1. Articles from angelika unterhuber

    1-24 of 27 1 2 »
    1. Functional optical coherence tomography and photoacoustic microscopy imaging for zebrafish larvae

      Functional optical coherence tomography and photoacoustic microscopy imaging for zebrafish larvae

      We present a dual modality functional optical coherence tomography and photoacoustic microscopy (OCT-PAM) system. The photoacoustic modality employs an akinetic optical sensor with a large imaging window. This imaging window enables direct reflection mode operation, and a seamless integration of optical coherence tomography (OCT) as a second imaging modality. Functional extensions to the OCT-PAM system include Doppler OCT (DOCT) and spectroscopic PAM (sPAM). This functional and non-invasive imaging system is applied to image zebrafish larvae, demonstrating its capability to extract both morphological and hemodynamic parameters in vivo in small animals, which are essential and critical in preclinical imaging for physiological ...

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    2. Automatic assessment of tear film and tear meniscus parameters in healthy subjects using ultrahigh-resolution optical coherence tomography

      Automatic assessment of tear film and tear meniscus parameters in healthy subjects using ultrahigh-resolution optical coherence tomography

      Many different parameters exist for the investigation of tear film dynamics. We present a new tear meniscus segmentation algorithm which automatically extracts tear meniscus area (TMA), height (TMH), depth (TMD) and radius (TMR) from UHR-OCT measurements and apply it to a data set including repeated measurements from ten healthy subjects. Mean values and standard deviations are 0.0174 ± 0.007 mm 2 , 0.272 ± 0.069 mm, 0.191 ± 0.049 mm and 0.309 ± 0.123 mm for TMA, TMH, TMD and TMR, respectively. A significant correlation was found between all respective tear meniscus parameter pairs (all p < 0 ...

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    3. Feature Of The Week 03/31/2019: Depth resolved label-free multimodal optical imaging platform to study morpho-molecular composition of tissue

      Feature Of The Week 03/31/2019: Depth resolved label-free multimodal optical imaging platform to study morpho-molecular composition of tissue

      We have developed a multimodal laser scanning microscope (LSM) platform combining optical coherence tomography (OCT), spectral focusing coherent anti-Stokes Raman scattering (SF-CARS), second harmonic generation (SHG) and two-photon excited fluorescence (TPF). Morphological, molecular and biochemical information from tissues can be collected in a non-invasive and label-free manner by merging ultra-fast Ti:sapphire lasers with well-developed optical imaging techniques. The combination of the proposed imaging modalities enables increased sensitivity and specificity for detection of early tissue alteration related to pathological condition and may offer novel insights in the diagnosis of diseases. OCT is fused with nonlinear optical microscopy techniques to perform ...

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    4. Depth resolved label-free multimodal optical imaging platform to study morpho-molecular composition of tissue

      Depth resolved label-free multimodal optical imaging platform to study morpho-molecular composition of tissue

      Multimodal imaging platforms offer a vast array of tissue information in a single image acquisition by combining complementary imaging techniques. By merging different systems, better tissue characterization can be achieved than is possible by the constituent imaging modalities alone. The combination of optical coherence tomography (OCT) with non-linear optical imaging (NLOI) techniques such as two-photon excited fluorescence (TPEF), second harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) provides access to detailed information of tissue structure and molecular composition in a fast, label-free and non-invasive manner. We introduce a multimodal label-free approach for morpho-molecular imaging and spectroscopy and validate the ...

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    5. Ultrahigh‐resolution anterior segment optical coherence tomography for analysis of corneal microarchitecture during wound healing

      Ultrahigh‐resolution anterior segment optical coherence tomography for analysis of corneal microarchitecture during wound healing

      Purpose To employ ultrahigh‐resolution (UHR) optical coherence tomography (OCT) for investigation of the early wound healing process in corneal epithelium. Methods A custom‐built UHR‐OCT system assessed epithelial healing in human keratoconic cornea after epi‐off crosslinking (CXL) procedure and a wound healing model in rabbits with iatrogenic corneal injury. 3D OCT data sets enhanced obtaining epithelial thickness maps and evaluation of reepithelization stage. Accompanying changes in deeper corneal microarchitecture were analysed. Results The mean central corneal thickness in 40 eyes with keratoconus at baseline was 482.7 ± 38.2 μ m, while mean central epithelial thickness (CET) was ...

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    6. Combination of High-Resolution Optical Coherence Tomography and Raman Spectroscopy for Improved Staging and Grading in Bladder Cancer

      Combination of High-Resolution Optical Coherence Tomography and Raman Spectroscopy for Improved Staging and Grading in Bladder Cancer

      We present a combination of optical coherence tomography (OCT) and Raman spectroscopy (RS) for improved diagnosis and discrimination of different stages and grades of bladder cancer ex vivo by linking the complementary information provided by these two techniques. Bladder samples were obtained from biopsies dissected via transurethral resection of the bladder tumor (TURBT). As OCT provides structural information rapidly, it was used as a red-flag technology to scan the bladder wall for suspicious lesions with the ability to discriminate malignant tissue from healthy urothelium. Upon identification of degenerated tissue via OCT, RS was implemented to determine the molecular characteristics via ...

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    7. In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain optical coherence tomography

      In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain optical coherence tomography

      Dry eye syndrome is a highly prevalent disease of the ocular surface characterized by an instability of the tear film. Traditional methods used for the evaluation of tear film stability are invasive or show limited repeatability. Here we propose a new non-invasive fully automated approach to measure tear film thickness based on spectral domain optical coherence tomography and on an efficient delay estimator. Silicon wafer phantom were used to validate the thickness measurement. The technique was applied in vivo in healthy subjects. Series of tear film thickness maps were generated, allowing for the visualization of tear film dynamics. Our results ...

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    8. Single-pulse CARS based multimodal nonlinear optical microscope for bioimaging

      Single-pulse CARS based multimodal nonlinear optical microscope for bioimaging

      Noninvasive label-free imaging of biological systems raises demand not only for high-speed three-dimensional prescreening of morphology over a wide-field of view but also it seeks to extract the microscopic functional and molecular details within. Capitalizing on the unique advantages brought out by different nonlinear optical effects, a multimodal nonlinear optical microscope can be a powerful tool for bioimaging. Bringing together the intensity-dependent contrast mechanisms via second harmonic generation, third harmonic generation and four-wave mixing for structural-sensitive imaging, and single-beam/single-pulse coherent anti-Stokes Raman scattering technique for chemical sensitive imaging in the finger-print region, we have developed a simple and nearly ...

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    9. Anisotropic aberration correction using region of interest based digital adaptive optics in Fourier domain OCT

      Anisotropic aberration correction using region of interest based digital adaptive optics in Fourier domain OCT

      In this paper a numerical technique is presented to compensate for anisotropic optical aberrations, which are usually present across the lateral field of view in the out of focus regions, in high resolution optical coherence tomography and microscopy (OCT/OCM) setups. The recorded enface image field at different depths in the tomogram is digitally divided into smaller sub-regions or the regions of interest (ROIs), processed individually using subaperture based digital adaptive optics (DAO), and finally stitched together to yield a final image with a uniform diffraction limited resolution across the entire field of view (FOV). Using this method, a sub-micron ...

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    10. Effect of hyaluronic acid on tear film thickness as assessed with ultra-high resolution optical coherence tomography

      Effect of hyaluronic acid on tear film thickness as assessed with ultra-high resolution optical coherence tomography

      Purpose The aim of this study was to assess the effect of a single drop of hyaluronic acid on tear film thickness (TFT) in healthy subjects. Methods Sixteen healthy subjects (eight male/eight female) aged between 20 and 36 years were included in this randomized, double-masked placebo-controlled study. One eye received a single dose of hyaluronic acid (Olixia pure ® ; Croma Pharma, Korneuburg, Austria) eye drops, and the fellow eye received physiologic saline solution as placebo control. The study eye was chosen randomly. TFT as measured with a custom-built Fourier-domain optical coherence tomography (FD-OCT) system was the main outcome variable and ...

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    11. Hybrid single-source online Fourier transform coherent anti-Stokes Raman scattering/optical coherence tomography

      Hybrid single-source online Fourier transform coherent anti-Stokes Raman scattering/optical coherence tomography

      We demonstrate a multimodal optical coherence tomography (OCT) and online Fourier transform coherent anti-Stokes Raman scattering (FTCARS) platform using a single sub-12 femtosecond (fs) Ti:sapphire laser enabling simultaneous extraction of structural and chemical (“morphomolecular”) information of biological samples. Spectral domain OCT prescreens the specimen providing a fast ultrahigh ( 4 × 12     μ m axial and transverse) resolution wide field morphologic overview. Additional complementary intrinsic molecular information is obtained by zooming into regions of interest for fast label-free chemical mapping with online FTCARS spectroscopy. Background-free CARS is based on a Michelson interferometer in combination with a highly linear piezo stage, which allows ...

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    12. Dual modality optical coherence and whole-body photoacoustic tomography imaging of chick embryos in multiple development stages

      Dual modality optical coherence and whole-body photoacoustic tomography imaging of chick embryos in multiple development stages

      Chick embryos are an important animal model for biomedical studies. The visualization of chick embryos, however, is limited mostly to postmortem sectional imaging methods. In this work, we present a dual modality optical imaging system that combines swept-source optical coherence tomography and whole-body photoacoustic tomography, and apply it to image chick embryos at three different development stages. The explanted chick embryos were imaged in toto with complementary contrast from both optical scattering and optical absorption. The results serve as a prelude to the use of the dual modality system in longitudinal whole-body monitoring of chick embryos in ovo .

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    13. Optical coherence tomography today: speed, contrast, and multimodality

      Optical coherence tomography today: speed, contrast, and multimodality

      In the last 25 years, optical coherence tomography (OCT) has advanced to be one of the most innovative and most successful translational optical imaging techniques, achieving substantial economic impact as well as clinical acceptance. This is largely owing to the resolution improvements by a factor of 10 to the submicron regime and to the imaging speed increase by more than half a million times to more than 5 million A-scans per second, with the latter one accomplished by the state-of-the-art swept source laser technologies that are reviewed in this article. In addition, parallelization of OCT detection, such as line-field and ...

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    14. Compact green-diode-based lasers for biophotonic bioimaging

      Compact green-diode-based lasers for biophotonic bioimaging

      Lasers based on semiconductor materials, so-called diode lasers, are highly efficient, compact light sources. 1 In high volume they can also be produced at very low cost. In contrast to lasers based on specific atomic transitions, such as solid-state or gas lasers, diode laser materials engineering enables generation of light in a large portion of the optical spectrum. 2 The great versatility of diode lasers allows their direct use in many biophotonics applications, including photocoagulation, 3 diffuse optical imaging, 4 and optical coherence tomography (OCT). 5, 6 Nonlinear frequency conversion of diode lasers is an attractive method of overcoming the ...

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    15. Measurement of Tear Film Thickness Using Ultrahigh Resolution Optical Coherence Tomography

      Measurement of Tear Film Thickness Using Ultrahigh Resolution Optical Coherence Tomography

      Purpose: To visualize the pre-corneal tear film with high resolution spectral domain optical coherence tomography, enabling quantification of tear film thickness in healthy subjects. Methods: A custom built spectral domain optical coherence tomography system comprising a broad band Ti:Sapphire laser operating at 800 nm and a high speed CCD camera with a read out rate of 47 kHz was used for measurement of pre-corneal tear film thickness. The system provides an axial resolution of 1.2 µm in tissue. A total of 26 healthy subjects were included in this study. Measurement was started immediately after blinking and averaged over ...

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    16. Precise Thickness Measurements of Bowman's Layer, Epithelium, and Tear Film

      Precise Thickness Measurements of Bowman's Layer, Epithelium, and Tear Film

      Purpose. To visualize corneal microstructure such as tear film, epithelium, and Bowman's layer in three dimensions with spectral domain optical coherence tomography (SDOCT) exhibiting 1.3 [mu]m axial resolution at 100,000 A-scans/s. This enables measurement of epithelial and Bowman layer thickness across an area of 8.4 mm x 8.4 mm and measuring the tear film thickness at the central cornea.Methods. We designed a high-performance SDOCT system, which uses a broad bandwidth TiSapph Laser and a high-speed complementary metal-oxide-semiconductor detector technology, providing a resolution in tissue of 1.3 [mu]m and an acquisition ...

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    17. Direct pumping of ultrashort Ti:sapphire lasers by a frequency doubled diode laser

      Direct pumping of ultrashort Ti:sapphire lasers by a frequency doubled diode laser

      A simple and robust diode laser system emitting 1.28 W of green light suitable for pumping an ultrafast Ti:sapphire laser is presented. To classify our results, the diode laser is compared to a standard, commercially available diode pumped solid-state (DPSS) laser system pumping the same oscillator. When using our diode laser system, the optical conversion efficiencies from green to near-infrared light reduces to 75 % of the values achieved with the commercial pump laser. Despite this reduction the overall efficiency of the Ti:sapphire laser is still increased by a factor > 2 due to the superior electro-optical efficiency of ...

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    18. Ultra-high-speed polarization sensitive OCT in the human retina using a single spectrometer

      Ultra-high-speed polarization sensitive OCT in the human retina using a single spectrometer

      We present a single spectrometer functional spectral domain optical coherence tomography system, which allows for encoding additional information within the spatial frequencies. The method is based on a differentiation between orthogonal polarization channels through spatial modulation introduced by an electro-optic modulator. This method is used to perform Ultrahigh- speed retinal polarization sensitive optical coherence tomography (PSOCT). With this setup, we realized for the first time polarization sensitive OCT measurements of the human retina in-vivo, with camera line rates of up to 160.000 A-scans per second. Compared to PSOCT systems, operating at traditional line rates, this significantly improves patient comfort ...

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    19. Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm

      Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm

      The dispersion mismatch between sample and reference arm in frequency-domain optical coherence tomography (OCT) can be used to iteratively suppress complex conjugate artifacts and thereby increase the imaging range. In this paper, we propose a fast dispersion encoded full range (DEFR) algorithm that detects multiple signal components per iteration. The influence of different dispersion levels on the reconstruction quality is analyzed experimentally using a multilayered scattering phantom and in vivo retinal tomograms at 800 nm. Best results have been achieved with 30 mm SF11, with neglectable resolution decrease due to finite resolution of the spectrometer. Our fast DEFR algorithm achieves ...

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    20. Mutant and wild type cell chemotaxis in 3D and 4D with ultrahigh- resolution optical coherence tomography

      Mutant and wild type cell chemotaxis in 3D and 4D with ultrahigh- resolution optical coherence tomography

      Conventionally, cell chemotaxis is studied on two-dimensional (2D) transparent surfaces due to limitations in optical and image data-collection techniques. However, substrates which more closely mimic the natural environment of cells are often opaque or three-dimensional (3D). The non-invasive label-free imaging technique of frequency domain optical coherence tomography (OCT) has high axial and transverse resolution of >4µm, comparatively high penetration depth and the ability to acquire volumes in a few seconds, therefore offering the potential to visualize moving cells in 3D (2D+time) and 4D (3D+time). Cell migration is demonstrated in 3D on opaque surfaces, and in 4D within ...

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    21. Adaptive optics optical coherence tomography at 120,000 depth scans/s for non-invasive cellular phenotyping of the living human retina

      Adaptive optics optical coherence tomography at 120,000 depth scans/s for non-invasive cellular phenotyping of the living human retina

      This paper presents a successful combination of ultra-high speed (120,000 depth scans/s), ultra-high resolution optical coherence tomography with adaptive optics and an achromatizing lens for compensation of monochromatic and longitudinal chromatic ocular aberrations, respectively, allowing for non-invasive volumetric imaging in normal and pathologic human retinas at cellular resolution. The capability of this imaging system is demonstrated here through preliminary studies by probing cellular intraretinal structures that have not been accessible so far with in vivo, noninvasive, label-free imaging techniques, including pigment epithelial cells, micro-vasculature of the choriocapillaris, single nerve fibre bundles and collagenous plates of the lamina cribrosa ...

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    22. Three- and four-dimensional visualization of cell migration using optical coherence tomography

      Conventionally, cell chemotaxis is studied on two-dimensional (2D) transparent surfaces, due to limitations in optical and image data-collection techniques. However, surfaces that more closely mimic the natural environment of cells are often opaque. Optical coherence tomography (OCT) is a noninvasive label-free imaging technique, which offers the potential to visualize moving cells on opaque surfaces and in three dimensions (3D). Here, we demonstrate that OCT is an effective means of time-lapse videomicroscopy of Dictyostelium cells undergoing 3D (2D+time) cell migration on nitrocellulose substrates and 4D (3D+time) chemotaxis within low-density agarose gels. The generated image sequences are compatible with current ...

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    23. Visualization of 3D cell migration using high speed ultrahigh resolution optical coherence tomography

      Visualization of 3D cell migration using high speed ultrahigh resolution optical coherence tomography

      Using high speed ultrahigh resolution optical coherence tomography (OCT) at 800nm, non-invasive 3D cellular imaging has been accomplished. Cellular resolution imaging on and within these types of substrates is not possible with conventional microscopy techniques such as interference contrast microscopy, and requires the use of fluorescent staining. It is possible to achieve data acquisition rates of 20,000 samples per second with OCT which, in combination with its high axial and transverse resolution (>2-3µm), allows it to be used as a non-invasive technique to analyze cell migration in 3D with time. Comparatively high penetration depth also makes OCT a ...

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    24. Dispersion encoded full range frequency domain OCT

      We propose an algorithm that effectively cancels complex conjugate mirror terms from single OCT A-scans by utilizing the dispersion mismatch between reference and sample arm to generate full range tomograms. This allows distinguishing between complex conjugate mirror terms and real structures and is therefore called dispersion encoded full range (DEFR). Whereas the computational complexity is higher, acquisition speed is not compromised since no additional A-scans need to be measured which makes this technique also robust against phase fluctuations. The iterative algorithm uses numeric dispersion compensation and exhibits no reduction in resolution compared to standard processing. Residual leakage of mirror terms ...

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    1-24 of 27 1 2 »
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    1. (27 articles) Angelika Unterhuber
    2. (20 articles) Medical University of Vienna
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    Dispersion encoded full range frequency domain optical coherence tomography Visualization of 3D cell migration using high speed ultrahigh resolution optical coherence tomography Serial Endoscopy in Azoxymethane Treated Mice Using Ultra-High Resolution Optical Coherence Tomography Adaptive optics optical coherence tomography at 120,000 depth scans/s for non-invasive cellular phenotyping of the living human retina Mutant and wild type cell chemotaxis in 3D and 4D with ultrahigh- resolution optical coherence tomography Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm Ultra-high-speed polarization sensitive OCT in the human retina using a single spectrometer Precise Thickness Measurements of Bowman's Layer, Epithelium, and Tear Film Long-Term Arterial Remodeling After Bioresorbable Scaffold Implantation 4-Year Follow-up of Quantitative Coronary Angiography, Histology and Optical Coherence Tomography Visualization of Bacterial Colonization and Cellular Layers in a Gut-on-a-Chip System Using Optical Coherence Tomography Optical Coherence Tomography Measurements as Potential Imaging Biomarkers for Parkinson's Disease: A Systematic Review and Meta-analysis Use of ultra-wide field retinal imaging and optical coherence tomography angiography in the diagnosis of incomplete Susac syndrome