1. 1-24 of 444 1 2 3 4 ... 17 18 19 »
    1. Preclinical quantitative in-vivo assessment of skin tissue vascularity in radiation-induced fibrosis with optical coherence tomography

      Preclinical quantitative in-vivo assessment of skin tissue vascularity in radiation-induced fibrosis with optical coherence tomography

      Radiation therapy (RT) is widely and effectively used for cancer treatment but can also cause deleterious side effects, such as a late-toxicity complication called radiation-induced fibrosis (RIF). Accurate diagnosis of RIF requires analysis of histological sections to assess extracellular matrix infiltration. This is invasive, prone to sampling limitations, and thus rarely used; instead, current practice relies on subjective clinical surrogates, including visual observation, palpation, and patient symptomatology questionnaires. This preclinical study demonstrates that functional optical coherence tomography (OCT) is a useful tool for objective noninvasive in-vivo assessment and quantification of fibrosis-associated microvascular changes in tissue. Data were collected from murine ...

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    2. Economical and compact briefcase spectral-domain optical coherence tomography system for primary care and point-of-care applications

      Economical and compact briefcase spectral-domain optical coherence tomography system for primary care and point-of-care applications

      Development of low-cost and portable optical coherence tomography (OCT) systems is of global interest in the OCT research community. Such systems enable utility broadly throughout a clinical facility, or in remote areas that often lack clinical infrastructure. We report the development and validation of a low-cost, portable briefcase spectral-domain optical coherence tomography (SD-OCT) system for point-of-care diagnostics in primary care centers and/or in remote settings. The self-contained briefcase OCT contains all associated optical hardware, including light source, spectrometer, hand-held probe, and a laptop. Additionally, this system utilizes unique real-time mosaicking of surface video images that are synchronized with rapid ...

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    3. Automatic segmentation of abnormal capillary nonperfusion regions in optical coherence tomography angiography images using marker-controlled watershed algorithm

      Automatic segmentation of abnormal capillary nonperfusion regions in optical coherence tomography angiography images using marker-controlled watershed algorithm

      Diabetic retinopathy (DR) is one of the most complications of diabetes. It is a progressive disease leading to significant vision loss in the patients. Abnormal capillary nonperfusion (CNP) regions are one of the important characteristics of DR increasing with its progression. Therefore, automatic segmentation and quantification of abnormal CNP regions can be helpful to monitor the patient’s treatment process. We propose an automatic method for segmentation of abnormal CNP regions on the superficial and deep capillary plexuses of optical coherence tomography angiography (OCTA) images using the marker-controlled watershed algorithm. The proposed method has three main steps. In the first ...

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    4. Quantifying scattering coefficient for multiple scattering effect by combining optical coherence tomography with finite-difference time-domain simulation method

      Quantifying scattering coefficient for multiple scattering effect by combining optical coherence tomography with finite-difference time-domain simulation method

      In optical coherence tomography (OCT) systems, to precisely obtain the scattering properties of samples is an essential issue in diagnostic applications. Especially with a higher density turbid medium, the light interferes among the adjacent scatters. Combining an OCT experiment with the finite-difference time-domain simulation method, the multiple scattering effect is shown to affect the scattering properties of medium depending on the interparticle spacing. The far-field scattering phase function of scatters with various diameters was simulated to further analyze the corresponding anisotropy factors, which can be introduced into the extended Huygens-Fresnel theory to find the scattering coefficient of measured samples.

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    5. Visualization of skin microvascular dysfunction of type 1 diabetic mice using in vivo skin optical clearing method

      Visualization of skin microvascular dysfunction of type 1 diabetic mice using in vivo skin optical clearing method

      To realize visualization of the skin microvascular dysfunction of type 1 diabetic mice, we combined laser speckle contrast imaging and hyperspectral imaging to simultaneously monitor the noradrenaline (NE)-induced responses of vascular blood flow and blood oxygen with the development of diabetes through optical clearing skin window. The main results showed that venous and arterious blood flow decreased without recovery after injection of NE; furthermore, the decrease of arterious blood oxygen induced by NE greatly weakened, especially for 2- and 4-week diabetic mice. This change in vasoconstricting effect of NE was related to the expression of α1-adrenergic receptor. This study ...

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    6. Needle-based optical coherence tomography for the detection of prostate cancer: a visual and quantitative analysis in 20 patients

      Needle-based optical coherence tomography for the detection of prostate cancer: a visual and quantitative analysis in 20 patients

      iagnostic accuracy of needle-based optical coherence tomography (OCT) for prostate cancer detection by visual and quantitative analysis is defined. 106 three-dimensional (3-D)-OCT data sets were acquired in 20 prostates after radical prostatectomy and precisely matched with pathology. OCT images were grouped per histological category. Two reviewers performed blind assessments of the OCT images. Sensitivity and specificity for malignancy detection were calculated. Quantitative analyses by automated optical attenuation coefficient calculation were performed. OCT can reliably differentiate between fat, cystic, and regular atrophy and benign glands. The overall sensitivity and specificity for malignancy detection was 79% and 88% for reviewer 1 ...

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    7. Assessment of pathological features in Alzheimer’s disease brain tissue with a large field-of-view visible-light optical coherence microscope

      Assessment of pathological features in Alzheimer’s disease brain tissue with a large field-of-view visible-light optical coherence microscope

      We implemented a wide field-of-view visible-light optical coherence microscope (OCM) for investigating ex-vivo brain tissue of patients diagnosed with Alzheimer’s disease (AD) and of a mouse model of AD. A submicrometer axial resolution in tissue was achieved using a broad visible light spectrum. The use of various objective lenses enabled reaching micrometer transversal resolution and the acquisition of images of microscopic brain features, such as cell structures, vessels, and white matter tracts. Amyloid-beta plaques in the range of 10 to 70  μm were visualized. Large field-of-view images of young and old mouse brain sections were imaged using an automated ...

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    8. Wide field of view optical coherence tomography for structural and functional diagnoses in dentistry

      Wide field of view optical coherence tomography for structural and functional diagnoses in dentistry

      We report herein the fabrication and performance response of a three-dimensional (3-D) intraoral scan probe based on optical coherence tomography (OCT) that enables 3-D structural and functional diagnoses of the human teeth. The OCT system was configured using a swept-source OCT (SS-OCT) with a center wavelength of 1310 nm. The scan probe was built using an MEMS mirror and an optical collimator. The implemented SS-OCT equipped with the MEMS-based scan probe yielded an axial resolution of 10  μm and a scan range of 8  ×  8  mm 2 . Two-dimensional (2-D) cross-sectional images of the teeth were acquired by the scan probe ...

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      Mentions: Jonghyun Eom
    9. Depth-resolved mapping of muscular bundles in myocardium pulmonary junction using optical coherence tomography

      Depth-resolved mapping of muscular bundles in myocardium pulmonary junction using optical coherence tomography

      Atrial fibrillation (AF) is the most common cardiac arrhythmia and has high patient morbidity. One of the root causes of AF is initiating triggers from atrial myocardium extending into the pulmonary veins. Visualizing the muscular bundles of myocardial extension is essential to guide the catheter radio-frequency ablation and confirm the curative tissue necrosis thereafter. We applied optical coherence tomography (OCT) for direct visualization of cardial muscle extension in myocardium pulmonary junction. Two perspectives (cross-sectional and en face images) are presented for imaging myocardial extensions. The results demonstrated that cross-sectional images can quickly locate the myocardium pulmonary junction. And en face ...

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    10. Endoscopic optical coherence tomography with a flexible fiber bundle

      Endoscopic optical coherence tomography with a flexible fiber bundle

      We demonstrate in vivo endoscopic optical coherence tomography (OCT) imaging in the forward direction using a flexible fiber bundle (FB). In comparison to current conventional forward-looking probe schemes, our approach simplifies the endoscope design by avoiding the integration of any beam steering components in the distal probe end due to two-dimensional scanning of a focused light beam over the proximal FB surface. We describe the challenges that arise when OCT imaging with an FB is performed, such as multimoding or cross coupling. The performance of different FBs varying in parameters, such as numerical aperture, core size, core structure, and flexibility ...

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    11. Adaptable switching schemes for time-encoded multichannel optical coherence tomography

      Adaptable switching schemes for time-encoded multichannel optical coherence tomography

      We introduce the approach of variable time encoding for multichannel optical coherence tomography (OCT). High-speed fiber optical switches are applied for sequential sample arm switching to enable quasisimultaneous image acquisition from three different orientation angles. In comparison with previous multichannel OCT (using simultaneous sample illumination), time-encoded multichannel OCT has no need for division of illumination power among the respective channels to satisfy laser safety requirements. Especially for ophthalmic applications—in particular retinal imaging, which the presented prototype was developed for—this advantage strongly influences image quality through an enhanced sensitivity. Nevertheless, time encoding comes at the cost of a decrease ...

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    12. Advances in optical coherence tomography in dermatology—a review

      Advances in optical coherence tomography in dermatology—a review

      Optical coherence tomography (OCT) was introduced as an imaging system, but like ultrasonography, other measures, such as blood perfusion and polarization of light, have enabled the technology to approach clinical utility. This review aims at providing an overview of the advances in clinical research based on the improving technical aspects. OCT provides cross-sectional and en face images down to skin depths of 0.4 to 2.00 mm with optical resolution of 3 to 15  μm. Dynamic optical coherence tomography (D-OCT) enables the visualization of cutaneous microvasculature via detection of rapid changes in the interferometric signal of blood flow. Nonmelanoma ...

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    13. Complex regression Doppler optical coherence tomography

      Complex regression Doppler optical coherence tomography

      We introduce a new method to measure Doppler shifts more accurately and extend the dynamic range of Doppler optical coherence tomography (OCT). The two-point estimate of the conventional Doppler method is replaced with a regression that is applied to high-density B-scans in polar coordinates. We built a high-speed OCT system using a 1.68-MHz Fourier domain mode locked laser to acquire high-density B-scans (16,000 A-lines) at high enough frame rates (∼100  fps) to accurately capture the dynamics of the beating embryonic heart. Flow phantom experiments confirm that the complex regression lowers the minimum detectable velocity from 12.25  mm ...

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    14. Understanding and improving optical coherence tomography imaging depth in selective laser sintering nylon 12 parts and powder

      Understanding and improving optical coherence tomography imaging depth in selective laser sintering nylon 12 parts and powder

      Optical coherence tomography (OCT) has shown promise as a process sensor in selective laser sintering (SLS) due to its ability to yield depth-resolved data not attainable with conventional sensors. However, OCT images of nylon 12 powder and nylon 12 components fabricated via SLS contain artifacts that have not been previously investigated in the literature. A better understanding of light interactions with SLS powder and components is foundational for further research expanding the utility of OCT imaging in SLS and other additive manufacturing (AM) sensing applications. Specifically, in this work, nylon powder and sintered parts were imaged in air and in ...

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    15. Nanoparticle-enabled experimentally trained wavelet-domain denoising method for optical coherence tomography

      Nanoparticle-enabled experimentally trained wavelet-domain denoising method for optical coherence tomography

      We present the nanoparticle-enabled experimentally trained wavelet-domain denoising method for optical coherence tomography (OCT). It employs an experimental training algorithm based on imaging of a test-object, made of the colloidal suspension of the monodisperse nanoparticles and contains the microscale inclusions. The geometry and the scattering properties of the test-object are known a priori allowing us to set the criteria for the training algorithm. Using a wide set of the wavelet kernels and the wavelet-domain filtration approaches, the appropriate filter is constructed based on the test-object imaging. We apply the proposed approach and chose an efficient wavelet denoising procedure by considering ...

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      Mentions: Valery V. Tuchin
    16. Speckle attenuation by adaptive singular value shrinking with generalized likelihood matching in optical coherence tomography

      Speckle attenuation by adaptive singular value shrinking with generalized likelihood matching in optical coherence tomography

      As a high-resolution imaging mode of biological tissues and materials, optical coherence tomography (OCT) is widely used in medical diagnosis and analysis. However, OCT images are often degraded by annoying speckle noise inherent in its imaging process. Employing the bilateral sparse representation an adaptive singular value shrinking method is proposed for its highly sparse approximation of image data. Adopting the generalized likelihood ratio as similarity criterion for block matching and an adaptive feature-oriented backward projection strategy, the proposed algorithm can restore better underlying layered structures and details of the OCT image with effective speckle attenuation. The experimental results demonstrate that ...

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    17. Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution

      Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution

      Most flying-spot Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM) systems use a symmetric confocal geometry, where the detection path retraces the illumination path starting from and ending with the spatial mode of a single mode optical fiber. Here, we describe a visible light OCM instrument that breaks this symmetry to improve transverse resolution without sacrificing collection efficiency in scattering tissue. This was achieved by overfilling a 0.3 numerical aperture (NA) water immersion objective on the illumination path, while maintaining a conventional Gaussian mode detection path (1/e 2 intensity diameter ~0.82 Airy disks), enabling ~1.1 ...

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    18. Large field of view adaptive optics scanning laser ophthalmoscopy and optical coherence tomography

      Large field of view adaptive optics scanning laser ophthalmoscopy and optical coherence tomography

      Adaptive Optics (AO) retinal imaging is revealing microscopic structures of the eye in a non-invasive way. Due to anisoplanatism, conventional AO systems are efficient on small 1°x1° field of view (FoV). We present a lens-based AO scanning laser ophthalmoscope (SLO) set-up with 2 deformable mirrors (DM), providing high-resolution retinal imaging on a 4°x4° FoV, for an eye pupil diameter of 7 mm. The first DM is in a pupil plane and is driven using a Shack-Hartmann (SH). The second DM is conjugated to a plane located 0.7 mm in front of the retina, to correct for aberrations ...

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    19. Simultaneous tissue birefringence and deformation measurement by polarization sensitive optical coherence elastography with active compression

      Simultaneous tissue birefringence and deformation measurement by polarization sensitive optical coherence elastography with active compression

      Polarization sensitive optical coherence tomography (PS-OCT) measures tissue birefringence, while optical coherence elastography (OCE) reveals the mechanical property of the tissue. Since both birefringence and mechanical properties are associated with tissue microstructures such as collagen, simultaneous PS-OCT and OCE measurement will provide useful insight for the tissue microstructures. In this paper, we present a combined PS-OCT and OCE technique. The PS-OCT is based on Jones matrix OCT theory. It measures a tomography of Jones matrix. Birefringence tomography is then deduced from the Jones matrix. The OCE is obtained with active tissue compression. The tissue compression was performed by a ring ...

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    20. Q-switched based supercontinuum source towards low-cost ultra-high resolution optical coherence tomography

      Q-switched based supercontinuum source towards low-cost ultra-high resolution optical coherence tomography

      Supercontinuum (SC) light source is certainly one of the best option for ultra-high resolution optical coherence tomography (UHR-OCT). Over the last few years several demonstrations have been done for each commonly used wavelength range [1-2-3]. Nowadays, SC dedicated to UHR-OCT is a mature technology with turn-key commercially available system [4]. The new challenge to answer for SC source is the cost reduction one. In this study, we demonstrate that a Q-switched based SC (QS-SC) could be an alternative to the current state of the art SC based on a Mode-Locked laser (ML-SC). This QS-SC, whose cost is less than 15 ...

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    21. Microscope-mounted intraoperative optical coherence tomography with actively tunable focus and optical path length

      Microscope-mounted intraoperative optical coherence tomography with actively tunable focus and optical path length

      We present a method for an intraoperative microscope-mounted Fourier-domain optical coherence tomography (FD-OCT) system to maintain high image contrast while dynamic adjusting focal planes. Because two imaging system with different imaging depth are integrated into one system, active control of OCT imaging conditions is indispensible for functioning high quality imaging modality. For the purpose of active adjustment of the focal plane, an electrically focus tunable lens (FTL) was used in the sample arm of the OCT system. Because the OCT image contrast at a depth is given by roll-off characteristics of the FD-OCT that is a function of difference in ...

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    22. Noninvasive measurement of glucose concentration on human fingertip by optical coherence tomography

      Noninvasive measurement of glucose concentration on human fingertip by optical coherence tomography

      A method is proposed for determining the glucose concentration on the human fingertip by extracting two optical parameters, namely the optical rotation angle and the depolarization index, using a Mueller optical coherence tomography technique and a genetic algorithm. The feasibility of the proposed method is demonstrated by measuring the optical rotation angle and depolarization index of aqueous glucose solutions with low and high scattering, respectively. It is shown that for both solutions, the optical rotation angle and depolarization index vary approximately linearly with the glucose concentration. As a result, the ability of the proposed method to obtain the glucose concentration ...

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    23. Feasibility of using optical coherence tomography to detect acute radiation-induced esophageal damage in small animal models

      Feasibility of using optical coherence tomography to detect acute radiation-induced esophageal damage in small animal models

      Lung cancer survival is poor, and radiation therapy patients often suffer serious treatment side effects. The esophagus is particularly sensitive leading to acute radiation-induced esophageal damage (ARIED). We investigated the feasibility of optical coherence tomography (OCT) for minimally invasive imaging of the esophagus with high resolution (10  μm) to detect ARIED in mice. Thirty mice underwent cone-beam computed tomography imaging for initial setup assessment and dose planning followed by a single-dose delivery of 4.0, 10.0, 16.0, and 20.0 Gy on 5.0-mm spots, spaced 10.0 mm apart in the esophagus. They were repeatedly imaged using ...

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    1-24 of 444 1 2 3 4 ... 17 18 19 »
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