1. Articles mentioning both Martin L. Villiger and Massachusetts General Hospital

    1-24 of 34 1 2 »
    1. Constrained polarization evolution simplifies depth-resolved retardation measurements with polarization-sensitive optical coherence tomography

      Constrained polarization evolution simplifies depth-resolved retardation measurements with polarization-sensitive optical coherence tomography
      We observed that the polarization state of light after round-trip propagation through a birefringent medium frequently aligns with the employed input polarization state mirrored by the horizontal plane of the Poincar sphere. We explored the predisposition for this mirror state and evidence that it constrains the evolution of polarization states as a function of the round-trip depth into weakly scattering birefringent samples, as measured with polarization-sensitive optical coherence tomography (PS-OCT ...
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    2. Distinguishing Tumor from Associated Fibrosis to Increase Diagnostic Biopsy Yield with Polarization-Sensitive Optical Coherence Tomography

      Distinguishing Tumor from Associated Fibrosis to Increase Diagnostic Biopsy Yield with Polarization-Sensitive Optical Coherence Tomography
      Purpose: With recent advancements in personalized medicine, biopsies must contain sufficient tumor for histologic diagnosis and molecular testing. However, inadvertent biopsy of tumor-associated fibrosis compromises tumor yield, resulting in delayed diagnoses and/or repeat procedures when additional tumor is needed. The ability to differentiate tumor from fibrosis intraprocedurally during biopsy could significantly increase tumor yield. Polarization-sensitive optical coherence tomography (PS-OCT) is an imaging modality that is endoscope- and/or needle-compatible ...
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    3. Balloon catheter-based radiofrequency ablation monitoring in porcine esophagus using optical coherence tomography

      Balloon catheter-based radiofrequency ablation monitoring in porcine esophagus using optical coherence tomography
      We present a microscopic image guidance platform for radiofrequency ablation (RFA) using a clinical balloon-catheter-based optical coherence tomography (OCT) system, currently used in the surveillance of Barretts esophagus patients. Our integrated thermal therapy delivery and monitoring platform consists of a flexible, customized bipolar RFA electrode array designed for use with a clinical balloon OCT catheter and a processing algorithm to accurately map the thermal coagulation process. Non-uniform rotation distortion was ...
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    4. Optic axis mapping with catheter-based polarization-sensitive optical coherence tomography

      Optic axis mapping with catheter-based polarization-sensitive optical coherence tomography
      Birefringence offers an intrinsic contrast mechanism related to the microstructure and arrangement of fibrillary tissue components. Here we present a reconstruction strategy to recover not only the scalar amount of birefringence, but also its optic axis orientation as a function of depth in tissue from measurements with catheter-based polarization-sensitive optical coherence tomography. A polarization symmetry constraint, intrinsic to imaging in the backscatter direction, facilitates the required compensation for wavelength-dependent transmission ...
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    5. Quantitative depolarization measurements for fiber‐based polarization‐sensitive optical frequency domain imaging of the retinal pigment epithelium

      Quantitative depolarization measurements for fiber‐based polarization‐sensitive optical frequency domain imaging of the retinal pigment epithelium
      A full quantitative evaluation of the depolarization of light may serve to assess concentrations of depolarizing particles in the retinal pigment epithelium and to investigate their role in retinal diseases in the human eye. Optical coherence tomography (OCT) and optical frequency domain imaging (OFDI) use spatial incoherent averaging to compute depolarization. Depolarization depends on accurate measurements of the polarization states at the receiver but also on the polarization state incident ...
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    6. Robust wavenumber and dispersion calibration for Fourier-domain optical coherence tomography

      Robust wavenumber and dispersion calibration for Fourier-domain optical coherence tomography
      Many Fourier-domain optical coherence tomography (FD-OCT) systems sample the interference fringes with a non-uniform wavenumber ( k ) interval, introducing a chirp to the signal that depends on the path length difference underlying each fringe. A dispersion imbalance between sample and reference arms also generates a chirp in the fringe signal which, in contrast, is independent of depth. Fringe interpolation to obtain a signal linear in k and compensate dispersion imbalance is ...
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    7. Symposium on Advances in Biomedical Polarimetry, March 12, 2018 in Boston

      Symposium on Advances in Biomedical Polarimetry, March 12, 2018 in Boston
      The Center for Biomedical OCT and Research (CBORT) is hosting the Advances in Biomedical Polarimetry with OCT symposium, taking place on Monday March 12, 2018 in Boston. The 1-day program is designed to provide an understanding of the latest PS-OCT instrumentation and signal processing techniques as well as present the use of PS-OCT in numerous biomedical application areas. We anticipate an interdisciplinary group of approximately 125 scientists, engineers, physicists, clinicians ...
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    8. Prediction of scar size in rats six months after burns based on early post injury polarization-sensitive optical frequency domain imaging

      Prediction of scar size in rats six months after burns based on early post injury polarization-sensitive optical frequency domain imaging
      Hypertrophic scars remain a major clinical problem in the rehabilitation of burn survivors and lead to physical, aesthetic, functional, psychological, and social stresses. Prediction of healing outcome and scar formation is critical for deciding on the best treatment plan. Both subjective and objective scales have been devised to assess scar severity. Whereas scales of the first type preclude cross-comparison between observers, those of the second type are based on imaging ...
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    9. Depolarization signatures map gold nanorods within biological tissue

      Depolarization signatures map gold nanorods within biological tissue
      Owing to their electromagnetic properties, tunability and biocompatibility, gold nanorods are being investigated as multifunctional probes for a range of biomedical applications. However, detection beyond the reach of traditional fluorescence and two-photon approaches and quantitation of their concentration in biological tissue remain challenging tasks in microscopy. Here, we show how the size and aspect ratio that impart gold nanorods with their plasmonic properties also make them a source of entropy ...
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    10. Massachusetts General Hospital Receives NIH Grant Quantitative Imaging of Collagen Morphology in Human Scars.

      Massachusetts General Hospital Receives NIH Grant Quantitative Imaging of Collagen Morphology in Human Scars.
      ...H Grant for $50,000 Quantitative Imaging of Collagen Morphology in Human Scars. The principal investigator is Martin Villiger. The program began in 2017 and ends in 2019. Below is a summary of the proposed work.

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    11. Intravascular optical coherence tomography [Invited]

      Intravascular optical coherence tomography [Invited]
      Shortly after the first demonstration of optical coherence tomography for imaging the microstructure of the human eye, work began on developing systems and catheters suitable for intravascular imaging in order to diagnose and investigate atherosclerosis and potentially to monitor therapy. This review covers the driving considerations of the clinical application and its constraints, the major engineering milestones that enabled the current, high-performance commercial imaging systems, the key studies that laid ...
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    12. Extended bandwidth wavelength swept laser source for high resolution optical frequency domain imaging

      Extended bandwidth wavelength swept laser source for high resolution optical frequency domain imaging
      Improving the axial resolution by providing wider bandwidth wavelength swept lasers remains an important issue for optical frequency domain imaging (OFDI). Here, we demonstrate a wide tuning range, all-fiber wavelength swept laser at a center wavelength of 1250 nm by combining two ring cavities that share a single Fabry-Perot tunable filter. The two cavities contain semiconductor optical amplifiers with central wavelengths of 1190 nm and 1292 nm, respectively. To avoid ...
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    13. Optimal selection of laser modulation parameters in photothermal optical coherence tomography

      Optimal selection of laser modulation parameters in photothermal optical coherence tomography
      Photothermal optical coherence tomography (PT-OCT) employs a secondary intensity-modulated photothermal laser to create modulated thermal strains that cause variations of the refractive index in the proximity of absorbing chromophores. These variations are directly detected with phase-sensitive OCT and offer insight to the molecular composition and thermo-elastic properties of the sample. Here, we define optimal PT laser modulation parameters by investigating the effect of PT laser power and modulation frequency on ...
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    14. Birefringence microscopy platform for assessing airway smooth muscle structure and function in vivo

      Birefringence microscopy platform for assessing airway smooth muscle structure and function in vivo
      The inability to visualize airway smooth muscle (ASM) cells in vivo is a major obstacle in understanding their role in normal physiology and diseases. At present, there is no imaging modality available to assess ASM in vivo. Confocal endomicroscopy lacks the penetration depth and field of view, and conventional optical coherence tomography (OCT) does not have sufficient contrast to differentiate ASM from surrounding tissues. We have developed a birefringence microscopy ...
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    15. Automatic classification of atherosclerotic plaques imaged with intravascular OCT

      Automatic classification of atherosclerotic plaques imaged with intravascular OCT
      Intravascular optical coherence tomography (IV-OCT) allows evaluation of atherosclerotic plaques; however, plaque characterization is performed by visual assessment and requires a trained expert for interpretation of the large data sets. Here, we present a novel computational method for automated IV-OCT plaque characterization. This method is based on the modeling of each A-line of an IV-OCT data set as a linear combination of a number of depth profiles. After estimating these ...
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    16. Laser thermal therapy monitoring using complex differential variance in optical coherence tomography

      Laser thermal therapy monitoring using complex differential variance in optical coherence tomography
      Conventional thermal therapy monitoring techniques based on temperature are often invasive, limited by point sampling, and are indirect measures of tissue injury, while techniques such as magnetic resonance and ultrasound thermometry are limited by their spatial resolution. The visualization of the thermal coagulation zone at high spatial resolution is particularly critical to the precise delivery of thermal energy to epithelial lesions. In this work, an integrated thulium laser thermal therapy ...
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    17. Deep tissue volume imaging of birefringence through fibre-optic needle probes for the delineation of breast tumour

      Deep tissue volume imaging of birefringence through fibre-optic needle probes for the delineation of breast tumour
      Identifying tumour margins during breast-conserving surgeries is a persistent challenge. We have previously developed miniature needle probes that could enable intraoperative volume imaging with optical coherence tomography. In many situations, however, scattering contrast alone is insufficient to clearly identify and delineate malignant regions. Additional polarization-sensitive measurements provide the means to assess birefringence, which is elevated in oriented collagen fibres and may offer an intrinsic biomarker to differentiate tumour from benign ...
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    18. Feature of the Week 03/26/2016: Longitudinal, 3D Imaging of Collagen Remodeling in Murine Hypertrophic Scars In Vivo Using Polarization-Sensitive Optical Frequency Domain Imaging

      Feature of the Week 03/26/2016: Longitudinal, 3D Imaging of Collagen Remodeling in Murine Hypertrophic Scars In Vivo Using Polarization-Sensitive Optical Frequency Domain Imaging
      ...iomedical OCT Research and Translation, Center for Engineering in Medicine at Massachusetts General Hospital (MGH) and Shriners Burn Hospital, Division of Plastic and Reconstructive Surgery at MGH, and Program in Dermato...
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    19. Towards in vivo laser coagulation and concurrent optical coherence tomography through double-clad fiber devices

      Towards in vivo laser coagulation and concurrent optical coherence tomography through double-clad fiber devices
      There is a strong clinical need for an optical coherence tomography (OCT) system capable of delivering concurrent coagulation light enabling image-guided dynamic laser marking for targeted collection of biopsies, as opposed to a random sampling, to reduce false-negative findings. Here, we present a system based on double-clad fiber (DCF) capable of delivering pulsed laser light through the inner cladding while performing OCT through the core. A previously clinically validated commercial ...
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    20. Longitudinal, 3D Imaging of Collagen Remodeling in Murine Hypertrophic Scars In Vivo Using Polarization-Sensitive Optical Frequency Domain Imaging

      Longitudinal, 3D Imaging of Collagen Remodeling in Murine Hypertrophic Scars In Vivo Using Polarization-Sensitive Optical Frequency Domain Imaging
      Hypertrophic scars (HTS), frequently seen after traumatic injuries and surgery, remain a major clinical challenge because of the limited success of existing therapies. A significant obstacle to understanding HTS etiology is the lack of tools to monitor scar remodeling longitudinally and noninvasively. We present an in vivo, label-free technique using polarization-sensitive optical frequency domain imaging for the 3D, longitudinal assessment of collagen remodeling in murine HTS. In this study, HTS ...
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    21. Ultrahigh-resolution optical coherence elastography

      Ultrahigh-resolution optical coherence elastography
      Visualizing stiffness within the local tissue environment at the cellular and subcellular level promises to provide insight into the genesis and progression of disease. In this Letter, we propose ultrahigh-resolution optical coherence elastography (UHROCE), and demonstrate 3D imaging of local axial strain of tissues undergoing compressive loading. We combine optical coherence microscopy (OCM) and phase-sensitive detection of local tissue displacement to produce strain elastograms with resolution (
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    22. Degree of polarization (uniformity) and depolarization index: unambiguous depolarization contrast for optical coherence tomography

      Degree of polarization (uniformity) and depolarization index: unambiguous depolarization contrast for optical coherence tomography
      The degree of polarization (uniformity) has attracted increased interest as a functional contrast in optical coherence tomography (OCT). However, its computation from a single polarization state suggests an ambiguity that is strongly dependent on a samples orientation. We here propose an improved metric to present depolarization with respect to the optical system rather than the propagating field. Using numerical simulations and optical frequency domain imaging, we evaluate the conventional DOP ...
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    23. Feature Of The Week 5/10/2015: Laser Tissue Coagulation and Concurrent Optical Coherence Tomography Through a Double-Clad Fiber Coupler

      Feature Of The Week 5/10/2015: Laser Tissue Coagulation and Concurrent Optical Coherence Tomography Through a Double-Clad Fiber Coupler
      ... Polytechnique Montréal (Canada) and Professor Brett E. Bouma’s team at the Wellman Center for Photomedicine (MGH, Boston). The goal is to assess whether OCT-guided biopsy could benefit from the use of double-clad fiber ...
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    24. 1-24 of 34 1 2 »
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  2. Organizations in the News

    1. (32 articles) Harvard University
    2. (8 articles) Massachusetts Institute of Technology
    3. (4 articles) Korea Advanced Institute of Science and Technology
    4. (2 articles) Polytechnique Montreal
    5. (2 articles) University of Western Australia
    6. (2 articles) Brigham and Women’s Hospital
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    8. (1 articles) National Institutes of Health
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    10. (1 articles) Erasmus University
    11. (1 articles) Sungkyunkwan University
    12. (1 articles) Ecole Polytechnique Fédérale de Lausanne
  3. People in the News

    1. (28 articles) Brett E. Bouma
    2. (6 articles) Benjamin J. Vakoc
    3. (6 articles) Wang Yuhl Oh
    4. (4 articles) Kathy Beaudette
    5. (4 articles) William C. Y. Lo
    6. (3 articles) Caroline Boudoux
    7. (3 articles) Lida P. Hariri
    8. (3 articles) Melissa J. Suter
    9. (2 articles) David D. Sampson
    10. (2 articles) Dirk Lorenser
    11. (1 articles) Guillermo J. Tearney
    12. (1 articles) Milen Shishkov
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    1. (1 articles) NinePoint Medical