of two consecutive log-scale intensity based structural images from the same position along depth direction to contrast blood flow. The en face microvascular images were then generated by calculating the standard deviation of the differential log-scale intensities within the specific depth range, resulting in an improvement in spatial resolution and SNR in microvascular images compared to speckle variance OCT and power intensity differential method. The ...

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    7. Imaginary part-based correlation mapping optical coherence tomography for imaging of blood vessels in vivo

      Imaginary part-based correlation mapping optical coherence tomography for imaging of blood vessels in vivo

      We present an imaginary part-based correlation mapping optical coherence tomography (IMcmOCT) technique for in vivo blood vessels imaging. In the conventional correlation mapping optical coherence tomography (cmOCT) method, two adjacent frames of intensity-based structural images are correlated to extract blood flow information and the size of correlation window has to be increased to improve the signal-to-noise ratio of microcirculation maps, which may cause image blur and miss the small blood vessels. In the IMcmOCT method, the imaginary part of a depth-resolved complex analytic signal in two adjacent B-scans is correlated to reconstruct microcirculation maps. Both phantom and in vivo experiments ...

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    1-7 of 7
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    1. (6 articles) Nanjing University of Science and Technology
    2. (6 articles) University of Toronto
    3. (5 articles) Sunnybrook Health Sciences Centre
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    Imaginary part-based correlation mapping optical coherence tomography for imaging of blood vessels in vivo Differential standard deviation of log-scale intensity based optical coherence tomography angiography Buffer-averaging super-continuum source based spectral domain optical coherence tomography for high speed imaging Beam-shifting technique for speckle reduction and flow rate measurement in optical coherence tomography 2D MEMS-based high-speed beam-shifting technique for speckle noise reduction and flow rate measurement in optical coherence tomography Gabor optical coherence tomographic angiography (GOCTA) (Part II): theoretical basis of sensitivity improvement and optimization for processing speed Real-time en-face Gabor optical coherence tomographic angiography on human skin using CUDA GPU Post-Doctoral and Graduate Student Research Positions at the University of Illinois Urbana-Champaign Multiscale correlation of microvascular changes on optical coherence tomography angiography with retinal sensitivity in diabetic retinopathy Macrophage targeted theranostic strategy for accurate detection and rapid stabilization of the inflamed high-risk plaque PERSONALIZED CHARACTERISTICS OF MORPHOMETRIC AND FUNCTIONAL PARAMETERS OF RETINA IN ARTERIAL HYPERTENTION ACCORDING TO OPTICAL COHERENCE TOMOGRAPHY-ANGIOGRAPHY DATA Coherence function-encoded optical palpation