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    1. High-resolution handheld rigid endomicroscope based on full-field optical coherence tomography

      High-resolution handheld rigid endomicroscope based on full-field optical coherence tomography

      Full-field optical coherence tomography (FF-OCT) is a powerful tool for nondestructive assessment of biological tissue, i.e., for the structural examination of tissue in depth at a cellular resolution. Mostly known as a microscopy device for ex vivo analysis, FF-OCT has also been adapted to endoscopy setups since it shows good potential for in situ cancer diagnosis and biopsy guidance. Nevertheless, all the attempts to perform endoscopic FF-OCT imaging did not go beyond lab setups. We describe here, to the best of our knowledge, the first handheld FF-OCT endoscope based on a tandem interferometry assembly using incoherent illumination. A common-path ...

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    2. Rotational imaging optical coherence tomography for full-body mouse embryonic imaging

      Rotational imaging optical coherence tomography for full-body mouse embryonic imaging

      Optical coherence tomography (OCT) has been widely used to study mammalian embryonic development with the advantages of high spatial and temporal resolutions and without the need for any contrast enhancement probes. However, the limited imaging depth of traditional OCT might prohibit visualization of the full embryonic body. To overcome this limitation, we have developed a new methodology to enhance the imaging range of OCT in embryonic day (E) 9.5 and 10.5 mouse embryos using rotational imaging. Rotational imaging OCT (RI-OCT) enables full-body imaging of mouse embryos by performing multiangle imaging. A series of postprocessing procedures was performed on ...

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    3. Minimally invasive surgical method to detect sound processing in the cochlear apex by optical coherence tomography

      Minimally invasive surgical method to detect sound processing in the cochlear apex by optical coherence tomography

      Sound processing in the inner ear involves separation of the constituent frequencies along the length of the cochlea. Frequencies relevant to human speech (100 to 500 Hz) are processed in the apex region. Among mammals, the guinea pig cochlear apex processes similar frequencies and is thus relevant for the study of speech processing in the cochlea. However, the requirement for extensive surgery has challenged the optical accessibility of this area to investigate cochlear processing of signals without significant intrusion. A simple method is developed to provide optical access to the guinea pig cochlear apex in two directions with minimal surgery ...

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    4. Dynamic light scattering by flowing Brownian particles measured with optical coherence tomography: impact of the optical system

      Dynamic light scattering by flowing Brownian particles measured with optical coherence tomography: impact of the optical system

      The study of flowing Brownian particles finds numerous biomedical applications, ranging from blood flow analysis to diffusion research. A mathematical model for the correlation function of laser radiation scattered by flowing Brownian particles measured with fiber-based optical coherence tomography (OCT), which accounts for the effects of sample arm optics, is presented. It is shown that the parameters of an OCT optical system of any complexity can be taken into account by using the ABCD ray tracing matrix approach. Specifically, the impact of any optical system can be characterized by the changes in the effective beam radius, which replaces the Gaussian ...

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    5. Advantages of microscope-integrated intraoperative online optical coherence tomography: usage in Boston keratoprosthesis type I surgery

      Advantages of microscope-integrated intraoperative online optical coherence tomography: usage in Boston keratoprosthesis type I surgery

      Boston keratoprosthesis (KPro) type I is a technique to treat patients with corneal diseases that are not amenable to conventional keratoplasty. Correct assembly and central implantation of the prosthesis are crucial for postoperative visual recovery. This study investigates the potential benefit of intraoperative optical coherence tomography (OCT) to monitor KPro surgery. Retrospective case series are presented for two patients who underwent Boston KPro type I implantation. The surgery in both patients was monitored intraoperatively using a commercially available intraoperative OCT (iOCT) device mounted on a surgical microscope. Microscope-integrated intraoperative OCT was able to evaluate the correct assembly and implantation of ...

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    6. Combined reflectance confocal microscopy-optical coherence tomography for delineation of basal cell carcinoma margins: an ex vivo study

      Combined reflectance confocal microscopy-optical coherence tomography for delineation of basal cell carcinoma margins: an ex vivo study

      We present a combined reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) approach, integrated within a single optical layout, for diagnosis of basal cell carcinomas (BCCs) and delineation of margins. While RCM imaging detects BCC presence (diagnoses) and its lateral spreading (margins) with measured resolution of ∼ 1    μ m ∼1  μm , OCT imaging delineates BCC depth spreading (margins) with resolution of ∼ 7    μ m ∼7  μm . When delineating margins in 20 specimens of superficial and nodular BCCs, depth could be reliably determined down to ∼600    μ m ∼600  μm , and agreement with histology was within about ±50    μ m ±50  μm .

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    7. Intraoperative imaging of pediatric vocal fold lesions using optical coherence tomography

      Intraoperative imaging of pediatric vocal fold lesions using optical coherence tomography

      Optical coherence tomography (OCT) has been previously identified as a promising tool for exploring laryngeal pathologies in adults. Here, we present an OCT handheld probe dedicated to imaging the unique geometry involved in pediatric laryngoscopy. A vertical cavity surface emitting laser-based wavelength-swept OCT system operating at 60 frames per second was coupled to the probe to acquire three-dimensional (3-D) volumes in vivo . In order to evaluate the performance of the proposed probe and system, we imaged pediatric vocal fold lesions of patients going under direct laryngoscopy. Through this in vivo study, we extracted OCT features characterizing each pediatric vocal fold ...

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    8. Validation of quantitative attenuation and backscattering coefficient measurements by optical coherence tomography in the concentration-dependent and multiple scattering regime

      Validation of quantitative attenuation and backscattering coefficient measurements by optical coherence tomography in the concentration-dependent and multiple scattering regime

      Optical coherence tomography (OCT) has the potential to quantitatively measure optical properties of tissue such as the attenuation coefficient and backscattering coefficient. However, to obtain reliable values for strong scattering tissues, accurate consideration of the effects of multiple scattering and the nonlinear relation between the scattering coefficient and scatterer concentration (concentration-dependent scattering) is required. We present a comprehensive model for the OCT signal in which we quantitatively account for both effects, as well as our system parameters (confocal point spread function and sensitivity roll-off). We verify our model with experimental data from controlled phantoms of monodisperse silica beads (scattering coefficients ...

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    9. Visualizing biofilm formation in endotracheal tubes using endoscopic three-dimensional optical coherence tomography

      Visualizing biofilm formation in endotracheal tubes using endoscopic three-dimensional optical coherence tomography

      Biofilm formation has been linked to ventilator-associated pneumonia, which is a prevalent infection in hospital intensive care units. Currently, there is no rapid diagnostic tool to assess the degree of biofilm formation or cellular biofilm composition. Optical coherence tomography (OCT) is a minimally invasive, nonionizing imaging modality that can be used to provide high-resolution cross-sectional images. Biofilm deposited in critical care patients’ endotracheal tubes was analyzed in vitro . This study demonstrates that OCT could potentially be used as a diagnostic tool to analyze and assess the degree of biofilm formation and extent of airway obstruction caused by biofilm in endotracheal ...

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    10. Toward an automated method for optical coherence tomography characterization

      Toward an automated method for optical coherence tomography characterization

      With the increasing use of optical coherence tomography (OCT) in biomedical applications, robust yet simple methods for calibrating and benchmarking a system are needed. We present here a procedure based on a calibration object complemented with an algorithm that analyzes three-dimensional OCT datasets to retrieve key characteristics of an OCT system. The calibration object combines state-of-the-art tissue phantom material with a diamond-turned aluminum multisegment mirror. This method is capable of determining rapidly volumetric field-of-view, axial resolution, and image curvature. Moreover, as the phantom material mimics biological tissue, the system’s signal and noise levels can be evaluated in conditions close ...

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    11. In vivo wide-field multispectral scanning laser ophthalmoscopy–optical coherence tomography mouse retinal imager: longitudinal imaging of ganglion cells, microglia, and Müller glia, and mapping of the mouse retinal and choroidal vasculature

      In vivo wide-field multispectral scanning laser ophthalmoscopy–optical coherence tomography mouse retinal imager: longitudinal imaging of ganglion cells, microglia, and Müller glia, and mapping of the mouse retinal and choroidal vasculature

      Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) provide complementary views of the retina, with the former collecting fluorescence data with good lateral but relatively low-axial resolution, and the latter collecting label-free backscattering data with comparable lateral but much higher axial resolution. To take maximal advantage of the information of both modalities in mouse retinal imaging, we have constructed a compact, four-channel, wide-field ( ∼ 50     deg ) system that simultaneously acquires and automatically coregisters three channels of confocal SLO and Fourier domain OCT data. The scanner control system allows “zoomed” imaging of a region of interest identified in a wide-field image ...

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    12. Tri-band spectroscopic optical coherence tomography based on optical parametric amplification for lipid and vessel visualization

      Tri-band spectroscopic optical coherence tomography based on optical parametric amplification for lipid and vessel visualization

      A tri-band spectroscopic optical coherence tomography (SOCT) system has been implemented for visualization of lipid and blood vessel distribution. The tri-band swept source, which covers output spectrum in 1.3, 1.5, and 1.6μ m wavelength windows, is based on a dual-band Fourier domain mode-locked laser and a fiber optical parametric amplifier. This tri-band SOCT can further differentiate materials, e.g., lipid and artery, qualitatively by contrasting attenuation coefficients difference within any two of these bands. Furthermore, ex vivo imaging of both porcine artery with artificial lipid plaque phantom and mice with coronary artery disease were demonstrated to showcase ...

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    13. Imaging the anterior eye with dynamic-focus swept-source optical coherence tomography.

      Imaging the anterior eye with dynamic-focus swept-source optical coherence tomography.

      A custom-built dynamic-focus swept-source optical coherence tomography (SS-OCT) system with a central wavelength of 1310 nm was used to image the anterior eye from the cornea to the lens. An electrically tunable lens was utilized to dynamically control the positions of focusing planes over the imaging range of 10 mm. The B-scan images were acquired consecutively at the same position but with different focus settings. The B-scan images were then registered and averaged after filtering the out-of-focus regions using a Gaussian window. By fusing images obtained at different depth focus locations, high-resolution and high signal-strength images were obtained over the ...

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    14. Learning curve and interobserver variance in quantification of the optical coherence tomography attenuation coefficient

      Learning curve and interobserver variance in quantification of the optical coherence tomography attenuation coefficient

      The learning curve and interobserver variance of attenuation coefficient ( μ OCT ) determination from optical coherence tomography (OCT) images were quantified. The μ OCT of normal and diseased vulvar tissues was determined at five time points by three novice students and three OCT experts who reached consensus for reference. Students received feedback between time points. Eventually, variance in μ OCT was smaller in images of diseased tissue than in images of normal vulvar tissue. The difference between the consensus and student μ OCT values was larger for smaller values of μ OCT . We conclude that routine μ OCT determination for tissue classification does not require extensive training.

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    15. Optical coherence tomography spectral analysis for detecting apoptosis in vitro and in vivo

      Optical coherence tomography spectral analysis for detecting apoptosis in vitro and in vivo

      Apoptosis is a form of programmed cell death characterized by a series of predictable morphological changes at the subcellular level, which modify the light-scattering properties of cells. We present a spectroscopic optical coherence tomography (OCT) technique to detect changes in subcellular morphology related to apoptosis in vitro and in vivo . OCT data were acquired from acute myeloid leukemia (AML) cells treated with cisplatin over a 48-h period. The backscatter spectrum of the OCT signal acquired from the cell samples was characterized by calculating its in vitro integrated backscatter (IB) and spectral slope (SS). The IB increased with treatment duration, while ...

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    16. Imaginary part-based correlation mapping optical coherence tomography for imaging of blood vessels in vivo

      Imaginary part-based correlation mapping optical coherence tomography for imaging of blood vessels in vivo

      We present an imaginary part-based correlation mapping optical coherence tomography (IMcmOCT) technique for in vivo blood vessels imaging. In the conventional correlation mapping optical coherence tomography (cmOCT) method, two adjacent frames of intensity-based structural images are correlated to extract blood flow information and the size of correlation window has to be increased to improve the signal-to-noise ratio of microcirculation maps, which may cause image blur and miss the small blood vessels. In the IMcmOCT method, the imaginary part of a depth-resolved complex analytic signal in two adjacent B-scans is correlated to reconstruct microcirculation maps. Both phantom and in vivo experiments ...

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      Mentions: Wanrong Gao
    17. Rapid and high-resolution imaging of human liver specimens by full-field optical coherence tomography

      Rapid and high-resolution imaging of human liver specimens by full-field optical coherence tomography

      We report rapid and high-resolution tomographic en face imaging of human liver specimens by full-field optical coherence tomography (FF-OCT). First, the arrangement of the FF-OCT system was described and the performance of the system was measured. The measured axial and lateral resolutions of the system are 0.8 and 0.9     μ m , respectively. The system has a sensitivity of ∼ 60     dB and can achieve an imaging rate of 7 fps and a penetration depth of ∼ 80     μ m . The histological structures of normal liver can be seen clearly in the en face tomographic images, including central veins, cords of hepatocytes separated ...

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      Mentions: Wanrong Gao
    18. Automatic segmentation of the optic nerve head for deformation measurements in video rate optical coherence tomography

      Automatic segmentation of the optic nerve head for deformation measurements in video rate optical coherence tomography

      Optical coherence tomography (OCT) imaging has become a standard diagnostic tool in ophthalmology, providing essential information associated with various eye diseases. In order to investigate the dynamics of the ocular fundus, we present a simple and accurate automated algorithm to segment the inner limiting membrane in video-rate optic nerve head spectral domain (SD) OCT images. The method is based on morphological operations including a two-step contrast enhancement technique, proving to be very robust when dealing with low signal-to-noise ratio images and pathological eyes. An analysis algorithm was also developed to measure neuroretinal tissue deformation from the segmented retinal profiles. The ...

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    19. Statistical analysis of motion contrast in optical coherence tomography angiography

      Statistical analysis of motion contrast in optical coherence tomography angiography

      Optical coherence tomography angiography (Angio-OCT), mainly based on the temporal dynamics of OCT scattering signals, has found a range of potential applications in clinical and scientific research. Based on the model of random phasor sums, temporal statistics of the complex-valued OCT signals are mathematically described. Statistical distributions of the amplitude differential and complex differential Angio-OCT signals are derived. The theories are validated through the flow phantom and live animal experiments. Using the model developed, the origin of the motion contrast in Angio-OCT is mathematically explained, and the implications in the improvement of motion contrast are further discussed, including threshold determination ...

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    20. Methods and algorithms for optical coherence tomography-based angiography: a review and comparison

      Methods and algorithms for optical coherence tomography-based angiography: a review and comparison

      Optical coherence tomography (OCT)-based angiography is increasingly becoming a clinically useful and important imaging technique due to its ability to provide volumetric microvascular networks innervating tissue beds in vivo without a need for exogenous contrast agent. Numerous OCT angiography algorithms have recently been proposed for the purpose of contrasting microvascular networks. A general literature review is provided on the recent progress of OCT angiography methods and algorithms. The basic physics and mathematics behind each method together with its contrast mechanism are described. Potential directions for future technical development of OCT based angiography is then briefly discussed. Finally, by the ...

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    21. Swept-source optical coherence tomography powered by a 1.3-μm vertical cavity surface emitting laser enables 2.3-mm-deep brain imaging in mice in vivo

      Swept-source optical coherence tomography powered by a 1.3-μm vertical cavity surface emitting laser enables 2.3-mm-deep brain imaging in mice in vivo

      We report noninvasive, in vivo optical imaging deep within a mouse brain by swept-source optical coherence tomography (SS-OCT), enabled by a 1.3 - μ m vertical cavity surface emitting laser (VCSEL). VCSEL SS-OCT offers a constant signal sensitivity of 105 dB throughout an entire depth of 4.25 mm in air, ensuring an extended usable imaging depth range of more than 2 mm in turbid biological tissue. Using this approach, we show deep brain imaging in mice with an open-skull cranial window preparation, revealing intact mouse brain anatomy from the superficial cerebral cortex to the deep hippocampus. VCSEL SS-OCT would be ...

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    22. Nondestructive observation of teeth post core-space using optical coherence tomography: comparison with microcomputed tomography and live images

      Nondestructive observation of teeth post core-space using optical coherence tomography: comparison with microcomputed tomography and live images

      No previous reports have observed inside the root canal using both optical coherence tomography (OCT) and x-ray microcomputed tomography ( μ CT ) for the same sample. The purpose of this study was to clarify both OCT and μ CT image properties from observations of the same root canal after resin core build-up treatment. As OCT allows real-time observation of samples, gap formation may be able to be shown in real time. A dual-cure, one-step, self-etch adhesive system bonding agent, and dual-cure resin composite core material were used in root canals in accordance with instructions from the manufacturer. The resulting OCT images were superior ...

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      Mentions: Osaka University
    23. In vivo molecular imaging of colorectal cancer using quantum dots targeted to vascular endothelial growth factor receptor 2 and optical coherence tomography/laser-induced fluorescence dual-modality imaging

      In vivo molecular imaging of colorectal cancer using quantum dots targeted to vascular endothelial growth factor receptor 2 and optical coherence tomography/laser-induced fluorescence dual-modality imaging

      Optical coherence tomography/laser induced fluorescence (OCT/LIF) dual-modality imaging allows for minimally invasive, nondestructive endoscopic visualization of colorectal cancer in mice. This technology enables simultaneous longitudinal tracking of morphological (OCT) and biochemical (fluorescence) changes as colorectal cancer develops, compared to current methods of colorectal cancer screening in humans that rely on morphological changes alone. We have shown that QDot655 targeted to vascular endothelial growth factor receptor 2 (QD655-VEGFR2) can be applied to the colon of carcinogen-treated mice and provides significantly increased contrast between the diseased and undiseased tissue with high sensitivity and specificity ex vivo . QD655-VEGFR2 was used in ...

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    24. Performance analysis of optical coherence tomography in the context of a thickness estimation task

      Performance analysis of optical coherence tomography in the context of a thickness estimation task

      Thickness estimation is a common task in optical coherence tomography (OCT). This study discusses and quantifies the intensity noise of three commonly used broadband sources, such as a supercontinuum source, a superluminescent diode (SLD), and a swept source. The performance of the three optical sources was evaluated for a thickness estimation task using both the fast Fourier transform (FFT) and maximum-likelihood (ML) estimators. We find that the source intensity noise has less impact on a thickness estimation task compared to the width of the axial point-spread function (PSF) and the trigger jittering noise of a swept source. Findings further show ...

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    1-24 of 212 1 2 3 4 5 6 7 8 9 »
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