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    1. Decreasing the Size of a Spectral Domain Optical Coherence Tomography System With Cascaded ...

      Decreasing the Size of a Spectral Domain Optical Coherence Tomography System With Cascaded ...

      This paper describes a proof-of-concept of a miniaturized spectral-domain optical coherence tomography system, based on photonic integrated circuit (PIC) technology. The integrated optics 512-channel spectrometer consists of cascaded arrayed waveguide gratings (AWG) with the output waveguides directly attached to a CCD detector. The spectrometer has a center wavelength of 850 nm and a spectral sampling interval of 0.22 nm. The PIC has a footprint of 2.0 × 2.7 cm 2 . The wavelength response of the cascaded AWG spectrometer is calibrated with a tunable laser. Free space OCT measurements are done with a mirror as sample. The signal-to-noise ratio ...

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    2. Geometric Validation of Continuous, Finely Sampled 3-D Reconstructions From aOCT and CT in Upper Airway Models

      Geometric Validation of Continuous, Finely Sampled 3-D Reconstructions From aOCT and CT in Upper Airway Models

      Identification and treatment of obstructive airway disorders (OADs) are greatly aided by imaging of the geometry of the airway lumen. Anatomical optical coherence tomography (aOCT) is a promising high-speed and minimally invasive endoscopic imaging modality for providing micrometer-resolution scans of the upper airway. Resistance to airflow in OADs is directly caused by the reduction in luminal cross-sectional area (CSA). It is hypothesized that aOCT can produce airway CSA measurements as accurate as that from computed tomography (CT). Scans of machine hollowed cylindrical tubes were used to develop methods for segmentation and measurement of airway lumen in CT and aOCT. Simulated ...

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    3. A FBG-OCT Catheter to reconstruct vascular shape in intravascular optical coherence tomography

      A FBG-OCT Catheter to reconstruct vascular shape in intravascular optical coherence tomography

      We propose a novel Fiber Bragg Grating (FBG)-Optical Coherence Tomography (OCT) catheter to reconstruct vascular shape by intravascular OCT imaging of the actual curvature as well as the bending direction of the vascular in real-time. Compared with the traditional OCT catheter, the FBG-OCT catheter uses the FBG encapsulated with half-sectioned stainless-steel tube as a flexural sensitive component. With the 360-degree rotation of the catheter, the encapsulated FBG will produce maximum tension and maximum compression at the bend of the blood vessel, and then get the solution of the curvature and direction of the bending catheter as well as the ...

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      Mentions: Tiegen Liu
    4. Establishment of an Automated Algorithm Utilizing Optical Coherence Tomography and Micro-Computed Tomography Imaging to Reconstruct the 3-D Deformed Stent Geometry

      Establishment of an Automated Algorithm Utilizing Optical Coherence Tomography and Micro-Computed Tomography Imaging to Reconstruct the 3-D Deformed Stent Geometry

      Percutaneous coronary intervention (PCI) is the prevalent treatment for coronary artery disease, with hundreds of thousands of stents implanted annually. Computational studies have demonstrated the role of biomechanics in the failure of vascular stents, but clinical studies is this area are limited by a lack of understanding of the deployed stent geometry, which is required to accurately model and predict the stent-induced in vivo biomechanical environment. Herein, we present an automated method to reconstruct the 3-D deployed stent configuration through the fusion of optical coherence tomography (OCT) and micro-computed tomography ( μ CT) imaging data. In an experimental setup, OCT and μ CT ...

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    5. Cardiac muscle energetics: Improved normalisation of heat using optical coherence tomography

      Cardiac muscle energetics: Improved normalisation of heat using optical coherence tomography

      Heat liberated from isolated cardiac muscle has been used to inform us of thermo-mechanical processes that occur during a contraction. However, for comparisons between different samples to be useful, the heat output needs to be normalized to volume. We have implemented an optical coherence tomograph (OCT), together with a flow-through calorimeter, to accurately determine both muscle volume and heat in the same measurement chamber. The heat rate for multiple stimulation frequencies were recorded and normalized to the volume captured by the OCT. There was a ~15 % difference in the volume estimated by the OCT compared to the standard 1D approximation ...

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    6. Attention to Lesion: Lesion-Aware Convolutional Neural Network for Retinal Optical Coherence Tomography Image Classification

      Attention to Lesion: Lesion-Aware Convolutional Neural Network for Retinal Optical Coherence Tomography Image Classification

      Automatic and accurate classification of retinal optical coherence tomography (OCT) images is essential to assist ophthalmologist in the diagnosis and grading of macular diseases. Clinically, ophthalmologists usually diagnose macular diseases according to the structures of macular lesions, whose morphologies, size, and numbers are important criteria. In this paper, we propose a novel lesion-aware convolutional neural network (LACNN) method for retinal OCT image classification, in which retinal lesions within OCT images are utilized to guide the CNN to achieve more accurate classification. The LACNN simulates the ophthalmologists’ diagnosis that focuses on local lesion-related regions when analyzing the OCT image. Specifically, we ...

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    7. 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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    8. Monitoring acute stroke progression: multi-parametric OCT imaging of cortical perfusion, flow, and tissue scattering in a mouse model of permanent focal ischemia

      Monitoring acute stroke progression: multi-parametric OCT imaging of cortical perfusion, flow, and tissue scattering in a mouse model of permanent focal ischemia

      Cerebral ischemic stroke causes injury to brain tissue characterized by a complex cascade of neuronal and vascular events. Imaging during early stages of its development allows prediction of tissue infarction and penumbra, so that optimal intervention can be determined in order to salvage brain function impairment. Therefore, there is a critical need for novel imaging techniques that can characterize brain injury in the earliest phases of ischemic stroke. This study examined optical coherence tomography (OCT) for imaging acute injury in experimental ischemic stroke in vivo. Based on endogenous optical scattering signals provided by OCT imaging, we have developed a single ...

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    9. Establishment of an Automated Algorithm Utilizing Optical Coherence Tomography and Micro-Computed Tomography Imaging to Reconstruct the 3D Deformed Stent Geometry

      Establishment of an Automated Algorithm Utilizing Optical Coherence Tomography and Micro-Computed Tomography Imaging to Reconstruct the 3D Deformed Stent Geometry

      Percutaneous coronary intervention (PCI) is the prevalent treatment for coronary artery disease, with hundreds of thousands of stents implanted annually. Computational studies have demonstrated the role of biomechanics in the failure of vascular stents, but clinical studies is this area are limited by a lack of understanding of the deployed stent geometry, which is required to accurately model and predict the stent induced in vivo biomechanical environment. Herein, we present an automated method to reconstruct the 3D deployed stent configuration through the fusion of optical coherence tomography (OCT) and micro-computed tomography (μCT) imaging data. In an experimental setup, OCT and ...

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    10. 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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    11. Automatic Plaque Detection in IVOCT Pullbacks Using Convolutional Neural Networks

      Automatic Plaque Detection in IVOCT Pullbacks Using Convolutional Neural Networks

      Coronary heart disease is a common cause of death despite being preventable. To treat the underlying plaque deposits in the arterial walls, intravascular optical coherence tomography can be used by experts to detect and characterize the lesions. In clinical routine, hundreds of images are acquired for each patient, which require automatic plaque detection for fast and accurate decision support. So far, automatic approaches rely on classic machine learning methods and deep learning solutions have rarely been studied. Given the success of deep learning methods with other imaging modalities, a thorough understanding of deep learning-based plaque detection for future clinical decision ...

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    12. Semi-Supervised Automatic Segmentation of Layer and Fluid Region in Retinal Optical Coherence Tomography Images Using Adversarial Learning

      Semi-Supervised Automatic Segmentation of Layer and Fluid Region in Retinal Optical Coherence Tomography Images Using Adversarial Learning

      Optical coherence tomography (OCT) is a primary imaging technique for ophthalmic diagnosis due to its advantages in high resolution and non-invasiveness. Diabetes is a chronic disease, which could cause retinal layer deformation and fluid accumulation. It might increase the risk of blindness, and thus, it is important to monitor the morphology change of the retinal layer and fluid accumulation for diabetes patients. Due to the existence of deformation and fluid accumulation, the retinal layer and fluid region segmentation in the OCT image is a challenging task. Machine learning-based segmentation methods have been proposed, but they depend on a significant number ...

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    13. Integrating Handcrafted and Deep Features for Optical Coherence Tomography Based Retinal Disease Classification

      Integrating Handcrafted and Deep Features for Optical Coherence Tomography Based Retinal Disease Classification

      Deep Neural Networks (DNNs) have been widely applied to automatic analysis of medical images for disease diagnosis, and to help human experts by efficiently processing immense amounts of images. While handcrafted feature has been used for eye disease detection or classification since the 1990s, DNN was recently adopted in this area and showed very promising performance. Since handcrafted and deep feature can extract complementary information, we propose in this paper three different integration frameworks to combine handcrafted and deep feature for optical coherence tomography (OCT) image based eye disease classification. In addition, to integrate the handcrafted feature at Input and ...

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    14. Ultrafast Wavenumber Linear-step-swept source Based on Synchronous Lightwave Synthesized Frequency Sweeper

      Ultrafast Wavenumber Linear-step-swept source Based on Synchronous Lightwave Synthesized Frequency Sweeper

      An ultrafast wavenumber linear-step-swept source based on a synchronous lightwave synthesized frequency sweeper (SLSFS) is demonstrated. A multi-wavelength source is used as a seed source. In SLSFS, the swept range of different wavelength components is precisely controlled by a stable programmable radio frequency (RF) signal applied on a dual-parallel Mach-Zehnder modulator (DP-MZM) instead of a conventional wavelength filter. The identical frequency shifting step of all the wavelength components promises high linear sweeping in frequency domain. The key significance of this technique is that the swept rate and the swept range increases as the number of the seed wavelengths increases. Experimentally ...

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    15. Polarization-Sensitive Optical Coherence Tomography for Brain Tumor Characterization

      Polarization-Sensitive Optical Coherence Tomography for Brain Tumor Characterization

      Complete removal of brain tumor is of the most interest to a surgeon because the resection area directly relates to recurrence rate. Although there are many biomedical imaging modalities applied to locate the positions of tumors, they lack the spatial resolution to precisely delineate the boundary between brain tumor and normal brain tissues and are also inconvenient to be used intraoperatively. This study aims to examine the feasibility of the label-free, polarization-sensitive optical coherence tomography (PS-OCT) for distinguishing brain tumors from normal brain tissues. Ex vivo samples were obtained from two patients with grade II and II-III glioma; healthy porcine ...

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    16. Non-ionized, High-resolution Measurement of Internal and Marginal Discrepancies of Dental Prosthesis Using Optical Coherence Tomography

      Non-ionized, High-resolution Measurement of Internal and Marginal Discrepancies of Dental Prosthesis Using Optical Coherence Tomography

      An internal and marginal fit between prosthesis and abutment are important factors of the durability of dental prosthesis. In this study we have proposed the use of swept-source optical coherence tomography (SS-OCT) as a novel application for non-ionized and high-resolution measurements of internal and marginal discrepancies at anatomically critical four points, such as occlusal, angle, axial, and margin during prosthesis attachment. A tooth model was fabricated by 3D printing technique and the dental prosthesis was designed using dental CAD software. The cross-sectional images along with intensity peak profile analysis of the sample were acquired using OCT system for measurements of ...

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    17. 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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    18. Large axial range frequency-domain optical low coherence interferometry

      Large axial range frequency-domain optical low coherence interferometry

      In this paper, we propose a new experimental setup to extend the measurement range of frequency-domain low coherence interferometry (FD-LCI) from 3 mm to 2 cm. The FD-LCI can be extended to the technique of frequency domain optical coherence tomography (FD-OCT) by performing additional lateral scanning. This new and simple arrangement just attaches an extra interferometer before the spectrometer in a typical FD-LCI setup. With this configuration, it is possible to overcome the limitation of the dynamic range of the conventional technique. This allows us to measure the optical path difference of the sample of interest, which is outside the ...

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    19. A Mechanical Approach for Smooth Surface Fitting to Delineate Vessel Walls in Optical Coherence Tomography Images

      A Mechanical Approach for Smooth Surface Fitting to Delineate Vessel Walls in Optical Coherence Tomography Images

      Automated analysis of vascular imaging techniques is limited by the inability to precisely determine arterial borders. Intravascular optical coherence tomography (OCT) offers unprecedented detail of artery wall structure and composition, but does not provide consistent visibility of the outer border of the vessel due to limited penetration depth. Existing interpolation and surface fitting methods prove insufficient to accurately fill the gaps between the irregularly-spaced and sometimes unreliably-identified visible segments of the vessel outer border. This paper describes an intuitive, efficient, and flexible new method of three-dimensional surface fitting and smoothing suitable for this task. An anisotropic linear-elastic mesh is fit ...

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    20. Non-destructive identification of weld-boundary and porosity formation during laser transmission welding by using optical coherence tomography

      Non-destructive identification of weld-boundary and porosity formation during laser transmission welding by using optical coherence tomography

      Laser transmission welding offers significant benefits over conventional welding techniques enabling single-stage rapid plastic joining. The quality of laser transmission welded products are commonly assessed by measuring the weld penetration depth, hardened weld boundary, and inspecting the formation of porosity. However, existing methods of verification are inevitably accompanied by destruction of the specimen. Thus, non-destructive quality assessment methods for laser transmission welding have gained attention recently. Here, we demonstrated an extended industrial application of 860 nm wavelength based spectral domain optical coherence tomography for the non-destructive inspection of the aforementioned quality parameters of laser transmission welded industrial plastic materials, i ...

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    21. Simultaneous Estimation of Corneal Topography, Pachymetry, and Curvature

      Simultaneous Estimation of Corneal Topography, Pachymetry, and Curvature

      dentification of objective criteria to correctly diagnose ectatic diseases of the cornea or to detect early stages of corneal ectasia is of great interest in ophthalmology and optometry. Metrics for diagnosis typically employed are curvature maps (axial/sagittal, tangential); elevation map of the anterior surface of the cornea with respect to a reference sphere; and pachymetry (thickness) map of the cornea. We present evidence that currently used curvature maps do not represent the actual curvatures (principal or mean) in a human cornea. A novel contribution of this paper is the computation of the true mean curvature over every point of ...

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    22. 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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    23. Geometric Validation of Continuous, Finely-Sampled 3D Reconstructions from aOCT and CT in Upper Airway Models

      Geometric Validation of Continuous, Finely-Sampled 3D Reconstructions from aOCT and CT in Upper Airway Models

      Identification and treatment of obstructive airway disorders (OADs) is greatly aided by imaging of the geometry of the airway lumen. Anatomical optical coherence tomography (aOCT) is a promising high-speed and minimally-invasive endoscopic imaging modality for providing micrometer-resolution scans of the upper airway. Resistance to airflow in OADs is directly caused by reduction in luminal cross-sectional area (CSA). It is hypothesized that aOCT can produce airway CSA measurements as accurate as that from computed tomography (CT). Scans of machine hollowed cylindrical tubes were used to develop methods for segmentation and measurement of airway lumen in CT and aOCT. Simulated scans of ...

      Read Full Article
    24. Quantitative evaluation of skin surface roughness using optical coherence tomography in vivo

      Quantitative evaluation of skin surface roughness using optical coherence tomography in vivo

      The quantitative monitoring of skin topography is important in the field of cosmetics and dermatology. The most widespread method for determining skin roughness in vivo is to use skin microrelief, PRIMOS device, which allows a noninvasive, fast and direct measurement of the skin surface. However, it has drawbacks, such as the interference of backscattering from volumetric skin and motion artifacts. In this study, we demonstrate the potential of OCT for providing reliable and quantitative skin surface roughness. In order to evaluate the performance of OCT for skin surface analysis, different types of skin phantoms were fabricated and measured. We utilized ...

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