1. Articles from Brett E. Bouma

    73-96 of 141 « 1 2 3 4 5 6 »
    1. Compensation of motion artifacts in intracoronary optical frequency domain imaging and optical coherence tomography

      Compensation of motion artifacts in intracoronary optical frequency domain imaging and optical coherence tomography

      Abstract  Intracoronary optical coherence tomography and optical frequency domain imaging (OFDI) have been utilized for two-dimensional and three-dimensional imaging of vascular microanatomy. Image quality and the spatial accuracy of multidimensional reconstructions, however, can be degraded due to artifacts resulting from relative motion between the intracoronary catheter and the vessel wall. To track the relative motion of a catheter with regard to the vessel, a motion tracking system was incorporated with a standard OFDI system by using wavelength division multiplexing techniques. Motion of the vessel was acquired by a frequency shift of the backscattered light caused by the Doppler effect. A ...

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    2. Conformational Change in Coronary Artery Structure Assessed by Optical Coherence Tomography in Patients With Vasospastic Angina

      Conformational Change in Coronary Artery Structure Assessed by Optical Coherence Tomography in Patients With Vasospastic Angina
      Objectives The aim of this study was to investigate the conformational change of arterial structure in the vasospastic lesion with optical coherence tomography. Background Coronary artery spasm plays an important role in the pathogenesis of ischemic heart diseases. The conformational change of each arterial layer during vasospasm has not been studied in detail. Methods We assessed 19 coronary arteries (10 spasm and 9 nonspasm lesions) with optical coherence tomography during the provocation test for coronary spasm. An intimal bump was defined as 1 or more intimal projections into the lumen that disappeared after the administration of nitroglycerine (NTG). Intimal gathering ...
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    3. Intravascular Optical Imaging Technology for Investigating the Coronary Artery

      Intravascular Optical Imaging Technology for Investigating the Coronary Artery
      There is an ever-increasing demand for new imaging methods that can provide additional information about the coronary wall to better characterize and stratify high-risk plaques, and to guide interventional and pharmacologic management of patients with coronary artery disease. While there are a number of imaging modalities that facilitate the assessment of coronary artery pathology, this review paper focuses on intravascular optical imaging modalities that provide information on the microstructural, compositional, biochemical, biomechanical, and molecular features of coronary lesions and stents. The optical imaging modalities discussed include angioscopy, optical coherence tomography, polarization sensitive-optical coherence tomography, laser speckle imaging, near-infrared spectroscopy, time-resolved ...
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    4. Systems, Apparatus And Methods For Extending Imaging Depth Range Of Optical Coherence Tomography Through Optical Sub-Sampling

      Systems, Apparatus And Methods For Extending Imaging Depth Range Of Optical Coherence Tomography Through Optical Sub-Sampling
      Exemplary embodiments of systems and methods can be provided which can generate data associated with at least one sample. For example, using at least one first arrangement, it is possible to forward at least one first radiation to the sample(s) so as to cause at least one second radiation to be provided from the sample(s) that can be based on the first radiation(s). In addition, using at least one second arrangement, it is possible to receive the second radiation from the sample(s), generate a plurality of distinct measurements regarding at least one portion of the sample ...
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    5. Imaging the subcellular structure of human coronary atherosclerosis using micro–optical coherence tomography

      Imaging the subcellular structure of human coronary atherosclerosis using micro–optical coherence tomography

      Progress in understanding, diagnosis, and treatment of coronary artery disease (CAD) has been hindered by our inability to observe cells and extracellular components associated with human coronary atherosclerosis in situ. The current standards for microstructural investigation, histology and electron microscopy are destructive and prone to artifacts. The highest-resolution intracoronary imaging modality, optical coherence tomography (OCT), has a resolution of ~10 μm, which is too coarse for visualizing most cells. Here we report a new form of OCT, termed micro–optical coherence tomography (μOCT), whose resolution is improved by an order of magnitude. We show that μOCT images of cadaver coronary ...

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    6. Witnessed Coronary Plaque Rupture During Cardiac Catheterization

      Witnessed Coronary Plaque Rupture During Cardiac Catheterization
      Acute myocardial infarction is primarily caused by atherosclerotic plaque rupture within coronary arteries accompanied by intraluminal thrombus formation, sudden vessel occlusion, and impaired oxygen supply to the myocardium. However, study of plaque rupture has been previously limited to histological analysis of autopsy specimens and animal experiments. Using a high-resolution imaging technique, called intracoronary optical frequency domain imaging (OFDI), we have directly observed the microstructural detail of human coronary plaque rupture in vivo at multiple time points (1). This case of a dynamic observation in a patient provides evidence to support hypotheses about coronary plaque rupture and is illustrative of our ...
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    7. Physiological homology between Drosophila melanogaster and vertebrate cardiovascular systems

      Physiological homology between Drosophila melanogaster and vertebrate cardiovascular systems
      The physiology of the Drosophila melanogaster cardiovascular system remains poorly characterized compared with its vertebrate counterparts. Basic measures of physiological performance remain unknown. It also is unclear whether subtle physiological defects observed in the human cardiovascular system can be reproduced in D. melanogaster. Here we characterize the cardiovascular physiology of D. melanogaster in its pre-pupal stage by using high-speed dye angiography and optical coherence tomography. The heart has vigorous pulsatile contractions that drive intracardiac, aortic and extracellular-extravascular hemolymph flow. Several physiological measures, including weight-adjusted cardiac output, body-length-adjusted aortic velocities and intracardiac shear forces, are similar to those in the closed ...
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    8. Heart wall velocimetry and exogenous contrast-based cardiac flow imaging in Drosophila melanogaster using Doppler optical coherence tomography

      Heart wall velocimetry and exogenous contrast-based cardiac flow imaging in Drosophila melanogaster using Doppler optical coherence tomography
      Drosophila melanogaster (fruit fly) is a central organism in biology and is becoming increasingly important in the cardiovascular sciences. Prior work in optical imaging of the D. melanogaster heart has focused on static and dynamic structural anatomy. In the study, it is demonstrated that Doppler optical coherence tomography can quantify dynamic heart wall velocity and hemolymph flow in adult D. melanogaster. Since hemolymph is optically transparent, a novel exogenous contrast technique is demonstrated to increase the backscatter-based intracardiac Doppler flow signal. The results presented here open up new possibilities for functional cardiovascular phenotyping of normal and mutant D. melanogaster.
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    9. >400 kHz repetition rate wavelength-swept laser and application to high-speed optical frequency domain imaging

      >400 kHz repetition rate wavelength-swept laser and application to high-speed optical frequency domain imaging
      We demonstrate a high-speed wavelength-swept laser with a tuning range of 104nm (1228–1332nm) and a repetition rate of 403kHz. The design of the laser utilizes a high-finesse polygon-based wavelength-scanning filter and a short-length unidirectional ring resonator. Optical frequency domain imaging of the human skin in vivo is presented using this laser, and the system shows sensitivity of higher than 98dB with single-side ranging depth of 1.7mm over 4dB sensitivity roll-off.
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    10. An automatic image processing algorithm for initiating and terminating intracoronary OFDI pullback

      An automatic image processing algorithm for initiating and terminating intracoronary OFDI pullback
      Intracoronary optical frequency domain imaging (OFDI) provides high resolution, three-dimensional views of coronary artery microstructure, but requires a non-occlusive saline/contrast purge to displace blood for clear artery views. Recent studies utilized manual pullback initiation/termination based on real-time image observation. Automated pullback initiation/termination by real-time OFDI signal analysis would enable more efficient data acquisition. We evaluate the use of simple imaging parameters to automatically and robustly differentiate between diagnostic-quality clear artery wall (CAW) versus blood-obstructed fields (BOF). Algorithms are tested using intracoronary OCT human data retrospectively and intracoronary OFDI swine and human data prospectively. In prospective analysis of ...
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    11. Progress in Intracoronary Optical Coherence Tomography

      Progress in Intracoronary Optical Coherence Tomography
      Understanding the etiology and evolution of the vulnerable coronary plaque is important for the early detection, treatment, and prevention of coronary artery disease. Intravascular optical coherence tomography (OCT) enables imaging of the coronary arteries in vivo with sufficient resolution to accurately differentiate arterial pathology, however, the clinical utility of this technology has been limited due to slow image acquisition rates. The development of high-speed Fourier-domain OCT techniques, including optical frequency-domain imaging, enables comprehensive microstructural imaging of long coronary artery segments. Other OCT advancements, including polarization sensitive OCT provide complementary birefringence information that is related to tissue composition. Together with new ...
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    12. System and method for identifying tissue using low-coherence interferometry

      System and method for identifying tissue using low-coherence interferometry
      An apparatus for needle biopsy with real time tissue differentiation using one dimensional interferometric ranging imaging, comprising a biopsy device having a barrel and a needle, an optical fiber inserted in the needle, and a fiber optic imaging system connected to the optical fiber. The imaging system obtains images and compares the optical properties and patterns to a database of normalized tissue sample images to determine different tissue types. The physician performing the biopsy obtains feedback via a feedback unit associated with the biopsy device and which is connected to the imaging system. The feedback unit can provide visual, audible ...
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    13. Systems, Apparatus And Methods For Extending Imaging Depth Range Of Optical Coherence Tomography Through Optical Sub-Sampling (Wo 2010/068764)

      Systems, Apparatus And Methods For Extending Imaging Depth Range Of Optical Coherence Tomography Through Optical Sub-Sampling (Wo 2010/068764)
      Exemplary embodiments of systems and methods can be provided which can generate data associated with at least one sample. For example, using at least one first arrangement, it is possible to forward at least one first radiation to the sample(s) so as to cause at least one second radiation to be provided from the sample(s) that can be based on the first radiation(s). In addition, using at least one second arrangement, it is possible to receive the second radiation from the sample(s), generate a plurality of distinct measurements regarding at least one portion of the sample ...
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    14. Multimodality Cardiovascular Molecular Imaging Technology

      Multimodality Cardiovascular Molecular Imaging Technology
      Cardiovascular molecular imaging is a new discipline that integrates scientific advances in both functional imaging and molecular probes to improve our understanding of the molecular basis of the cardiovascular system. These advances are driven by in vivo imaging of molecular processes in animals, usually small animals, and are rapidly moving toward clinical applications. Molecular imaging has the potential to revolutionize the diagnosis and treatment of cardiovascular disease. The 2 key components of all molecular imaging systems are the molecular contrast agents and the imaging system providing spatial and temporal localization of these agents within the body. They must deliver images ...
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    15. A Case of Lipid Core Plaque Progression and Rupture at the Edge of a Coronary Stent: Elucidating the Mechanisms of Drug-Eluting Stent Failure

      A Case of Lipid Core Plaque Progression and Rupture at the Edge of a Coronary Stent: Elucidating the Mechanisms of Drug-Eluting Stent Failure
      Understanding the mechanisms of coronary drug-eluting stent (DES) failure remains relevant in light of concerns brought on by clinical reports of life-threatening late and very late stent thrombosis and by autopsy studies showing delayed and incomplete healing inside the stents, which may be related to underlying necrotic lipid core.1 Frequency-domain optical coherence tomography, also known as optical frequency-domain imaging (OFDI), is a new intracoronary imaging technology that enables 3-dimensional visualization of coronary structure in vivo at a resolution (6 µm) sufficient to identify many microscopic features of the coronary wall and stents.2 Here, we present a case of ...
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    16. Barrett's Esophagus Screening Using Balloon-Based Optical Frequency Domain Imaging: A Comparison With Endoscopy

      Abstracts submitted to ASGE 2010. Optical coherence tomography (OCT) is a high-resolution cross-sectional imaging modality that has been shown to accurately differentiate esophageal pathology relevant to screening and surveillance in Barrett's patients. We have previously demonstrated that optical frequency domain imaging (OFDI), a high speed 2nd generation embodiment of OCT, may be used to perform volumetric microscopy of the distal esophagus in patients. In this present study we compare the sensitivity of OFDI to endoscopy for the diagnosis of specialized intestinal metaplasia (SIM), using histopathology as the gold standard.

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    17. Challenges on the frontier of intracoronary imaging: atherosclerotic plaque macrophage measurement by optical coherence tomography

      Challenges on the frontier of intracoronary imaging: atherosclerotic plaque macrophage measurement by optical coherence tomography
      Cellularity of the fibrous caps of coronary atheromas, manifested by the infiltration of macrophages (average size, 20 to 30 µm), is thought to weaken the structural integrity of the cap and predispose plaques to rupture. Therefore, an imaging technology capable of identifying macrophages within fibroatheroma caps in patients could provide valuable information for assessing plaque rupture risk. Recently, intravascular optical coherence tomography (OCT), a high-resolution coronary imaging modality, with an axial resolution of ~10 µm, has been introduced into the clinical setting. OCT images of the microstructure of the coronary artery wall enable accurate plaque-type characterization, supported by histopathological comparison ...
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    18. Image-guided biopsy in the esophagus through comprehensive optical frequency domain imaging and laser marking: a study in living swine

      Image-guided biopsy in the esophagus through comprehensive optical frequency domain imaging and laser marking: a study in living swine
      Background: Random biopsy esophageal surveillance can be subject to sampling errors, resulting in diagnostic uncertainty. Optical frequency domain imaging (OFDI) is a high-speed, 3-dimensional endoscopic microscopy technique. When deployed through a balloon-centering catheter, OFDI can automatically image the entire distal esophagus (6.0 cm length) in approximately 2 minutes. Objective: To test a new platform for guided biopsy that allows the operator to select target regions of interest on an OFDI dataset, and then use a laser to mark the esophagus at corresponding locations. The specific goals include determining the optimal laser parameters, testing the accuracy of the laser marking ...
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    19. Atherosclerotic tissue characterization in vivo by optical coherence tomography attenuation imaging

      Optical coherence tomography (OCT) is rapidly becoming the method of choice for assessing arterial wall pathology in vivo. Atherosclerotic plaques can be diagnosed with high accuracy, including measurement of the thickness of fibrous caps, enabling an assessment of the risk of rupture. While the OCT image presents morphological information in highly resolved detail, it relies on interpretation of the images by trained readers for the identification of vessel wall components and tissue type. We present a framework to enable systematic and automatic classification of atherosclerotic plaque constituents, based on the optical attenuation coefficient µt of the tissue. OCT images of ...
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    20. Three-dimensional microscopy of the tumor microenvironment in vivo using optical frequency domain imaging

      Three-dimensional microscopy of the tumor microenvironment in vivo using optical frequency domain imaging
      Intravital multiphoton microscopy has provided powerful mechanistic insights into health and disease and has become a common instrument in the modern biological laboratory. The requisite high numerical aperture and exogenous contrast agents that enable multiphoton microscopy, however, limit the ability to investigate substantial tissue volumes or to probe dynamic changes repeatedly over prolonged periods. Here we introduce optical frequency domain imaging (OFDI) as an intravital microscopy that circumvents the technical limitations of multiphoton microscopy and, as a result, provides unprecedented access to previously unexplored, crucial aspects of tissue biology. Using unique OFDI-based approaches and entirely intrinsic mechanisms of contrast, we ...
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    21. Performance of reduced bit-depth acquisition for optical frequency domain imaging

      Performance of reduced bit-depth acquisition for optical frequency domain imaging
      High-speed optical frequency domain imaging (OFDI) has enabled practical wide-field microscopic imaging in the biological laboratory and clinical medicine. The imaging speed of OFDI, and therefore the field of view, of current systems is limited by the rate at which data can be digitized and archived rather than the system sensitivity or laser performance. One solution to this bottleneck is to natively digitize OFDI signals at reduced bit depths, e.g., at 8-bit depth rather than the conventional 12-14 bit depth, thereby reducing overall bandwidth. However, the implications of reduced bit-depth acquisition on image quality have not been studied. In ...
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    22. Method and apparatus for three-dimensional spectrally encoded imaging

      A method and apparatus for providing information associated with at least one portion of a sample can be provided. For example, at least one wavelength of electro-magnetic radiation provided on a sample can be encoded to determine at least one transverse location of the portion. A relative phase between at least one first electro-magnetic radiation electro-magnetic radiation being returned from a sample and at least one second electro-magnetic radiation returned from a reference can be obtained to determine at least one relative depth location of the portion. Further, the information of the portion can be provided based on the transverse ...
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    23. In vivo characterisation of coronary plaques with conventional grey-scale intravascular ultrasound: correlation with optical coherence tomography.

      AIMS: Although intravascular ultrasound (IVUS) is widely used, there is limited published data on its accuracy in defining plaque characteristics in vivo. Optical coherence tomography (OCT) is a high-resolution imaging technique that takes advantage of the pronounced optical contrast between the components of normal and diseased vessels. The aim of this study was to evaluate the ability of conventional grey-scale IVUS in identifying in vivo coronary plaque characteristics, in particular lipid content as a marker of the vulnerable plaque, when compared to OCT. METHODS AND RESULTS: In patients undergoing cardiac catheterisation, IVUS and OCT imaging was performed. Detailed qualitative analysis ...
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    73-96 of 141 « 1 2 3 4 5 6 »
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