1. Harvard University

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    1. Mentioned In 508 Articles

    2. Multi-functional angiographic OFDI using frequency-multiplexed dual-beam illumination

      Multi-functional angiographic OFDI using frequency-multiplexed dual-beam illumination

      Detection of blood flow inside the tissue sample can be achieved by measuring the local change of complex signal over time in angiographic optical coherence tomography (OCT). In conventional angiographic OCT, the transverse displacement of the imaging beam during the time interval between a pair of OCT signal measurements must be significantly reduced to minimize the noise due to the beam scanning-induced phase decorrelation at the expense of the imaging speed. Recent introduction of dual-beam scan method either using polarization encoding or two identical imaging systems in spectral-domain (SD) OCT scheme shows potential for high-sensitivity vasculature imaging without suffering from ...

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    3. Multimodal reconstruction of microvascular-flow distributions using combined two-photon microscopy and Doppler optical coherence tomography

      Multimodal reconstruction of microvascular-flow distributions using combined two-photon microscopy and Doppler optical coherence tomography

      Computing microvascular cerebral blood flow ( μ CBF ) in real cortical angiograms is challenging. Here, we investigated whether the use of Doppler optical coherence tomography (DOCT) flow measurements in individual vessel segments can help in reconstructing μ CBF across the entire vasculature of a truncated cortical angiogram. A μ CBF computational framework integrating DOCT measurements is presented. Simulations performed on a synthetic angiogram showed that the addition of DOCT measurements, especially close to large inflowing or outflowing vessels, reduces the impact of pressure boundary conditions and estimated vessel resistances resulting in a more accurate reconstruction of μ CBF . Our technique was then applied to reconstruct ...

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    4. Laser tissue coagulation and concurrent optical coherence tomography through a double-clad fiber coupler

      Laser tissue coagulation and concurrent optical coherence tomography through a double-clad fiber coupler
      ...ntreal, Department of Engineering Physics, Montreal, QC H3C 3A7, Canada ^2Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114, USA ^3School of Elec...
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    5. Feature Of The Week 03/08/2015: Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature

      Feature Of The Week 03/08/2015: Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature

      Endoscopic imaging technologies such as confocal laser endomicroscopy (CLE) and narrowband imaging (NBI) have been used to investigate vascular changes as hallmarks of early cancer in the GI tract. However, the limited frame rate and field of view make CLE imaging sensitive to motion artifacts, whereas NBI has limited resolution and visualizes only the surface vascular pattern. Endoscopic optical coherence tomography (OCT) enables high speed volumetric imaging of subsurface features at near-microscopic resolution, and can image microvasculature without exogenous contrast agents such as fluorescein, which obliterates the image in areas of bleeding, or after biopsies and resections. OCT has been ...

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    6. Optical coherence tomography visualizes neurons in human entorhinal cortex

      Optical coherence tomography visualizes neurons in human entorhinal cortex

      The cytoarchitecture of the human brain is of great interest in diverse fields: neuroanatomy, neurology, neuroscience, and neuropathology. Traditional histology is a method that has been historically used to assess cell and fiber content in the ex vivo human brain. However, this technique suffers from significant distortions. We used a previously demonstrated optical coherence microscopy technique to image individual neurons in several square millimeters of en-face tissue blocks from layer II of the human entorhinal cortex, over 50     μ m in depth. The same slices were then sectioned and stained for Nissl substance. We registered the optical coherence tomography (OCT) images ...

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    7. Practical Challenges of Current Video Rate OCT Elastography: Accounting for Dynamic and Static Tissue Properties

      Practical Challenges of Current Video Rate OCT Elastography: Accounting for Dynamic and Static Tissue Properties

      Optical coherence tomography (OCT) elastography (OCTE) has the potential to be an important diagnostic tool for pathologies including coronary artery disease, osteoarthritis, malignancies, and even dental caries. Many groups have performed OCTE, including our own, using a wide range of approaches. However, we will demonstrate current OCTE approaches are not scalable to real-time, in vivo imaging. As will be discussed, among the most important reasons is current designs focus on the system and not the target. Specifically, tissue dynamic responses are not accounted, with examples being the tissue strain response time, preload variability, and conditioning variability. Tissue dynamic responses, and ...

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    8. Correlation of localized glaucomatous visual field defects and spectral domain optical coherence tomography retinal nerve fiber layer thinning using a modified structure-function map for OCT

      Correlation of localized glaucomatous visual field defects and spectral domain optical coherence tomography retinal nerve fiber layer thinning using a modified structure-function map for OCT

      Purpose To study the correlation between glaucomatous visual field (VF) defects assessed by standard automated perimetry (SAP) and peripapillary retinal nerve fiber layer (RNFL) thinning measured by spectral domain optical coherence tomography (OCT) using a modified OCT-based peripapillary RNFL structure–function map. Patients and methods Perimetric glaucoma patients and age-matched normal control subjects were recruited from a university hospital clinic. All eyes underwent testing with the Spectralis spectral domain OCT and SAP on the same day. An OCT-based correspondence map, which correlated VF areas with peripapillary RNFL sectors was created to evaluate the relationship between glaucomatous RNFL thinning and VF ...

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    9. Reproducibility of Optovue RTVue Optical Coherence Tomography Retinal Thickness Measurements and Conversion to Equivalent Zeiss Stratus Metrics in Diabetic Macular Edema

      Reproducibility of Optovue RTVue Optical Coherence Tomography Retinal Thickness Measurements and Conversion to Equivalent Zeiss Stratus Metrics in Diabetic Macular Edema
      ...iversity, Durham, NC, USA ^6Department of Ophthalmology, Joslin Diabetes Center, Beetham Eye Institute, Harvard University, Boston, MA, USA Purpose: To evaluate the reproducibility of central subfield thickness (...
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    10. Optical Coherence Tomographic Evaluation of the Effect of Cigarette Smoking on Vascular Healing after Sirolimus-Eluting Stent Implantation

      Optical Coherence Tomographic Evaluation of the Effect of Cigarette Smoking on Vascular Healing after Sirolimus-Eluting Stent Implantation

      Cigarette smoking is known to be deleterious to patients with coronary artery disease, however the effect of smoking on vascular responses after coronary drug-eluting stent implantation is unknown. We sought to examine vascular response after sirolimus-eluting stent (SES) implantation in patients with ongoing smoking using optical coherence tomography (OCT), compared with former smokers and nonsmokers. We identified 181 SESs in 140 subjects who underwent follow-up OCT imaging. Subjects were divided into 3 groups: current smokers (n = 28), former smokers (n = 35), and nonsmokers (n = 77). Stent strut coverage, neointimal characteristics, and strut malapposition were evaluated. The incidence of uncovered stent ...

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    11. 1-15 of 508 1 2 3 4 ... 32 33 34 »
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  2. About Harvard University

    Harvard University

    Harvard University is a private university in Cambridge, Massachusetts, U.S. Founded in 1636 by the colonial Massachusetts legislature Harvard is the oldest institution of higher learning in the United States.  Harvard Medical School  is one of the graduate schools of Harvard University. It is a prestigious American medical school located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts.  Schepens Eye Research Institute fights blindness by developing new technologies, therapies and knowledge to retain and restore vision. Through a continuum of discovery, the Institute works toward a future in which blindness is prevented, alleviated, and, ultimately, cured.