1. Articles from Daniel Szlag

    1-24 of 28 1 2 »
    1. Imaging of cortical structures and microvasculature using extended-focus optical coherence tomography at 1.3  μm

      Imaging of cortical structures and microvasculature using extended-focus optical coherence tomography at 1.3  μm

      Extended-focus optical coherence tomography (xf-OCT) is a variant of optical coherence tomography (OCT) wherein the illumination and/or detection modes are engineered to provide a constant diffractionless lateral resolution over an extended depth of field (typically 3 to 10 × 10× the Rayleigh range). xf-OCT systems operating at 800 nm have been devised and used in the past to image brain structures at high-resolution in vivo , but are limited to ∼ 500    μm ∼500  μm in penetration depth due to their short illumination wavelength. Here we present an xf-OCT system optimized to an image deeper within the cortex by using a longer ...

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    2. In vivo high-resolution cortical imaging with extended-focus optical coherence microscopy in the visible-NIR wavelength range

      In vivo high-resolution cortical imaging with extended-focus optical coherence microscopy in the visible-NIR wavelength range

      Visible light optical coherence tomography has shown great interest in recent years for spectroscopic and high-resolution retinal and cerebral imaging. Here, we present an extended-focus optical coherence microscopy system operating from the visible to the near-infrared wavelength range for high axial and lateral resolution imaging of cortical structures in vivo . The system exploits an ultrabroad illumination spectrum centered in the visible wavelength range (λ c   =  650  nm, Δλ  ∼  250  nm) offering a submicron axial resolution (∼0.85  μm in water) and an extended-focus configuration providing a high lateral resolution of ∼1.4  μm maintained over ∼150  μm in depth in water. The ...

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    3. Label-free three-dimensional imaging of Caenorhabditis elegans with visible optical coherence microscopy

      Label-free three-dimensional imaging of Caenorhabditis elegans with visible optical coherence microscopy

      Fast, label-free, high-resolution, three-dimensional imaging platforms are crucial for high-throughput in vivo time-lapse studies of the anatomy of Caenorhabditis elegans , one of the most commonly used model organisms in biomedical research. Despite the needs, methods combining all these characteristics have been lacking. Here, we present label-free imaging of live Caenorhabditis elegans with three-dimensional sub-micrometer resolution using visible optical coherence microscopy (visOCM). visOCM is a versatile optical imaging method which we introduced recently for tomography of cell cultures and tissue samples. Our method is based on Fourier domain optical coherence tomography, an interferometric technique that provides three-dimensional images with high sensitivity ...

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    4. Massively parallel data processing for quantitative total flow imaging with optical coherence microscopy and tomography

      Massively parallel data processing for quantitative total flow imaging with optical coherence microscopy and tomography

      We present an application of massively parallel processing of quantitative flow measurements data acquired using spectral optical coherence microscopy (SOCM). The need for massive signal processing of these particular datasets have been a major hurdle for many applications based on SOCM. In view of this difficulty, we implemented and adapted quantitative total flow estimation algorithms on graphics processing units (GPU) and achieved a 150 fold reduction in processing time when compared to a former CPU implementation. As SOCM constitutes the microscopy counterpart to spectral optical coherence tomography (SOCT), the developed processing procedure can be applied to both imaging modalities. We ...

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    5. Extended-focus optical coherence microscopy for high-resolution imaging of the murine brain

      Extended-focus optical coherence microscopy for high-resolution imaging of the murine brain

      We propose a new method and optical instrumentation for mouse brain imaging based on extended-focus optical coherence microscopy. This in vivo imaging technique allows the evaluation of the cytoarchitecture at cellular level and the circulation system dynamics in three dimensions. This minimally invasive and non-contact approach is performed without the application of contrasting agents. The optical design achieved a resolution of 2.2 μm over a distance of 800 μm, which was sufficient to obtain a detailed three-dimensional image of a wild-type mouse’s brain down to the layer III of the cortex. Intrinsically contrasted microvessels and structures similar to ...

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    6. Imaging of the stroke-related changes in the vascular system of the mouse brain with the use of extended focus Optical Coherence Microscopy

      Imaging of the stroke-related changes in the vascular system of the mouse brain with the use of extended focus Optical Coherence Microscopy

      We used Optical Coherence Microscopy (OCM) to monitor structural and functional changes due to ischemic stroke in small animals brains in vivo. To obtain lateral resolution of 2.2 μm over the range of 600 μm we used extended focus configuration of OCM instrument involving Bessel beam. It provided access to detailed 3D information about the changes in brain vascular system up to the level of capillaries across I and II/III layers of neocortex. We used photothrombotic stroke model involving photoactive application of rose bengal to assure minimal invasiveness of the procedure and precise localization of the clot distribution ...

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    7. Combined Optical Coherence and Fluorescence Microscopy to assess dynamics and specificity of pancreatic beta-cell tracers

      Combined Optical Coherence and Fluorescence Microscopy to assess dynamics and specificity of pancreatic beta-cell tracers

      The identification of a beta-cell tracer is a major quest in diabetes research. However, since MRI, PET and SPECT cannot resolve individual islets, optical techniques are required to assess the specificity of these tracers. We propose to combine Optical Coherence Microscopy (OCM) with fluorescence detection in a single optical platform to facilitate these initial screening steps from cell culture up to living rodents. OCM can image islets and vascularization without any labeling. Thereby, it alleviates the need of both genetically modified mice to detect islets and injection of external dye to reveal vascularization. We characterized Cy5.5-exendin-3, an agonist of ...

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    8. Visible light optical coherence correlation spectroscopy

      Visible light optical coherence correlation spectroscopy

      Optical coherence correlation spectroscopy (OCCS) allows studying kinetic processes at the single particle level using the backscattered light of nanoparticles. We extend the possibilities of this technique by increasing its signal-to-noise ratio by a factor of more than 25 and by generalizing the method to solutions containing multiple nanoparticle species. We applied these improvements by measuring protein adsorption and formation of a protein monolayer on superparamagnetic iron oxide nanoparticles under physiological conditions.

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    9. Quantitative cerebral blood flow imaging with extended-focus optical coherence microscopy

      Quantitative cerebral blood flow imaging with extended-focus optical coherence microscopy

      Quantitative three-dimensional blood flow imaging is a valuable technique to investigate the physiology of the brain. Two-photon microscopy (2PM) allows quantification of the local blood flow velocity with micrometric resolution by performing repeated line scans, but prohibitively long measurement times would be required to apply this technique to full three-dimensional volumes. By multiplexing the image acquisition over depth, Fourier domain optical coherence tomography (FDOCT) enables quantification of blood flow velocities with a high volume acquisition rate, albeit at a relatively low spatial resolution. Extended-focus optical coherence microscopy (xfOCM) increases the lateral resolution without sacrificing depth of field and therefore combines ...

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    10. Quantitative lateral and axial flow imaging with optical coherence microscopy and tomography

      Quantitative lateral and axial flow imaging with optical coherence microscopy and tomography

      Optical coherence tomography (OCT) and optical coherence microscopy (OCM) allow the acquisition of quantitative three-dimensional axial flow by estimating the Doppler shift caused by moving scatterers. Measuring the velocity of red blood cells is currently the principal application of these methods. In many biological tissues, blood flow is often perpendicular to the optical axis, creating the need for a quantitative measurement of lateral flow. Previous work has shown that lateral flow can be measured from the Doppler bandwidth, albeit only for simplified optical systems. In this work, we present a generalized model to analyze the influence of relevant OCT/OCM ...

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    11. Feature Of The Week 11/25/12: Nicolaus Copernicus University Presents Work on Four-Dimensional OCT Imaging Using Graphics Processing Units

      Feature Of The Week 11/25/12: Nicolaus Copernicus University Presents Work on Four-Dimensional OCT Imaging Using Graphics Processing Units

      Nicolaus Copernicus University present the application of graphics processing unit (GPU) programming for real-time three-dimensional (3-D) Fourier domain optical coherence tomography (FdOCT) imaging with implementation of flow visualization algorithms. One of the limitations of FdOCT is data processing time, which is generally longer than data acquisition time. Utilizing additional algorithms, such as Doppler analysis, further increases computation time. The general purpose computing on GPU (GPGPU) has been used successfully for structural OCT imaging, but real-time 3-D imaging of flows has so far not been presented. NCU has developed software for structural and Doppler OCT processing capable of visualization of two-dimensional ...

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    12. Four-dimensional structural and Doppler optical coherence tomography imaging on graphics processing units

      Four-dimensional structural and Doppler optical coherence tomography imaging on graphics processing units

      The authors present the application of graphics processing unit (GPU) programming for real-time three-dimensional (3-D) Fourier domain optical coherence tomography (FdOCT) imaging with implementation of flow visualization algorithms. One of the limitations of FdOCT is data processing time, which is generally longer than data acquisition time. Utilizing additional algorithms, such as Doppler analysis, further increases computation time. The general purpose computing on GPU (GPGPU) has been used successfully for structural OCT imaging, but real-time 3-D imaging of flows has so far not been presented. We have developed software for structural and Doppler OCT processing capable of visualization of two-dimensional (2-D ...

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    13. Optical Coherence Tomography Apparatus And Method With Speckle Suppression

      Optical Coherence Tomography Apparatus And Method With Speckle Suppression

      The invention relates to an optical coherence tomography apparatus and method. It improves speckle suppression by modifying the scanning trajectory (18) of the probing light beam so that groups of A scans close to the imaged segments (22) can be recorded and averaged. The invention facilitates effective speckle suppression combined with high resolution and little dependence of sample motions during the measurement.

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    14. 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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    15. Efficient reduction of speckle noise in Optical Coherence Tomography

      Efficient reduction of speckle noise in Optical Coherence Tomography
      Speckle pattern, which is inherent in coherence imaging, influences significantly axial and transversal resolution of Optical Coherence Tomography (OCT) instruments. The well known speckle removal techniques are either sensitive to sample motion, require sophisticated and expensive sample tracking systems, or involve sophisticated numerical procedures. As a result, their applicability to in vivo real-time imaging is limited. In this work, we propose to average multiple A-scans collected in a fully controlled way to reduce the speckle contrast. This procedure involves non-coherent averaging of OCT A-scans acquired from adjacent locations on the sample. The technique exploits scanning protocol with fast beam deflection ...
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    16. Analysis of ocular hemodynamic using combined STdOCT and ultrasonic methods

      Analysis of ocular hemodynamic using combined STdOCT and ultrasonic methods
      Optical coherence microscopy (OCM) is relatively new, noninvasive method of biomedical imaging. It uses Michelson interferometer to locate successive layers in tissue and enables reconstructing cross-sectional images that can be useful for medical diagnosis. In this work, we propose to develop new light sources for OCM to increase the resolution of images by introducing blue light. To achieve this goal, we decided to test a method known as achromatic second harmonic generation in our own, new configuration. Full Text: PDF References: A.M. Zysk et al., "Optical coherence tomography: a review of clinical development from bench to bedside", J Biomed ...
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    17. Real-time massively parallel processing of spectral optical coherence tomography data on graphics processing units

      Real-time massively parallel processing of spectral optical coherence tomography data on graphics processing units
      In this contribution we describe a specialised data processing system for Spectral Optical Coherence Tomography (SOCT) biomedical imaging which utilises massively parallel data processing on a low-cost, Graphics Processing Unit (GPU). One of the most significant limitations of SOCT is the data processing time on the main processor of the computer (CPU), which is generally longer than the data acquisition. Therefore, real-time imaging with acceptable quality is limited to a small number of tomogram lines (A-scans). Recent progress in graphics cards technology gives a promising solution of this problem. The newest graphics processing units allow not only for a very ...
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    18. Segmented scanning protocols for speckle contrast reduction in Spectral OCT images

      Segmented scanning protocols for speckle contrast reduction in Spectral OCT images

      Recently introduced smart scanning protocols called segmented protocols offer possibility to create Spectral Optical Coherence Tomography images with strongly reduced speckle contrast. The algorithm is fast, robust and gives cross-sectional images with preserved high lateral resolution. To obtain efficient speckle reduction only slight modification to the optical setup is required. Cross-sectional images of anterior and posterior parts of the human eye with reduced speckle noise are presented.

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    19. Feature Of The Week 10/31/10: Nicolaus Copernicus University Researchers Describe Work on Massively Parallel Data Processing for OCT

      Feature Of The Week 10/31/10: Nicolaus Copernicus University Researchers Describe Work on Massively Parallel Data Processing for OCT

      Feature Of The Week 10/31/10: One of the significant limitations of the Fourier domain OCT is the time of data processing on main processor of the computer (CPU), which is longer than the acquisition time. As a result, the real-time 3D volume rendering is possible only for volumes imaged with a little amount of OCT data. Recent progress in massively parallel processing gives a promising solution to this problem. Recently developed graphic processing units (GPUs) allow not only for a very high speed of 3D rendering, but also, for general purpose parallel numerical calculations with efficiency higher than ...

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    20. Real-time imaging for Spectral Optical Coherence Tomography with massively parallel data processing

      Real-time imaging for Spectral Optical Coherence Tomography with massively parallel data processing
      In this paper the application of massively parallel processing of Spectral Optical Coherence Tomography (SOCT) data with the aid of a low-cost Graphic Processing Unit (GPU) is presented. The reported system may be used for real-time imaging of high resolution 2D tomograms or for presenting volume data. The overall imaging speed is over 100 frames/second for 2D tomograms built of 1024 A-scans and 9 frames/second for 3D volume images containing 100 slices of 100 A-scans. This includes t he acquisition of 2048 pixels from a CCD camera per A-scan, data transfer to the processor, all necessary processing and ...
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    21. Real-time bulk motion insensitive flow segmentation algorithm for doppler spectral optical coherence tomography

      Real-time bulk motion insensitive flow segmentation algorithm for doppler spectral optical coherence tomography
      We present a simple and efficient numerical technique for segmentation retinal and choroidal blood vasculature with bulk motion correction in functional Doppler Spectral Optical Coherence Tomography (Doppler SOCT). The technique uses local variance of velocity tomogram which is higher in the areas of the tomogram with internal flow. The resulting variance map reveals the position of vessels. This can be used either for vessel segmentation purposes or for masking the vessels on velocity tomograms. The remaining velocity information is connected only with static structure velocity offset. As only Fourier transformations are used in calculations the algorithm removes the bulk motion ...
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    22. Scanning protocols dedicated to smart velocity ranging in Spectral OCT

      Scanning protocols dedicated to smart velocity ranging in Spectral OCT
      We introduce a new type of scanning protocols, called segmented protocols, which enable extracting multi-range flow velocity information from a single Spectral OCT data set. The protocols are evaluated using a well defined flow in a glass capillary. As an example of in vivo studies, we demonstrate two- and three-dimensional imaging of the retinal vascular system in the eyes of healthy volunteers. The flow velocity detection is performed using a method of Joint Spectral and Time domain OCT. Velocity ranging is demonstrated in imaging of retinal vasculature in the macular region and in the optic disk area characterized by different ...
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    23. Flow velocity estimation by complex ambiguity free joint Spectral and Time domain Optical Coherence Tomography

      Flow velocity estimation by complex ambiguity free joint Spectral and Time domain Optical Coherence Tomography
      We show that recently introduced joint Spectral and Time domain Optical Coherence Tomography (STdOCT) can be used for simultaneous complex ambiguity removal and functional Spectral OCT images. This permits to take advantage of higher sensitivity achievable near the zero-path delay. The technique can be used with all Spectral OCT systems that are equipped with an optical delay line (ODL) and provide oversampled scanning patterns. High sensitivity provided by STdOCT allows this technique to be used in Spectral OCT setups with acquisition speed of 100 000 lines/s. We show that different imaging ranges and velocity ranges can be achieved by ...
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    24. Three-dimensional quantitative imaging
of retinal and choroidal blood flow velocity using joint Spectral and Time domain Optical Coherence Tomography

      Three-dimensional quantitative imaging
of retinal and choroidal blood flow velocity using joint Spectral and Time domain Optical Coherence Tomography
      Recently, joint Spectral and Time domain Optical Coherence Tomography (joint STdOCT) has been proposed to measure ocular blood flow velocity. Limitations of CCD technology allowed only for two-dimensional imaging at that time. In this paper we demonstrate fast three-dimensional STdOCT based on ultrahigh speed CMOS camera. Proposed method is straightforward, fully automatic and does not require any advanced image processing techniques. Three-dimensional distributions of axial velocity components of the blood in human eye vasculature are presented: in retinal and, for the first time, in choroidal layer. Different factors that affect quality of velocity images are discussed. Additionally, the quantitative measurement ...
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    1-24 of 28 1 2 »
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    1. (28 articles) Daniel Szlag
    2. (22 articles) Nicolaus Copernicus University
    3. (19 articles) Maciej Wojtkowski
    4. (18 articles) Maciej Szkulmowski
    5. (11 articles) Andrzej A. Kowalczyk
    6. (10 articles) Theo Lasser
    7. (8 articles) Ecole Polytechnique Fédérale de Lausanne
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    Anterior segment imaging with Spectral OCT system using a high-speed CMOS camera Flow velocity estimation by complex ambiguity free joint Spectral and Time domain Optical Coherence Tomography Scanning protocols dedicated to smart velocity ranging in Spectral OCT Real-time bulk motion insensitive flow segmentation algorithm for doppler spectral optical coherence tomography Real-time imaging for Spectral Optical Coherence Tomography with massively parallel data processing Feature Of The Week 10/31/10: Nicolaus Copernicus University Researchers Describe Work on Massively Parallel Data Processing for OCT Real-time massively parallel processing of spectral optical coherence tomography data on graphics processing units Multi-parametric imaging of murine brain using spectral and time domain optical coherence tomography Chalcogenide-glass polarization-maintaining photonic crystal fiber for mid-infrared supercontinuum generation Supervised machine learning based multi-task artificial intelligence classification of retinopathies OCT-Detected Optic Nerve Head Neural Canal Direction, Obliqueness and Minimum Cross-Sectional Area in Healthy Eyes Combined intracoronary assessment and treatment of a patient with coronary plaque rapid progression prior to acute myocardial infarction A case report