1. Articles from Gereon Hüttmann

    1-24 of 51 1 2 3 »
    1. Microscopic optical coherence tomography (mOCT) at 600 kHz for 4D volumetric imaging and dynamic contrast

      Microscopic optical coherence tomography (mOCT) at 600 kHz for 4D volumetric imaging and dynamic contrast

      Volumetric imaging of dynamic processes with microscopic resolution holds a huge potential in biomedical research and clinical diagnosis. Using supercontinuum light sources and high numerical aperture (NA) objectives, optical coherence tomography (OCT) achieves microscopic resolution and is well suited for imaging cellular and subcellular structures of biological tissues. Currently, the imaging speed of microscopic OCT (mOCT) is limited by the line-scan rate of the spectrometer camera and ranges from 30 to 250 kHz. This is not fast enough for volumetric imaging of dynamic processes in vivo and limits endoscopic application. Using a novel CMOS camera, we demonstrate fast 3-dimensional OCT ...

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    2. Imaging Inflammation – From Whole Body Imaging to Cellular Resolution

      Imaging Inflammation – From Whole Body Imaging to Cellular Resolution

      Imaging techniques have evolved impressively lately, allowing whole new concepts like multimodal imaging, personal medicine, theranostic therapies, and molecular imaging to increase general awareness of possiblities of imaging to medicine field. Here, we have collected the selected (3D) imaging modalities and evaluated the recent findings on preclinical and clinical inflammation imaging. The focus has been on the feasibility of imaging to aid in inflammation precision medicine, and the key challenges and opportunities of the imaging modalities are presented. Some examples of the current usage in clinics/close to clinics have been brought out as an example. This review evaluates the ...

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    3. Self-examination low-cost full-field OCT (SELFF-OCT) for patients with various macular diseases

      Self-examination low-cost full-field OCT (SELFF-OCT) for patients with various macular diseases

      Purpose The treatment guidelines for many macular diseases rely on frequent monitoring with optical coherence tomography (OCT). However, the burden of frequent disease control leads to low therapy adherence in real life. OCT home monitoring would address this issue but requires an inexpensive and self-operable device. With self-examination low-cost full-field OCT (SELFF-OCT), our group has introduced a novel technology that may fulfill both requirements. In this pilot study, we report the initial experiences with a clinical prototype. Methods Fifty-one patients with different macular diseases were recruited in a cross-sectional study. The most common diseases were age-related macular degeneration (AMD; 39 ...

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    4. An Intraoral OCT Probe to Enhanced Detection of Approximal Carious Lesions and Assessment of Restorations

      An Intraoral OCT Probe to Enhanced Detection of Approximal Carious Lesions and Assessment of Restorations

      Caries, the world’s most common chronic disease, remains a major cause of invasive restorative dental treatment. To take advantage of the diagnostic potential of optical coherence tomography (OCT) in contemporary dental prevention and treatment, an intraorally applicable spectral-domain OCT probe has been developed based on an OCT hand-held scanner equipped with a rigid 90°-optics endoscope. The probe was verified in vitro. In vivo, all tooth surfaces could be imaged with the OCT probe, except the vestibular surfaces of third molars and the proximal surface sections of molars within a "blind spot" at a distance greater than 2.5 ...

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    5. Dynamic contrast in scanning microscopic OCT

      Dynamic contrast in scanning microscopic OCT

      While optical coherence tomography (OCT) provides a resolution down to 1 µm, it has difficulties in visualizing cellular structures due to a lack of scattering contrast. By evaluating signal fluctuations, a significant contrast enhancement was demonstrated using time-domain full-field OCT (FF-OCT), which makes cellular and subcellular structures visible. The putative cause of the dynamic OCT signal is the site-dependent active motion of cellular structures in a sub-micrometer range, which provides histology-like contrast. Here we demonstrate dynamic contrast with a scanning frequency-domain OCT (FD-OCT), which we believe has crucial advantages. Given the inherent sectional imaging geometry, scanning FD-OCT provides depth-resolved images ...

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    6. Determination and correction of aberrations in full field OCT using phase gradient autofocus by maximizing the likelihood function

      Determination and correction of aberrations in full field OCT using phase gradient autofocus by maximizing the likelihood function

      A method for numerical estimation and correction of aberrations of the eye in fundus imaging with optical coherence tomography (OCT) is presented. Aberrations are determined statistically by using the estimate based on likelihood function maximization. The method can be considered as an extension of the phase gradient autofocusing algorithm in synthetic aperture radar imaging to 2D optical aberration correction. The efficacy of the proposed method has been demonstrated in OCT fundus imaging with 6λ aberrations. After correction, single photoreceptors were resolved. It is also shown that wavefront distortions with high spatial frequencies can be determined and corrected.

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    7. Coregistered Spectral Optical Coherence Tomography and Two-Photon Microscopy for Multimodal NearInstantaneous Deep-Tissue Imaging

      Coregistered Spectral Optical Coherence Tomography and Two-Photon Microscopy for Multimodal NearInstantaneous Deep-Tissue Imaging

      Two-photon microscopy (2PM) has brought unique insight into the mechanisms underlying immune system dynamics and function since it enables monitoring of cellular motility and communication in complex systems within their genuine environment—the living organism. However, use of 2PM in clinical settings is limited. In contrast, optical coherence tomography (OCT), a noninvasive label-free diagnostic imaging method, which allows monitoring morphologic changes of large tissue regions in vivo, has found broad application in the clinic. Here we developed a combined multimodal technology to achieve near-instantaneous coregistered OCT, 2PM, and second harmonic generation (SHG) imaging over large volumes (up to 1,000 ...

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    8. Dynamic contrast in scanning microscopic OCT

      Dynamic contrast in scanning microscopic OCT

      While optical coherence tomography (OCT) provides a resolution down to 1 micrometer it has difficulties to visualize cellular structures due to a lack of scattering contrast. By evaluating signal fluctuations, a significant contrast enhancement was demonstrated using time-domain full-field OCT (FF-OCT), which makes cellular and subcellular structures visible. The putative cause of the dynamic OCT signal is ATP-dependent motion of cellular structures in a sub-micrometer range, which provides histology-like contrast. Here we demonstrate dynamic contrast with a scanning frequency-domain OCT (FD-OCT). Given the inherent sectional imaging geometry, scanning FD-OCT provides depth-resolved images across tissue layers, a perspective known from histopathology ...

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    9. Intravital microscopic optical coherence tomography imaging to assess mucus mobilizing interventions for muco-obstructive lung disease in mice

      Intravital microscopic optical coherence tomography imaging to assess mucus mobilizing interventions for muco-obstructive lung disease in mice

      Airway mucus obstruction is a hallmark of chronic lung diseases such as cystic fibrosis, asthma and COPD, and the development of more effective mucus mobilizing therapies remains an important unmet need for patients with these muco-obstructive lung diseases. However, methods for sensitive visualization and quantitative assessment of immediate effects of therapeutic interventions on mucus clearance in vivo are lacking. In this study, we determined if newly developed high-speed microscopic optical coherence tomography (mOCT) is sensitive to detect and compare in vivo effects of inhaled isotonic saline, hypertonic saline and bicarbonate on mucus mobilization and clearance in Scnn1b -transgenic mice with ...

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    10. Investigation of cell dynamics in 3D cell spheroids and cell interaction with 3D printed scaffolds by mOCT

      Investigation of cell dynamics in 3D cell spheroids and cell interaction with 3D printed scaffolds by mOCT

      Optical coherence tomography is a non-invasive and label-free imaging modality based on the detection of backscattered light in samples. As microscopic OCT (mOCT) combines high axial and lateral resolution, an investigation of biological and printed samples at subcellular level is feasible. The additional excellent depth resolution enables mOCT to be a suitable quality control of 3D printed samples. The use of speckle variance adds information about cell viability. Here we present the feasibility of investigating cell viability within a cell spheroid and monitoring the cell interaction with bioprinted scaffolds using mOCT.

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    11. Computational adaptive optics for optical coherence tomography using multiple randomized subaperture correlations

      Computational adaptive optics for optical coherence tomography using multiple randomized subaperture correlations

      Computational adaptive optics (CAO) is emerging as a viable alternative to hardware-based adaptive optics—in particular when applied to optical coherence tomography of the retina. For this technique, algorithms are required that detect wavefront errors precisely and quickly. Here we propose an extension of the frequently used subaperture image correlation. By applying this algorithm iteratively and, more importantly, comparing each subaperture not to the central subaperture but to several randomly selected apertures, we improved aberration correction. Since these modifications only slightly increase the run time of the correction, we believe this method can become the algorithm of choice for many ...

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    12. Segmentation of mouse skin layers in optical coherence tomography image data using deep convolutional neural networks

      Segmentation of mouse skin layers in optical coherence tomography image data using deep convolutional neural networks

      Optical coherence tomography (OCT) enables the non-invasive acquisition of high-resolution three-dimensional cross-sectional images at micrometer scale and is mainly used in the field of ophthalmology for diagnosis as well as monitoring of eye diseases. Also in other areas, such as dermatology, OCT is already well established. Due to its non-invasive nature, OCT is also employed for research studies involving animal models. Manual evaluation of OCT images of animal models is a challenging task due to the lack of imaging standards and the varying anatomy between models. In this paper, we present a deep learning algorithm for the automatic segmentation of ...

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    13. Optimization-based vessel segmentation pipeline for robust quantification of capillary networks in skin with optical coherence tomography angiography

      Optimization-based vessel segmentation pipeline for robust quantification of capillary networks in skin with optical coherence tomography angiography

      Optical coherence tomography angiography (OCTA) provides in-vivo images of microvascular perfusion in high resolution. For its application to basic and clinical research, an automatic and robust quantification of the capillary architecture is mandatory. Only this makes it possible to reliably analyze large amounts of image data, to establish biomarkers, and to monitor disease developments. However, due to its optical properties, OCTA images of skin often suffer from a poor signal-to-noise ratio and contain imaging artifacts. Previous work on automatic vessel segmentation in OCTA mostly focuses on retinal and cerebral vasculature. Its applicability to skin and, furthermore, its robustness against imaging ...

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    14. Artifacts in speckle tracking and multi-aperture Doppler OCT imaging of lateral motion

      Artifacts in speckle tracking and multi-aperture Doppler OCT imaging of lateral motion

      In optical coherence tomography (OCT), lateral motion is determined either by speckle tracking or by multi-aperture Doppler OCT. Here we show that both methods may provide incorrect results because, outside the focal plane, non-uniform axial motion is misinterpreted as lateral motion. First, we demonstrate the existence of this artifact by means of a simulation for speckle tracking. Then the physical origin of the artifact and its mathematical relation to defocus and axial motion are explained. It is shown that speckle tracking and multi-aperture Doppler OCT are equally affected by the artifact, which has a considerable effect, even for a defocus ...

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    15. Method for filtering reflexes in full-field setups for ophthalmologic imaging by separated illumination and detection apertures

      Method for filtering reflexes in full-field setups for ophthalmologic imaging by separated illumination and detection apertures

      A parallel detecting optical coherence tomography (OCT) setup and method, in which the light paths of the illumination of the sample and of the detection of the backscattered light do not use the same apertures. The separation of illumination and detection apertures filters these disturbing reflexes from the backscattered light of the sample and significantly increases image quality.

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      Mentions: Thorlabs
    16. Simple approach for aberration-corrected OCT imaging of the human retina

      Simple approach for aberration-corrected OCT imaging of the human retina

      Aberration-corrected imaging of human photoreceptor cells, whether hardware or software based, presently requires a complex and expensive setup. Here we use a simple and inexpensive off-axis full-field time-domain optical coherence tomography (OCT) approach to acquire volumetric data of an in vivo human retina. Full volumetric data are recorded in 1.3 s. After computationally correcting for aberrations, single photoreceptor cells were visualized. In addition, the numerical correction of ametropia is demonstrated. Our implementation of full-field optical coherence tomography combines a low technical complexity with the possibility for computational image correction.

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    17. High-speed fiber scanning endoscope for volumetric multi-megahertz optical coherence tomography

      High-speed fiber scanning endoscope for volumetric multi-megahertz optical coherence tomography

      We present a forward-viewing fiber scanning endoscope (FSE) for high-speed volumetric optical coherence tomography (OCT). The reduction in size of the probe was achieved by substituting the focusing optics by an all-fiber-based imaging system which consists of a combination of scanning single-mode fibers, a glass spacer, made from a step-index multi-mode fiber, and a gradient-index fiber. A lateral resolution of 11 μm was achieved at a working distance of 1.2 mm. The newly designed piezo-based FSE has an outer diameter of 1.6 mm and a rigid length of 13.5 mm. By moving the whole imaging optic in ...

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    18. Interferometric detection of 3D motion using computational subapertures in optical coherence tomography

      Interferometric detection of 3D motion using computational subapertures in optical coherence tomography

      Doppler optical coherence tomography (OCT) quantifies axial motion with high precision, whereas lateral motion cannot be detected by a mere evaluation of phase changes. This problem was solved by the introduction of three-beam Doppler OCT, which, however, entails a high experimental effort. Here, we present the numerical analogue to this experimental approach. Phase-stable complex-valued OCT datasets, recorded with full-field swept-source OCT, are filtered in the Fourier domain to limit imaging to different computational subapertures. These are used to calculate all three components of the motion vector with interferometric precision. As known from conventional Doppler OCT for axial motion only, the ...

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    19. Novel endoscope with increased depth of field for imaging human nasal tissue by microscopic optical coherence tomography

      Novel endoscope with increased depth of field for imaging human nasal tissue by microscopic optical coherence tomography

      Intravital microscopy (IVM) offers the opportunity to visualize static and dynamic changes of tissue on a cellular level. It is a valuable tool in research and may considerably improve clinical diagnosis. In contrast to confocal and non-linear microscopy, optical coherence tomography (OCT) with microscopic resolution (mOCT) provides intrinsically cross-sectional imaging. Changing focus position is not needed, which simplifies especially endoscopic imaging. For in-vivo imaging, here we are presenting endo-microscopic OCT (emOCT). A graded-index-lens (GRIN) based 2.75 mm outer diameter rigid endoscope is providing 1.5 – 2 µm nearly isotropic resolution over an extended field of depth. Spherical and chromatic ...

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    20. Retinal pulse wave velocity measurement using spectral-domain optical coherence tomography

      Retinal pulse wave velocity measurement using spectral-domain optical coherence tomography

      In their latest publication on retinal pulse wave velocity measurement using optical co-herence tomography (OCT), Qian Li et al. propose a method to determine the pulse wave velocity in retinal arteries and veins [1]. This should enable a non-invasive determination of biomechanical properties of the vessel network, particularly the elasticity of the vessel walls [2].

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    21. Label-Free In Vivo Imaging of Corneal Lymphatic Vessels Using Microscopic Optical Coherence Tomography

      Label-Free In Vivo Imaging of Corneal Lymphatic Vessels Using Microscopic Optical Coherence Tomography

      Purpose : Corneal neovascularization, in particular lymphangiogenesis, is a limiting factor in corneal transplant survival. Novel treatment approaches focus on (selective) inhibition and regression of lymphatic vessels. Imaging clinically invisible corneal lymphatic vessels is a prerequisite for these strategies. Using a murine model, this study investigates whether corneal lymphatic vessels can be imaged using microscopic optical coherence tomography (mOCT). Methods : Corneal neovascularization was induced by intrastromal placement of 11.0 nylon sutures in one eye of BALB/c mice. After 2 weeks, cross-sectional images and volumes of the corneas with a 0.5 mm lateral and axial field of view were ...

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    22. An Approach for Needle Based Optical Coherence Elastography Measurements

      An Approach for Needle Based Optical Coherence Elastography Measurements

      While navigation and interventional guidance are typically based on image data, the images do not necessarily reflect mechanical tissue properties. Optical coherence elastography (OCE) presents a modality with high sensitivity and very high spatial and temporal resolution. However, OCE has a limited field of view of only 2–5 mm depth. We present a side-facing needle probe to image externally induced shear waves from within soft tissue. A first method of quantitative needle-based OCE is provided. Using a time of flight setup, we establish the shear wave velocity and estimate the tissue elasticity. For comparison, an external scan head is ...

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    23. Reduction of frame rate in full-field swept-source optical coherence tomography by numerical motion correction [Invited]

      Reduction of frame rate in full-field swept-source optical coherence tomography by numerical motion correction [Invited]

      Full-field swept-source optical coherence tomography (FF-SS-OCT) was recently shown to allow new and exciting applications for imaging the human eye that were previously not possible using current scanning OCT systems. However, especially when using cameras that do not acquire data with hundreds of kHz frame rate, uncorrected phase errors due to axial motion of the eye lead to a drastic loss in image quality of the reconstructed volumes. Here we first give a short overview of recent advances in techniques and applications of parallelized OCT and finally present an iterative and statistical algorithm that estimates and corrects motion-induced phase errors ...

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    24. In-vivo retinal imaging with off-axis full-field time-domain optical coherence tomography

      In-vivo retinal imaging with off-axis full-field time-domain optical coherence tomography

      With a simple setup, mainly composed of a low coherence light source and a camera, full-field optical coherence tomography (FF-OCT) allows volumetric tissue imaging. However, fringe washout constrains its use in retinal imaging. Here, we present a novel motion-insensitive approach to FF-OCT, which introduces path-length differences between the reference and the sample light in neighboring pixels using an off-axis reference beam. The temporal carrier frequency in scanned time-domain OCT is replaced by a spatial carrier frequency. Volumetric in-vivo FF-OCT measurements of the human retina were acquired in only 1.3 s, comparable to the acquisition times of current clinically used ...

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    1-24 of 51 1 2 3 »
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    Optical coherence tomography allows for the reliable identification of laryngeal epithelial dysplasia and for precise biopsy: A clinicopathological study of 61 patients undergoing microlaryngoscopy In vivo Fourier-domain full-field OCT of the human retina with 1.5 million A-lines/s Comparison of fast swept source full-field OCT with conventional scanning OCT Holoscopy: holographic optical coherence tomography 3D OPTICAL IMAGING: Holoscopy makes ultrafast lensless imaging of scattering tissues possible Optimizing Descemet Membrane Endothelial Keratoplasty Using Intraoperative Optical Coherence Tomography Feature Of The Week 10/25/2015: Imaging Pulse Wave Propagation in Human Retina using Full-Field Swept-Source OCT Deep learning models comparison for tissue classification using optical coherence tomography images: toward smart laser osteotomy Optical coherence tomography angiography features of macular neovascularization in wet age-related macular degeneration: A cross-sectional study Automatic focus method using interference fringes magnitudes in retinal optical coherence tomography Improved U-Net for Plaque Segmentation of Intracoronary Optical Coherence Tomography Images The Precision of a New Anterior Segment Optical Coherence Tomographer and Its Comparison With a Swept-Source OCT-Based Optical Biometer in Patients With Cataract