1. Articles from Xingde Li

    1-24 of 42 1 2 »
    1. Ultra-sensitive optical coherence elastography using a high-dynamic-range force loading scheme for cervical rigidity assessment

      Ultra-sensitive optical coherence elastography using a high-dynamic-range force loading scheme for cervical rigidity assessment

      An ultra-sensitive, wide-range force loading scheme is proposed for compression optical coherence elastography (OCE) that allows for the quantitative analysis of cervical tissue elasticity ex vivo . We designed a force loading apparatus featuring a water sink for minuscule incremental loading through a volume-controlled water droplet, from which the Young’s modulus can be calculated by fitting the stress-strain curve. We validated the performance of the proposed OCE system on homogenous agar phantoms, showing the Young’s modulus can be accurately estimated using this scheme. We then measured the Young’s modulus of rodent cervical tissues acquired at different gestational ages ...

      Read Full Article
    2. AI-Assisted In Situ Detection of Human Glioma Infiltration Using a Novel Computational Method for Optical Coherence Tomography

      AI-Assisted In Situ Detection of Human Glioma Infiltration Using a Novel Computational Method for Optical Coherence Tomography

      Purpose: In glioma surgery, it is critical to maximize tumor resection without compromising adjacent non-cancerous brain tissue. Optical Coherence Tomography (OCT) is a non-invasive, label-free, real-time, high-resolution imaging modality that has been explored for glioma infiltration detection. Here we report a novel artificial intelligence (AI) assisted method for automated, real-time, in situ detection of glioma infiltration at high spatial resolution. Experimental Design: Volumetric OCT datasets were intraoperatively obtained from resected brain tissue specimens of 21 patients with glioma tumors of different stages and labeled as either non-cancerous or glioma-infiltrated based on histopathology evaluation of the tissue specimens (gold standard). Labeled ...

      Read Full Article
    3. Ultralow-voltage electrothermal MEMS based fiber-optic scanning probe for forward-viewing endoscopic OCT

      Ultralow-voltage electrothermal MEMS based fiber-optic scanning probe for forward-viewing endoscopic OCT

      We report an ultralow-voltage, electrothermal (ET) micro-electro-mechanical system (MEMS) based probe for forward-viewing endoscopic optical coherence tomography (OCT) imaging. The fully assembled probe has a diameter of 5.5 mm and a length of 55 mm, including the imaging optics and a 40 mm long fiber-optic cantilever attached on a micro-platform of the bimorph ET MEMS actuator. The ET MEMS actuator provides a sufficient mechanical actuation force as well as a large vertical displacement, achieving up to a 3 mm optical scanning range with only a 3

      Read Full Article
    4. Super‐achromatic Optical Coherence Tomography Capsule for Ultrahigh‐resolution Imaging of Esophagus

      Super‐achromatic Optical Coherence Tomography Capsule for Ultrahigh‐resolution Imaging of Esophagus

      Endoscopic optical coherence tomography (OCT) is a noninvasive technology allowing for imaging of tissue microanatomies of luminal organs in real time. Conventional endoscopic OCT operates at 1,300 nm wavelength region with a sub‐optimal axial resolution limited to 8‐20 μm. In this paper we present the first ultrahigh‐resolution tethered OCT capsule operating at 800 nm and offering about 3‐4 fold improvement of axial resolution (plus enhanced imaging contrast). The capsule uses diffractive optics to manage chromatic aberration over a full ~200 nm spectral bandwidth centering around 830 nm, enabling to achieve super‐achromaticity and an axial ...

      Read Full Article
    5. Cycloid scanning for wide field optical coherence tomography endomicroscopy and angiography in vivo

      Cycloid scanning for wide field optical coherence tomography endomicroscopy and angiography in vivo

      Devices that perform wide field-of-view (FOV) precision optical scanning are important for endoscopic assessment and diagnosis of luminal organ disease such as in gastroenterology. Optical scanning for in vivo endoscopic imaging has traditionally relied on one or more proximal mechanical actuators, limiting scan accuracy and imaging speed. There is a need for rapid and precise two-dimensional (2D) microscanning technologies to enable the translation of benchtop scanning microscopies to in vivo endoscopic imaging. We demonstrate a new cycloid scanner in a tethered capsule for ultrahigh speed, side-viewing optical coherence tomography (OCT) endomicroscopy in vivo . The cycloid capsule incorporates two scanners: a ...

      Read Full Article
    6. Broadband rotary joint for high-speed ultrahigh-resolution endoscopic OCT imaging at 800  nm

      Broadband rotary joint for high-speed ultrahigh-resolution endoscopic OCT imaging at 800  nm

      We report the development of a broadband rotary joint for high-speed ultrahigh-resolution endoscopic optical coherence tomography (OCT) imaging in the 800 nm spectral range. This rotary joint features a pair of achromatic doublets in order to achieve broadband operation for a 3 dB bandwidth over 150 nm. The measured one-way throughput of the rotary joint is greater than 80%, while the fluctuation of the double-pass coupling efficiency during 360 deg rotation is less than ± 5 % ±5% at a near video-rate speed of 20 revolutions/s (rps). The rotary joint is used in conjunction with a diffractive-optics-based endoscope and 800 nm ...

      Read Full Article
    7. Super-achromatic monolithic microprobe for ultrahigh-resolution endoscopic optical coherence tomography at 800 nm

      Super-achromatic monolithic microprobe for ultrahigh-resolution endoscopic optical coherence tomography at 800 nm

      Endoscopic optical coherence tomography (OCT) has emerged as a valuable tool for advancing our understanding of the histomorphology of various internal luminal organs and studying the pathogenesis of relevant diseases. To date, this technology affords limited resolving power for discerning subtle pathological changes associated with early diseases. In addition, it remains challenging to access small luminal organs or pass through narrow luminal sections without potentially causing trauma to tissue with a traditional OCT endoscope of a 1-1.5 mm diameter. Here we report an ultracompact (520 µm in outer diameter and 5 mm in rigid length) and super-achromatic microprobe made ...

      Read Full Article
    8. Endoscopic forward-viewing optical coherence tomography and angiography with MHz swept source

      Endoscopic forward-viewing optical coherence tomography and angiography with MHz swept source

      Endoscopic optical coherence tomography (OCT) instruments are mostly side viewing and rely on at least one proximal scan, thus limiting accuracy of volumetric imaging and en face visualization. Previous forward-viewing OCT devices had limited axial scan speeds. We report a forward-viewing fiber scanning 3D-OCT probe with 900 μm field of view and 5 μm transverse resolution, imaging at 1 MHz axial scan rate in the human gastrointestinal tract. The probe is 3.3 mm diameter and 20 mm rigid length, thus enabling passage through the endoscopic channel. The scanner has 1.8 kHz resonant frequency, and each volumetric acquisition takes ...

      Read Full Article
    9. Introduction to the feature issue on the 25 year anniversary of optical coherence tomography

      Introduction to the feature issue on the 25 year anniversary of optical coherence tomography

      This feature issue commemorates the approximately 25 year history of Optical Coherence Tomography (OCT), one of the most successful biophotonic technologies. While OCT has technological origins traceable to ultrafast laser development and fiber optic system test instrumentation of the 1980’s, innovations in low coherence interferometry for optical ranging and imaging for biomedical applications in the U.S., Europe and Japan by the early 1990’s led to coinage of the now widely known term OCT in 1991 [1]. As discussed in the following cited Invited Review and Invited Research articles in this issue, remarkable strides have since been made ...

      Read Full Article
    10. Robust and fast characterization of OCT-based optical attenuation using a novel frequency-domain algorithm for brain cancer detection

      Robust and fast characterization of OCT-based optical attenuation using a novel frequency-domain algorithm for brain cancer detection

      Cancer is known to alter the local optical properties of tissues. The detection of OCT-based optical attenuation provides a quantitative method to efficiently differentiate cancer from non-cancer tissues. In particular, the intraoperative use of quantitative OCT is able to provide a direct visual guidance in real time for accurate identification of cancer tissues, especially these without any obvious structural layers, such as brain cancer. However, current methods are suboptimal in providing high-speed and accurate OCT attenuation mapping for intraoperative brain cancer detection. In this paper, we report a novel frequency-domain (FD) algorithm to enable robust and fast characterization of optical ...

      Read Full Article
    11. Endoscopic optical coherence tomography: technologies and clinical applications [Invited]

      Endoscopic optical coherence tomography: technologies and clinical applications [Invited]

      In this paper, we review the current state of technology development and clinical applications of endoscopic optical coherence tomography (OCT). Key design and engineering considerations are discussed for most OCT endoscopes, including side-viewing and forward-viewing probes, along with different scanning mechanisms (proximal-scanning versus distal-scanning). Multi-modal endoscopes that integrate OCT with other imaging modalities are also discussed. The review of clinical applications of endoscopic OCT focuses heavily on diagnosis of diseases and guidance of interventions. Representative applications in several organ systems are presented, such as in the cardiovascular, digestive, respiratory, and reproductive systems. A brief outlook of the field of endoscopic ...

      Read Full Article
    12. Optical clearing for luminal organ imaging with ultrahigh-resolution optical coherence tomography

      Optical clearing for luminal organ imaging with ultrahigh-resolution optical coherence tomography

      The imaging depth of optical coherence tomography (OCT) in highly scattering biological tissues (such as luminal organs) is limited, particularly for OCT operating at shorter wavelength regions (such as around 800 nm). For the first time, the optical clearing effect of the mixture of liquid paraffin and glycerol on luminal organs was explored with ultrahigh-resolution spectral domain OCT at 800 nm. Ex vivo studies were performed on pig esophagus and bronchus, and guinea pig esophagus with different volume ratios of the mixture. We found that the mixture of 40% liquid paraffin had the best optical clearing effect on esophageal tissues ...

      Read Full Article
    13. Optimal operational conditions for supercontinuum-based ultrahigh-resolution endoscopic OCT imaging

      Optimal operational conditions for supercontinuum-based ultrahigh-resolution endoscopic OCT imaging

      We investigated the optimal operational conditions for utilizing a broadband supercontinuum (SC) source in a portable 800 nm spectral-domain (SD) endoscopic OCT system to enable high resolution, high-sensitivity, and high-speed imaging in vivo . A SC source with a 3-dB bandwidth of ∼ 246     nm was employed to obtain an axial resolution of ∼ 2.7     μm (in air) and an optimal detection sensitivity of ∼ − 107     dB with an imaging speed up to 35 frames/s (at 70 k A-scans/s). The performance of the SC-based SD-OCT endoscopy system was demonstrated by imaging guinea pig esophagus in vivo , achieving image quality comparable to ...

      Read Full Article
    14. Detection of human brain cancer infiltration ex vivo and in vivo using quantitative optical coherence tomography

      Detection of human brain cancer infiltration ex vivo and in vivo using quantitative optical coherence tomography

      More complete brain cancer resection can prolong survival and delay recurrence. However, it is challenging to distinguish cancer from noncancer tissues intraoperatively, especially at the transitional, infiltrative zones. This is especially critical in eloquent regions (for example, speech and motor areas). This study tested the feasibility of label-free, quantitative optical coherence tomography (OCT) for differentiating cancer from noncancer in human brain tissues. Fresh ex vivo human brain tissues were obtained from 32 patients with grade II to IV brain cancer and 5 patients with noncancer brain pathologies. On the basis of volumetric OCT imaging data, pathologically confirmed brain cancer tissues ...

      Read Full Article
    15. MEMS scanning micromirror for optical coherence tomography

      MEMS scanning micromirror for optical coherence tomography

      This paper describes an endoscopic-inspired imaging system employing a micro-electromechanical system (MEMS) micromirror scanner to achieve beam scanning for optical coherence tomography (OCT) imaging. Miniaturization of a scanning mirror using MEMS technology can allow a fully functional imaging probe to be contained in a package sufficiently small for utilization in a working channel of a standard gastroesophageal endoscope. This work employs advanced image processing techniques to enhance the images acquired using the MEMS scanner to correct non-idealities in mirror performance. The experimental results demonstrate the effectiveness of the proposed technique.

      Read Full Article
    16. Generic pixel-wise speckle detection in Fourier-domain optical coherence tomography images

      Generic pixel-wise speckle detection in Fourier-domain optical coherence tomography images

      We present a generic phase-domain processing method for detecting speckles in Fourier-domain optical coherence tomography (OCT) images. The physics behind the interferometry is revisited and analytically along with simulation results it indicates that the speckle formation comes with phase distortion to the complex OCT signal. The first and the second derivatives of phase along the imaging depth are then calculated for speckle identification. The phase-domain processing method was applied to images acquired by both spectral-domain OCT and swept-source OCT systems, and the experimental results show that this method enables pixel-wise speckle identification.

      Read Full Article
    17. Diffractive catheter for ultrahigh-resolution spectral-domain volumetric OCT imaging

      Diffractive catheter for ultrahigh-resolution spectral-domain volumetric OCT imaging

      We present a novel design for an endoscopic imaging catheter utilizing diffractive optics for ultrahigh-resolution optical coherence tomography (OCT) imaging at 800 nm. A diffractive microlens was developed to alleviate severe chromatic aberration when a broadband light source was employed at the 800 nm wavelength range. Combined with a home-built fiber rotary joint and a broadband Ti:sapphire laser, the imaging catheter achieved a lateral resolution of 6.2 μm and an axial resolution of 3.0 μm in air. The performance of the catheter was demonstrated by three-dimensional full-circumferential endoscopic OCT imaging of guinea pig esophagus in vivo . 14)]

      Read Full Article
    18. Compact piezoelectric transducer fiber scanning probe for optical coherence tomography

      Compact piezoelectric transducer fiber scanning probe for optical coherence tomography

      We developed a compact, optical fiber scanning piezoelectric transducer (PZT) probe for endoscopic and minimally invasive optical coherence tomography (OCT). Compared with previous forward-mount fiber designs, we present a reverse-mount design that achieves a shorter rigid length. The fiber was mounted at the proximal end of a quadruple PZT tube and scanned inside the hollow PZT tube to reduce the probe length. The fiber resonant frequency was 338 Hz using a 17-mm-long fiber. A 0.9 mm fiber deflection was achieved with a driving amplitude of 35 V. Using a GRIN lens-based optical design with a 1.3 × magnification, a ...

      Read Full Article
    19. Diagnostic Endoscopy (Textbook)

      Diagnostic Endoscopy (Textbook)

      Combining a professional development course on diagnostic endoscopy from SPIE (the international society advancing light-based research) and the authors’ graduate course on biomedical optics, this work is written for researchers in medical optics and biomedical engineering as well as graduate medical optics students. It uses extensive examples/case studies to familiarize readers with the basics of endoscopic optics, the pros and cons of white light endoscopy and fluorescence endoscopy for diagnostic applications, and various microscopic endoscopy imaging modalities. It covers basic optics, details of design and biomedical uses, as well as microscopic endoscopy, and endoscopic spectroscopy.

      Read Full Article
    20. Dynamic focus-tracking MEMS scanning micromirror with low actuation voltages for endoscopic imaging

      Dynamic focus-tracking MEMS scanning micromirror with low actuation voltages for endoscopic imaging

      We demonstrate a 3-D scanning micromirror device that combines 2-D beam scanning with focus control in the same device using micro-electro-mechanical-systems (MEMS) technology. 2-D beam scanning is achieved with a biaxial gimbal structure and focus control is obtained with a deformable mirror membrane surface. The micromirror with 800 micrometer diameter is designed to be sufficiently compact and efficient so that it can be incorporated into an endoscopic imaging probe in the future. The design, fabrication and characterization of the device are described in this paper. Using the focus-tracking MEMS scanning mirror, we achieved an optical scanning range of >16 degrees ...

      Read Full Article
    21. Characterizing optical properties of nano contrast agents by using cross-referencing OCT imaging

      Characterizing optical properties of nano contrast agents by using cross-referencing OCT imaging

      We report a cross-referencing method to quickly and accurately characterize the optical properties of nanoparticles including the extinction, scattering, absorption and backscattering cross sections by using an OCT system alone. Among other applications, such a method is particularly useful for developing nanoparticle-based OCT imaging contrast agents. The method involves comparing two depth-dependent OCT intensity signals collected from two samples (with one having and the other not having the nanoparticles), to extract the extinction and backscattering coefficient, from which the absorption coefficient can be further deduced (with the help of the established scattering theories for predicting the ratio of the backscattering ...

      Read Full Article
    22. An all-fiber-optic endoscopy platform for simultaneous OCT and fluorescence imaging

      An all-fiber-optic endoscopy platform for simultaneous OCT and fluorescence imaging

      We present an all-fiber-optically based endoscope platform for simultaneous optical coherence tomography (OCT) and fluorescence imaging. This design entails the use of double-clad fiber (DCF) in the endoscope for delivery of OCT source and fluorescence excitation light while collecting the backscattered OCT signal through the single-mode core and fluorescence emission through the large inner cladding of the DCF. Circumferential beam scanning was performed by rotating a 45° reflector using a miniature DC motor at the distal end of the endoscope. Additionally, a custom DCF coupler and a wavelength division multiplexer (WDM) were utilized to seamlessly integrate both imaging modalities to ...

      Read Full Article
    23. Endomicroscopy Technologies and Biomedical Applications

      Endomicroscopy Technologies and Biomedical Applications

      Recent years have witnessed rapid developments of highresolution optical imaging technologies, including (but not limited to) confocal, multispectral, optical coherence tomography, multiphoton fluorescence, second harmonic generation, Raman and/or coherent anti-Stokes Raman spectroscopy, and stimulated Raman scattering microscopy. The highresolution, noninvasive (or minimally invasive), and real-time imaging capability make these technologies well positioned for performing “optical biopsy” in situ and in real time, with a resolution approaching or at that of standard histology. Clinical translation of these technologies, particularly for assessing internal organs, requires miniature probes for delivery, scanning, and collection of the probing/imaging beams. Endomicroscopy is emerging as ...

      Read Full Article
    24. Barrett's esophagus: surveillance and reversal

      Barrett's esophagus: surveillance and reversal
      The following on surveillance and reversal of Barrett's esophagus (BE) includes commentaries on criteria for surveillance even when squamous epithelium stains normally with a variety of biomarkers; the long-term follow-up of surgery versus endoscopic ablation of BE; the recommended surveillance intervals in patients without dysplasia; the sampling problems related to anatomic changes following fundoplication; the value of tissue spectroscopy and optical coherence tomography; the cost-effectiveness of biopsy protocols for surveillance; the quality of life of Barrett's patients; and risk stratification and surveillance strategies.
      Read Full Article
    1-24 of 42 1 2 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (41 articles) Xingde Li
    2. (30 articles) Johns Hopkins University
    3. (14 articles) University of Washington
    4. (13 articles) Jiefeng Xi
    5. (7 articles) Massachusetts Institute of Technology
    6. (7 articles) Joo Ha Hwang
    7. (7 articles) James G. Fujimoto
    8. (5 articles) Harvard University
    9. (3 articles) Osman O. Ahsen
    10. (3 articles) Costas D. Pitris
    11. (2 articles) Topcon Medical Systems
    12. (1 articles) Tohoku University
    13. (1 articles) Duke University
    14. (1 articles) Massachusetts Institute of Technology
    15. (1 articles) Hiroshi Mashimo
    16. (1 articles) James G. Fujimoto
    17. (1 articles) Oscar Carrasco-Zevallos
    18. (1 articles) Joseph A. Izatt
    19. (1 articles) Thorlabs
    20. (1 articles) Topcon 3D OCT-2000
  3. Popular Articles

  4. Picture Gallery

    Fiber optic needle probes for optical coherence tomography imaging High-resolution OCT balloon imaging catheter with astigmatism correction Imaging needle for optical coherence tomography Generic real-time uniform K-space sampling method for high-speed swept-Source optical coherence tomography Robust High-Resolution Fine OCT Needle for Side-Viewing Interstitial Tissue Imaging Noninvasive optical coherence tomography monitoring of structure and hydration changes of human corneas in different preservation media Optimal operational conditions for supercontinuum-based ultrahigh-resolution endoscopic OCT imaging Spectral Domain Optical Coherence Tomography Imaging Performance Improvement Based on Field Curvature Aberration-Corrected Spectrometer Pentosan polysulfate maculopathy versus inherited macular dystrophies: comparative assessment with multimodal imaging Complementary Use of Active Infrared Thermography and Optical Coherent Tomography in Non-destructive Testing Inspection of Ancient Marquetries Spectral domain optical coherence tomography–based prevalence of hydroxychloroquine maculopathy in Indian patients on hydroxychloroquine therapy: A utopia of underdiagnosis Consistency Between Optical Coherence Tomography and Humphrey Visual Field for Evaluating Glaucomatous Defects in High Myopic Eyes