1. Articles from Wolfgang Drexler

    1-24 of 100 1 2 3 4 5 »
    1. Towards ultrahigh resolution OCT based endoscopical pituitary gland and adenoma screening: a performance parameter evaluation

      Towards ultrahigh resolution OCT based endoscopical pituitary gland and adenoma screening: a performance parameter evaluation

      Ultrahigh resolution optical coherence tomography (UHR-OCT) for differentiating pituitary gland versus adenoma tissue has been investigated for the first time, indicating more than 80% accuracy. For biomarker identification, OCT images of paraffin embedded tissue are correlated to histopathological slices. The identified biomarkers are verified on fresh biopsies. Additionally, an approach, based on resolution modified UHR-OCT ex vivo data, investigating optical performance parameters for the realization in an in vivo endoscope is presented and evaluated. The identified morphological features–cell groups with reticulin framework–detectable with UHR-OCT showcase a promising differentiation ability, encouraging endoscopic OCT probe development for in vivo application.

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    2. Three-dimensional composition of the photoreceptor cone layers in healthy eyes using adaptive-optics optical coherence tomography (AO-OCT)

      Three-dimensional composition of the photoreceptor cone layers in healthy eyes using adaptive-optics optical coherence tomography (AO-OCT)

      Purpose To assess the signal composition of cone photoreceptors three-dimensionally in healthy retinas using adaptive optics optical coherence tomography (AO-OCT). Methods Study population. Twenty healthy eyes of ten subjects (age 23 to 67). Procedures. After routine ophthalmological assessments, eyes were examined using AO-OCT. Three-dimensional volumes were acquired at 2.5° and 6.5° foveal eccentricity in four main meridians (superior, nasal, inferior, temporal). Cone densities and signal compositions were investigated in four different planes: the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST) and ...

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    3. Toward optical coherence tomography on a chip: in vivo three-dimensional human retinal imaging using photonic integrated circuit-based arrayed waveguide gratings

      Toward optical coherence tomography on a chip: in vivo three-dimensional human retinal imaging using photonic integrated circuit-based arrayed waveguide gratings

      In this work, we present a significant step toward in vivo ophthalmic optical coherence tomography and angiography on a photonic integrated chip. The diffraction gratings used in spectral-domain optical coherence tomography can be replaced by photonic integrated circuits comprising an arrayed waveguide grating. Two arrayed waveguide grating designs with 256 channels were tested, which enabled the first chip-based optical coherence tomography and angiography in vivo three-dimensional human retinal measurements. Design 1 supports a bandwidth of 22 nm, with which a sensitivity of up to 91 dB (830 µW ) and an axial resolution of 10.7 µm was measured. Design 2 ...

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    4. Three-dimensional assessment of para- and perifoveal photoreceptor densities and the impact of meridians and age in healthy eyes with adaptive-optics optical coherence tomography (AO-OCT)

      Three-dimensional assessment of para- and perifoveal photoreceptor densities and the impact of meridians and age in healthy eyes with adaptive-optics optical coherence tomography (AO-OCT)

      An adaptive optics optical coherence tomography (AO-OCT) system is used to assess sixty healthy eyes of thirty subjects (age 22 to 75) to evaluate how the outer retinal layers, foveal eccentricity and age effect the mean cone density. The cone mosaics of different retinal planes (the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST), and the full en-face plane (FEF)) at four main meridians (superior, nasal, inferior, temporal) and para- and perifoveal eccentricities (ecc 2.5° and 6.5°) were analyzed quantitatively. The mean ...

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    5. Ultra-high-resolution 3D optical coherence tomography reveals inner structures of human placenta-derived trophoblast organoids

      Ultra-high-resolution 3D optical coherence tomography reveals inner structures of human placenta-derived trophoblast organoids

      Objective: 3D optical coherence tomography (OCT) is used for analyses of human placenta organoids in situ without sample preparation. Methods: The trophoblast organoids analyzed were derived from primary human trophoblast. In this study a custom made ultra-high-resolution spectral domain OCT system with uniform spatial and axial resolution of 2.48 m in organoid tissue was used. The obtained OCT results align to differentiation status tested via quantitative polymerase chain reaction, Western blot analyses, immunohistochemistry, and immunofluorescence of histological sections. Results: 3D OCT enables a more detailed placenta organoid monitoring compared to brightfield microscopy. Inner architecture with light scattering bridges surrounding ...

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    6. Multi-channel swept source optical coherence tomography concept based on photonic integrated circuits

      Multi-channel swept source optical coherence tomography concept based on photonic integrated circuits

      In this paper, we present a novel concept for a multi-channel swept source optical coherence tomography (OCT) system based on photonic integrated circuits (PICs). At the core of this concept is a low-loss polarization dependent path routing approach allowing for lower excess loss compared to previously shown PIC-based OCT systems, facilitating a parallelization of measurement units. As a proof of concept for the low-loss path routing, a silicon nitride PIC-based single-channel swept source OCT system operating at 840 nm was implemented and used to acquire in-vivo tomograms of a human retina. The fabrication of the PIC was done via CMOS-compatible ...

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      Mentions: Wolfgang Drexler
    7. Ex-vivo Alzheimer’s disease brain tissue investigation: a multiscale approach using 1060-nm swept source optical coherence tomography for a direct correlation to histology

      Ex-vivo Alzheimer’s disease brain tissue investigation: a multiscale approach using 1060-nm swept source optical coherence tomography for a direct correlation to histology

      Significance: Amyloid-beta (A-β) plaques are pathological protein deposits formed in the brain of Alzheimer’s disease (AD) patients upon disease progression. Further research is needed to elucidate the complex underlying mechanisms involved in their formation using label-free, tissue preserving, and volumetric techniques. Aim: The aim is to achieve a one-to-one correlation of optical coherence tomography (OCT) data to histological micrographs of brain tissue using 1060-nm swept source OCT. Approach: A-β plaques were investigated in ex-vivo AD brain tissue using OCT with the capability of switching between two magnifications. For the exact correlation to histology, a 3D-printed tool was designed to ...

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    8. Ultra-high-resolution SD-OCM imaging with a compact polarization-aligned 840 nm broadband combined-SLED source

      Ultra-high-resolution SD-OCM imaging with a compact polarization-aligned 840 nm broadband combined-SLED source

      We analyze the influence of intrinsic polarization alignment on image quality and axial resolution employing a broadband 840 nm light source with an optical bandwidth of 160 nm and an output power of 12 mW tailored for spectral-domain optical coherence microscopy (SD-OCM) applications. Three superluminescent diodes (SLEDs) are integrated into a 14-pin butterfly module using a free-space micro-optical bench architecture, maintaining a constant polarization state across the full spectral output. We demonstrate superior imaging performance in comparison to traditionally coupled-SLED broadband light sources in a teleost model organism in-vivo .

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    9. 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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    10. Morpho-molecular ex vivo detection and grading of non-muscle-invasive bladder cancer using forward imaging probe based multimodal optical coherence tomography and Raman spectroscop

      Morpho-molecular ex vivo detection and grading of non-muscle-invasive bladder cancer using forward imaging probe based multimodal optical coherence tomography and Raman spectroscop

      Non-muscle-invasive bladder cancer affects millions of people worldwide, resulting in significant discomfort to the patient and potential death. Today, cystoscopy is the gold standard for bladder cancer assessment, using white light endoscopy to detect tumor suspected lesion areas, followed by resection of these areas and subsequent histopathological evaluation. Not only does the pathological examination take days, but due to the invasive nature, the performed biopsy can result in significant harm to the patient. Nowadays, optical modalities, such as optical coherence tomography (OCT) and Raman spectroscopy (RS), have proven to detect cancer in real time and can provide more detailed clinical ...

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    11. Comparison of optical coherence tomography angiography and narrow-band imaging using a bimodal endoscope

      Comparison of optical coherence tomography angiography and narrow-band imaging using a bimodal endoscope

      We present coregistered images of tissue vasculature that allow a direct comparison between the performance of narrow-band imaging (NBI) and optical coherence tomography angiography (OCTA). Images were generated with a bimodal endomicroscope having a size of 15  ×  2.4  ×  3.3  mm 3   (   l   ,   w   ,   h   )   that combines two imaging channels. The white light imaging channel was used to perform NBI, the current gold standard for endoscopic visualization of vessels. The second channel allowed the simultaneous acquisition of optical coherence tomography (OCT) and OCTA images, enabling a three-dimensional (3-D) visualization of morphological as well as functional tissue information. In order ...

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    12. 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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    13. 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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    14. 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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    15. Optical coherence tomography angiography and photoacoustic imaging in dermatology

      Optical coherence tomography angiography and photoacoustic imaging in dermatology

      Optical coherence tomography angiography (OCTA) is a relatively novel functional extension of the widely accepted ophthalmic imaging tool named optical coherence tomography (OCT). Since OCTA’s debut in ophthalmology, researchers have also been trying to expand its translational application into dermatology. The ability of OCTA in resolving microvasculature has shown promising results in imaging skin diseases. Meanwhile, photoacoustic imaging (PAI), which uses laser pulse induced ultrasound waves as the signal, has been studied to differentiate human skin layers and to help skin disease diagnosis. This perspective article gives a short review of OCTA and PAI in the field of photodermatology ...

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    16. Dynamic Changes of Retinal Microaneurysms in Diabetes Imaged With In Vivo Adaptive Optics Optical Coherence Tomography

      Dynamic Changes of Retinal Microaneurysms in Diabetes Imaged With In Vivo Adaptive Optics Optical Coherence Tomography

      Purpose : To prospectively monitor microaneurysms (MAs) in three dimensions using adaptive optics optical coherence tomography (AOOCT). Methods : Patients with diabetes mellitus and parafoveal MAs were included in this longitudinal study. At baseline, MAs were identified in standard fluorescein angiography (FA) and subsequently imaged with an AOOCT prototype, incorporated into an AO fundus camera (RTX1, Imagine Eyes) device. Imaging was repeated every 3 months in each patient to explore the potential structural change of MAs over time including size, shape, intraretinal position, (intra-) luminal reflectivity, and other qualitative morphologic characteristics. Results : We imaged 18 MAs in seven eyes (two left eyes ...

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    17. 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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    18. Handheld multi‐modal imaging for point‐of‐care skin diagnosis based on akinetic integrated optics optical coherence tomography

      Handheld multi‐modal imaging for point‐of‐care skin diagnosis based on akinetic integrated optics optical coherence tomography

      A handheld skin imaging system with joint optical coherence tomography (OCT) at 1300 nm and digital epiluminescence microscopy (EM) is presented. The two modalities are physically co‐registered in a common‐path configuration. The instrument is enabled by a dedicated planar lightwave circuit with a footprint of only 1.1 x 19.5 mm 2 that provides akinetic axial OCT scanning at speeds up to 24 kHz. Lateral scanning is implemented through a low‐voltage MEMS mirror packaged with the axial scanner in a hermetic butterfly module. The OCT system, with a volume of only 80 x 27 x 14 ...

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    19. Compact akinetic swept source optical coherence tomography angiography at 1060 nm supporting a wide field of view and adaptive optics imaging modes of the posterior eye

      Compact akinetic swept source optical coherence tomography angiography at 1060 nm supporting a wide field of view and adaptive optics imaging modes of the posterior eye

      Imaging of the human retina with high resolution is an essential step towards improved diagnosis and treatment control. In this paper, we introduce a compact, clinically user-friendly instrument based on swept source optical coherence tomography (SS-OCT). A key feature of the system is the realization of two different operation modes. The first operation mode is similar to conventional OCT imaging and provides large field of view (FoV) images (up to 45° × 30°) of the human retina and choroid with standard resolution. The second operation mode enables it to optically zoom into regions of interest with high transverse resolution using adaptive ...

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    20. Optophysiological Characterisation of Inner Retina Responses with High-Resolution Optical Coherence Tomography

      Optophysiological Characterisation of Inner Retina Responses with High-Resolution Optical Coherence Tomography

      Low coherence laser interferometry has revolutionised quantitative biomedical imaging of optically transparent structures at cellular resolutions. We report the first optical recording of neuronal excitation at cellular resolution in the inner retina by quantifying optically recorded stimulus-evoked responses from the retinal ganglion cell layer and comparing them with an electrophysiological standard. We imaged anaesthetised paralysed tree shrews, gated image acquisition, and used numerical filters to eliminate noise arising from retinal movements during respiratory and cardiac cycles. We observed increases in contrast variability in the retinal ganglion cell layer and nerve fibre layer with flash stimuli and gratings. Regions of interest ...

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    21. THREE-DIMENSIONAL ANALYSIS OF RETINAL MICROANEURYSMS WITH ADAPTIVE OPTICS OPTICAL COHERENCE TOMOGRAPHY

      THREE-DIMENSIONAL ANALYSIS OF RETINAL MICROANEURYSMS WITH ADAPTIVE OPTICS OPTICAL COHERENCE TOMOGRAPHY

      Purpose: To characterize retinal microaneurysms (MAs) in patients with diabetes using adaptive optics optical coherence tomography (AOOCT) and compare details found in AOOCT with those found in commercially available retinal imaging techniques. Methods: Patients with diabetes and MA in the macular area were included in this pilot study. The area of interest, identified in standard fluorescein angiography, was imaged using an AO fundus camera and AOOCT. Microaneurysms were characterized in AOOCT (visibility, reflectivity, feeding/draining vessels, and intraretinal location) and compared with findings in AO fundus camera, OCT angiography, and fluorescein angiography. Results: Fifty-three MAs were imaged in 15 eyes ...

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    22. Non-invasive multimodal optical coherence and photoacoustic tomography for human skin imaging

      Non-invasive multimodal optical coherence and photoacoustic tomography for human skin imaging

      The cutaneous vasculature is involved in many diseases. Current clinical examination techniques, however, cannot resolve the human vasculature with all plexus in a non-invasive manner. By combining an optical coherence tomography system with angiography extension and an all optical photoacoustic tomography system, we can resolve in 3D the blood vessels in human skin for all plexus non-invasively. With a customized imaging unit that permits access to various parts of patients’ bodies, we applied our multimodality imaging system to investigate several different types of skin conditions. Quantitative vascular analysis is given for each of the dermatological conditions to show the potential ...

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    23. 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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    24. 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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    1. (99 articles) Wolfgang Drexler
    2. (72 articles) Medical University of Vienna
    3. (40 articles) Cardiff University
    4. (39 articles) Boris Považay
    5. (31 articles) Bernd M. Hofer
    6. (26 articles) Boris Hermann
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    Optical Coherence Tomography: Technology & Applications (Book) Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm Multispectral in vivo three-dimensional optical coherence tomography of human skin Robust segmentation of intraretinal layers in the normal human fovea using a novel statistical model based on texture and shape analysis Highly reproducible swept-source, dispersion-encoded full-range biometry and imaging of the mouse eye Three-Dimensional 1060-nm OCT: Choroidal Thickness Maps in Normal Subjects and Improved Posterior Segment Visualization in Cataract Patients Feature Of The Week 10/2/11: Heritability of Ocular Component Dimensions in Mice Phenotyped using Depth-Enhanced SS-OCT Residual thrombus following plaque disruption contributes to rapid plaque progression: in-vivo serial optical coherence tomography imaging Pigmented Iris Lesion on Anterior-Segment Swept-Source Optical Coherence Tomography Corneal epithelial thickness analysis of forme fruste keratoconus with optical coherence tomography Saline as an alternative to radio-contrast for optical coherence tomography guided percutaneous coronary intervention: A prospective comparison Soliton microcomb based spectral domain optical coherence tomography