1. Articles in category: Gastroenterology

    457-480 of 548 « 1 2 ... 17 18 19 20 21 22 23 »
    1. From chromoendoscopy to confocal microscopy: Recent developments in endoscopic imaging of the colon

      Abstract  Recent advances in optical physics and bioengineering have given rise to a wealth of novel technologies for gastrointestinal endoscopy, which may make possible the real-time detection of neoplasia in the colon. Conventional diagnostic endoscopy is limited to a gross view of gastrointestinal mucosa, but several new, light-based technologies allow a glimpse of the colon at the subcellular level. Currently, “optical biopsies” must still be correlated with pathologic biopsies to ensure accuracy. Soon, however, these modalities, alone or in combination, will provide accurate, real-time subcellular imaging and in vivo histopathologic diagnoses. Content Type Journal ArticleDOI 10.1007/s11888-007-0028-0Authors Caren PaleseSharmila ...
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    2. Endoscopic spectral-domain polarization-sensitive optical coherence tomography system

      Yi Wang, Xiaodong Chen, Zhiqiang Hu et al. In this paper, we introduced a fiber-based endoscopic Spectral-domain Polarization-sensitive OCT (SD-PS-OCT)experimental scheme for detecting the internal organ disease, which is based on low-coherence interferometer and twospectrometers. The SD-PS-OCT has the advantages of both Spectral-domain OCT ... [Proc. SPIE Int. Soc. Opt. Eng. 6621, 66211K (2008)] published Mon Mar 3, 2008.
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    3. Recent advances and novel methods in pancreatic imaging

      Traditional imaging studies for evaluating pancreatic disease including abdominal ultrasound (US) and computerized tomography (CT) are widely utilized due to their availability, non-invasiveness, and familiarity to practitioners. The addition of endoscopic ultrasound (EUS) and magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) has contributed significantly to the clinician's the ability to safely sample tissue, stage malignancy, evaluate the pancreatic ductal anatomy, and look for subtle parenchymal changes in the setting of chronic pancreatitis. The role of endoscopic retrograde cholangiopancreatography (ERCP) has diminished with the use of these less invasive modalities. Limitations in these conventional techniques include a lack ...
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    4. Three-dimensional endomicroscopy using optical coherence tomography

      Optical coherence tomography enables micrometre-scale, subsurface imaging of biological tissue by measuring the magnitude and echo time delay of backscattered light. Endoscopic optical coherence tomography imaging inside the body can be performed using fibre-optic probes. To perform three-dimensional optical coherence tomography endomicroscopy with ultrahigh volumetric resolution, however, requires extremely high imaging speeds. Here we report advances in optical coherence tomography technology using a Fourier-domain mode-locked frequency-swept laser as the light source. The laser, with a 160-nm tuning range at a wavelength of 1,315 nm, can produce images with axial resolutions of 5–7 m. In vivo three-dimensional optical coherence ...
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    5. Detailed comparison between endocytoscopy and horizontal histology of an esophageal intraepithelial squamous cell carcinoma

      SUMMARY. Endocytoscopy allows the real-time microscopic observation of living cells. Unlike the cross-sectional images obtained by conventional histology, endocytoscopy provides cellular images in a plane parallel to the surface of the mucosa. However, there is little knowledge about the endocytoscopic diagnosis of carcinomas. Using a specimen obtained by the endoscopic submucosal dissection of an intraepithelial esophageal squamous cell carcinoma, a detailed comparison between endocytoscopic and horizontal histological images was made, revealing the similarity between the images. Sharp lateral borders between atypical and normal epithelium and differences in cellularity and the sizes and shapes of the nuclei were clearly identified by ...
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    6. Endoscopic OCT Approaches Toward Cancer Diagnosis

      A majority of human cancers originate in the epithelial tissues of the body. These include cancers in the oral cavity and pharynx, the digestive system, the respiratory system, the genital system, and the urinary system. It has been shown that early detection of these cancers can significantly improve the prognosis of affected patients. These cancers are currently diagnosed using endoscopic methods during which video imaging systems are inserted to visualize the tissue surface and guide tissue biopsies. Endoscopic optical coherence tomography (EOCT) has the potential to improve the early detection of epithelial cancers by providing high resolution, subsurface images of ...
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    7. In vivo endomicroscopy using three-dimensional optical coherence tomography and Fourier domain mode locked lasers

      We report an endoscopic optical coherence tomography (OCT) system based on a Fourier Domain Mode Locked (FDML) laser, a novel data acquisition (DAQ) system with optical frequency clocking, and a high-speed spiralscanning fiber probe. The system is capable of acquiring three-dimensional (3D) in vivo ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 684708 (2008)] published Tue Feb 19, 2008.
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    8. In vitro 3D articular cartilage imaging using endoscopic spectral domain optical coherence tomography (sd-oct) with a GRIN (gradient index) lens rod based probe

      Tuqiang Xie, Yehchan Ahn, Zhongping Chen et al. In this paper, a GRIN lens rod based dynamic focusing spectral domain optical coherence tomography (OCT) system with 2D scanners is presented and is used to investigate a fresh bovine joint in vitro by 3D OCT with lateral and axial resolutions of 10 [mu]m at the speed of 8 frames/s. The experimental ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 684730 (2008)] published Mon Feb 18, 2008.
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    9. In vivo 3-D imaging of gastrointestinal tract by use of an endoscopic swept source optical coherence tomography with a microelectromechanical endoscopic rotational probe

      Jun Zhang, Jianping Su, Kenneth Chang et al. In vivo three dimensional endoscopic imaging of rabbit and human gastrointestinal tracts was demonstrated based on an endoscopic swept source optical coherence tomography (SSOCT) system. The endoscopic SSOCT system is composed of a high speed SSOCT, a fast scanning rotational microelectromechanical ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 68472Y (2008)] published Mon Feb 18, 2008.
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    10. All-fiber probe for optical coherence tomography

      Seon Young Ryu, Hae Young Choi, Jihoon Na et al. We propose an all-fiber probe for the sample arm of an optical coherence tomography (OCT) system. By forming a focusing lens directly on the tip of an optical fiber, a compact sample probe could be implemented. To achieve a long enough working distance and a high enough lateral resolution at the sam ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 68472L (2008)] published Mon Feb 18, 2008.
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    11. 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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    12. 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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    13. 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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    14. 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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    15. 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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    16. 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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    17. 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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    18. 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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    19. 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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    20. 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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    21. 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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    22. 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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