1. Articles from Wolfgang Drexler

    1-24 of 86 1 2 3 4 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. 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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    13. 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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    14. 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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    15. 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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    16. 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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    17. 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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    18. 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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    19. 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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    20. Optical Coherence Tomography: Technology and Applications Second Edition (Textbook)

      Optical Coherence Tomography: Technology and Applications Second Edition (Textbook)

      New medical imaging technologies can improve the diagnosis and clinical management of many diseases. Furthermore, advanced imaging also contributes to a better understanding of pathogenesis and therefore to the development of new pharmaceuticals and novel therapies. Thus, imaging plays a critical role in modern medical research and clinical practice. Noninvasive or minimally invasive imaging techniques have revolutionized diagnostic medicine during the last decades, e.g., X-ray computed tomography (CT), magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), radioisotope imaging (position emission tomography (PET)), single-photon emission computed tomography (SPECT), and diffuse optical tomography (DOT). These techniques permit three-dimensional visualization; however ...

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

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

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

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    23. Line-field parallel swept source MHz OCT for structural and functional retinal imaging

      Line-field parallel swept source MHz OCT for structural and functional retinal imaging

      We demonstrate three-dimensional structural and functional retinal imaging with line-field parallel swept source imaging (LPSI) at acquisition speeds of up to 1 MHz equivalent A-scan rate with sensitivity better than 93.5 dB at a central wavelength of 840 nm. The results demonstrate competitive sensitivity, speed, image contrast and penetration depth when compared to conventional point scanning OCT. LPSI allows high-speed retinal imaging of function and morphology with commercially available components. We further demonstrate a method that mitigates the effect of the lateral Gaussian intensity distribution across the line focus and demonstrate and discuss the feasibility of high-speed optical angiography ...

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    24. 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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    1-24 of 86 1 2 3 4 »
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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 Attention to Lesion: Lesion-Aware Convolutional Neural Network for Retinal Optical Coherence Tomography Image Classification Telecentric broadband objective lenses for optical coherence tomography Extending Optical Coherence Tomography Toward Multiple-Contrast Imaging (Cost)-Effectiveness of OCT in BCC (ROCTI) Precision analysis and optimization in phase decorrelation OCT velocimetry