1. Articles from Stephen Lam

    1-24 of 31 1 2 »
    1. 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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    2. Early Cancer Detection (Book Chapter)

      Early Cancer Detection (Book Chapter)

      Lung cancer is the leading cause of cancer deaths worldwide as the majority of patient shave advanced disease at diagnosis.  Detection and early treatment of pre-invasive and minimally invasive lung cancer can significantly improve the current 5-year survival of <18%,  Endoscopic optical imaging (such as autoflourescence imaging), NBI, and OCT provide sensitive means to rapidly scan the central airways , in order to detect early lung cancer for biopsy confirmation and delineation of the extent of the tumor spread to guide treatment.

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    3. 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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    4. Sex Differences in Airway Remodeling in a Mouse Model of Chronic Obstructive Pulmonary Disease

      Sex Differences in Airway Remodeling in a Mouse Model of Chronic Obstructive Pulmonary Disease

      Rationale: Adjusting for the amount of smoking, women have a 50% increased risk of COPD compared with men. It is not known what the anatomic basis/mechanism(s) of these sex-related differences in COPD might be. Objective: To characterize the impact of female sex hormones on chronic cigarette smoke-induced airway remodeling and emphysema in a mouse model of COPD. Methods: Airway remodeling and emphysema were determined morphometrically in male, female, and ovariectomized mice exposed to 6 months of cigarette smoke. Antioxidant- and transforming growth factor (TGFβ)-related genes were profiled in airway tissues. The selective estrogen receptor modulator, tamoxifen, was ...

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    5. Reproducibility of optical coherence tomography airway imaging

      Reproducibility of optical coherence tomography airway imaging

      Optical coherence tomography (OCT) is a promising imaging technique to evaluate small airway remodeling. However, the short-term insertion-reinsertion reproducibility of OCT for evaluating the same bronchial pathway has yet to be established. We evaluated 74 OCT data sets from 38 current or former smokers twice within a single imaging session. Although the overall insertion-reinsertion airway wall thickness (WT) measurement coefficient of variation (CV) was moderate at 12%, much of the variability between repeat imaging was attributed to the observer; CV for repeated measurements of the same airway (intra-observer CV) was 9%. Therefore, reproducibility may be improved by introduction of automated ...

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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 ...

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    8. Bronchial thermoplasty in asthma: 2-year follow-up using optical coherence tomography

      Bronchial thermoplasty in asthma: 2-year follow-up using optical coherence tomography

      Bronchial thermoplasty (BT) is a novel, nonpharmacological procedure for treatment of severe asthma. Recently, the Asthma Intervention Research 2 clinical trial demonstrated asthmatics had fewer hospitalisations following BT, which persisted 5 years after therapy [1]. However, it is well recognised that asthma is a heterogeneous disease with distinct asthma phenotypes and, not surprisingly, not all asthmatics in that trial benefited from BT [2].

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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. 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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    11. 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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    12. Validation of Airway Wall Measurements by Optical Coherence Tomography in Porcine Airways

      Validation of Airway Wall Measurements by Optical Coherence Tomography in Porcine Airways

      Examining and quantifying changes in airway morphology is critical for studying longitudinal pathogenesis and interventions in diseases such as chronic obstructive pulmonary disease and asthma. Here we present fiber-optic optical coherence tomography (OCT) as a nondestructive technique to precisely and accurately measure the 2-dimensional cross-sectional areas of airway wall substructure divided into the mucosa (WA muc ), submucosa (WA sub ), cartilage (WA cart ), and the airway total wall area (WAt). Porcine lung airway specimens were dissected from freshly resected lung lobes (N = 10). Three-dimensional OCT imaging using a fiber-optic rotary-pullback probe was performed immediately on airways greater than 0.9 mm ...

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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. High speed, wide velocity dynamic range Doppler optical coherence tomography (Part IV): split spectrum processing in rotary catheter probes

      High speed, wide velocity dynamic range Doppler optical coherence tomography (Part IV): split spectrum processing in rotary catheter probes

      We report a technique for blood flow detection using split spectrum Doppler optical coherence tomography (ssDOCT) that shows improved sensitivity over existing Doppler OCT methods. In ssDOCT, the Doppler signal is averaged over multiple sub-bands of the interferogram, increasing the SNR of the Doppler signal. We explore the parameterization of this technique in terms of number of sub-band windows, width and overlap of the windows, and their effect on the Doppler signal to noise in a flow phantom. Compared to conventional DOCT, ssDOCT processing has increased flow sensitivity. We demonstrate the effectiveness of ssDOCT in-vivo for intravascular flow detection within ...

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    16. Automated segmentation of porcine airway wall layers using optical coherence tomography: comparison with manual segmentation and histology

      Automated segmentation of porcine airway wall layers using optical coherence tomography: comparison with manual segmentation and histology

      The objective was to develop an automated optical coherence tomography (OCT) segmentation method. We evaluated three ex-vivo porcine airway specimens; six non-sequential OCT images were selected from each airway specimen. Histology was also performed for each airway and histology images were co-registered to OCT images for comparison. Manual segmentation of the airway luminal area, mucosa area, submucosa area and the outer airway wall area were performed for histology and OCT images. Automated segmentation of OCT images employed a despecking filter for pre-processing, a hessian-based filter for lumen and outer airway wall area segmentation, and K-means clustering for mucosa and submucosa ...

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    17. Sex differences in chronic obstructive pulmonary disease evaluated using optical coherence tomography

      Sex differences in chronic obstructive pulmonary disease evaluated using optical coherence tomography

      Although there are more women than men dying of chronic obstructive pulmonary disease (COPD) in the United States and elsewhere, we still do not have a clear understanding of the differences in the pathophysiology of airflow obstruction between the sexes. Optical coherence tomography (OCT) is an emerging imaging technology that has the capability of imaging small bronchioles with resolution approaching histology. Therefore, our objective was to compare OCT-derived airway wall measurements between males and females matched for lung size and in anatomically matched small airways. Subjects 50-80 yrs were enrolled in the British Columbia Lung Health Study and underwent OCT ...

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    18. Diagnostic bronchoscopy--current and future perspectives

      Diagnostic bronchoscopy--current and future perspectives

      Lung cancer is the leading cause of cancer-related mortality worldwide. Standard bronchoscopy has limited ability to accurately localise and biopsy pulmonary lesions that cannot be directly visualised. The field of advanced diagnostic bronchoscopy is rapidly evolving due to advances in electronics and miniaturisation. Bronchoscopes with smaller outer working diameters, coupled with miniature radial and convex ultrasound probes, allow accurate central and peripheral pulmonary lesion localisation and biopsy while at the same time avoiding vascular structures. Increases in computational processing power allow three-dimensional reconstruction of computed tomographic raw data to enable virtual bronchoscopy (VB), providing the bronchoscopist with a preview of ...

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    19. 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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    20. In vivo lung microvasculature visualized in three dimensions using fiber-optic color Doppler optical coherence tomography

      In vivo lung microvasculature visualized in three dimensions using fiber-optic color Doppler optical coherence tomography

      For the first time, the use of fiber-optic color Doppler optical coherence tomography (CDOCT) to map in vivo the three-dimensional (3-D) vascular network of airway segments in human lungs is demonstrated. Visualizing the 3-D vascular network in the lungs may provide new opportunities for detecting and monitoring lung diseases such as asthma, chronic obstructive pulmonary disease, and lung cancer. Our CDOCT instrument employs a rotary fiber-optic probe that provides simultaneous two-dimensional (2-D) real-time structural optical coherence tomography (OCT) and CDOCT imaging at frame rates up to 12.5 frames per second. Controlled pullback of the probe allows 3-D vascular mapping ...

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    21. Interventions in Pulmonary Medicine (Book)

      Interventions in Pulmonary Medicine (Book)

      Optical coherence tomography (OCT) is a promising technique for clinical diagnosis of various types of tissue, because high-resolution tomography is easily obtained by its compact imaging optics. The fundamental principles of OCT evolved from optical one-dimensional low-coherence reflectometry, which uses a Michelson interferometer and a broadband light source. Due to the additional transverse scanning (B-scan), two-dimensional imaging was obtained, and this technique was named OCT by Fujimoto and rapidly expanded to numerous biomedical and clinical applications

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    22. Fluorescence and Navigational Bronchoscopy

      Fluorescence and Navigational Bronchoscopy

      Bronchoscopy is a minimally invasive method for lung cancer diagnosis. Smaller and more maneuverable bronchoscopes with higher image resolution and an adequate biopsy channel are being developed. High-resolution multiplanar computed tomography (CT) is used to produce 3-dimensional virtual images of the bronchial tree. The target lesion can be confirmed by a miniradial ultrasound probe and potentially other technologies such as optical coherence tomography. These tools may provide a safer alternative method to CT-guided transthoracic lung biopsy for peripheral lung lesions that are not pleural based.

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    23. Lung vasculature imaging using speckle variance optical coherence tomography

      Lung vasculature imaging using speckle variance optical coherence tomography

      Architectural changes in and remodeling of the bronchial and pulmonary vasculature are important pathways in diseases such as asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. However, there is a lack of methods that can find and examine small bronchial vasculature in vivo. Structural lung airway imaging using optical coherence tomography (OCT) has previously been shown to be of great utility in examining bronchial lesions during lung cancer screening under the guidance of autofluorescence bronchoscopy. Using a fiber optic endoscopic OCT probe, we acquire OCT images from in vivo human subjects. The side-looking, circumferentially-scanning probe is inserted down the ...

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    24. Frontiers in Bronchoscopic Imaging

      Frontiers in Bronchoscopic Imaging
      Bronchoscopy is a minimally-invasive method for diagnosis of diseases of the airways and the lung parenchyma. Standard bronchoscopy uses the reflectance/scattering properties of white light from tissue to examine the macroscopic appearance of airways. It does not exploit the full spectrum of the optical properties of bronchial tissues. Advances in optical imaging such as optical coherence tomography (OCT), confocal endomicroscopy, autofluorescence imaging and laser Raman spectroscopy are at the forefront to allow in-vivo high resolution probing of the microscopic structure, biochemical compositions and even molecular alterations in disease states. OCT can visualize cellular and extracellular structures at and below ...
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    1-24 of 31 1 2 »
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    1. (31 articles) Stephen Lam
    2. (26 articles) British Columbia Cancer Agency
    3. (17 articles) Pierre M. Lane
    4. (12 articles) University of British Columbia
    5. (10 articles) Harvey O. Coxson
    6. (9 articles) Hamid Pahlevaninezhad
    7. (7 articles) Tawimas Shaipanich
    8. (7 articles) Victor X. D. Yang
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