1. Articles from boris hermann

    1-24 of 28 1 2 »
    1. Histologic Correlation of Pig Retina Radial Stratification with Ultrahigh-Resolution Optical Coherence Tomography

      Histologic Correlation of Pig Retina Radial Stratification with Ultrahigh-Resolution Optical Coherence Tomography

      purpose. To compare ultrahigh-resolution optical coherence tomography (OCT) cross-sectional images of the pig retina with histology, to evaluate the potential of ultrahigh-resolution OCT for enhanced visualization of intra- and subretinal structures. methods. Ultrahigh-resolution OCT images were acquired with 1.4-μm axial × 3-μm transverse resolution from in vitro posterior eyecup preparations of the domestic pig. Frozen sections were obtained in precise alignment with OCT tomograms, by using major blood vessels as orientation markers and were counterstained with cresyl violet or unstained and examined by differential interference contrast microscopy. Micrographs from histologic sections were linearly scaled to correct for tissue ...

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    2. Mapping Retinal and Choroidal Thickness in Unilateral Nongranulomatous Acute Anterior Uveitis Using Three-Dimensional 1060-nm Optical Coherence Tomography

      Mapping Retinal and Choroidal Thickness in Unilateral Nongranulomatous Acute Anterior Uveitis Using Three-Dimensional 1060-nm Optical Coherence Tomography

      Purpose : To analyze retinal thickness (RT) and choroidal thickness (ChT) changes in patients with unilateral nongranulomatous acute anterior uveitis (AAU) using three-dimensional (3D) 1060-nm optical coherence tomography (OCT). Methods : Retinal and choroidal thickness maps were statistically analyzed for 24 patients with newly diagnosed unilateral AAU before therapy. A total of 17 patients were followed until resolution of inflammatory activity (twice in the first week, then weekly). Resolution occurred in all subjects within 6 weeks after the initial diagnosis. After resolution, thickness maps were again generated. All patients were imaged by high-speed spectral-domain (SD) 3D 1060-nm OCT over a 10 × 10-mm ...

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    3. Mapping diurnal changes in choroidal, Haller’s and Sattler’s layer thickness using 3-dimensional 1060-nm optical coherence tomography

      Mapping diurnal changes in choroidal, Haller’s and Sattler’s layer thickness using 3-dimensional 1060-nm optical coherence tomography

      Purpose To test the significance of diurnal changes in choroidal, Haller’s and Sattler’s layer thickness in healthy subjects using spatial analysis of three-dimensional (3D) 1060-nm optical coherence tomography (OCT) scans. Methods Automatically generated choroidal, Haller’s and Sattler’s layer thickness maps were statistically analyzed for 19 healthy subjects at two time points (8 a.m. and 6 p.m.) that represent the currently proposed ChT peak and nadir. All subjects were imaged by high-speed 1060-nm OCT over a 36° × 36° field of view. Spatial distribution of layer thickness was analyzed using the Early Treatment Diabetic Retinopathy Study ...

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    4. In vivo dual-modality photoacoustic and optical coherence tomography imaging of human dermatological pathologies

      In vivo dual-modality photoacoustic and optical coherence tomography imaging of human dermatological pathologies

      Vascular abnormalities serve as a key indicator for many skin diseases. Currently available methods in dermatology such as histopathology and dermatoscopy analyze underlying vasculature in human skin but are either invasive, time-consuming, and laborious or incapable of providing 3D images. In this work, we applied for the first time dual-modality photoacoustic and optical coherence tomography that provides complementary information about tissue morphology and vasculature of patients with different types of dermatitis. Its noninvasiveness and relatively short imaging time and the wide range of diseases that it can detect prove the merits of the dual-modality imaging system and show the great ...

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    5. Speckle reduction process based on digital filtering and wavelet compounding in optical coherence tomography for dermatology

      Speckle reduction process based on digital filtering and wavelet compounding in optical coherence tomography for dermatology

      Optical Coherence Tomography (OCT) has shown a great potential as a complementary imaging tool in the diagnosis of skin diseases. Speckle noise is the most prominent artifact present in OCT images and could limit the interpretation and detection capabilities. In this work we propose a new speckle reduction process and compare it with various denoising filters with high edge-preserving potential, using several sets of dermatological OCT B-scans. To validate the performance we used a custom-designed spectral domain OCT and two different data set groups. The first group consisted in five datasets of a single B-scan captured N times (with N ...

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    6. 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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    7. 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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    8. 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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    9. In vivo three dimensional dual wavelength photoacoustic tomography imaging of the far red fluorescent protein E2-Crimson expressed in adult zebrafish

      In vivo three dimensional dual wavelength photoacoustic tomography imaging of the far red fluorescent protein E2-Crimson expressed in adult zebrafish

      For the first time the far red fluorescent protein (FP) E2-Crimson genetically expressed in the exocrine pancreas of adult zebrafish has been non-invasively mapped in 3D in vivo using photoacoustic tomography (PAT). The distribution of E2-Crimson in the exocrine pancreas acquired by PAT was confirmed using epifluorescence imaging and histology, with optical coherence tomography (OCT) providing complementary structural information. This work demonstrates the depth advantage of PAT to resolve FP in an animal model and establishes the value of E2-Crimson for PAT studies of transgenic models, laying the foundation for future longitudinal studies of the zebrafish as a model of ...

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    10. Mapping Choroidal and Retinal Thickness Variation in Type 2 Diabetes using Three-Dimensional 1060-nm Optical Coherence Tomography

      Mapping Choroidal and Retinal Thickness Variation in Type 2 Diabetes using Three-Dimensional 1060-nm Optical Coherence Tomography
      Purpose. To map choroidal (ChT) and retinal thickness (RT) in healthy subjects and patients with diabetes with and without maculopathy using three dimensional 1060-nm optical coherence tomography (3D-1060nm-OCT). Methods. Sixty-three eyes from 42 diabetic subjects (41–82 years of age; 11 females) grouped according to a custom scheme using Early Treatment Diabetic Retinopathy Study definitions for pathology within 1 disc-diameter of fovea (without pathology [NDR], microaneurysms [M1], exudates [M2], clinically significant macular edema [CSME]) and 16 eyes from 16 healthy age matched subjects (38–79 years of age; 11 females) were imaged by 3D-1060nm-OCT performed over a 36° × 36° field ...
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    11. Artefact reduction for cell migration visualization using spectral domain optical coherence tomography

      Artefact reduction for cell migration visualization using spectral domain optical coherence tomography
      Visualization of cell migration during chemotaxis using spectral domain optical coherence tomography (OCT) requires non-standard processing techniques. Stripe artefacts and camera noise floor present in OCT data prevent detailed computer-assisted reconstruction and quantification of cell locomotion. Furthermore, imaging artefacts lead to unreliable results in automated texture based cell analysis. Here we characterize three pronounced artefacts that become visible when imaging sample structures with high dynamic range, e.g. cultured cells: (i) time-varying fixed-pattern noise; (ii) stripe artefacts generated by background estimation using tomogram averaging; (iii) image modulations due to spectral shaping. We evaluate techniques to minimize the above mentioned artefacts ...
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    12. Three-Dimensional 1060-nm OCT: Choroidal Thickness Maps in Normal Subjects and Improved Posterior Segment Visualization in Cataract Patients

      Three-Dimensional 1060-nm OCT: Choroidal Thickness Maps in Normal Subjects and Improved Posterior Segment Visualization in Cataract Patients
      Purpose. To evaluate the performance and potential clinical role of three-dimensional (3D) 1060-nm OCT by generating choroidal thickness (ChT) maps in patients of different ages with different degrees of ametropia and axial lengths and to investigate the effect of cataract grade on OCT retinal imaging quality. Methods. Axial lengths (ALs) and 45° fundus photographs were acquired from 64 eyes (34 healthy subjects, 19 to 80 years, ametropia +3 to –10 D). 3D 1060-nm OCT was performed over a 36° x 36° field of view with 7-µm axial resolution and up to 70 frames/s (512 A-scans/frame). ChT maps between ...
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    13. Robust segmentation of intraretinal layers in the normal human fovea using a novel statistical model based on texture and shape analysis

      Robust segmentation of intraretinal layers in the normal human fovea using a novel statistical model based on texture and shape analysis
      A novel statistical model based on texture and shape for fully automatic intraretinal layer segmentation of normal retinal tomograms obtained by a commercial 800nm optical coherence tomography (OCT) system is developed. While existing algorithms often fail dramatically due to strong speckle noise, non-optimal imaging conditions, shadows and other artefacts, the novel algorithm’s accuracy only slowly deteriorates when progressively increasing segmentation task difficulty. Evaluation against a large set of manual segmentations shows unprecedented robustness, even in the presence of additional strong speckle noise, with dynamic range tested down to 12dB, enabling segmentation of almost all intraretinal layers in cases previously ...
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    14. Three-dimensional 1060nm OCT: Choroidal thickness maps in normals and improved posterior segment visualization in cataract patients

      Three-dimensional 1060nm OCT: Choroidal thickness maps in normals and improved posterior segment visualization in cataract patients
      Purpose. To evaluate the performance and potential clinical role of 3D-1060nm-OCT by generating choroidal thickness (ChT) maps in patients of different age, ametropia and axial lengths and to investigate the effect of cataract grade on OCT retinal imaging quality. Methods. Axial lengths (AL) and 45° fundus photographs were acquired from 64 eyes (34 healthy subjects, 19-80 years, ametropia +3 to -10D). 3D-1060nm-OCT was performed over 36°x36° field of view with ~7µm axial resolution and up to 70 frames/second (512 A-scans/frame). ChT-maps between retinal pigment epithelium and the choroidal/scleral-interface, were generated and statistically analyzed. A further thirty ...
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    15. 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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    16. Spectroscopic measurements with dispersion encoded full range frequency domain optical coherence tomography in single- and multilayered weakly scattering phantoms

      Spectroscopic measurements with dispersion encoded full range frequency domain optical coherence tomography in single- and multilayered weakly scattering phantoms
      In this study, depth resolved measurements of absorption profiles in the wavelength range of 800 nm with a bandwidth of 140 nm are demonstrated using high speed spectroscopic frequency domain OCT(SOCT) and a full range reconstruction algorithm (dispersion encoded full range, DEFR). The feasibility of the algorithm for SOCT is tested in simulation and experiment. With proper calibration, SOCT with DEFR is able to extract absolute, depth resolved absorption profiles over the whole wavelength range at once without the need of tuning and performing measurements at single wavelengths sequentially. The superior acquisition speed and better phase stability in frequency ...
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    17. Techniques for extraction of depth-resolved in vivo human retinal intrinsic optical signals with optical coherence tomography

      Purpose To demonstrate acquisition and analysis methods for depth-resolved observation of slow retinal physiology induced changes in infrared backscatter in vivo. Methods A dark-adapted human was briefly subjected to a localized photobleach. For 20 min before and 30 min after the stimulus, volumetric optical coherence tomograms were collected partially overlapping the bleached region. Tomograms were segmented into retinal layers by a newly described algorithm exploiting information in adjacent B-scans. En face fundus images extracted from major intraretinal layers were laterally registered manually. Time series summarizing the observed backscatter in selected layers for the bleached and unbleached areas are shown with ...
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    18. 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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    19. Wide-Field Optical Coherence Tomography of the Choroid In Vivo

      PURPOSE. To demonstrate high-speed, high axial resolution optical coherence tomography (OCT) at 1060 nm with penetration to the sclera. The clinical feasibility of dense, high-speed sampling for higher levels of detail at the macula and optic nerve head is explored with respect to motion artifacts. METHODS. A three-dimensional (3D) OCT system making use of a high-speed camera operating at 47,000 depth scans/s was developed. The 1010- to 1080-nm wavelength band leads to 6.7 µm effective axial resolution and enables the acquisition of retinal and choroidal 130 Megavoxel volumes of human subjects within 7 seconds. Motion artifacts were ...
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    20. Impact of enhanced resolution, speed and penetration on three-dimensional retinal optical coherence tomography

      Impact of enhanced resolution, speed and penetration on three-dimensional retinal optical coherence tomography
      Recent substantial developments in light source and detector technology have initiated a paradigm shift in retinal optical coherence tomography (OCT) performance. Broad bandwidth light sources in the 800 nm and 1060 nm wavelength region enable axial OCT resolutions of 2-3 μm and 5-7 ... [Opt. Express 17, 4134-4150 (2009)]
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    21. 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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    22. Wide field visualization of retinal and choroidal microstructure in vivo using frequency domain OCT at 1060 nm with up to 47000 lines/s

      We present in vivo frequency domain optical coherence tomography of the human retina and choroid in the 1060 nm water transmission window with 72 nm optical bandwidth (<8 µm axial resolution in tissue) and up to 74 frames per second (`a 512 x 512 pixels). A novel InGaAs stripe array with 1024 pixels and 47000 lines/s read out rate is utilized in combination with an all reflective spectrometer to enable densely sampled wide field scans (35°x°35), i.e. ~10x10 mm2) acquired in less than 7 seconds. At this speed numerical motion artifact removal algorithms are sufficient to ...
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    23. 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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    24. Dispersion encoded full range frequency domain optical coherence tomography

      Dispersion encoded full range frequency domain optical coherence tomography

      We propose an iterative algorithm that exploits the dispersion mismatch between reference and sample arm in frequency-domain optical coherence tomography (FD-OCT) to effectively cancel complex conjugate mirror terms in individual A-scans and thereby generate full range tomograms. The resulting ... [Opt. Express 17, 7-24 (2009)]

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    1-24 of 28 1 2 »
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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 Spectroscopic measurements with dispersion encoded full range frequency domain optical coherence tomography in single- and multilayered weakly scattering phantoms Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm Three-dimensional 1060nm OCT: Choroidal thickness maps in normals and improved posterior segment visualization in cataract patients Robust segmentation of intraretinal layers in the normal human fovea using a novel statistical model based on texture and shape analysis Three-Dimensional 1060-nm OCT: Choroidal Thickness Maps in Normal Subjects and Improved Posterior Segment Visualization in Cataract Patients Fantom Encore Sirolimus-eluting Bioresorbable Scaffold for Treatment of De-novo CAD: the ENCORE-I Study Assessment of Microcirculatory Dysfunction in Septic Shock Patients by OCTA OCT system used at home demonstrates potential for daily monitoring of AMD Optical Coherence Tomography Biomarkers of the Outer Blood—Retina Barrier in Patients with Diabetic Macular Oedema Retinal Boundary Segmentation in Stargardt Disease Optical Coherence Tomography Images Using Automated