1. Articles in category: Gastroenterology

    481-504 of 552 « 1 2 ... 18 19 20 21 22 23 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. 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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    13. 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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    14. Methods of detecting inflammation of an epithelium layer in the oral region with a probe using diffuse-reflectance spectroscopy

      The invention provides a device and method for monitoring inflammation of the epithelium. The device consists of a head region, a handle region and an optical bundle. At least two of the optical fibers in the bundle are utilized as a source of radiation, these two fibers are at two different angles from normal. At least one of the other optical fibers is utilized as a detector for the reflected radiation, or alternatively an image guide can be used as the detector. The device of the invention can be part of an external or internal system that can include a ...
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    15. Parallel optical coherence tomography system

      Yuan Luo, Lina J. Arauz, Jose E. Castillo, Jennifer K. Barton, Raymond K. KostukWe present the design and procedures for implementing a parallel optical coherence tomography (POCT) imaging system that can be adapted to an endoscopic format. The POCT system consists of a single mode fiber (SMF) array with multiple reduced diameter (15 μm) SMFs in the sample arm ... [Appl. Opt. 46, 8291-8297 (2007)]
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    16. Pilot study on the correlation of optical coherence tomography with histology in celiac disease and normal subjects

      Background and Aim: Celiac disease (CD) is a common condition but often it goes unrecognized because characteristic histopathological abnormalities must be found to confirm the diagnosis. A way is needed to select patients who need biopsy of the duodenal mucosa to detect CD. No data are currently available on the use of in vivo optical coherence tomography (OCT), during real-time endoscopic imaging, in the small intestine and, particularly, in the diagnosis of CD. The aim of the present study was to test the utility of OCT in patients undergoing esophagogastroduodenoscopy (EGD) for histological diagnosis. Methods: Eighteen patients with suspected CD ...

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    17. Common-path optical coherence tomography with side-viewing bare fiber probe for endoscopic optical coherence tomography

      Common-path optical coherence tomography with side-viewing bare fiber probe for endoscopic optical coherence tomography
      All-fiber-optic common-path optical coherence tomography (OCT) using a side-viewing bare fiber probe has been demonstrated and analyzed. A bare single mode fiber tip is angle cleaved at ∼ 49° to enable side illumination due to total internal reflection. The bare fiber probe was inserted in an arterial tissue and a circumferential OCT scan was obtained. The research is aimed at realizing highly miniaturized monolithic probes for possible applications in miniature endoscopic OCT or intravascular OCT. The effects of the angle of the cleaved fiber on reference reflection and the sensitivity of the common-path OCT system have been studied theoretically. The angle ...
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    18. Strategies to reduce intraluminal clot formation in endoscopically harvested saphenous veins

      Strategies to reduce intraluminal clot formation in endoscopically harvested saphenous veins Emile N. Brown, BS^a, Zachary N. Kon, BA^a, Richard Tran, BS^a, Nicholas S. Burris, BS^a, Junyen Gu, MD, PhD^a, Patrick Laird, BA^a, Philip S. Brazio, BS, BA^a, Seeta Kallam, MD^a, Kimberly Schwartz, RNFA, MBA^a, Lisa Bechtel, PA-C^b, Ashish Joshi, MD, MPH^c, Shaosong Zhang, MD, PhD^d, Robert S. Poston, MD^a^, ^a Department of Surgery, Division of Cardiac Surgery, University of Maryland School of Medi
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    19. In vivo three-dimensional spectral domain endoscopic optical coherence tomography using a microelectromechanical system mirror

      Woonggyu Jung, Daniel T. McCormick, Yeh-Chan Ahn, Ali Sepehr, Matt Brenner, Brian Wong, Norman C. Tien, Zhongping Chen A biopsy is a well-known medical test used to evaluate tissue abnormality. Biopsy specimens are invasively taken from part of a lesion and visualized by microscope after chemical treatment. However, diagnosis by means of biopsy is not only variable due to depth and location of specimen but may also ... [Opt. Lett. 32, 3239-3241 (2007)]
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    20. Detection and treatment of dysplasia in Barrett's esophagus: a pivotal challenge in translating biophotonics from bench to bedside

      Brian C. Wilson Barrett's esophagus (BE) is a condition that poses high risk of developing dysplasia leading to cancer. Detection of dysplasia is a critical element in determining therapy but is extremely challenging, so that standard white-light endoscopy is used only as a means to guide biopsy. Many novel optical ... [J. Biomed. Opt. 12, 051401 (2007)] published Thu Nov 1, 2007.
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    21. Serial Endoscopy in Azoxymethane Treated Mice Using Ultra-High Resolution Optical Coherence Tomography

      Serial Endoscopy in Azoxymethane Treated Mice Using Ultra-High Resolution Optical Coherence Tomography

      Purpose: Optical coherence tomography (OCT) is a minimally invasive, depth-resolved imaging tool that can be implemented in a small diameter endoscope for imaging mouse models of colorectal cancer (CRC). In this study, we utilized ultrahigh resolution (UHR) OCT to serially image the lower colon of azoxymethane (AOM) treated A/J mouse models of CRC in order to monitor the progression of neoplastic transformations and determine if OCT is capable of identifying early disease. Experimental Design: Thirteen AOM treated A/J and two control A/J mice were surveyed at four timepoints (8, 14, 22, and 26 weeks post AOM treatment ...

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    22. Illuminating optical system for endoscope

      An endoscope illuminating optical system having a gradient index lens capable of illuminating by a sufficient light amount and by a wider angle is provided. The endoscope illuminating optical system is constituted to illuminate an observed region by light guided by a light guide 1, by way of a gradient index lens 2, and the gradient index lens 2 satisfies Condition Equations (2) and (3) below: (AR).sup.2.ltoreq.0.6 (2) 0.5k+0.35.ltoreq.AL/.pi..ltoreq.0.5k+0.65 (3) where, R designates an effective radius of the gradient index lens, L designates a ...
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    23. Ultrahigh-Resolution Endoscopic Optical Coherence Tomography for In Vivo Mouse Colonoscopy (Thesis)

      Ultrahigh-Resolution Endoscopic Optical Coherence Tomography for In Vivo Mouse Colonoscopy (Thesis)
      In vivo monitoring of mouse models of colon cancer promises to reduce the cost of research by improving sacrifice timing and allowing serial studies that observe the progression of disease and drug efficacy in a relatively small set of animals. Optical coherence tomography (OCT) is an optical analog of ultrasound imaging, capable of minimally-invasive mapping of light scatter intensity up to 2 mm deep in tissue. In this work, factors limiting resolution in OCT were examined and devices were created and applied to mouse colon imaging that extended the state-of-the-art in endoscopic ultrahigh-resolution OCT. First, axial chromatic aberration of the ...
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