1. Articles from Hamid Pahlevaninezhad

    1-15 of 15
    1. Systems for optical imaging of biological tissues

      Systems for optical imaging of biological tissues

      A fiber-based polarization sensitive optical coherence tomography (PS-OCT) system uses a new polarization diversity detection (PDD) scheme and requires no active polarization modulating components. Retardation of the sample can be determined from amplitudes of arbitrarily-oriented x- and y-components of the reflected light. A hybrid custom 50/50 coupler with single-mode fiber inputs and polarization maintaining (PM) fiber outputs combines light from sample and reference arms of an interferometer. Another embodiment provides a system adapted to provide co-registered autofluorescence-optical coherence tomography (AF-OCT) imaging. AF excitation light is introduced and collected AF light is extracted at a fiber optic rotary joint (FORJ ...

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    2. Nano-optic endoscope for high-resolution optical coherence tomography in vivo

      Nano-optic endoscope for high-resolution optical coherence tomography in vivo

      Acquisition of high-resolution images from within internal organs using endoscopic optical imaging has numerous clinical applications. However, difficulties associated with optical aberrations and the trade-off between transverse resolution and depth of focus significantly limit the scope of applications. Here, we integrate a metalens, with the ability to modify the phase of incident light at subwavelength level, into the design of an endoscopic optical coherence tomography catheter (termed nano-optic endoscope) to achieve near diffraction-limited imaging through negating non-chromatic aberrations. Remarkably, the tailored chromatic dispersion of the metalens in the context of spectral interferometry is utilized to maintain high-resolution imaging beyond the ...

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    3. Correction of motion artifacts in endoscopic optical coherence tomography and autofluorescence images based on azimuthal en face image registration

      Correction of motion artifacts in endoscopic optical coherence tomography and autofluorescence images based on azimuthal en face image registration

      We present a method for the correction of motion artifacts present in two- and three-dimensional in vivoendoscopic images produced by rotary-pullback catheters. This method can correct for cardiac/breathing-based motion artifacts and catheter-based motion artifacts such as nonuniform rotational distortion (NURD). This method assumes that en face tissue imaging contains slowly varying structures that are roughly parallel to the pullback axis. The method reduces motion artifacts using a dynamic time warping solution through a cost matrix that measures similarities between adjacent frames in en face images. We optimize and demonstrate the suitability of this method using a real and ...

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    4. Optical Coherence Tomography: A Review (Book Chapter)

      Optical Coherence Tomography: A Review (Book Chapter)

      Optical coherence tomography (OCT), with polarization-sensitive (PS), Doppler, and autofluorescence (AF) capabilities, is emerging as a promising bronchoscopic diagnostic tool. In the upper and central airways, it allows accurate real-time airway measurements to assist bronchoscopic assessment of obstructive sleep apnea, severity of tracheomalacia, airway stenosis, or extent of tumor involvement into the bronchial wall or distally beyond the bronchoscopic view. OCT can visualize cellular and extracellular structures at and below the tissue surface with near histologic resolution as well as to provide three-dimensional imaging of the airways. Blood vessels in the bronchial wall or peribronchial space can be displayed using ...

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    5. Automated segmentation and quantification of airway mucus with endobronchial optical coherence tomography

      Automated segmentation and quantification of airway mucus with endobronchial optical coherence tomography

      We propose a novel suite of algorithms for automatically segmenting the airway lumen and mucus in endobronchial optical coherence tomography (OCT) data sets, as well as a novel approach for quantifying the contents of the mucus. Mucus and lumen were segmented using a robust, multi-stage algorithm that requires only minimal input regarding sheath geometry. The algorithm performance was highly accurate in a wide range of airway and noise conditions. Mucus was classified using mean backscattering intensity and grey level co-occurrence matrix (GLCM) statistics. We evaluated our techniques in vivo in asthmatic and non-asthmatic volunteers.

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    6. Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature

      Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature

      We present the first endoscopic Doppler optical coherence tomography and co-registered autofluorescence imaging (DOCT-AFI) of peripheral pulmonary nodules and vascular networks in vivo using a small 0.9 mm diameter catheter. Using exemplary images from volumetric data sets collected from 31 patients during flexible bronchoscopy, we demonstrate how DOCT and AFI offer complementary information that may increase the ability to locate and characterize pulmonary nodules. AFI offers a sensitive visual presentation for the rapid identification of suspicious airway sites, while co-registered OCT provides detailed structural information to assess the airway morphology. We demonstrate the ability of AFI to visualize vascular ...

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    7. Systems For Optical Imaging Of Biological Tissues

      Systems For Optical Imaging Of Biological Tissues

      A fiber-based polarization sensitive optical coherence tomography (PS-OCT) system uses a new polarization diversity detection (PDD) scheme and requires no active polarization modulating components. Retardation of the sample can be determined from amplitudes of arbitrarily-oriented x- and y-components of the reflected light. A hybrid custom 50/50 coupler with single-mode fiber inputs and polarization maintaining (PM) fiber outputs combines light from sample and reference arms of an interferometer. Another embodiment provides a system adapted to provide co-registered autofluorescence-optical coherence tomography (AF-OCT) imaging. AF excitation light is introduced and collected AF light is extracted at a fiber optic rotary joint (FORJ ...

      Read Full Article
    8. Passive endoscopic polarization sensitive optical coherence tomography with completely fiber based optical components

      Passive endoscopic polarization sensitive optical coherence tomography with completely fiber based optical components

      Polarization Sensitive Optical Coherence Tomography (PSOCT) is a functional extension of Optical Coherence Tomography (OCT) that is sensitive to well-structured, birefringent tissue such as scars, smooth muscle and cartilage. In this work, we present a novel completely fiber based swept source PSOCT system using a fiber-optic rotary pullback catheter. This PSOCT implementation uses only passive optical components and requires no calibration while adding minimal additional cost to a standard structural OCT imaging system. Due to its complete fiber construction, the system can be made compact and robust, while the fiber-optic catheter allows access to most endoscopic imaging sites. The 1 ...

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    9. Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer

      Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer

      Diagnosis of peripheral lung nodules is challenging because they are rarely visualized endobronchially. Imaging techniques such as endobronchial ultrasound (EBUS) are employed to improve tumor localization. The current EBUS probe provides limited nodule characterization and has an outer diameter of 1.4 mm that restricts access to small peripheral airways. We report a novel co-registered autofluoresence Doppler optical coherence tomography (AF/DOCT) system with a 0.9 mm diameter probe to characterize peripheral lung nodules prior to biopsy in vivo. Method: Patients referred for evaluation of peripheral lung nodules underwent bronchoscopy with examination of standard EBUS and the novel AF ...

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    10. Optical coherence tomography and autofluorescence imaging of human tonsil

      Optical coherence tomography and autofluorescence imaging of human tonsil

      For the first time, we present co-registered autofluorescence imaging and optical coherence tomography (AF/OCT) of excised human palatine tonsils to evaluate the capabilities of OCT to visualize tonsil tissue components. Despite limited penetration depth, OCT can provide detailed structural information about tonsil tissue with much higher resolution than that of computed tomography, magnetic resonance imaging, and Ultrasound. Different tonsil tissue components such as epithelium, dense connective tissue, lymphoid nodules, and crypts can be visualized by OCT. The co-registered AF imaging can provide matching biochemical information. AF/OCT scans may provide a non-invasive tool for detecting tonsillar cancers and for ...

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    11. Fiber-Based Polarization Diversity Detection for Polarization-Sensitive Optical Coherence Tomography

      Fiber-Based Polarization Diversity Detection for  Polarization-Sensitive Optical Coherence Tomography

      We present a new fiber-based polarization diversity detection (PDD) scheme for polarization sensitive optical coherence tomography (PSOCT). This implementation uses a new custom miniaturized polarization-maintaining fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the two orthogonal OCT polarization channels prior to interference while the PM fiber outputs ensure defined orthogonal axes after interference. Advantages of this detection scheme over those with bulk optics PDD include lower cost, easier miniaturization, and more relaxed alignment and handling issues. We incorporate this PDD scheme into a galvanometer-scanned ...

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    12. A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography

      A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography

      We present a power-efficient fiber-based imaging system capable of co-registered autofluorescence imaging and optical coherence tomography (AF/OCT). The system employs a custom fiber optic rotary joint (FORJ) with an embedded dichroic mirror to efficiently combine the OCT and AF pathways. This three-port wavelength multiplexing FORJ setup has a throughput of more than 83% for collected AF emission, significantly more efficient compared to previously reported fiber-based methods. A custom 900 µm diameter catheter ‒ consisting of a rotating lens assembly, double-clad fiber (DCF), and torque cable in a stationary plastic tube ‒ was fabricated to allow AF/OCT imaging of small airways ...

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    13. Fiber-optic polarization diversity detection for rotary probe optical coherence tomography

      Fiber-optic polarization diversity detection for rotary probe optical coherence tomography

      We report a polarization diversity detection scheme for optical coherence tomography with a new, custom, miniaturized fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the X and Y OCT polarization channels prior to interference and the PM fiber outputs ensure defined X and Y axes after interference. Advantages for this scheme include easier alignment, lower cost, and easier miniaturization compared to designs with free-space bulk optical components. We demonstrate the utility of the detection system to mitigate the effects of rapidly changing polarization states ...

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    14. Coregistered autofluorescence-optical coherence tomography imaging of human lung sections

      Coregistered autofluorescence-optical coherence tomography imaging of human lung sections

      Autofluorescence (AF) imaging can provide valuable information about the structural and metabolic state of tissue that can be useful for elucidating physiological and pathological processes. Optical coherence tomography (OCT) provides high resolution detailed information about tissue morphology. We present coregistered AF-OCT imaging of human lung sections. Adjacent hematoxylin and eosin stained histological sections are used to identify tissue structures observed in the OCT images. Segmentation of these structures in the OCT images allowed determination of relative AF intensities of human lung components. Since the AF imaging was performed on tissue sections perpendicular to the airway axis, the results show the ...

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    15. Multimodal tissue imaging: using coregistered optical tomography data to estimate tissue autofluorescence intensity change due to scattering and absorption by neoplastic epithelial cells

      Multimodal tissue imaging: using coregistered optical tomography data to estimate tissue autofluorescence intensity change due to scattering and absorption by neoplastic epithelial cells

      Autofluorescence (AF) imaging provides valuable information about the structural and chemical states of tissue that can be used for early cancer detection. Optical scattering and absorption of excitation and emission light by the epithelium can significantly affect observed tissue AF intensity. Determining the effect of epithelial attenuation on the AF intensity could lead to a more accurate interpretation of AF intensity. We propose to use optical coherence tomography coregistered with AF imaging to characterize the AF attenuation due to the epithelium. We present imaging results from three vital tissue models, each consisting of a three-dimensional tissue culture grown from one ...

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    1-15 of 15
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  2. Topics in the News

    1. (13 articles) British Columbia Cancer Agency
    2. (13 articles) Hamid Pahlevaninezhad
    3. (12 articles) Stephen Lam
    4. (12 articles) Pierre M. Lane
    5. (4 articles) Lucas Cahill
    6. (3 articles) Tawimas Shaipanich
    7. (2 articles) Ryerson University
    8. (2 articles) University of British Columbia
    9. (2 articles) Matthew Brenner
    10. (2 articles) Victor X. D. Yang
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    Multimodal tissue imaging: using coregistered optical tomography data to estimate tissue autofluorescence intensity change due to scattering and absorption by neoplastic epithelial cells Coregistered autofluorescence-optical coherence tomography imaging of human lung sections Fiber-optic polarization diversity detection for rotary probe optical coherence tomography A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography Fiber-Based Polarization Diversity Detection for  Polarization-Sensitive Optical Coherence Tomography Optical coherence tomography and autofluorescence imaging of human tonsil Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer Passive endoscopic polarization sensitive optical coherence tomography with completely fiber based optical components Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature Nano-optic endoscope for high-resolution optical coherence tomography in vivo ORCA study: real-world versus reading centre assessment of disease activity of neovascular age-related macular degeneration (nAMD) Role of visual evoked potentials and optical coherence tomography in the screening for optic pathway gliomas in patients with neurofibromatosis type I