1. Articles in category: Gastroenterology

    481-504 of 562 « 1 2 ... 18 19 20 21 22 23 24 »
    1. Anatomical optical coherence tomography: a safe and effective tool for quantitative long-term monitoring of upper airway size and shape

      J. J. Armstrong, S. Becker, R. A. McLaughlin et al. Anatomical optical coherence tomography (aOCT) is an endoscopic optical technique that enables continuous, quantitative assessment of hollow organ size and shape in three dimensions. It is a powerful alternative to X-ray computed tomography, magnetic resonance imaging, and video endoscopy for the as ... [Proc. SPIE Int. Soc. Opt. Eng. 6842, 68421N (2008)] published Fri Feb 8, 2008.
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    2. Effects of axial resolution improvement on optical coherence tomography (OCT) imaging of gastrointestinal tissues

      Effects of axial resolution improvement on optical coherence tomography (OCT) imaging of gastrointestinal tissues

      Yu Chen, Aaron D. Aguirre, Pei-Lin Hsiung, Shu-Wei Huang, Hiroshi Mashimo, Joseph M. Schmitt, James G. Fujimoto. Optical coherence tomography (OCT) is an emerging medical imaging technology which generates high resolution, cross-sectional images in situ, without the need for excisional biopsy. Previous clinical studies using endoscopic OCT with standard 10-15 μm axial resolution have demonstrated its ... [Opt. Express 16, 2469-2485 (2008)]

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    3. Curled optical patch cord for bending insensitive biomedical imaging endoscope

      Biomedical optical imaging technologies based on optical fibers have been of great interest because of their superiority over conventional bulk-optic counter part in size and integration. Flexible endoscope is a key component to deliver the reflected optical signal from biological tissue to the optical imaging system, such as Optical Coherence Tomography (OCT) and Fiber Confocal Microscopy (FCM). However, conventional optical fibers for the biomedical imaging endoscope have been suffered from a critical wiring problem of a fiber waveguide, which induces additional loss severely. In this work, we have shown excellent properties of holey optical fibers with low bending loss under ...

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    4. A dual-reflective electrothermal MEMS micromirror for full circumferential scanning endoscopic imaging

      This paper reports the design, fabrication and measurements of a dual-reflective, single-crystal silicon based micromirror that can perform full circumferential scanning (FCS) for endoscopic optical coherence tomography (EOCT). In the proposed FCS-EOCT probe, two optical fibers are used to deliver l ... [Proc. SPIE Int. Soc. Opt. Eng. 6885, 688508 (2008)] published Wed Feb 6, 2008.
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    5. Endoscopic common-path OCT based on sweeping laser source and curled optical patch cord

      Several technical problems have to be overcome before Optical Coherence Tomography (OCT) can be accepted among the established endoscopic imaging modalities. Most of conventional Michelson-based OCT systems need to have two separated paths of the sample and reference arms, which limits the flexibility of endoscopic probe. Recently, common-path interferometer based OCT have been demonstrated to circumvent the mismatch problems of length, polarization, and dispersion between the reference and sample arms, but the interferometric scanning methods have been realized with time-domain PZT or spectral-domain CCD. In this work, we demonstrate a novel Fourier-domain common-path OCT based on sweeping laser source, which ...

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    6. Optoelectronic Applications: In Vivo Imaging: Microendoscopy takes a practical turn

      Discussions about how to motivate the medical community to embrace new technologies often focus on form and function-user-friendliness, compactness, ergonomics, speed, cost, and so on. For biomedical optics, these discussions further require demonstrating that a laser-based device can do something more-conventional approaches cannot, or at least do it better (such as laser refractive surgery, skin rejuvenation, hair removal, and optical coherence tomography). But with the advent of collaborative
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    7. Volumetric sub-surface imaging using spectrally encoded endoscopy

      D. Yelin, B. E. Bouma, G. J. Tearney Endoscopic imaging below tissue surfaces and through turbid media may provide improved diagnostic capabilities and visibility in surgical settings. Spectrally encoded endoscopy (SEE) is a recently developed method that utilizes a single optical fiber, miniature optics and a diffractive grating for ... [Opt. Express 16, 1748-1757 (2008)]
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    8. Screening for esophageal cancer and Barrett’s esophagus

      Abstract  The incidence of esophageal adenocarcinoma is rapidly increasing. Because endoscopically recognizing the associated premalignant condition (Barrett’s esophagus) is feasible, many have recommended endoscopic screening and surveillance to decrease mortality from this cancer. However, such a strategy remains controversial, because it is impaired by poor ability to select high-risk patients for screening, limited ability to stratify patients on the risk of progression to cancer, and unproven efficacy for reducing mortality. This review summarizes the published guideline recommendations for screening and surveillance for esophageal adenocarcinoma, the limitations of such a strategy, and emerging progress toward a more rational, effective strategy ...
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    9. Imaging technologies take charge in the war on cancer

      Quantitative spectroscopy, elastic light scattering, optical frequency-domain imaging, in vivo fluorescent imaging, vibrational microspectroscopy—these and similar optical techniques have made molecular imaging the fastest-growing approach to understanding and diagnosing cancers today. Researchers in biomedicine and physical science highlighted their efforts last November at Optical Imaging for Medicine and Biology: Applications in Cancer Detection, a one-day seminar hosted by Boston University’
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    10. Wavelength encoded OCT imaging using swept-source

      Wavelength-encoded imaging uses wavelength division multiplexing to produce cross-sectional images without mechanical scanning, and could be of a great interest in endoscope applications. In this paper, a scheme for wavelength-encoded imaging using time-encoded Frequency-domain optical coherence tomography (swept-source optical coherence tomography, SS-OCT) is presented. This approach implements swept broadband source with narrow instantaneous spectral width and low dispersion diffraction grating to simultaneously produce depth-lateral imaging of the sample. Compared to previous spectral-domain wavelength-encoded endoscope, the proposed method enables high-speed and high dynamic range detection. System design such as image resolvable points, imaging resolution as well as theoretical analysis of the ...

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    11. Common path endoscopic optical coherence tomography with outside path length compensation

      Endoscopic optical coherence tomography (OCT) allowing high-resolution imaging of internal tissue is attractive for medical imaging. Fibre, fibre bundle or GRIN lens rod acting as endoscopic probe is placed in the sample arm of a Michelson interferometer in current endoscopic OCT systems, this arrangement has to be carefully configured to avoid dispersion and polarization fading. In this study, a common path OCT system with outside path length compensation is presented. The system based on Fizeau configuration requires a Michelson interferometer to compensate the optical path difference between the reference and signal light in the Fizeau sensing interferometer. Experiments of path ...

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    12. Design and implementation of fiber lenses for ultra-small probes used in biomedical imaging

      Quality and parameters of probing optical beams are extremely important in biomedical imaging systems both for image quality and light coupling efficiency considerations. For example, the shape, size, focal position, and focal range of such beams could have a great impact on the lateral resolution, ... [Proc. SPIE Int. Soc. Opt. Eng. 6826, 68261A (2008)] published Tue Jan 8, 2008.
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    13. Super-Achromatic Rapid Scanning Microendoscope for Ultrahigh-Resolution OCT Imaging

      Microendoscope is a critical technology to enable high-resolution imaging of internal luminal organs with optical coherence tomography. This paper reports the development of an achromatic compound microlens and a rapid scanning microendoscope based on the microlens that offers an ultrahigh transverse resolution of 4 $mu$m (and an axial resolution of 2.2 $mu$m when using a low-coherence light source with a broad spectrum bandwidth of 150 nm). The rapid scanning endoscope is capable of ultrahigh-resolution (UHR) optical coherence tomography (OCT) imaging in real time at an imaging speed of about 1220 lateral scans/s, with the image quality ...
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    14. Tunable Endoscopic MEMS-Probe for Optical Coherence Tomography

      A novel miniaturized tunable endoscopic MEMS probe employable in an endoscopic optical coherence tomography (OCT) system is presented. The probe consists of a pneumatically-actuated micro-lens and a GRIN lens coupled to an optical fiber. Silicon micromachining using polydimethylsiloxane was used to fabricate the lens. The probe has a diameter of 5 mm. The successful integration of the tunable endoscopic probe with an OCT imager promises to be of value in medical diagnostics, particularly for the early detection of internal tumors and cancers.
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    15. Two-axis magnetically-driven MEMS scanning catheter for endoscopic high-speed optical coherence tomography

      Ki Hean Kim, B. H. Park, Gopi N. Maguluri, Tom W. Lee, Fran J. Rogomentich, Mirela G. Bancu, Brett E. Bouma, Johannes F. de Boer, Jonathan J. Bernstein A two-axis scanning catheter was developed for 3D endoscopic imaging with spectral domain optical coherence tomography (SD-OCT). The catheter incorporates a micro-mirror scanner implemented with microelectromechanical systems (MEMS) technology: the micro-mirror is mounted on a two-axis gimbal ... [Opt. Express 15, 18130-18140 (2007)]
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    16. Real-time in vivo imaging of human gastrointestinal ultrastructure by use of endoscopic optical coherence tomography with a novel efficient interferometer design.

      Opt Lett. 1999 Oct 1;24(19):1358-60 Authors: Rollins AM, Ung-Arunyawee R, Chak A, Wong RC, Kobayashi K, Sivak MV, Izatt JA We report on the design and initial clinical experience with a real-time endoscopic optical coherence tomography (EOCT) imaging system. The EOCT unit includes a high-speed optical coherence tomography interferometer, endoscope-compatible catheter probes, and real-time data capture and display hardware and software. Several technological innovations are introduced that improve EOCT efficiency and performance. In initial clinical studies using the EOCT system, the esophagus, stomach, duodenum, ileum, colon, and rectum of patients with normal endoscopic findings were examined. In ...
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    17. Endoscopic imaging: emerging optical techniques for the detection of colorectal neoplasia.

      PURPOSE OF REVIEW: Advances in bioengineering have spawned various imaging modalities which have revolutionized endoscopy. Some of these technologies provide real-time, high-resolution, subcellular imaging. This review provides an update on these technologies and their role in the evaluation of colorectal neoplasia. RECENT FINDINGS: Narrow band imaging has been shown to visualize capillary patterns in early cancer and is complementary to magnification endoscopy. Optical coherence tomography has been used to evaluate neoplastic progression and distinguish Crohn's from ulcerative colitis. Confocal endomicroscopy has been shown to accurately predict neoplastic changes in polyps and identify areas of neoplasia in patients with colitis ...
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    18. Power-efficient nonreciprocal interferometer and linear-scanning fiber-optic catheter for optical coherence tomography.

      A nonreciprocal fiber-optic interferometer is demonstrated in an optical coherence tomography (OCT) system. The increased power efficiency of this system provides a 4.1-dB advantage over standard Michelson implementations. In addition, a new linear-scanning fiber-optic catheter is demonstrated that avoids the rotary optical junction that is required in circumferential scanning systems. These advancements have permitted the clinical implementation of OCT imaging in the human gastrointestinal tract. PMID: 18071562 [PubMed - in process]
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    19. A two axes scanning Soi Mems micromirror for endoscopic bioimaging

      A two axes scanning SOI MEMS micromirror for endoscopic bioimaging 1 A-STAR Institute of Microelectronics, Science Park Road, Singapore 117685 2 Division of Bioengineering, NUS, 21 Lower Kent Ridge Road, Singapore 119077 3 National Cancer Centre, 11 Hospital Drive, Singapore 169610 E-mail: janak@ime.a-star.edu.sg Abstract. A novel silicon on insulator (SOI) MEMS process has been designed and developed to realize a two axes thermally actuated single crystal silicon micromirror device, which consi
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    20. Imaging of the Pediatric Airway Using Optical Coherence Tomography.

      Laryngoscope. 117(12):2206-2212, December 2007. Ridgway, James Matthew MD; Ahuja, Gurpreet MD; Guo, Shuguang PhD; Su, Jianping BS; Mahmood, Usama BS; Chen, Zhongping PhD; Wong, Brian MD, PhD Abstract: Objectives: Optical coherence tomography (OCT) is an imaging modality that uses a broadband light source to produce high-resolution cross-sectional images in living tissue (8-20 [mu]m). A prospective study of normal, benign, and pathologic tissues in the pediatric airway was conducted to assess the
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    21. BLI Research Featured by OSA in Whats Hot in Optics

      What’s Hot in Optics in Biology and Medicine Greg Faris, Division Chair FTuD1, Tuesday 8:00 a.m., Adam Wax and Matthew Crow, Duke Molecular Imaging of EGFR in Live Cells • New epi-illumination darkfield microspectroscopy scheme •NPs are non-cytotoxic & not susceptible to photobleaching Can immunolabeled NPs be used to better characterize cancer cells compared to fluorescent tags? Curry, A. et al. Molecular imaging of EGFR in live cells with refractive index sensitivity using darkfield micros
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