1. 1-24 of 63 1 2 3 »
    1. Flexible, high-resolution micro-optical coherence tomography endobronchial probe toward in vivo imaging of cilia

      Flexible, high-resolution micro-optical coherence tomography endobronchial probe toward in vivo imaging of cilia

      We report the design and fabrication of a flexible, longitudinally scanning high-resolution micro-optical coherence tomography (μOCT) endobronchial probe, optimized for micro-anatomical imaging in airways. The 2.4 mm diameter and flexibility of the probe allows it to be inserted into the instrument channel of a standard bronchoscope, enabling real-time video guidance of probe placement. To generate a depth-of-focus enhancing annular beam, we utilized a new fabrication method, whereby a hollow glass ferrule was angle-polished and gold-coated to produce an elongated annular reflector. We present validation data that verifies the preservation of linear scanning, despite the use of flexible materials. When ...

      Read Full Article
    2. In vivo detection of plaque erosion by intravascular optical coherence tomography using artificial intelligence

      In vivo detection of plaque erosion by intravascular optical coherence tomography using artificial intelligence

      Plaque erosion is one of the most common underlying mechanisms for acute coronary syndrome (ACS). Optical coherence tomography (OCT) allows in vivo diagnosis of plaque erosion. However, challenge remains due to high inter- and intra-observer variability. We developed an artificial intelligence method based on deep learning for fully automated detection of plaque erosion in vivo , which achieved a recall of 0.800 ± 0.175, a precision of 0.734 ± 0.254, and an area under the precision-recall curve (AUC) of 0.707. Our proposed method is in good agreement with physicians, and can help improve the clinical diagnosis of plaque ...

      Read Full Article
    3. Using the dynamic forward scattering signal for optical coherence tomography based blood flow quantification

      Using the dynamic forward scattering signal for optical coherence tomography based blood flow quantification

      To our knowledge, all existing optical coherence tomography approaches for quantifying blood flow, whether Doppler-based or decorrelation-based, analyze light that is back-scattered by moving red blood cells (RBCs). This work investigates the potential advantages of basing these measurements on light that is forward-scattered by RBCs, i.e., by looking at the signals back-scattered from below the vessel. We show experimentally that flowmetry based on forward-scattering is insensitive to vessel orientation for vessels that are approximately orthogonal to the imaging beam. We further provide proof-of-principle demonstrations of dynamic forward-scattering (DFS) flowmetry in human retinal and choroidal vessels.

      Read Full Article
    4. De-aliased depth-range-extended optical coherence tomography based on dual under-sampling

      De-aliased depth-range-extended optical coherence tomography based on dual under-sampling

      We demonstrate a dual under-sampling (DUS) method to achieve de-aliased and depth-range-extended optical coherence tomography (OCT) imaging. The spectral under-sampling can significantly reduce the data size but causes well-known aliasing artifacts. A change in the sampling frequency used to acquire the interference spectrum alters the aliasing period within the output window except for the true image; this feature is utilized to distinguish the true image from the aliasing artifacts. We demonstrate that with DUS, the data size is reduced to 37% at an extended depth range of 24 mm, over which the true depth can be precisely measured without ambiguity ...

      Read Full Article
    5. Spectral interference contrast based non-contact photoacoustic microscopy realized by SDOCT

      Spectral interference contrast based non-contact photoacoustic microscopy realized by SDOCT

      We introduce a method to extract the photoacoustic (PA) signal from a contrast reduction of the interference spectrum acquired by spectral domain optical coherence tomography (SDOCT). This all-optical detection is achieved in a noncontact manner directly on the water surface covered on the sample by using its specular reflection. During SDOCT exposure, the phase of the interference spectrum keeps shaking according to the water surface vibration induced by PA excitation. This results in an interference contrast reduction which is quantified by a fast Fourier transform (FFT) for PA imaging. A tungsten filament, asparagus fern leaf, and mouse auricle are imaged ...

      Read Full Article
    6. Ultra-broadband wavelength-swept Ti:sapphire crystal fiber laser

      Ultra-broadband wavelength-swept Ti:sapphire crystal fiber laser

      An ultra-broadband wavelength-swept laser (WSL) was generated using glass-clad Ti:sapphire crystal fiber as the gain media. Due to the low signal propagation loss of the crystal fiber, the swept laser has a tuning bandwidth of 250 nm (i.e., 683 nm to 933 nm) at a repetition rate of 1200 Hz. The steady-state and pulsed dynamics of the WSL were analyzed. The 0.018-nm instantaneous linewidth corresponds to a 3-dB coherence roll-off of 7 mm. When using the laser for swept-source optical coherence tomography, an estimated axial resolution of 1.8 µm can be achieved.

      Read Full Article
    7. Intraoral optical coherence tomography and angiography combined with autofluorescence for dental assessment

      Intraoral optical coherence tomography and angiography combined with autofluorescence for dental assessment

      There remains a clinical need for an accurate and non-invasive imaging tool for intraoral evaluation of dental conditions. Optical coherence tomography (OCT) is a potential candidate to meet this need, but the design of current OCT systems limits their utility in the intraoral examinations. The inclusion of light-induced autofluorescence (LIAF) can expedite the image collection process and provides a large field of view for viewing the condition of oral tissues. This study describes a novel LIAF-OCT system equipped with a handheld probe designed for intraoral examination of microstructural (via OCT) and microvascular information (via OCT angiography, OCTA). The handheld probe ...

      Read Full Article
    8. Three-dimensional opto-thermo-mechanical model for predicting photo-thermal optical coherence tomography responses in multilayer geometries

      Three-dimensional opto-thermo-mechanical model for predicting photo-thermal optical coherence tomography responses in multilayer geometries

      Photothermal optical coherence tomography (PT-OCT) is a functional extension of OCT with the ability to generate qualitative maps of molecular absorptions co-registered with the micron-resolution structural tomograms of OCT. Obtaining refined insight into chemical information from PT-OCT images, however, requires solid understanding of the multifactorial physics behind generation of PT-OCT signals and their dependence on system and sample parameters. Such understanding is needed to decouple the various physical effects involved in the PT-OCT signal to obtain more accurate insight into sample composition. In this work, we propose an analytical model that considers the opto-thermo-mechanical properties of multi-layered samples in 3-D ...

      Read Full Article
    9. Classifying breast cancer in ultrahigh-resolution optical coherence tomography images using convolutional neural networks

      Classifying breast cancer in ultrahigh-resolution optical coherence tomography images using convolutional neural networks

      Optical coherence tomography (OCT) is being investigated in breast cancer diagnostics as a real-time histology evaluation tool. We present a customized deep convolutional neural network (CNN) for classification of breast tissues in OCT B-scans. Images of human breast samples from mastectomies and breast reductions were acquired using a custom ultrahigh-resolution OCT system with 2.72 µm axial resolution and 5.52 µm lateral resolution. The network achieved 96.7% accuracy, 92% sensitivity, and 99.7% specificity on a dataset of 23 patients. The usage of deep learning will be important for the practical integration of OCT into clinical practice.

      Read Full Article
    10. Unsupervised despeckling of optical coherence tomography images by combining cross-scale CNN with an intra-patch and inter-patch based transformer

      Unsupervised despeckling of optical coherence tomography images by combining cross-scale CNN with an intra-patch and inter-patch based transformer

      Optical coherence tomography (OCT) has found wide application to the diagnosis of ophthalmic diseases, but the quality of OCT images is degraded by speckle noise. The convolutional neural network (CNN) based methods have attracted much attention in OCT image despeckling. However, these methods generally need noisy-clean image pairs for training and they are difficult to capture the global context information effectively. To address these issues, we have proposed a novel unsupervised despeckling method. This method uses the cross-scale CNN to extract the local features and uses the intra-patch and inter-patch based transformer to extract and merge the local and global ...

      Read Full Article
    11. Multi-class classification of breast tissue using optical coherence tomography and attenuation imaging combined via deep learning

      Multi-class classification of breast tissue using optical coherence tomography and attenuation imaging combined via deep learning

      We demonstrate a convolutional neural network (CNN) for multi-class breast tissue classification as adipose tissue, benign dense tissue, or malignant tissue, using multi-channel optical coherence tomography (OCT) and attenuation images, and a novel Matthews correlation coefficient (MCC)-based loss function that correlates more strongly with performance metrics than the commonly used cross-entropy loss. We hypothesized that using multi-channel images would increase tumor detection performance compared to using OCT alone. 5,804 images from 29 patients were used to fine-tune a pre-trained ResNet-18 network. Adding attenuation images to OCT images yields statistically significant improvements in several performance metrics, including benign dense ...

      Read Full Article
    12. Convolutional dictionary learning for blind deconvolution of optical coherence tomography images

      Convolutional dictionary learning for blind deconvolution of optical coherence tomography images

      In this study, we demonstrate a sparsity-regularized, complex, blind deconvolution method for removing sidelobe artefacts and stochastic noise from optical coherence tomography (OCT) images. Our method estimates the complex scattering amplitude of tissue on a line-by-line basis by estimating and deconvolving the complex, one-dimensional axial point spread function (PSF) from measured OCT A-line data. We also present a strategy for employing a sparsity weighting mask to mitigate the loss of speckle brightness within tissue-containing regions caused by the sparse deconvolution. Qualitative and quantitative analyses show that this approach suppresses sidelobe artefacts and background noise better than traditional spectral reshaping techniques ...

      Read Full Article
    13. Ultrahigh resolution spectral-domain optical coherence tomography using the 1000-1600 nm spectral band

      Ultrahigh resolution spectral-domain optical coherence tomography using the 1000-1600 nm spectral band

      Ultrahigh resolution optical coherence tomography (UHR-OCT) can image microscopic features that are not visible with the standard OCT resolution of 5-15 µm. In previous studies, high-speed UHR-OCT has been accomplished within the visible (VIS) and near-infrared (NIR-I) spectral ranges, specifically within 550-950 nm. Here, we present a spectral domain UHR-OCT system operating in a short-wavelength infrared (SWIR) range from 1000 to 1600 nm using a supercontinuum light source and an InGaAs-based spectrometer. We obtained an axial resolution of 2.6 µm in air, the highest ever recorded in the SWIR window to our knowledge, with deeper penetration into tissues than ...

      Read Full Article
    14. Vector of motion measurements in the living cochlea using a 3D OCT vibrometry system

      Vector of motion measurements in the living cochlea using a 3D OCT vibrometry system

      Optical coherence tomography (OCT) has become an important tool for measuring the vibratory response of the living cochlea. It stands alone in its capacity to measure the intricate motion of the hearing organ through the surrounding otic capsule bone. Nevertheless, as an extension of phase-sensitive OCT, it is only capable of measuring motion along the optical axis. Hence, measurements are 1-D. To overcome this limitation and provide a measure of the 3-D vector of motion in the cochlea, we developed an OCT system with three sample arms in a single interferometer. Taking advantage of the long coherence length of our ...

      Read Full Article
    15. Surgical scene generation and adversarial networks for physics-based iOCT synthesis

      Surgical scene generation and adversarial networks for physics-based iOCT synthesis

      The development and integration of intraoperative optical coherence tomography (iOCT) into modern operating rooms has motivated novel procedures directed at improving the outcome of ophthalmic surgeries. Although computer-assisted algorithms could further advance such interventions, the limited availability and accessibility of iOCT systems constrains the generation of dedicated data sets. This paper introduces a novel framework combining a virtual setup and deep learning algorithms to generate synthetic iOCT data in a simulated environment. The virtual setup reproduces the geometry of retinal layers extracted from real data and allows the integration of virtual microsurgical instrument models. Our scene rendering approach extracts information ...

      Read Full Article
    16. Local Burr distribution estimator for speckle statistics

      Local Burr distribution estimator for speckle statistics

      Speckle statistics in ultrasound and optical coherence tomography have been studied using various distributions, including the Rayleigh, the K, and the more recently proposed Burr distribution. In this paper, we expand on the utility of the Burr distribution by first validating its theoretical framework with numerical simulations and then introducing a new local estimator to characterize sample tissues of liver, brain, and skin using optical coherence tomography. The spatially local estimates of the Burr distribution’s power-law or exponent parameter enable a new type of parametric image. The simulation and experimental results confirm the potential for various applications of the ...

      Read Full Article
    17. Fiber-laser platform for precision brain surgery

      Fiber-laser platform for precision brain surgery

      Minimally invasive neurological surgeries are increasingly being sought after for treatment in neurological pathologies and oncology. A critical limitation in these minimally invasive procedures is lack of specialized tools that allow for space-time controlled delivery of sufficient energy for coagulation and cutting of tissue. Advent of fiber-lasers provide high average power with improved beam quality (lower M 2 ), biocompatible silica fiber delivery, reduced cost of manufacturing, and radiant output stability over long operating periods. Despite these advancements, no fiber-laser based surgical tools are currently available for tissue resection in vivo . Here we demonstrate a first to our knowledge, fiber-laser platform ...

      Read Full Article
    18. Dynamic microscopic optical coherence tomography to visualize the morphological and functional micro-anatomy of the airways

      Dynamic microscopic optical coherence tomography to visualize the morphological and functional micro-anatomy of the airways

      In the imaging of airway tissue, optical coherence tomography (OCT) provides cross-sectional images of tissue structures, shows cilia movement and mucus secretion, but does not provide sufficient contrast to differentiate individual cells. By using fast sequences of microscopic resolution OCT (mOCT) images, OCT can use small signal fluctuations to overcome lack in contrast and speckle noise. In this way, OCT visualizes airway morphology on a cellular level and allows the tracking of the dynamic behavior of immune cells, as well as mucus transport and secretion. Here, we demonstrate that mOCT, by using temporal tissue fluctuation as contrast (dynamic mOCT), provides ...

      Read Full Article
    19. Linewidth considerations for MEMS tunable VCSEL LiDAR

      Linewidth considerations for MEMS tunable VCSEL LiDAR

      The flexible membranes used in MEMS tunable VCSELs are so small and light that thermally induced vibrations can impact laser performance. We measure the thermal vibration spectrum of such a membrane showing peaks at the spatial vibration mode resonant frequencies of the membrane/plate. These vibrations result in a theoretical floor to the linewidth of the VCSEL. Frequency domain LiDAR and optical coherence tomography systems can get around this thermal linewidth limit with adequate clock measurement and processing. Essentially an OCT/LiDAR sweep with a concomitantly measured clock is a feed-forward linewidth reduction scheme. This can be achieved because the ...

      Read Full Article
    20. Depth-resolved transverse-plane motion tracking with configurable measurement features via optical coherence tomography

      Depth-resolved transverse-plane motion tracking with configurable measurement features via optical coherence tomography

      Optical coherence tomography (OCT), a promising noninvasive bioimaging technique, has become one of the most successful optical technologies implemented in medicine and clinical practice. Here we report a novel technique of depth-resolved transverse-plane motion tracking with configurable measurement features via optical coherence tomography, termed OCT-MT. Based on OCT circular scanning combined with speckle spatial oversampling, the OCT-MT technique can perform depth-resolved transverse-plane motion tracking. Benefitting from the optical interference and depth-resolved feature, the proposed OCT-MT can reduce the requirements on the input power of the irradiation signal and the surface reflectivity and roughness of the target, when performing motion tracking ...

      Read Full Article
    21. Laboratory system for optical coherence tomography (OCT) using a laser plasma source of soft x-rays and extreme ultraviolet and focusing ellipsoidal optics

      Laboratory system for optical coherence tomography (OCT) using a laser plasma source of soft x-rays and extreme ultraviolet and focusing ellipsoidal optics

      Optical coherence tomography (OCT) with the use of soft x-rays (SXR) and extreme ultraviolet (EUV) has been recently demonstrated [Fuchs et al. Sci. Rep.6, 20658 (2016)10.1038/srep20658; Fuchs et al. Optica4, 903 (2017)10.1364/OPTICA.4.000903]. This new imaging technique, named XCT, makes it possible to obtain cross-sectional and tomographic images of objects with nanometer spatial resolution. The article presents a newly developed laboratory system for XCT using a compact laser plasma light source operating in the SXR and EUV spectral ranges. The source is based on a gas puff target containing Kr gas or ...

      Read Full Article
    22. Imaging-photoplethysmography-guided optical microangiography

      Imaging-photoplethysmography-guided optical microangiography

      We report a method to image facial cutaneous microvascular perfusion using wide-field imaging photoplethysmography (iPPG) and handheld swept-source optical coherence tomography (OCT). The iPPG system employs a 16-bit-depth camera to provide a 2D wide-field blood pulsation map that is then used as a positioning guidance for OCT imaging of cutaneous microvasculature. We show the results from iPPG and OCT to demonstrate the ability of guided imaging of cutaneous microvasculature, which is potentially useful for the assessment of skin conditions in dermatology and cosmetology.

      Read Full Article
    23. Extended depth of focus by self-imaging wavefront division with the mirror tunnel

      Extended depth of focus by self-imaging wavefront division with the mirror tunnel

      The mirror tunnel is a component used to extend the depth of focus for compact imaging probes used in endoscopic optical coherence tomography (OCT). A fast and accurate method for mirror tunnel probe simulation, characterization, and optimization is needed, with the aim of reconciling wave- and ray-optics simulation methods and providing a thorough description of the physical operating principle of the mirror tunnel. BeamLab software, employing the beam propagation method, was used to explore the parameter space and quantify lateral resolution and depth of focus extension. The lateral resolution performance was found to depend heavily on the metric chosen, implying ...

      Read Full Article
    24. Digital refocusing based on deep learning in optical coherence tomography

      Digital refocusing based on deep learning in optical coherence tomography

      We present a deep learning-based digital refocusing approach to extend depth of focus for optical coherence tomography (OCT) in this paper. We built pixel-level registered pairs of en face low-resolution (LR) and high-resolution (HR) OCT images based on experimental data and introduced the receptive field block into the generative adversarial networks to learn the complex mapping relationship between LR-HR image pairs. It was demonstrated by results of phantom and biological samples that the lateral resolutions of OCT images were improved in a large imaging depth clearly. We firmly believe deep learning methods have broad prospects in optimizing OCT imaging.

      Read Full Article
    1-24 of 63 1 2 3 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks