1. 25-48 of 143 « 1 2 3 4 5 6 »
    1. Intravascular atherosclerotic imaging with combined fluorescence and optical coherence tomography probe based on a double-clad fiber combiner

      Intravascular atherosclerotic imaging with combined fluorescence and optical coherence tomography probe based on a double-clad fiber combiner

      We developed a multimodality fluorescence and optical coherence tomography probe based on a double-clad fiber (DCF) combiner. The probe is composed of a DCF combiner, grin lens, and micromotor in the distal end. An integrated swept-source optical coherence tomography and fluorescence intensity imaging system was developed based on the combined probe for the early diagnoses of atherosclerosis. This system is capable of real-time data acquisition and processing as well as image display. For fluorescence imaging, the inflammation of atherosclerosis and necrotic core formed with the annexin V–conjugated Cy5.5 were imaged. Ex vivo imaging of New Zealand white rabbit ...

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    2. Volumetric quantification of in vitro sonothrombolysis with microbubbles using high-resolution optical coherence tomography

      Volumetric quantification of in vitro sonothrombolysis with microbubbles using high-resolution optical coherence tomography

      Several in vitro and in vivo studies have established accelerated thrombolysis using ultrasound (US) induced microbubble (MB) cavitation. However, the mechanisms underlying MB mediated sonothrombolysis are still not completely elucidated. We performed three-dimensional (3-D) volumetric optical coherence tomography (OCT) imaging before and after the application of contrast US to thrombus. The most dramatic reduction in clot volume was observed with US + MB + recombinant tissue plasminogen activator (rt-PA). Thrombus surface erosion in this group on the side of the thrombus exposed to MB and ultrasound was evident on the OCT images. This technique may assist in clarifying the mechanisms underlying sonothrombolysis ...

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    3. Multi-parametric imaging of murine brain using spectral and time domain optical coherence tomography

      Multi-parametric imaging of murine brain using spectral and time domain optical coherence tomography

      Examination of brain functions in small animal models may help improve the diagnosis and treatment of neurological conditions. Transcranial imaging of small rodents’ brains poses a major challenge for optical microscopy. Another challenge is to reduce the measurement time. We describe methods and algorithms for three-dimensional assessment of blood flow in the brains of small animals, through the intact skull, using spectral and time domain optical coherence tomography. By introducing a resonant scanner to the optical setup of the optical coherence tomography (OCT) system, we have developed and applied a high-speed spectral OCT technique that allows us to vary the ...

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    4. Criteria for pathology recognition in optical coherence tomography of fallopian tubes

      Criteria for pathology recognition in optical coherence tomography of fallopian tubes

      An increase of infertility and chronic pelvic pains syndrome, a growing level of latent diseases of this group, as well as a stably high percentage (up to 25% for infertility and up to 60% for the chronic pelvic pains syndrome) of undetermined origin raises the requirement for novel introscopic diagnostic techniques. We demonstrate abilities of optical coherence tomography (OCT) as a complementary technique to laparoscopy in diagnostics of fallopian tubes pathologies. We have acquired OCT images of different parts of fallopian tubes in norm and with morphologically proven pathology. Based on comparative analysis of the OCT data and the results ...

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    5. Three-dimensional simultaneous optical coherence tomography and confocal fluorescence microscopy for investigation of lung tissue

      Three-dimensional simultaneous optical coherence tomography and confocal fluorescence microscopy for investigation of lung tissue

      Although several strategies exist for a minimal-invasive treatment of patients with lung failure, the mortality rate of acute respiratory distress syndrome still reaches 30% at minimum. This striking number indicates the necessity of understanding lung dynamics on an alveolar level. To investigate the dynamical behavior on a microscale, we used three-dimensional geometrical and functional imaging to observe tissue parameters including alveolar size and length of embedded elastic fibers during ventilation. We established a combined optical coherence tomography (OCT) and confocal fluorescence microscopy system that is able to monitor the distension of alveolar tissue and elastin fibers simultaneously within three dimensions ...

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    6. Enhanced optical clearing of skin in vivo and optical coherence tomography in-depth imaging

      Enhanced optical clearing of skin in vivo and optical coherence tomography in-depth imaging

      The strong optical scattering of skin tissue makes it very difficult for optical coherence tomography (OCT) to achieve deep imaging in skin. Significant optical clearing of in vivo rat skin sites was achieved within 15 min by topical application of an optical clearing agent PEG-400, a chemical enhancer (thiazone or propanediol), and physical massage. Only when all three components were applied together could a 15 min treatment achieve a three fold increase in the OCT reflectance from a 300 μm depth and 31% enhancement in image depth Zthreshold.

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    7. Optical phase nanoscopy in red blood cells using low-coherence spectroscopy

      Optical phase nanoscopy in red blood cells using low-coherence spectroscopy

      We propose a low-coherence spectral-domain phase microscopy (SDPM) system for accurate quantitative phase measurements in red blood cells (RBCs) for the prognosis and monitoring of disease conditions that affect the visco-elastic properties of RBCs. Using the system, we performed time-recordings of cell membrane fluctuations, and compared the nano-scale fluctuation dynamics of healthy and glutaraldehyde-treated RBCs. Glutaraldehyde-treated RBCs possess lower amplitudes of fluctuations, reflecting an increased membrane stiffness. To demonstrate the ability of our system to measure fluctuations of lower amplitudes than those measured by the commonly used holographic phase microscopy techniques, we also constructed wide-field digital interferometry (WFDI) system and ...

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    8. Evaluation of optical reflectance techniques for imaging of alveolar structure

      Evaluation of optical reflectance techniques for imaging of alveolar structure

      Three-dimensional (3-D) visualization of the fine structures within the lung parenchyma could advance our understanding of alveolar physiology and pathophysiology. Current knowledge has been primarily based on histology, but it is a destructive two-dimensional (2-D) technique that is limited by tissue processing artifacts. Micro-CT provides high-resolution three-dimensional (3-D) imaging within a limited sample size, but is not applicable to intact lungs from larger animals or humans. Optical reflectance techniques offer the promise to visualize alveolar regions of the large animal or human lung with sub-cellular resolution in three dimensions. Here, we present the capabilities of three optical reflectance techniques, namely ...

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    9. Feasibility of spectral-domain phase-sensitive optical coherence tomography for middle ear vibrometry

      Feasibility of spectral-domain phase-sensitive optical coherence tomography for middle ear vibrometry

      We describe a novel application of spectral-domain phase-sensitive optical coherence tomography (SD PS-OCT) to detect the tiny motions of the middle ear structures, such as the tympanic membrane and ossicular chain, and their morphological features for differential diagnosis of CHL. This technique has the potential to provide meaningful vibration of ossicles with a vibration sensitivity of ∼ 0.5  nm at 1 kHz of acoustic stimulation. To the best of our knowledge, this is the first demonstration of depth-resolved vibration imaging of ossicles with a PS-OCT system at a nanometer scale.

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    10. Investigation of the hyper-reflective inner/outer segment band in optical coherence tomography of living frog retina

      Investigation of the hyper-reflective inner/outer segment band in optical coherence tomography of living frog retina

      This study is to test anatomic correlates, including connecting cilium (CC) and inner segment (IS) ellipsoid, to the hyper-reflective band visualized by optical coherence tomography (OCT) and commonly attributed to the photoreceptor inner/outer segment (IS/OS) junction. A line-scan OCT (LS-OCT) was constructed to achieve sub-cellular resolution (lateral: ∼ 2  μm; axial: ∼ 4  μm) of excised living frog retinas. An electro-optic phase modulator was employed for rapid and vibration-free phase modulation. Comparison of normalized distance measurements between LS-OCT images and histological images revealed that the dominant source of the signal reported as the IS/OS OCT band actually originates from ...

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    11. Practical approach for dispersion compensation in spectral-domain optical coherence tomography

      Practical approach for dispersion compensation in spectral-domain optical coherence tomography

      e proposed and demonstrated a digital method of dispersion compensation suitable for spectral-domain optical coherence tomography. The wavelength coordinate of the coherence spectrum was calibrated digitally using a two-order polynomial. A software-based scheme was introduced to determine the polynomial coefficients of the polynomial fitting spectrum wavelength. Therefore, the spectrum deformation introduced by dispersion can be compensated effectively. This method was experimentally validated by in vivo imaging an early-stage chick embryonic heart.

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      Mentions: Yi Wang
    12. In situ gold nanoparticles formation: contrast agent for dental optical coherence tomography

      In situ gold nanoparticles formation: contrast agent for dental optical coherence tomography

      In this work we demonstrate the potential use of gold nanoparticles as contrast agents for the optical coherence tomography (OCT) imaging technique in dentistry. Here, a new in situ photothermal reduction procedure was developed, producing spherical gold nanoparticles inside dentinal layers and tubules. Gold ions were dispersed in the primer of commercially available dental bonding systems. After the application and permeation in dentin by the modified adhesive systems, the dental bonding materials were photopolymerized concurrently with the formation of gold nanoparticles. The gold nanoparticles were visualized by scanning electron microscopy (SEM). The SEM images show the presence of gold nanospheres ...

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    13. Quantitative analysis of the intraretinal layers and optic nerve head using ultra-high resolution optical coherence tomography

      Quantitative analysis of the intraretinal layers and optic nerve head using ultra-high resolution optical coherence tomography

      This study is designed to test the repeatability of the quantitative analysis of intraretinal layer thickness and cup-disc ratio of the optic nerve head using ultra-high resolution optical coherence tomography (UHR-OCT). Group A, containing 23 eyes of 12 healthy subjects, was imaged twice and group B, containing eight eyes of four subjects, was imaged three times. Intraretinal layers were segmented manually and the cup-to-disc ratio of the optic nerve head was analyzed. Custom-built automatic segmentation software was also used to segment a set of images for comparison. A total of nine intraretinal layers were visualized and extracted manually. With group ...

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    14. In vivo imaging of human burn injuries with polarization-sensitive optical coherence tomography

      In vivo imaging of human burn injuries with polarization-sensitive optical coherence tomography

      The accurate determination of burn depth is critical in the clinical management of burn wounds. Polarization-sensitive optical coherence tomography (PS-OCT) has been proposed as a potentially non-invasive method for determining burn depth by measuring thermally induced changes in the structure and birefringence of skin, and has been investigated in pre-clinical burn studies with animal models and ex vivo human skin. In this study, we applied PS-OCT to the in-vivo imaging of two pediatric burn patients. Deep and superficial burned skins along with contralateral controls were imaged in 3D. The imaging size was 8  mm×6  mm×2  mm in width ...

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    15. Prehistological evaluation of benign and malignant pigmented skin lesions with optical computed tomography

      Prehistological evaluation of benign and malignant pigmented skin lesions with optical computed tomography

      Discrimination of benign and malignant melanocytic lesions is a major issue in clinical dermatology. Assessment of the thickness of melanoma is critical for prognosis and treatment selection. We aimed to evaluate a novel optical computed tomography (optical-CT) system as a tool for three-dimensional (3-D) imaging of melanocytic lesions and its ability to discriminate benign from malignant melanocytic lesions while simultaneously determining the thickness of invasive melanoma. Seventeen melanocytic lesions, one hemangioma, and normal skin were assessed immediately after their excision by optical-CT and subsequently underwent histopathological examination. Tomographic reconstructions were performed with a back-propagation algorithm calculating a 3-D map of ...

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    16. Effects of optical clearing agents on noninvasive blood glucose monitoring with optical coherence tomography: a pilot study

      Effects of optical clearing agents on noninvasive blood glucose monitoring with optical coherence tomography: a pilot study

      Recently, the capability of optical coherence tomography (OCT) has been demonstrated for noninvasive blood glucose monitoring. In this work, we investigate the administration of chemical agents onto human skin tissue to increase the transparency of the surface of the skin, as a means of improving the capability of OCT imaging for clinically relevant applications. Eight groups of experiments were proposed, in which different optical clearing agents (OCA) were used. The results indicate that, when properly used, some OCAs perform well in promoting the capability of OCT for noninvasive blood glucose monitoring. Among the four kinds of OCA we used, 50 ...

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    17. Three-dimensional broadband terahertz synthetic aperture imaging

      Three-dimensional broadband terahertz synthetic aperture imaging

      Terahertz (THz) technology holds great promise for applications such as explosives detection and nondestructive evaluation. In recent years, three-dimensional (3-D) THz imaging has been considered as a potential method to detect concealed explosives due to the transparent properties of packaging materials in the THz range. Another important advantage of THz systems is they measure the electric field directly. They are also phase coherent, supporting synthetic aperture (SA) imaging. In this paper, a near-field synthetic aperture THz imaging system is investigated for its potential use in detecting hidden objects. Frequency averaging techniques are used to reduce noise side-lobe artifacts, and improve ...

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      Mentions: Donald D. Duncan
    18. Quantification of fiber orientation in the canine atrial pacemaker complex using optical coherence tomography

      Quantification of fiber orientation in the canine atrial pacemaker complex using optical coherence tomography

      The atrial pacemaker complex is responsible for the initiation and early propagation of cardiac impulses. Optical coherence tomography (OCT), a nondestructive imaging modality with spatial resolutions of ∼ 1 to 15 μm, can be used to identify unique fiber orientation patterns in this region of the heart. Functionally characterized canine sinoatrial nodes (SAN) (n = 7) were imaged using OCT up to ∼ 1  mm below the endocardial tissue surface. OCT images were directly compared to their corresponding histological sections. Fiber orientation patterns unique to the crista terminalis (CT), SAN, and surrounding atrial myocardium were identified with dominant average fiber angles of 89 ...

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    19. Automatic montage of retinal images in adaptive optics confocal scanning laser ophthalmoscope

      Automatic montage of retinal images in adaptive optics confocal scanning laser ophthalmoscope

      We introduce an automatic technique to stitch retinal images recorded with an adaptive optics confocal scanning laser ophthalmoscope (AOSLO). The AOSLO images whose field size is 1.5 deg are recorded while the fixation target is moving according to a square pattern so as to cover a wide field of view. Principal components analysis–scale invariant feature transform is used to extract and match point features of the retinal images. With the matched point features, the affine transformation is used to stitch the images to generate eight montaged images. Then, the eight images are stitched together to construct a wide-field ...

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    20. Analysis of the efficiency of hair removal by different optical methods: comparison of Trichoscan, reflectance confocal microscopy, and optical coherence tomography

      Analysis of the efficiency of hair removal by different optical methods: comparison of Trichoscan, reflectance confocal microscopy, and optical coherence tomography

      Noninvasive diagnostic tools, such as Trichoscan®, reflectance confocal microscopy (RCM), and optical coherence tomography (OCT), are efficient methods of hair shaft and growth evaluation. The aim of this study was to carry out a comparative assessment of these three medical procedures by measuring the hair shaft and hair growth after hair removal for a defined period of five days. The application of these techniques was demonstrated by measuring hair growth on the lower leg of six female volunteers. After removal of the hair shaft with a shaving system, the hair follicle infundibula and the length of the growing hairs were ...

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    21. In-situ imaging of articular cartilage of the first carpometacarpal joint using co-registered optical coherence tomography and computed tomography

      In-situ imaging of articular cartilage of the first carpometacarpal joint using co-registered optical coherence tomography and computed tomography

      Conventional imaging modalities are unable to depict the early degeneration of articular cartilage in osteoarthritis, especially in small joints. Optical coherence tomography has previously been used successfully in high-resolution imaging of cartilage tissue. This pilot cadaver study demonstrates the use of intra-articular optical coherence tomography in imaging of articular cartilage of the first carpometacarpal joint, producing high resolution images of the articular surface in which cartilage thickness and surface characteristics were assessed. Findings on optical coherence tomography were confirmed with histology. Furthermore, co-registration of optical coherence tomography and computed tomography was used to accurately determine the scanned trajectory and reconstruct ...

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    22. Endoscopic optical coherence tomography device for forward imaging with broad field of view

      Endoscopic optical coherence tomography device for forward imaging with broad field of view

      One current challenge of studying human tympanic membranes (TM) with optical coherence tomography (OCT) is the implementation of optics that avoid direct contact with the inflamed tissue. At the moment, no commercial device is available. We report an optics design for contactless forward imaging endoscopic optical coherence tomography (EOCT) with a large working distance (WD) and a broad field of view (FOV) by restricting the overall diameter of the probe to be small (3.5 mm), ensuring a sufficient numerical aperture. Our system uses a gradient-index (GRIN) relay lens and a GRIN objective lens, and executes a fan-shaped optical scanning ...

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    23. Axial resolution improvement by modulated deconvolution in Fourier domain optical coherence tomography

      Axial resolution improvement by modulated deconvolution in Fourier domain optical coherence tomography

      A novel technique for axial resolution improvement in Fourier domain optical coherence tomography (FDOCT) is presented. The technique is based on the deconvolution of modulated optical coherence tomography signals. In FDOCT, the real part of the Fourier transform of the interferogram is modulated by a frequency which depends on the position of the interferogram in k space. A slight numerical k shift results in a different modulation frequency. By adding two shifted signals, beating can appear in the A-scan. When the amount of shifting is appropriately selected, deconvolution of the resulting depth profile, using suitable modulated kernels, yields a narrower ...

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    24. Real-time three-dimensional Fourier-domain optical coherence tomography video image guided microsurgeries

      Real-time three-dimensional Fourier-domain optical coherence tomography video image guided microsurgeries

      The authors describe the development of an ultrafast three-dimensional (3D) optical coherence tomography (OCT) imaging system that provides real-time intraoperative video images of the surgical site to assist surgeons during microsurgical procedures. This system is based on a full-range complex conjugate free Fourier-domain OCT (FD-OCT). The system was built in a CPU-GPU heterogeneous computing architecture capable of video OCT image processing. The system displays at a maximum speed of 10  volume/?startsend? for an image volume size of 160×80×1024 (X×Y×Z) pixels. We have used this system to visualize and guide two prototypical microsurgical maneuvers: microvascular anastomosis ...

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    25-48 of 143 « 1 2 3 4 5 6 »
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