1. Articles from Cedric Blatter

    1-20 of 20
    1. High-speed optical coherence tomography by circular interferometric ranging

      High-speed optical coherence tomography by circular interferometric ranging

      Existing three-dimensional optical imaging methods excel in controlled environments, but are difficult to deploy over large, irregular and dynamic fields. This means that they can be ill-suited for use in areas such as material inspection and medicine. To better address these applications, we developed methods in optical coherence tomography to efficiently interrogate sparse scattering fields, that is, those in which most locations (voxels) do not generate meaningful signal. Frequency comb sources are used to superimpose reflected signals from equispaced locations through optical subsampling. This results in circular ranging, and reduces the number of measurements required to interrogate large volumetric fields ...

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    2. Simultaneous measurements of lymphatic vessel contraction, flow and valve dynamics in multiple lymphangions using optical coherence tomography

      Simultaneous measurements of lymphatic vessel contraction, flow and valve dynamics in multiple lymphangions using optical coherence tomography

      Lymphatic dysfunction is involved in many diseases including lymphedema, hypertension, autoimmune responses, graft rejection, atherosclerosis, microbial infections, cancer and cancer metastasis. Expanding our knowledge of lymphatic system function can lead to a better understanding of these disease processes and improve treatment options. Here, optical coherence tomography (OCT) methods were used to reveal intraluminal valve dynamics in 3D, and measure lymph flow and vessel contraction simultaneously in three neighboring lymphangions of the afferent collecting lymphatic vessels to the popliteal lymph node in mice. Flow measurements were based on Doppler OCT techniques in combination with exogenous lymph labelling by Intralipid. Through these ...

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    3. Murine chronic lymph node window for longitudinal intravital lymph node imaging

      Murine chronic lymph node window for longitudinal intravital lymph node imaging

      Chronic imaging windows in mice have been developed to allow intravital microscopy of many different organs and have proven to be of paramount importance in advancing our knowledge of normal and disease processes. A model system that allows long-term intravital imaging of lymph nodes would facilitate the study of cell behavior in lymph nodes during the generation of immune responses in a variety of disease settings and during the formation of metastatic lesions in cancer-bearing mice. We describe a chronic lymph node window (CLNW) surgical preparation that allows intravital imaging of the inguinal lymph node in mice. The CLNW is ...

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    4. In vivo label-free measurement of lymph flow velocity and volumetric flow rates using Doppler optical coherence tomography

      In vivo label-free measurement of lymph flow velocity and volumetric flow rates using Doppler optical coherence tomography

      Direct in vivo imaging of lymph flow is key to understanding lymphatic system function in normal and disease states. Optical microscopy techniques provide the resolution required for these measurements, but existing optical techniques for measuring lymph flow require complex protocols and provide limited temporal resolution. Here, we describe a Doppler optical coherence tomography platform that allows direct, label-free quantification of lymph velocity and volumetric flow rates. We overcome the challenge of very low scattering by employing a Doppler algorithm that operates on low signal-to-noise measurements. We show that this technique can measure lymph velocity at sufficiently high temporal resolution to ...

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    5. Systems and methods for bidirectional functional optical coherence tomography

      Systems and methods for bidirectional functional optical coherence tomography

      Methods for determining improving quantitative and qualitative motion contrast information collected with optical coherence tomography (OCT) data are presented. In one embodiment, flow within a cross-sectional area of a sample is calculated independent of the Doppler and en face angles using a bidirectional OCT system. In another embodiment, motion contrast images are improved by averaging motion contrast information collected from a bidirectional OCT system.

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    6. Intra- and Inter-Frame Differential Doppler Optical Coherence Tomography

      Intra- and Inter-Frame Differential Doppler Optical Coherence Tomography

      Spectrometer based optical coherence tomography suffers from fringe washout for fast flow, a drawback for flow visualization, which is of interest for both lable-free optical angiography and flow quantification. We presented a method, which can be used to contrast very fast flows, while maintaining relatively low A-scan rates. It is based on introducing a phase shift of during acquisition such that the interference fringes associated to moving sample structures are recovered depending on the axial velocity. This enables the use of slower line scan cameras for measuring the fast blood flows within the large vessels in the region of the ...

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    7. 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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    8. Wide-Field OCT Angiography at 400 kHz Utilizing Spectral Splitting

      Wide-Field OCT Angiography at 400 kHz Utilizing Spectral Splitting

      Optical angiography systems based on optical coherence tomography (OCT) require dense sampling in order to maintain good vascular contrast. We demonstrate a way to gain acquisition speed and spatial sampling by using spectral splitting with a swept source OCT system. This method splits the recorded spectra into two to several subspectra. Using continuous lateral scanning, the lateral sampling is then increased by the same factor. This allows increasing the field of view of OCT angiography, while keeping the same transverse resolution and measurement time. The performance of our method is demonstrated in vivo at different locations of the human retina ...

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    9. Doppler Optical Coherence Tomography

      Doppler Optical Coherence Tomography

      Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A ...

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    10. Angle independent flow assessment with bidirectional Doppler optical coherence tomography

      Angle independent flow assessment with bidirectional Doppler optical coherence tomography

      Bidirectional Doppler optical coherence tomography is a stable and accurate method to extract the absolute velocity of vessels close to perpendicular to the optical axis by illuminating the sample under two different angles. However it requires knowledge of the vessel angle in the en face plane. In this Letter, we demonstrate that a direct calculation of the flow out of bidirectional Doppler cross sections perpendicular to the illumination plane is independent of that angle and of the Doppler angle, thereby improving the accuracy and flexibility of that technique. We validate our approach with an in vitro experiment and in vivo ...

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    11. Dove prism based rotating dual beam bidirectional Doppler OCT

      Dove prism based rotating dual beam bidirectional Doppler OCT

      Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism. The volume is probed from two distinct illumination directions with variable controlled incidence plane, allowing for reconstruction of the true flow velocity at arbitrary vessel orientations. The principle is implemented with Swept Source OCT at 1060nm with 100,000 A-Scans/s. We apply the system to resolve pulsatile retinal absolute blood velocity by performing ...

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    12. Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging

      Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging

      We introduce a method to extract the photoacoustic (PA) signal from the phase time evolution of an optical coherence tomography (OCT) swept source spectral sweep. This all-optical detection is achieved in a noncontact fashion directly on the sample surface by using its specular reflection. High-speed measurement and referencing allow for close to shot noise limited phase-sensitive detection. It offers a simple way to perform OCT and PA imaging by sharing the same system components.

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    13. In situ structural and microangiographic assessment of human skin lesions with high-speed OCT

      In situ structural and microangiographic assessment of human skin lesions with high-speed OCT

      We demonstrate noninvasive structural and microvascular contrast imaging of different human skin diseases in vivo using an intensity difference analysis of OCT tomograms. The high-speed swept source OCT system operates at 1310 nm with 220 kHz A-scan rate. It provides an extended focus by employing a Bessel beam. The studied lesions were two cases of dermatitis and two cases of basal cell carcinoma. The lesions show characteristic vascular patterns that are significantly different from healthy skin. In case of inflammation, vessels are dilated and perfusion is increased. In case of basal cell carcinoma, the angiogram shows a denser network of ...

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    14. Ultrahigh-speed non-invasive widefield angiography

      Ultrahigh-speed non-invasive widefield angiography

      tinal and choroidal vascular imaging is an important diagnostic benefit for ocular diseases such as age-related macular degeneration. The current gold standard for vessel visualization is fluorescence angiography. We present a potential non-invasive alternative to image blood vessels based on functional Fourier domain optical coherence tomography (OCT). For OCT to compete with the field of view and resolution of angiography while maintaining motion artifacts to a minimum, ultrahigh-speed imaging has to be introduced. We employ Fourier domain mode locking swept source technology that offers high quality imaging at an A-scan rate of up to 1.68 MHz. We present retinal ...

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    15. High-resolution phase mapping with parallel Fourier domain optical coherence microscopy for dispersion contrast imaging

      High-resolution phase mapping with parallel Fourier domain optical coherence microscopy for dispersion contrast imaging

      We demonstrate a high-speed parallel line field optical coherence microscopy (OCM) system that exhibits intrinsically high phase stability even with lateral scanning. The presented Fourier domain (FD) OCM system employs a high speed CMOS detector and achieves up to 512 000 equivalent A-scans per second. The microscopy system is shown to resolve the smallest elements of the USAF resolution test target (Group 7, Element 6), indicating the transverse (Y- non-scanning parallel direction)) resolution and resolution in X (scanning) direction less than 2.2 µm. The capability of imaging biological samples is demonstrated on human red blood cells (RBC). The high ...

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    16. Extended focus high-speed swept source OCT with self-reconstructive illumination

      Extended focus high-speed swept source OCT with self-reconstructive illumination

      We present a Bessel beam illumination FDOCT setup using a FDML Swept Source at 1300nm with up to 440kHz A-scan rate, and discuss its advantages for structural and functional imaging of highly scattering samples. An extended focus is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Furthermore, Bessel beams exhibit a self-reconstruction property that allows imaging even behind obstacles such as hairs on skin. Decoupling the illumination from the Gaussian detection increases the global sensitivity and enables dark field imaging. Dark field imaging is useful to avoid strong reflexes from the sample ...

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    17. High-speed functional OCT with self-reconstructive Bessel illumination at 1300nm

      High-speed functional OCT with self-reconstructive Bessel illumination at 1300nm

      Cedric Blatter, Branislav Grajciar, and Christoph M. Eigenwillig et al. We present a Bessel beam illumination FDOCT setup with FDML buffered swept source at 1300nm. An extended focus is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Decoupling the illumination from the Gaussian detection improves the sensitivity as compared t ... [Proc. SPIE 8091, 809104 (2011)] published Thu Jun 09, 2011.

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    18. Imaging of the parafoveal capillary network and its integrity analysis using fractal dimension

      Imaging of the parafoveal capillary network and its integrity analysis using fractal dimension

      Using a spectral domain OCT system, equipped with a broadband Ti:sapphire laser, we imaged the human retina with 5 µm x 1.3 µm transverse and axial resolution at acquisition rate of 100 kHz. Such imaging speed significantly reduces motion artifacts. Combined with the ultra-high resolution, this allows observing microscopic retinal details with high axial definition without the help of adaptive optics. In this work we apply our system to image the parafoveal capillary network. We demonstrate how already on the intensity level the parafoveal capillaries can be segmented by a simple structural high pass filtering algorithm. This data ...

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    19. Structural and functional imaging with extended focus dark-field OCT at 1300nm

      Structural and functional imaging with extended focus dark-field OCT at 1300nm

      We present an extended focus FDOCT setup with FDML swept source centered at 1310nm. The illumination, preserving its lateral extend over a large depth range thanks to the use of a Bessel beam, is decoupled from the Gaussian detection in order to increase the global sensitivity. The efficient spatial separation enables dark-field imaging. In-vivo measurements in the skin were performed to demonstrate the gain in lateral resolution while preserving the imaging depth. More, the calculation of the speckle variance between B-Scans allows a clear visualization of the microvasculature.

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    20. Frequency encoded optical assessment of human retinal physiology

      Rainer A. Leitgeb, Roland Michaely, Adrian Bachmann et al. We demonstrate in-vivo functional imaging of the human retina with Fourier domain optical coherence tomography employing frequency encoding of an excitation pattern. The principle is based on projecting a modulated rectangular pattern across the foveal region and acquiring a time series of B-Scans a ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68440I (2008)] published Mon Feb 11, 2008.

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    1-20 of 20
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  2. Topics in the News

    1. (20 articles) Cedric Blatter
    2. (16 articles) Rainer A. Leitgeb
    3. (13 articles) Medical University of Vienna
    4. (10 articles) Branislav Grajciar
    5. (6 articles) Robert A. Huber
    6. (5 articles) Ludwig Maximilian University of Munich
    7. (5 articles) Tilman Schmoll
    8. (5 articles) Wolfgang Wieser
    9. (4 articles) Massachusetts General Hospital
    10. (4 articles) Harvard University
    11. (1 articles) Medical University of Vienna
    12. (1 articles) University of Florence
    13. (1 articles) UCLA
    14. (1 articles) National Institutes of Health
    15. (1 articles) Shanghai Jiao Tong University
    16. (1 articles) Srinivas R. Sadda
    17. (1 articles) Xincheng Yao
    18. (1 articles) Bo Yu
    19. (1 articles) Qian Li
    20. (1 articles) Heidelberg Engineering
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    Structural and functional imaging with extended focus dark-field OCT at 1300nm Imaging of the parafoveal capillary network and its integrity analysis using fractal dimension High-speed functional OCT with self-reconstructive Bessel illumination at 1300nm Extended focus high-speed swept source OCT with self-reconstructive illumination High-resolution phase mapping with parallel Fourier domain optical coherence microscopy for dispersion contrast imaging Ultrahigh-speed non-invasive widefield angiography Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging Dove prism based rotating dual beam bidirectional Doppler OCT High-speed optical coherence tomography by circular interferometric ranging In-stent restenosis and longitudinal stent deformation: a case report Microvascular Features of Treated Retinoblastoma Tumors in Children Assessed Using OCTA OCTA characterisation of microvascular retinal alterations in patients with central serous chorioretinopathy