1. Articles from Wolfgang Drexler

    1-24 of 93 1 2 3 4 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. 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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    13. 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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    14. 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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    15. 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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    16. 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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    17. 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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    18. Introduction to the feature issue on the 25 year anniversary of optical coherence tomography

      Introduction to the feature issue on the 25 year anniversary of optical coherence tomography

      This feature issue commemorates the approximately 25 year history of Optical Coherence Tomography (OCT), one of the most successful biophotonic technologies. While OCT has technological origins traceable to ultrafast laser development and fiber optic system test instrumentation of the 1980’s, innovations in low coherence interferometry for optical ranging and imaging for biomedical applications in the U.S., Europe and Japan by the early 1990’s led to coinage of the now widely known term OCT in 1991 [1]. As discussed in the following cited Invited Review and Invited Research articles in this issue, remarkable strides have since been made ...

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    19. Visualization of micro-capillaries using optical coherence tomography angiography with and without adaptive optics

      Visualization of micro-capillaries using optical coherence tomography angiography with and without adaptive optics

      The purpose of this work is to investigate the benefits of adaptive optics (AO) technology for optical coherence tomography angiography (OCTA). OCTA has shown great potential in non-invasively enhancing the contrast of vessels and small capillaries. Especially the capability of the technique to visualize capillaries with a lateral extension that is below the transverse resolution of the system opens unique opportunities in diagnosing retinal vascular diseases. However, there are some limitations of this technology such as shadowing and projection artifacts caused by overlying vasculature or the inability to determine the true extension of a vessel. Thus, the evaluation of the ...

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    20. Comprehensive vascular imaging using optical coherence tomography-based angiography and photoacoustic tomography

      Comprehensive vascular imaging using optical coherence tomography-based angiography and photoacoustic tomography

      Studies have proven the relationship between cutaneous vasculature abnormalities and dermatological disorders, but to image vasculature noninvasively in vivo , advanced optical imaging techniques are required. In this study, we imaged a palm of a healthy volunteer and three subjects with cutaneous abnormalities with photoacoustic tomography (PAT) and optical coherence tomography with angiography extension (OCTA). Capillaries in the papillary dermis that are too small to be discerned with PAT are visualized with OCTA. From our results, we speculate that the PA signal from the palm is mostly from hemoglobin in capillaries rather than melanin, knowing that melanin concentration in volar skin ...

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    21. Combined multi-modal photoacoustic tomography, optical coherence tomography (OCT) and OCT angiography system with an articulated probe for in vivo human skin structure and vasculature imaging

      Combined multi-modal photoacoustic tomography, optical coherence tomography (OCT) and OCT angiography system with an articulated probe for in vivo human skin structure and vasculature imaging

      Cutaneous blood flow accounts for approximately 5% of cardiac output in human and plays a key role in a number of a physiological and pathological processes. We show for the first time a multi-modal photoacoustic tomography (PAT), optical coherence tomography (OCT) and OCT angiography system with an articulated probe to extract human cutaneous vasculature in vivo in various skin regions. OCT angiography supplements the microvasculature which PAT alone is unable to provide. Co-registered volumes for vessel network is further embedded in the morphologic image provided by OCT. This multi-modal system is therefore demonstrated as a valuable tool for comprehensive non-invasive ...

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    22. Key Developments for Partial Coherence Biometry and Optical Coherence Tomography in the Human Eye Made in Vienna

      Key Developments for Partial Coherence Biometry and Optical Coherence Tomography in the Human Eye Made in Vienna

      Purpose : To describe key developments of optical biometry and optical coherence tomography (OCT) for ophthalmic applications made by one of the pioneering research groups. Methods : Partial coherence interferometry (PCI) as the basic ranging technology for modern optical biometry and for OCT was introduced for biomedical applications in the 1980s. Later, Fourier domain (FD) OCT was introduced and demonstrated to provide superior sensitivity as compared to time domain OCT. Further developments comprised ultrahigh-resolution OCT and deep-penetration OCT at wavelengths of approximately 1050 nm. Important functional extensions comprise Doppler OCT/OCT angiography, polarization-sensitive OCT, and adaptive optics OCT. Results : High-precision PCI biometry ...

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    23. Multi-modal adaptive optics system including fundus photography and optical coherence tomography for the clinical setting

      Multi-modal adaptive optics system including fundus photography and optical coherence tomography for the clinical setting

      We present a new compact multi-modal imaging prototype that combines an adaptive optics (AO) fundus camera with AO-optical coherence tomography (OCT) in a single instrument. The prototype allows acquiring AO fundus images with a field of view of 4°x4° and with a frame rate of 10fps. The exposure time of a single image is 10 ms. The short exposure time results in nearly motion artifact-free high resolution images of the retina. The AO-OCT mode allows acquiring volumetric data of the retina at 200kHz A-scan rate with a transverse resolution of ~4 µm and an axial resolution of ~5 µm ...

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    24. Line-field parallel swept source interferometric imaging at up to 1  MHz

      Line-field parallel swept source interferometric imaging at up to 1  MHz

      We present a novel medical imaging modality based on optical coherence tomography (OCT) that enables in vivo 3D tomography at acquisition rates up to 1 MHz. Line field parallel swept source interferometric imaging (LPSI) combines line-field swept source OCT with modulation of the interferometric signal in spatial direction for full range imaging. This method enables high speed imaging with cost-effective and commercially available technology. We explain the realization of the LPSI setup, acquisition, and postprocessing and finally demonstrate 3D in vivo imaging of human nail fold. To the best of our knowledge, sensitivity and depth penetration are competitive with respective ...

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    1-24 of 93 1 2 3 4 »
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    1. (92 articles) Wolfgang Drexler
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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 Postdoctoral opening in optical instrumentation and retinal imaging at University of Illinois at Chicago Detection of intracranial hypertension in children using optical coherence tomography: a systematic review protocol Optical coherence tomography versus intravascular ultrasound for culprit lesion assessment in patients with acute myocardial infarction Insulin-like growth factor-1 levels predict myocardial injury and infarction after elective percutaneous coronary intervention: an optical coherence tomography study Short-term healing response after implantation of the thin-strut, fast-releasing sirolimus-eluting biodegradable polymer-coated Alex Plus stent: optical coherence tomography study