1. Articles from Kenneth K. C. Lee

    1-11 of 11
    1. Histogram flow mapping with optical coherence tomography for in vivo skin angiography of hereditary hemorrhagic telangiectasia

      Histogram flow mapping with optical coherence tomography for in vivo skin angiography of hereditary hemorrhagic telangiectasia

      Speckle statistics of flowing scatterers have been well documented in the literature. Speckle variance optical coherence tomography exploits the large variance values of intensity changes in time caused mainly by the random backscattering of light resulting from translational activity of red blood cells to map out the microvascular networks. A method to map out the microvasculature malformation of skin based on the time-domain histograms of individual pixels is presented with results obtained from both normal skin and skin containing vascular malformation. Results demonstrated that this method can potentially map out deeper blood vessels and enhance the visualization of microvasculature in ...

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    2. Blood flow velocity measurement by endovascular Doppler optical coherence tomography

      Blood flow velocity measurement by endovascular Doppler optical coherence tomography

      Blood flow velocity and volumetric flow measurements are important parameters for assessment of the severity of stenosis and the outcome of interventional therapy. However, feasibility of intravascular flow measurement using a rotational catheter based phase resolved Doppler optical coherence tomography (DOCT) is difficult. Motion artefacts induced by the rotating optical imaging catheter, and the radially dependent noise background of measured Doppler signals are the main challenges encountered. In this study, a custom-made data acquisition system and developed algorithms to remove non-uniform rotational distortion (NURD) induced phase shift artefact by tracking the phase shift observed on catheter sheath. The flow velocity ...

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    3. In vivo feasibility of endovascular Doppler optical coherence tomography

      In vivo feasibility of endovascular Doppler optical coherence tomography

      Feasibility of detecting intravascular flow using a catheter based endovascular optical coherence tomography (OCT) system is demonstrated in a porcine carotid model in vivo. The effects of A-line density, radial distance, signal-to-noise ratio, non-uniform rotational distortion (NURD), phase stability of the swept wavelength laser and interferometer system on Doppler shift detection limit were investigated in stationary and flow phantoms. Techniques for NURD induced phase shift artifact removal were developed by tracking the catheter sheath. Detection of high flow velocity (~51 cm/s) present in the porcine carotid artery was obtained by phase unwrapping techniques and compared to numerical simulation, taking ...

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    4. Real-time speckle variance swept-source optical coherence tomography using a graphics processing unit

      Real-time speckle variance swept-source optical coherence tomography using a graphics processing unit

      Abstract: Advances in swept source laser technology continues to increase the imaging speed of swept-source optical coherence tomography (SS-OCT) systems. These fast imaging speeds are ideal for microvascular detection schemes, such as speckle variance (SV), where interframe motion can cause severe imaging artifacts and loss of vascular contrast. However, full utilization of the laser scan speed has been hindered by the computationally intensive signal processing required by SS-OCT and SV calculations. Using a commercial graphics processing unit that has been optimized for parallel data processing, we report a complete high-speed SS-OCT platform capable of real-time data acquisition, processing, display, and ...

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    5. Intraoperative handheld optical coherence tomography forward-viewing probe: physical performance and preliminary animal imaging

      Intraoperative handheld optical coherence tomography forward-viewing probe: physical performance and preliminary animal imaging

      A prototype intraoperative hand-held optical coherence tomography (OCT) imaging probe was developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic probe was designed based on electrostatically driven optical fibers, and packaged into a catheter probe in the form factor of clinically accepted Bayonet shaped neurosurgical probes. Optical properties of the probe were measured to have a ~20 μm spot size, 5 mm working distance and 4 mm field of view. Feasibility of this probe for structural and Doppler shift imaging was tested on porcine femoral blood vessel imaging.

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    6. Speckle variance optical coherence tomography of the rodent spinal cord: in vivo feasibility

      Speckle variance optical coherence tomography of the rodent spinal cord: in vivo feasibility

      Optical coherence tomography (OCT) has the combined advantage of high temporal (µsec) and spatial (less than 10µm) resolution. These features make it an attractive tool to study the dynamic relationship between neural activity and the surrounding blood vessels in the spinal cord, a topic that is poorly understood. Here we present work that aims to optimize an in vivo OCT imaging model of the rodent spinal cord. In this study we image the microvascular networks of both rats and mice using speckle variance OCT. This is the first report of depth resolved imaging of the in vivo spinal cord using ...

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    7. Neurosurgical hand-held optical coherence tomography (OCT) forward-viewing probe

      Neurosurgical hand-held optical coherence tomography (OCT) forward-viewing probe

      A prototype neurosurgical hand-held optical coherence tomography (OCT) imaging probe has been developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic hand-held probe has been designed based on our group's previous work on electrostatically driven optical fibers. It has been packaged into a catheter probe in the familiar form factor of the clinically accepted Bayonet shaped neurosurgical non-imaging Doppler ultrasound probes. The optical design was optimized using ZEMAX simulation. Optical properties of the probe were tested to yield an ~20 um spot size, 5 mm working distance and a 3.5 mm ...

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    8. Endovascular optical coherence tomography intensity kurtosis: visualization of vasa vasorum in porcine carotid artery

      Endovascular optical coherence tomography intensity kurtosis: visualization of vasa vasorum in porcine carotid artery

      lication of speckle variance optical coherence tomography (OCT) to endovascular imaging faces difficulty of extensive motion artifacts inherently associated with arterial pulsations in addition to other physiological movements. In this study, we employed a technique involving a fourth order statistical method, kurtosis, operating on the endovascular OCT intensity images to visualize the vasa vasorum of carotid artery in vivo and identify its flow dynamic in a porcine model. The intensity kurtosis technique can distinguish vasa vasorum from the surrounding tissues in the presence of extensive time varying noises and dynamic motions of the arterial wall. Imaging of vasa vasorum and ...

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    9. Simultaneous 6-channel optical coherence tomography using a high-power telescope-less polygon-based swept laser in dual amplifier configuration

      Simultaneous 6-channel optical coherence tomography using a high-power telescope-less polygon-based swept laser in dual amplifier configuration
      Multichannel optical coherence tomography (MOCT) imaging is demonstrated using a high-power wavelength-swept laser source. The main benefit of MOCT is faster image acquisition rates without a corresponding increase in the laser tuning speed. The wavelength-swept laser was constructed using a compact telescope-less polygon-based filter in Littman arrangement. High output power, necessary for MOCT, was achieved by incorporating two serial semiconductor optical amplifiers in a ring laser cavity in Fourier domain mode-locked configuration. The laser has a measured wavelength tuning range of 111 nm centered at 1329 nm, coherence length of 5.5 mm, and total average output power of 131 ...
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    10. In vivo endoscopic multi-beam optical coherence tomography

      In vivo endoscopic multi-beam optical coherence tomography
      multichannel optical coherence tomography (multi-beam OCT) system and an in vivo endoscopic imaging probe were developed using a swept-source OCT system. The distal optics were micro-machined to produce a high numerical aperture, multi-focus fibre optic array. This combination resulted in a transverse design resolution of <10 µm full width half maximum (FWHM) throughout the entire imaging range, while also increasing the signal intensity within the focus of the individual channels. The system was used in a pre-clinical rabbit study to acquire in vivo structural images of the colon and ex vivo images of the oesophagus and trachea. A good correlation ...
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    11. Interstitial Doppler Optical Coherence Tomography as a Local Tumor Necrosis Predictor in Photodynamic Therapy of Prostatic Carcinoma: An In vivo Study

      We have tested the feasibility of real-time localized blood flow measurements, obtained with interstitial (IS) Doppler optical coherence tomography (DOCT), to predict photodynamic therapy (PDT)-induced tumor necrosis deep within solid Dunning rat prostate tumors. IS-DOCT was used to quantify the PDT-induced microvascular shutdown rate in s.c. Dunning prostate tumors (n = 28). Photofrin (12.5 mg/kg) was administered 20 to 24 hours before tumor irradiation, with 635 nm surface irradiance of 8 to 133 mWcm–2 for 25 minutes. High frequency ultrasound and calipers were used to measure the thickness of the skin covering the tumor and the ...
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    1-11 of 11
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  2. Topics in the News

    1. (11 articles) Kenneth K. C. Lee
    2. (11 articles) Victor X. D. Yang
    3. (10 articles) University of Toronto
    4. (10 articles) Ryerson University
    5. (9 articles) Adrian Mariampillai
    6. (8 articles) Beau A. Standish
    7. (5 articles) Cuiru Sun
    8. (4 articles) Sunnybrook Health Sciences Centre
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    In vivo endoscopic multi-beam optical coherence tomography Simultaneous 6-channel optical coherence tomography using a high-power telescope-less polygon-based swept laser in dual amplifier configuration Endovascular optical coherence tomography intensity kurtosis: visualization of vasa vasorum in porcine carotid artery Neurosurgical hand-held optical coherence tomography (OCT) forward-viewing probe Speckle variance optical coherence tomography of the rodent spinal cord: in vivo feasibility Intraoperative handheld optical coherence tomography forward-viewing probe: physical performance and preliminary animal imaging Real-time speckle variance swept-source optical coherence tomography using a graphics processing unit In vivo feasibility of endovascular Doppler optical coherence tomography Blood flow velocity measurement by endovascular Doppler optical coherence tomography Non Exudative AMD Imaged With SS-OCT- Extension High space-bandwidth in quantitative phase imaging using partially spatially coherent optical coherence microscopy and deep neural network Optical coherence tomography assessment of macrophages accumulation in non-ST-segment elevation acute coronary syndromes