1. Articles in category: Gastroenterology

    457-480 of 563 « 1 2 ... 17 18 19 20 21 22 23 24 »
    1. Respiratory gating of endoscopic OCT images of the upper airway

      Robert A. McLaughlin, Julian J. Armstrong, Sven Becker et al. Anatomical optical coherence tomography (aOCT) is an endoscopic imaging modality that can be used to quantify size and shape of the upper airway. We report the application of respiratory gating to aOCT images. Our results show that respiratory gating can reduce motion artefact in upper airway images ... [Proc. SPIE 7004, 70045V (2008)] published Fri May 16, 2008.
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    2. Evaluation of pharyngeal shape and size using anatomical optical coherence tomography in individuals with and without obstructive sleep apnoea

      Journal of Sleep Research, Volume 17, Issue 2, Page 230-238, June 2008. SummaryThis study compared shape, size and length of the pharyngeal airway in individuals with and without obstructive sleep apnoea (OSA) using a novel endoscopic imaging technique, anatomical optical coherence tomography (aOCT). The study population ...
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    3. Computer-Aided Diagnosis of Early Cancers in the Gastrointestinal Tract Using Optical Coherence Tomography (Thesis)

      Computer-Aided Diagnosis of Early Cancers in the Gastrointestinal Tract Using Optical Coherence Tomography (Thesis)
      Optical coherence tomography (OCT) is an emerging optical technique based on low-coherence interferometry that provides noninvasive, subsurface, high-resolution imaging of biological microstructure. Endoscopic OCT (EOCT) differentiates the tissue layers of the gastrointestinal (GI) wall and can identify dysplasia in the mucosa. The objective of this research was the characterization of dysplasia in the GI tract, by EOCT in Barretts esophagus in the upper GI tract and by OCT in colonic crypts in the lower GI tract. Barretts esophagus (BE) and associated adenocarcinoma have emerged as a major health care problem over the last two decades. We developed computer-aided diagnosis (CAD ...
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    4. Paired angled rotation scanning probes and methods of use

      Probes, and systems and methods for optically scanning a conical volume in front of a probe, for use with an imaging modality, such as Optical Coherence Tomography (OCT). A probe includes an optical fiber having a proximal end and a distal end and defining an axis, with the proximal end of the optical fiber being proximate a light source, and the distal end having a first angled surface. A refractive lens element is positioned proximate the distal end of the optical fiber. The lens element and the fiber end are both configured to separately rotate about the axis so as ...
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    5. Optical design of a dynamic focus catheter for high-resolution endoscopic optical coherence tomography

      Optical design of a dynamic focus catheter for high-resolution endoscopic optical coherence tomography
      The optical system design of a dynamic focus endoscopic probe for optical coherence tomography is reported. The dynamic focus capability is based on a liquid lens technology that provides variable focus by changing its curvatures in response to an electric field variation. The effects of a cylindrical exit window present, in practice, for a catheter were accounted for. Degradation in image quality caused by this window was corrected to get diffraction limited imaging performance. As a result, the dynamically focusing catheter with a lateral resolution ranging from 4 to 6 μm through an ∼5mm imaging distance was designed without mechanically ...
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    6. Handheld forward-imaging needle endoscope for ophthalmic optical coherence tomography inspection

      Shuo Han, Marinko V. Sarunic, Jigang Wu et al. We report the narrowest to-date (21 gauge, 820-[mu]m-diam) handheld forward-imaging optical coherence tomography (OCT) needle endoscope and demonstrate its feasibility for ophthalmic OCT inspection. The probe design is based on paired-angle-rotation scanning (PARS), which enables a linear B-scan pat ... [J. Biomed. Opt. 13, 020505 (2008)] published Mon Apr 21, 2008.
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    7. Forward-Looking, Optical Coherence Tomography Endoscope (Wo 2008/045851)

      A forward-looking, optical coherence tomography, endoscopic probe is disclosed capable of high resolution with a small diameter. Light is focused and scanned during three passes through a lens. A light source supplies light to the proximal side of the lens. The light makes a first pass through the lens, and is reflected from a fixed mirror on the distal side. The reflected light makes a second pass from the distal side to the proximal side, and exits the lens at the proximal side, and is reflected by a scanning mirror. The light makes a third pass through the lens from ...
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    8. Anatomical Optical Coherence Tomography for Long-Term, Portable, Quantitative Endoscopy

      n this paper, we report on anatomical optical coherence tomography, a catheter-based optical modality designed to provide quantitative sectional images of internal hollow organ anatomy over extended observational periods. We consider the design and performance of an instrument and its initial intended application in the human upper airway for the characterization of obstructive sleep apnea (OSA). Compared with current modalities, the technique uniquely combines quantitative imaging, bedside operation, and safety for use over extended periods of time with no cumulative dose limit. Our experiments show that the instrument is capable of imaging subjects during sleep, and that it can record ...
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    9. In vivo Optical Coherence Tomography Imaging of Preinvasive Bronchial Lesions

      Purpose: Optical coherence tomography (OCT) is an optical imaging method that can visualize cellular and extracellular structures at and below tissue surface. The objective of the study was to determine if OCT could characterize preneoplastic changes in the bronchial epithelium identified by autofluorescence bronchoscopy. Experimental Design: A 1.5-mm fiberoptic probe was inserted via a bronchoscope into the airways of 138 volunteer heavy smokers participating in a chemoprevention trial and 10 patients with lung cancer to evaluate areas that were found to be normal or abnormal on autofluorescence bronchoscopy. Radial scanning of the airways was done to generate OCT images ...
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    10. Fiber optic tunable probe for endoscopic optical coherence tomography

      Khaled Aljasem, Armin Werber, Andreas Seifert and Hans Zappe Abstract. A novel miniaturized fiber optic tunable endoscopic probe based on a pneumatically actuated micro-lens is presented. The probe has a diameter of ~4 mm and is integrated into a time-domain optical coherence tomography (OCT) system. The integration of the tunable lens with the OCT system leads to a uniformly high lateral resolution and high contrast of the OCT images over the entire scan depth. In addition, the tunable probe can be considered as a platform for integrating multiple microsystems, including particularly scanning micro-mirrors, in a single high-performance endoscopic OCT system.
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    11. Optical Coherence Tomography Imaging as a Quality Assurance Tool for Evaluating Endoscopic Harvest of the Radial Artery

      Background: Concerns about intimal disruption and spasm have limited enthusiasm for endoscopic radial artery harvest (ERAH), although the risk of these problems after this procedure remains uncertain. Radial artery conduits were screened intraoperatively before and after ERAH vs open harvest using catheter-based high-resolution optical coherence tomography (OCT) imaging. Methods: Twenty-four cadavers and 60 coronary artery bypass graft (CABG) patients scheduled to receive a RA graft underwent OCT imaging before (in situ) and after (ex vivo) open harvest or ERAH. Spasm was quantified by the percentage change in luminal volume between images. Intimal disruption was classified as minor or severe depending ...
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    12. Role of optical techniques in combined use of selected methods of medical imaging

      Abstract  The subject matter of this paper concerns advanced techniques of imaging used in diagnosis and minimally invasive procedures applied in non-operable cases of the digestive tract tumour therapy. The role of optical techniques in current medical imaging is significant. Optical properties of transilluminated or illuminated tissues and organs depend on strong light absorption and scattering. Numerous issues related to the result interpretation still remain unsolved. Effectiveness and precision can be especially improved when some combined methods of imaging are used. Videoendoscopy imaging, X-ray imaging, and endoscopic ultrasound imaging are three complementary methods applied during the interventions described in this ...
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    13. Electrostatic forward-viewing scanning probe for Doppler optical coherence tomography using a dissipative polymer catheter

      Nigel R. Munce, Adrian Mariampillai, Beau A. Standish, Mihaela Pop, Kevan J. Anderson, George Y. Liu, Tim Luk, Brian K. Courtney, Graham A. Wright, I. Alex Vitkin, Victor X. D. Yang. A novel flexible scanning optical probe is constructed with a finely etched optical fiber strung through a platinum coil in the lumen of a dissipative polymer. The packaged probe is 2.2mm in diameter with a rigid length of 6mm when using a ball lens or 12mm when scanning the fiber proximal to a ... [Opt. Lett. 33, 657-659 (2008)]
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    14. 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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    15. 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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    16. 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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    17. 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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    18. 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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    19. 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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    20. 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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    21. 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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    22. 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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