1. Articles from Linbo Liu

    1-24 of 58 1 2 3 »
    1. Rapid, High-Resolution, Label-Free, and 3-Dimensional Imaging to Differentiate Colorectal Adenomas and Non-Neoplastic Polyps With Micro-Optical Coherence Tomography

      Rapid, High-Resolution, Label-Free, and 3-Dimensional Imaging to Differentiate Colorectal Adenomas and Non-Neoplastic Polyps With Micro-Optical Coherence Tomography

      INTRODUCTION: “ Resectanddiscard ” paradigmisoneofthemainstrategiestodealwithcolorectaldiminutivepolyps after optical diagnosis. However, there are risks that unrecognized potentially malignant lesions are discarded without accurate diagnosis. The purpose of this study is to validate the potential of micro- optical coherence tomography ( m OCT) to improve the diagnostic accuracy of colorectal lesions and help endoscopists make better clinical decision without additional pathology costs. METHODS: RESULTS: DISCUSSION: Fresh tissue samples were obtained from patients with colorectal polyps or colorectal cancer who received endoscopic therapy or laparoscopic surgery. These samples were instantly imaged by m OCT and then sent to pathological evaluation. Then, m OCT images were compared with ...

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    2. Automatic evaluation of stratum basale and dermal papillae using ultrahigh resolution optical coherence tomography

      Automatic evaluation of stratum basale and dermal papillae using ultrahigh resolution optical coherence tomography

      Diagnosis of many skin conditions requires evaluation of dermal papillae and stratum basale, such as vitiligo. In clinical practice, imaging dermal papillae structures relies on excisional biopsy followed by histological processing and analysis. As biopsy is invasive and associated with complications, a noninvasive imaging method such as optical coherence tomography (OCT) can complement the existing method by enabling large area scanning. However, because OCT image analysis requires training and it takes time to review OCT images from large skin areas, an automatic evaluation method is preferred to reduce the workload and avoid ‘sampling errors’ during image analysis. Here we report ...

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    3. Methods, systems, arrangements and computer-accessible medium for providing micro-optical coherence tomography procedures

      Methods, systems, arrangements and computer-accessible medium for providing micro-optical coherence tomography procedures

      Exemplary apparatus and method can be provided for obtaining data regarding a plurality of samples. For example, using at least one arrangement, it is possible to receive interferometric information that is based on radiations provided from a reference and the samples that are provided in respective chambers. Alternatively and/or in addition, based on the interferometric information, it is possible to discriminate between agents to identify a particular agent that affects a particular function within at least one of the samples.

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    4. Are nuclei in stratified squamous epithelium high scattering or low scattering?

      Are nuclei in stratified squamous epithelium high scattering or low scattering?

      Imaging nuclei of keratinocytes in the stratified squamous epithelium has been a subject of intense research since nucleus associated cellular atypia is the key criteria for the screening and diagnosis of epithelial cancers and their precursors. However, keratinocyte nuclei have been reported to be either low scattering or high scattering, so that these inconsistent reports might have led to misinterpretations of optical images, and more importantly, hindered the establishment of optical diagnostic criteria. We disclose that they are generally low scattering in the core using Micro-optical coherence tomography (µOCT) of 1.28-µm axial resolution in vivo; those previously reported ...

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    5. Single input state polarization-sensitive optical coherence tomography with high resolution and polarization distortion correction

      Single input state polarization-sensitive optical coherence tomography with high resolution and polarization distortion correction

      Abstract: In single input state polarization-sensitive optical coherence tomography (PS-OCT) with high resolution, the imperfections of quarter-wave plate (QWP) and the sensitivity roll-off mismatch between the two detection channels cause unpredictable polarization distortion. We present a correction method based on the Jones matrix modeling of the system. In a single input PS-OCT system working at 840 nm with an axial resolution of ~2.3 μm, the method yielded better estimation of retardation and optic axis orientation with significantly reduced noise level, especially in weakly birefringent samples. Numerical simulations and quantitative imaging of a sample of known birefringence were performed to ...

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    6. Optical coherence tomography with gapped spectrum

      Optical coherence tomography with gapped spectrum

      The axial resolution of optical coherence tomography (OCT) is determined by the spectral shape and bandwidth of the detected light, which are limited by the gaps in the wavelength range of illumination, transmission, and detection. In this work, we demonstrate that the axial resolution deteriorated by gaps in OCT spectra can be restored by adopting the gapped amplitude and phase estimation (GAPES) method. GAPES estimates the missing parts between separated spectral bands and obtains the axial profile of tissue with reduced sidelobe artifacts compared to the gapped spectra and significantly improved axial resolution over the individual bands. This technique may ...

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    7. Nondestructive Measurement of Conformal Coating Thickness on Printed Circuit Board with Ultra-high Resolution Optical Coherence Tomography

      Nondestructive Measurement of Conformal Coating Thickness on Printed Circuit Board with Ultra-high Resolution Optical Coherence Tomography

      Conformal coating (CC) is widely used to protect printed circuit board (PCB) from corrosion, mould growth and electrical failures. To ensure an effective protection, the thickness of the conformal coating layer needs to be well controlled. However, to date, the coating thickness is usually measured in a destructive way under microscopes. In this study, we proposed to use optical coherence tomography (OCT) to measure the CC thickness nondestructively. Specifically, to obtain a good accuracy in thickness measurement, we constructed a spectral domain OCT (SD-OCT) with ultra-high axial resolution to image the CC layer in three dimensions, and developed an image ...

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    8. Cellular resolution corneal imaging with extended imaging range

      Cellular resolution corneal imaging with extended imaging range

      Current optical coherence tomography (OCT) technology, which is used for imaging the eye’s anterior segment, has been established as a clinical gold standard for the diagnosis of corneal diseases. However, the cellular resolution level information that is critical for many clinical applications is still not available. The major technical challenges toward cellular resolution OCT imaging are the limited ranging depth and depth of focus (DOF). In this work, we present a novel ultrahigh resolution OCT system that achieves an isotropic spatial resolution of <2 µm in tissue. The proposed system could approximately double the ranging depth and extend the ...

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    9. Estimation of refractive index for biological tissue using micro-optical coherence tomography

      Estimation of refractive index for biological tissue using micro-optical coherence tomography

      The refractive index of biological tissue is required for investigating the tissue's optical properties. Efforts have been made to characterize refractive indices of biological tissues at a single wavelength, but it is more convenient to know the Cauchy's coefficients, which provide refractive index over a wide range of wavelengths. We demonstrate a method to noninvasively provide the Cauchy's dispersion coefficients of biological tissues using micro-optical coherence tomography. Using short-frequency Fourier transforms, the relative optical thickness of the sample in the wavelength range of the broadband source was obtained from interferograms. The coefficients of Cauchy's equation were ...

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    10. Imaging cellular structures of atherosclerotic coronary arteries using circumferentially scanning micro-optical coherence tomography fiber probe ex vivo

      Imaging cellular structures of atherosclerotic coronary arteries using circumferentially scanning micro-optical coherence tomography fiber probe ex vivo

      Development and progression of coronary atherosclerotic lesions is mediated by a number of cellular components, which are not readily visualized using the current clinical investigation tools. Visualizing these cellular components in situ and in vivo may allow early detection of the vulnerable plaques, with implications for coronary artery disease (CAD) therapy and for the prevention of acute myocardial infarction (AMI). In this study, we have developed a fiber-optic micro-optical coherence tomography (µOCT) probe for intravascular use. We conducted ex vivo imaging experiments in normal swine aorta and human atherosclerotic coronary arteries, and demonstrate that the fiber-probe based µOCT could delineate ...

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    11. Novel application of In Vivo Micro-Optical Coherence Tomography to assess Cornea scarring in an Animal Model

      Novel application of In Vivo Micro-Optical Coherence Tomography to assess Cornea scarring in an Animal Model

      This pilot study uses a micro-optical coherence tomography (micro-OCT) system with ~1 μm axial resolution specifically to image the cornea and corneal scars in vivo . We used an established murine corneal scar model by irregular phototherapeutic keratectomy in ten C57BL/6 mice, with serial imaging using the micro-OCT and compared to anterior segment (AS-OCT) (RTvue, Optovue, Fremont, CA) before and after scar induction. Main outcome was agreement between the AS-OCT and micro-OCT using Bland-Altman plots (95% limits of agreement, LoA).We analysed 10 control eyes and 10 eyes with corneal scars and found that there was good agreement between AS-OCT ...

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    12. Extending the depth of focus of fiber-optic optical coherence tomography using a chromatic dual-focus design

      Extending the depth of focus of fiber-optic optical coherence tomography using a chromatic dual-focus design

      We report a dual-focus fiber-optic probe designed to extend depth of focus (DOF) in high-resolution endoscopic optical coherence tomography. We exploited the broad spectral bandwidth of a supercontinuum source and, in the fiber probe, the foci of the 750–1000 nm and 1100–1450 nm inputs were axially chromatically shifted. The interference signals from the two spectral bands were measured with a Si camera-based spectrometer and an InGaAs camera-based spectrometer, respectively. We verified the feasibility of the design using a phantom composed of microparticles and swine small intestine tissue ex vivo . The results showed that a transverse resolution below 5 ...

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    13. Multiscale skin imaging in vivo using optical coherence tomography

      Multiscale skin imaging in vivo using optical coherence tomography

      Optical coherence tomography (OCT) is a noninvasive high-resolution diagnostic imaging modality that plays an increasingly important role in dermatology. Diagnosis of skin diseases using OCT requires both cellular-level high resolution and large area skin coverage. In practice, however, there exists a trade-off between the achievable spatial resolutions and the transverse scanning range. In this study, we report a Micro-OCT ( μ OCT) system that is capable of providing three-dimensional images of the skin at multiple spatial scales with both cellular-level resolution (1–2 μ m) mode and large area (~ mm 2 ) scanning mode. Specifically, in the cellular-level scanning mode, we achieve a transverse ...

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    14. Evaluating micro-optical coherence tomography (μOCT) as a feasible imaging tool for pancreatic disease diagnosis

      Evaluating micro-optical coherence tomography (μOCT) as a feasible imaging tool for pancreatic disease diagnosis

      Pancreatic cancer is one of the leading causes of cancer mortality worldwide due to the lack of reliable tools for early diagnosis of this cancer. In this study, we evaluated the feasibility of micro-optical coherence tomography (μOCT) as an imaging tool for the diagnosis of pancreatic cancers. Specifically, we constructed a μOCT device that achieves a resolution of ∼1.67 μm and 1.79 μm in axial and lateral directions, respectively, and acquires three-dimensional μOCT images of mouse, rat and human pancreatic specimens ex vivo. We compared the results of μOCT with those of the corresponding histology. In μOCT images ...

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    15. Extending axial focus of optical coherence tomography using parallel multiple aperture synthesis

      Extending axial focus of optical coherence tomography using parallel multiple aperture synthesis

      Compromising the inherent trade-off between transverse resolution and depth of focus (DOF) remains a long-standing issue in optical coherence tomography (OCT). In this work, we report a novel technique—parallel multiple aperture synthesis (pMAS) to simultaneously generate multiple optical apertures in an OCT sample arm by employing a two-surface coated mirror. In the proposed pMAS, the DOF is extended by a factor of 16.49 without sacrificing the transverse resolution for proof-of-concept experiments when multiple distinctive apertures are digitally synthesized. The microparticles and tissue experiments demonstrate the feasibility of pMAS to address the fundamental problem of limited DOF in high-resolution ...

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    16. Multiple aperture synthetic optical coherence tomography for biological tissue imaging

      Multiple aperture synthetic optical coherence tomography for biological tissue imaging

      An inherent compromise must be made between transverse resolution and depth of focus (DOF) in spectral domain optical coherence tomography (SD-OCT). Thus far, OCT has not been capable of providing a sufficient DOF to stably acquire cellular-resolution images. We previously reported a novel technique named multiple aperture synthesis (MAS) to extend the DOF in high-resolution OCT [Optica 4, 701 (2017)]. In this technique, the illumination beam is scanned across the objective lens pupil plane by being steered at the pinhole using a custom-made microcylindrical lens. Images captured via multiple distinctive apertures were digitally refocused, which is similar to synthetic aperture ...

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    17. Visualizing Micro-anatomical Structures of the Posterior Cornea with Micro-optical Coherence Tomography

      Visualizing Micro-anatomical Structures of the Posterior Cornea with Micro-optical Coherence Tomography

      Diagnosis of corneal disease and challenges in corneal transplantation require comprehensive understanding of corneal anatomy, particularly that of the posterior cornea. Micro-optical coherence tomography (µOCT) is a potentially suitable tool to meet this need, owing to its ultrahigh isotropic spatial resolution, high image acquisition rate and depth priority scanning mode. In this study, we explored the ability of µOCT to visualize micro-anatomical structures of the posterior cornea ex vivo and in vivo using small and large animals. µOCT clearly delineated cornea layers and revealed micro-anatomical structures, including not only polygonal endothelial cells, stellate keratocytes, collagen fibres and corneal nerve fibres ...

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    18. Endomicroscopic optical coherence tomography for cellular resolution imaging of gastrointestinal tracts

      Endomicroscopic optical coherence tomography for cellular resolution imaging of gastrointestinal tracts

      Our ability to detect neoplastic changes in gastrointestinal (GI) tracts is limited by the lack of an endomicroscopic imaging tool that provides cellular-level structural details of GI mucosa over a large tissue area. In this paper, we report a fiber-optic based micro-optical coherence tomography (μOCT) system and demonstrate its capability to acquire cellular-level details of GI tissue through circumferential scanning. The system achieves an axial resolution of 2.48 µm in air and a transverse resolution of 4.8 µm with a depth-of-focus (DOF) of ~150 µm. To mitigate the issue of limited DOF, we used a rigid sheath to ...

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    19. Polarization management to mitigate misalignment-induced fringe fading in fiber-based optical coherence tomography

      Polarization management to mitigate misalignment-induced fringe fading in fiber-based optical coherence tomography

      In fiber-based optical coherence tomography (OCT), the interference fringes suffer from the fading effect due to misalignment of the light polarization states between the reference and sample arms, resulting in sensitivity degradation and image intensity variation. We theoretically and experimentally analyzed the relation between the misalignment and the fading coefficient. Assuming that the variation of the light polarization in single-mode fiber (SMF) was a random process, we statistically quantified the fading effect. Furthermore, in OCT configuration based on the Michelson interferometer, we reported an interesting observation that the polarization states of light traveling a round-trip in SMF are not evenly ...

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    20. Feature Of The Week 06/27/2017: Depth-of-Focus Extension in Optical Coherence Tomography via Multiple Aperture Synthesis

      Feature Of The Week 06/27/2017: Depth-of-Focus Extension in Optical Coherence Tomography via Multiple Aperture Synthesis

      In this paper, we report what we believe is a novel technique to overcome the depth-of-focus (DOF) limitation in optical coherence tomography (OCT). Using confocal optics on a sample arm, we scanned the illumination beam across the under-filled objective lens pupil plane by steering the beam at the pinhole using a microcylindrical lens. The detected interferometric signals from multiple distinctive apertures were digitally refocused, which is analogous to synthetic aperture radar (SAR). Using numerical simulations and imaging experiments, we verified that this technique can maintain a diffraction-limited transverse resolution along a DOF that is ∼10 times larger than the confocal ...

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    21. Depth-of-focus extension in optical coherence tomography via multiple aperture synthesis

      Depth-of-focus extension in optical coherence tomography via multiple aperture synthesis

      In this paper, we report what we believe is a novel technique to overcome the depth-of-focus (DOF) limitation in optical coherence tomography (OCT). Using confocal optics on a sample arm, we scanned the illumination beam across the under-filled objective lens pupil plane by steering the beam at the pinhole using a microcylindrical lens. The detected interferometric signals from multiple distinctive apertures were digitally refocused, which is analogous to synthetic aperture radar (SAR). Using numerical simulations and imaging experiments, we verified that this technique can maintain a diffraction-limited transverse resolution along a DOF that is ∼ 10 ∼10 times larger than the ...

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    22. Iron-oxide nanoparticles powered micro optical coherence tomography for in situ imaging the penetration and swelling of polymeric microneedles in skin

      Iron-oxide nanoparticles powered micro optical coherence tomography for in situ imaging the penetration and swelling of polymeric microneedles in skin

      In recent years, polymeric microneedles (MNs) have attracted keen interests among researchers for their applicability in transdermal drug delivery and interstitial skin fluid (ISF) extraction. When design and characterize such devices, it is critical to monitor their real-time in vitro and in vivo performances to optimize the desired effects, yet most of the existing methods are incapable of such functions. To address this unmet need, we develop a real-time non-invasive imaging methodology by integrating iron oxide (Fe3O4) nanoparticles into polymeric MNs to enhance image contrast for micro-optical coherence tomography (µOCT) imaging. Using the Fe3O4 integrated polystyrene-block-poly (acrylic acid) (PS-b-PAA) MNs ...

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      Mentions: Linbo Liu
    23. Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

      Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

      A model of neutrophil migration across epithelia is desirable to interrogate the underlying mechanisms of neutrophilic breach of mucosal barriers. A co-culture system consisting of a polarized mucosal epithelium and human neutrophils can provide a versatile model of trans-epithelial migration in vitro , but observations are typically limited to quantification of migrated neutrophils by myeloperoxidase correlation, a destructive assay that precludes direct longitudinal study. Our laboratory has recently developed a new isotropic 1-μm resolution optical imaging technique termed micro-optical coherence tomography (μOCT) that enables 4D (x,y,z,t) visualization of neutrophils in the co-culture environment. By applying μOCT to ...

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    24. Flexible, high-resolution micro-optical coherence tomography endobronchial probe toward in vivo imaging of cilia

      Flexible, high-resolution micro-optical coherence tomography endobronchial probe toward in vivo imaging of cilia

      We report the design and fabrication of a flexible, longitudinally scanning high-resolution micro-optical coherence tomography (μOCT) endobronchial probe, optimized for micro-anatomical imaging in airways. The 2.4 mm diameter and flexibility of the probe allows it to be inserted into the instrument channel of a standard bronchoscope, enabling real-time video guidance of probe placement. To generate a depth-of-focus enhancing annular beam, we utilized a new fabrication method, whereby a hollow glass ferrule was angle-polished and gold-coated to produce an elongated annular reflector. We present validation data that verifies the preservation of linear scanning, despite the use of flexible materials. When ...

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    1-24 of 58 1 2 3 »
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    1. (57 articles) Linbo Liu
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    Imaging the subcellular structure of human coronary atherosclerosis using micro–optical coherence tomography Dual-modality fluorescence and full-field optical coherence microscopy for biomedical imaging applications Evaluation of optical reflectance techniques for imaging of alveolar structure Method for Quantitative Study of Airway Functional Microanatomy Using Micro-Optical Coherence Tomography Feature of The Week 12/14/14: Penetrate Deeper Using Extended Source OCT Postdoctoral research fellowships and studentship (optical coherence tomography) at Nanyang Technological University Postdoctoral research fellowship, research associate position, and PhD scholarship (optical coherence tomography) at Nanyang Technological University Feature Of The Week 06/27/2017: Depth-of-Focus Extension in Optical Coherence Tomography via Multiple Aperture Synthesis Evaluating micro-optical coherence tomography (μOCT) as a feasible imaging tool for pancreatic disease diagnosis Postdoctoral Associate Position at Duke Vision and Image Processing Laborator Anterior segment optical coherence tomography angiography Refining percutaneous coronary intervention: intracoronary imaging, haemodynamics, P2Y12 antagonists, and public outcomes reporting