1. 1-24 of 781 1 2 3 4 ... 31 32 33 »
    1. High-resolution polarization-sensitive optical coherence tomography for zebrafish muscle imaging

      High-resolution polarization-sensitive optical coherence tomography for zebrafish muscle imaging

      Zebrafish are an important animal model, whose structure and function information can be used to study development, pathologic changes and genetic mutations. However, limited by the penetration depth, the available optical methods are difficult to image the whole-body zebrafish in juvenile and adult stages. Based on a home-made high-resolution polarization-sensitive optical coherence tomography (PS-OCT) system, we finished in vivo volumetric imaging for zebrafish, and various muscles can be clearly discerned by scanning from dorsal, ventral, and lateral directions. Besides structure information, polarization properties extracted from PS-OCT images provide abundant function information to distinguish different muscles. Furthermore, we found local retardation ...

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    2. 3D co-registration algorithm for catheter-based optical coherence tomography

      3D co-registration algorithm for catheter-based optical coherence tomography

      Applications of catheter-based optical coherence tomography (OCT) - originally developed for cardiovascular imaging - have expanded to other organ systems. However, currently available algorithms to co-register 3D OCT data to a second imaging modality were developed for cardiovascular applications and with it, are tailored to small tubular tissue structures. The available algorithms can often not be applied outside the cardiovascular system, e.g. when an OCT probe is introduced into the kidney, lungs, or wrist. Here, we develop a generic co-registration algorithm with potentially numerous applications. This algorithm only requires that the OCT probe is visible on the second imaging modality and ...

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    3. Semi-automated registration and segmentation for gingival tissue volume measurement on 3D OCT images

      Semi-automated registration and segmentation for gingival tissue volume measurement on 3D OCT images

      The change in gingival tissue volume may be used to indicate changes in gingival inflammation, which may be useful for the clinical assessment of gingival health. Properly quantifying gingival tissue volume requires a robust technique for accurate registration and segmentation of longitudinally captured 3-dimensional (3D) images. In this paper, a semi-automated registration and segmentation method for micrometer resolution measurement of gingival-tissue volume is proposed for 3D optical coherence tomography (OCT) imaging. For quantification, relative changes in gingiva tissue volume are measured based on changes in the gingiva surface height using the tooth surface as a reference. This report conducted repeatability ...

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    4. Classification of advanced and early stages of diabetic retinopathy from non-diabetic subjects by an ordinary least squares modeling method applied to OCTA images

      Classification of advanced and early stages of diabetic retinopathy from non-diabetic subjects by an ordinary least squares modeling method applied to OCTA images

      As the prevalence of diabetic retinopathy (DR) continues to rise, there is a need to develop computer-aided screening methods. The current study reports and validates an ordinary least squares (OLS) method to model optical coherence tomography angiography (OCTA) images and derive OLS parameters for classifying proliferative DR (PDR) and no/mild non-proliferative DR (NPDR) from non-diabetic subjects. OLS parameters were correlated with vessel metrics quantified from OCTA images and were used to determine predicted probabilities of PDR, no/mild NPDR, and non-diabetics. The classification rates of PDR and no/mild NPDR from non-diabetic subjects were 94% and 91%, respectively. The ...

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      Mentions: UCLA
    5. Evaluation of the influence of scattered radiation on image quality in spectral optical coherence tomography systems with electronic scanning of objects

      Evaluation of the influence of scattered radiation on image quality in spectral optical coherence tomography systems with electronic scanning of objects

      A comparative evaluation of the influence of scattered radiation on the quality of generated tomographic images in spectral optical coherence tomography systems with a tunable wavelength is presented. Simulation and experimental results demonstrate that systems with a linear illumination field provide a high operating speed and reduce the noise component of the image by about half compared with the full-field method when a tomographic image of a scattering object is obtained.

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    6. Using a dual-tree complex wavelet transform for denoising an optical coherence tomography angiography blood vessel image

      Using a dual-tree complex wavelet transform for denoising an optical coherence tomography angiography blood vessel image

      High image quality is of great importance for precise diagnosis and therapeutics of eye disease in clinic. A human retina OCT angiography (OCTA) image can be extracted from multiple OCT B-scans to visualize the distribution of blood vessels. However, OCTA suffer from the degeneration of image quality due to inherent Gaussian noise of the OCT system while the blood vessel’s signal is extracted. The degeneration of the noise in OCTA image will be more conducive to the evaluation of abnormal and normal blood vessels in the human eye. To precisely assist diagnosis and therapeutics in clinic by reducing the ...

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    7. Correlative infrared optical coherence tomography and hyperspectral chemical imaging

      Correlative infrared optical coherence tomography and hyperspectral chemical imaging

      Optical coherence tomography (OCT) is a high-resolution three-dimensional imaging technique that enables nondestructive measurements of surface and subsurface microstructures. Recent developments of OCT operating in the mid-infrared (MIR) range (around 4 µm) lifted fundamental scattering limitations and initiated applied material research in formerly inaccessible fields. The MIR spectral region, however, is also of great interest for spectroscopy and hyperspectral imaging, which allow highly selective and sensitive chemical studies of materials. In this contribution, we introduce an OCT system (dual-band, central wavelengths of 2 µm and 4 µm) combined with MIR spectroscopy that is implemented as a raster scanning chemical imaging ...

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    8. In vivo SS-OCT imaging of crystalline lens sutures

      In vivo SS-OCT imaging of crystalline lens sutures

      We demonstrate in vivo three-dimensional (3-D) visualization of crystalline lens sutures in healthy eyes using swept source optical coherence tomography (SS-OCT). Volumetric data sets of the crystalline lenses were acquired and processed to obtain enhanced contrast projection images and to extract suture patterns in both anterior and posterior lens. The results presented different types of the sutures including Y-sutures, simple and complex star sutures. Age-related changes in suture arrangement were characterized quantitatively. Crystalline lens suture imaging with SS-OCT might be a useful tool in fundamental studies on development and ageing of human lens.

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    9. Astigmatism-corrected endoscopic imaging probe for optical coherence tomography using soft lithography

      Astigmatism-corrected endoscopic imaging probe for optical coherence tomography using soft lithography

      In endoscopic optical coherence tomography, a transparent protective sheath is used to protect the optics and tissue. However, the sheath causes astigmatism, which degrades transverse resolution and signal-to-noise ratio due to the cylindrical lens effect. Generally used methods for correcting this astigmatism are complex, difficult to control precisely, high-cost, and increase the dimensions of the imaging probe. To overcome these problems, we have developed an astigmatism-corrected imaging probe with an epoxy window. The astigmatism is precisely and cost-effectively adjusted controlling the curvature radius of the epoxy window, which is produced by soft lithography. Using the fiber optic fusion splicing, the ...

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    10. Dynamic contrast in scanning microscopic OCT

      Dynamic contrast in scanning microscopic OCT

      While optical coherence tomography (OCT) provides a resolution down to 1 µm, it has difficulties in visualizing cellular structures due to a lack of scattering contrast. By evaluating signal fluctuations, a significant contrast enhancement was demonstrated using time-domain full-field OCT (FF-OCT), which makes cellular and subcellular structures visible. The putative cause of the dynamic OCT signal is the site-dependent active motion of cellular structures in a sub-micrometer range, which provides histology-like contrast. Here we demonstrate dynamic contrast with a scanning frequency-domain OCT (FD-OCT), which we believe has crucial advantages. Given the inherent sectional imaging geometry, scanning FD-OCT provides depth-resolved images ...

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    11. Functional optical coherence tomography enables in vivo optoretinography of photoreceptor dysfunction due to retinal degeneration

      Functional optical coherence tomography enables in vivo optoretinography of photoreceptor dysfunction due to retinal degeneration

      Stimulus-evoked intrinsic optical signal (IOS), which occurs almost immediately after the onset of retinal stimulus has been observed in retinal photoreceptors, promises to be a unique biomarker for objective optoretinography (ORG) of photoreceptor function. We report here the first-time in vivo ORG detection of photoreceptor dysfunction due to retinal degeneration. A custom-designed optical coherence tomography (OCT) was employed for longitudinal ORG monitoring of photoreceptor-IOS distortions in retinal degeneration mice. Depth-resolved OCT analysis confirmed the outer segment (OS) as the physical source of the photoreceptor-IOS. Comparative ERG measurement verified the phototransduction activation as the physiological correlator of the photoreceptor-IOS. Histological examination ...

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    12. In vivo imaging of the depth-resolved optic axis of birefringence in human skin

      In vivo imaging of the depth-resolved optic axis of birefringence in human skin

      Recent progress has enabled the reconstruction of the local (i.e., depth-resolved) optic axis (OAx) of biological tissue from measurements made with polarization-sensitive optical coherence tomography (PS-OCT). Here we demonstrate local OAx imaging in healthy human skin in vivo . The images reveal dense, weaving patterns that are imperceptible in OCT intensity tomograms or conventional PS-OCT metrics and that suggest a mesh-like tissue organization, consistent with the morphology of dermal collagen. Using co-registered polarization-sensitive optical coherence microscopy, we furthermore investigated the impact of spatial resolution on the recovered OAx patterns and confirmed their consistency. OAx orientation as a contrast mechanism merits ...

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    13. Multimodal imaging with spectral-domain optical coherence tomography and photoacoustic remote sensing microscopy

      Multimodal imaging with spectral-domain optical coherence tomography and photoacoustic remote sensing microscopy

      We develop a multimodal imaging platform, combining depth-resolved scattering contrast from spectral-domain optical coherence tomography (SD-OCT) with complementary, non-contact absorption contrast using photoacoustic remote sensing (PARS) microscopy. The system provides a widefield OCT mode using a telecentric scan lens, and a high-resolution, dual-contrast mode using a 0.26 numerical aperture apochromatic objective. An interlaced acquisition approach is used to achieve simultaneous, co-registered imaging. The SD-OCT modality provides a 9.7 µm axial resolution. Comprehensive in vivo imaging of a nude mouse ear is demonstrated, with the SD-OCT scattering intensity revealing dermal morphology, and PARS microscopy providing a map of microvasculature.

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    14. Automated full-field polarization-sensitive optical coherence tomography diagnostic systems for breast cancer

      Automated full-field polarization-sensitive optical coherence tomography diagnostic systems for breast cancer

      Intraoperative delineation of breast cancer is a major challenge. An effective breast tissue screening technique may reduce the risk of re-excision during surgery by specifically identifying positive margins. In this study, a high-resolution automated full-field polarization-sensitive optical coherence tomography (FF-PS-OCT) system was developed to classify healthy and malignant human breast tissue from quantitative phase retardation information of the tissues in ex vivo . Twelve breast tissue samples [four healthy, eight malignant (cancerous)] were imaged with the FF-PS-OCT system and the different phase features were extracted from the acquired OCT images (106), based on the differences in the optical signatures of the ...

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    15. Optical coherence tomography interpreted by diffractive optics: A-scan image formation with wavelength-scale diffraction gratings as samples

      Optical coherence tomography interpreted by diffractive optics: A-scan image formation with wavelength-scale diffraction gratings as samples

      Seeking a detailed investigation of polarization sensitive optical coherence tomography, electromagnetic numerical simulation of optical coherence tomography is carried out assuming deep diffraction gratings, some of which are in the resonance domain, as a sample to be measured. This is an approach from diffractive optics, and its simplification of the problem makes analysis more focused on its fundamental nature. The combination of the two disciplines provides previously unnoticed issues such as detection of a structure that does not exist.

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    16. Retinal choroidal vessel imaging based on multi-wavelength fundus imaging with the guidance of optical coherence tomography

      Retinal choroidal vessel imaging based on multi-wavelength fundus imaging with the guidance of optical coherence tomography

      A multispectral fundus camera (MSFC), as a novel noninvasive technology, uses an extensive range of monochromatic light sources that enable the view of different sectional planes of the retinal and choroidal structures. However, MSFC imaging involves complex processes affected by various factors, and the recognized theory based on light absorption above the choroid is not sufficient. In an attempt to supplement the relevant explanations, in this study, we used optical coherence tomography (OCT), a three-dimensional tomography modality, to analyze MSFC results at the retina and choroid. The swept-source OCT system at 1060 nm wavelength with a 200 kHz A-scan rate ...

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    17. Multi-scale optical coherence tomography imaging and visualization of Vermeer’s Girl with a Pearl Earring

      Multi-scale optical coherence tomography imaging and visualization of Vermeer’s Girl with a Pearl Earring

      We demonstrate multi-scale multi-parameter optical coherence tomography (OCT) imaging and visualization of Johannes Vermeer’s painting Girl with a Pearl Earring . Through automated acquisition, OCT image segmentation, and 3D volume stitching we realize OCT imaging at the scale of an entire painting. This makes it possible to image, with micrometer axial and lateral resolution, an entire painting over more than 5 orders of length scale. From the multi-scale OCT data we quantify multiple parameters in a fully automated way: the surface height, the scattering strength, and the combined glaze and varnish layer thickness. The multi-parameter OCT data of Girl with ...

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    18. Optical flow optical coherence tomography for determining accurate velocity fields

      Optical flow optical coherence tomography for determining accurate velocity fields

      Determining micron-scale fluid flow velocities using optical coherence tomography (OCT) is important in both biomedical research and clinical diagnosis. Numerous methods have been explored to quantify the flow information, which can be divided into either phase-based or amplitude-based methods. However, phase-based methods, such as Doppler methods, are less sensitive to transverse velocity components and suffer from wrapped phase and phase instability problems for axial velocity components. On the other hand, amplitude-based methods, such as speckle variance OCT, correlation mapping OCT and split-spectrum amplitude-decorrelation angiography, focus more on segmenting flow areas than quantifying flow velocities. In this paper, we propose optical ...

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    19. Optoretinogram: optical measurement of human cone and rod photoreceptor responses to light

      Optoretinogram: optical measurement of human cone and rod photoreceptor responses to light

      Noninvasive, objective measurement of rod function is as significant as that of cone function, and for retinal diseases such as retinitis pigmentosa and age-related macular degeneration, rod function may be a more sensitive biomarker of disease progression and efficacy of treatment than cone function. Functional imaging of single human rod photoreceptors, however, has proven difficult because their small size and rapid functional response pose challenges for the resolution and speed of the imaging system. Here, we describe light-evoked, functional responses of human rods and cones, measured noninvasively using a synchronized adaptive optics optical coherence tomography (OCT) and scanning light ophthalmoscopy ...

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    20. Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples

      Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples

      Optical coherence tomography (OCT) is being increasingly adopted as a label-free and non-invasive technique for biomedical applications such as cancer and ocular disease diagnosis. Diagnostic information for these tissues is manifest in textural and geometric features of the OCT images, which are used by human expertise to interpret and triage. However, it suffers delays due to the long process of the conventional diagnostic procedure and shortage of human expertise. Here, a custom deep learning architecture, LightOCT, is proposed for the classification of OCT images into diagnostically relevant classes. LightOCT is a convolutional neural network with only two convolutional layers and ...

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    21. Spectrometer calibration with reduced dispersion for optical coherence tomography

      Spectrometer calibration with reduced dispersion for optical coherence tomography

      A wavelength calibration method is proposed for Fourier domain optical coherence tomography. In the present study, the wavelength remapping procedure is based on the spectral phase function determined by the calibration signal. To accomplish high accuracy feature for wavelength calibration, a common-path interferometer is employed. Two autocorrelation interferograms generated from the common-path interferometer are utilized as the calibration signals. The advantage of the interferometer proposed here is that the accurate optical path difference of the calibration signals could be acquired easily. The wavelength distribution in the spectrometer was deduced with the phase signal. The approach was compared to a wavelength-determined ...

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    22. Point spread function degradation model of a polarization imaging system for wide-field subwavelength nanoparticles

      Point spread function degradation model of a polarization imaging system for wide-field subwavelength nanoparticles

      We propose a comprehensive point spread function (PSF) degradation model, which considers multiple factors consisting of degradation of specimen retardant sampling and polarization angularly anamorphic sampling, to indicate the image degradation characteristics of polarization imaging systems. First, a one-layer optical coherence tomography (OCT) model was established to express the retardancy of medium-loading specimens. Then, a PSF degradation model of angularly anamorphic polarization sampling was deduced through the retrieval of Stokes parameters. Finally, maximum a posteriori probability (MAP) was adopted to assess the distribution of the proposed model. Hypothesis testing using actual data and numerical simulations demonstrated that the error of ...

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    23. Full-range space-division multiplexing optical coherence tomography angiography

      Full-range space-division multiplexing optical coherence tomography angiography

      Abstract In this study, we demonstrated a full-range space-division multiplexing optical coherence tomography (FR-SDM-OCT) system. Utilizing the galvanometer-based phase modulation full-range technique, the total imaging range of FR-SDM-OCT can be extended to >20 mm in tissue, with a digitizer sampling rate of 500 MS/s and a laser sweeping rate of 100 kHz. Complex conjugate terms were suppressed in FR-SDM-OCT images with a measured rejection ratio of up to ∼46 dB at ∼1.4 mm depth and ∼30 dB at ∼19.4 mm depth. The feasibility of FR-SDM-OCT was validated by imaging Scotch tapes and human fingernails. Furthermore, we demonstrated ...

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    24. Split-spectrum amplitude-decorrelation angiography with optical coherence tomography

      Split-spectrum amplitude-decorrelation angiography with optical coherence tomography

      Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction. To overcome this limitation, we developed split-spectrum amplitude-decorrelation angiography (SSADA) to improve the signal-to-noise ratio (SNR) of flow detection. The full OCT spectrum was split into several narrower bands. Inter-B-scan decorrelation was computed using the spectral bands separately and then averaged. The SSADA algorithm was tested on in vivo images of the human macula and optic nerve head ...

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    1-24 of 781 1 2 3 4 ... 31 32 33 »
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