1. Articles from Johannes F. de Boer

    1-24 of 63 1 2 3 »
    1. In vivo polarization-sensitive optical coherence tomography of human burn scars: birefringence quantification and correspondence with histologically determined collagen density

      In vivo polarization-sensitive optical coherence tomography of human burn scars: birefringence quantification and correspondence with histologically determined collagen density

      Obtaining adequate information on scar characteristics is important for monitoring their evolution and the effectiveness of clinical treatment. The aberrant type of collagen in scars may give rise to specific birefringent properties, which can be determined using polarization-sensitive optical coherence tomography (PS-OCT). The aim of this pilot study was to evaluate a method to quantify the birefringence of the scanned volume and correlate it with the collagen density as measured from histological slides. Five human burn scars were measured in vivo using a handheld probe and custom-made PS-OCT system. The local retardation caused by the tissue birefringence was extracted using ...

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    2. Visibility of Fiducial Markers used for Image-Guided Radiation Therapy on Optical Coherence Tomography for Registration with CT: an Esophageal Phantom Study

      Visibility of Fiducial Markers used for Image-Guided Radiation Therapy on Optical Coherence Tomography for Registration with CT: an Esophageal Phantom Study

      Purpose Optical coherence tomography (OCT) is of interest to visualize microscopic esophageal tumor extensions to improve tumor delineation for radiation therapy (RT) planning. Fiducial marker placement is a common method to ensure target localization during planning and treatment. Visualization of these fiducial markers on OCT permits integrating OCT and computed tomography (CT) images used for RT planning via image registration. We studied the visibility of 13 (8 types) commercially available solid and liquid fiducial markers in OCT images at different depths using dedicated esophageal phantoms and evaluated marker placement depth in clinical practice. Materials and Methods We designed and fabricated ...

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    3. Twenty-five years of optical coherence tomography: the paradigm shift in sensitivity and speed provided by Fourier domain OCT

      Twenty-five years of optical coherence tomography: the paradigm shift in sensitivity and speed provided by Fourier domain OCT

      Optical coherence tomography (OCT) has become one of the most successful optical technologies implemented in medicine and clinical practice mostly due to the possibility of non-invasive and non-contact imaging by detecting back-scattered light. OCT has gone through a tremendous development over the past 25 years. From its initial inception in 1991 [Science 254 , 1178 (1991)] it has become an indispensable medical imaging technology in ophthalmology. Also in fields like cardiology and gastro-enterology the technology is envisioned to become a standard of care. A key contributor to the success of OCT has been the sensitivity and speed advantage offered by Fourier ...

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    4. Automatic estimation of retinal nerve fiber bundle orientation in SD-OCT images using a structure-oriented smoothing filter

      Automatic estimation of retinal nerve fiber bundle orientation in SD-OCT images using a structure-oriented smoothing filter

      Optical coherence tomography (OCT) yields high-resolution, three-dimensional images of the retina. A better understanding of retinal nerve fiber bundle (RNFB) trajectories in combination with visual field data may be used for future diagnosis and monitoring of glaucoma. However, manual tracing of these bundles is a tedious task. In this work, we present an automatic technique to estimate the orientation of RNFBs from volumetric OCT scans. Our method consists of several steps, starting from automatic segmentation of the RNFL. Then, a stack of en face images around the posterior nerve fiber layer interface was extracted. The image showing the best visibility ...

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    5. Polarization sensitive optical coherence tomography – a review [Invited]

      Polarization sensitive optical coherence tomography – a review [Invited]

      Optical coherence tomography (OCT) is now a well-established modality for high-resolution cross-sectional and three-dimensional imaging of transparent and translucent samples and tissues. Conventional, intensity based OCT, however, does not provide a tissue-specific contrast, causing an ambiguity with image interpretation in several cases. Polarization sensitive (PS) OCT draws advantage from the fact that several materials and tissues can change the light’s polarization state, adding an additional contrast channel and providing quantitative information. In this paper, we review basic and advanced methods of PS-OCT and demonstrate its use in selected biomedical applications.

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    6. Enhanced Diagnostic Capability for Glaucoma of 3-Dimensional Versus 2-Dimensional Neuroretinal Rim Parameters Using Spectral Domain Optical Coherence Tomography

      Enhanced Diagnostic Capability for Glaucoma of 3-Dimensional Versus 2-Dimensional Neuroretinal Rim Parameters Using Spectral Domain Optical Coherence Tomography

      Purpose: To compare the diagnostic capability of 3-dimensional (3D) neuroretinal rim parameters with existing 2-dimensional (2D) neuroretinal and retinal nerve fiber layer (RNFL) thickness rim parameters using spectral domain optical coherence tomography (SD-OCT) volume scans. Materials and Methods: Design: Institutional prospective pilot study. Study population: 65 subjects (35 open-angle glaucoma patients, 30 normal patients). Observation procedures: One eye of each subject was included. SD-OCT was used to obtain 2D RNFL thickness values and 5 neuroretinal rim parameters [ie, 3D minimum distance band (MDB) thickness, 3D Bruch's membrane opening-minimum rim width (BMO-MRW), 3D rim volume, 2D rim area, and 2D ...

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    7. Loosely coupled level sets for simultaneous 3D retinal layer segmentation in optical coherence tomography

      Loosely coupled level sets for simultaneous 3D retinal layer segmentation in optical coherence tomography

      Optical coherence tomography (OCT) yields high-resolution, three-dimensional images of the retina. Reliable segmentation of the retinal layers is necessary for the extraction of clinically useful information. We present a novel segmentation method that operates on attenuation coefficients and incorporates anatomical knowledge about the retina. The attenuation coefficients are derived from in-vivo human retinal OCT data and represent an optical property of the tissue. Then, the layers in the retina are simultaneously segmented via a new flexible coupling approach that exploits the predefined order of the layers. The accuracy of the method was evaluated on 20 peripapillary scans of healthy subjects ...

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    8. Phase-resolved Doppler Optical Coherence Tomographic features in Retinal Angiomatous Proliferation

      Phase-resolved Doppler Optical Coherence Tomographic features in Retinal Angiomatous Proliferation

      Purpose To study patients diagnosed with retinal angiomatous proliferation (RAP) based on conventional imaging techniques with phase-resolved Doppler optical coherence tomography (OCT) to detect and localize blood flow in RAP lesions and to compare these findings to conventional imaging, which are mostly invasive and give limited information concerning intra- and transretinal blood flow. Design Single-center, consecutive observational case series. Methods Twelve treatment-naïve patients diagnosed with RAP based on fundus examination, fluorescein and indocyanine-green angiography, were included. Median age was 79 years (range 65-90). Patients were imaged with an experimental 1040 nm swept-source phase-resolved Doppler-OCT instrument. Abnormal flow was defined ...

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    9. Apparatus, method and system for performing phase-resolved optical frequency domain imaging

      Apparatus, method and system for performing phase-resolved optical frequency domain imaging

      Apparatus, system and method are provided which utilize signals received from a reference and a sample. In particular, a radiation is provided which includes at least one first electro-magnetic radiation directed to the sample and at least one second electro-magnetic radiation directed to the reference. A frequency of the radiation varies over time. An interference can be detected between at least one third radiation associated with the first radiation and at least one fourth radiation associated with the second radiation. It is possible to obtain a particular signal associated with at least one phase of at least one frequency component ...

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    10. In vivo optical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography

      In vivo optical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography

      Assessing nerve integrity and myelination after injury is necessary to provide insight for treatment strategies aimed at restoring neuromuscular function. Currently, this is largely done with electrical analysis, which lacks direct quantitative information. In vivo optical imaging with sufficient imaging depth and resolution could be used to assess the nerve microarchitecture. In this study, we examine the use of polarization sensitive-optical coherence tomography (PS-OCT) to quantitatively assess the sciatic nerve microenvironment through measurements of birefringence after applying a nerve crush injury in a rat model. Initial loss of function and subsequent recovery were demonstrated by calculating the sciatic function index ...

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    11. Depth-encoded synthetic aperture optical coherence tomography of biological tissues with extended focal depth

      Depth-encoded synthetic aperture optical coherence tomography of biological tissues with extended focal depth

      Optical coherence tomography (OCT) has proven to be able to provide three-dimensional (3D) volumetric images of scattering biological tissues for in vivo medical diagnostics. Unlike conventional optical microscopy, its depth-resolving ability (axial resolution) is exclusively determined by the laser source and therefore invariant over the full imaging depth. In contrast, its transverse resolution is determined by the objective’s numerical aperture and the wavelength which is only approximately maintained over twice the Rayleigh range. However, the prevailing laser sources for OCT allow image depths of more than 5 mm which is considerably longer than the Rayleigh range. This limits high ...

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    12. Polarization sensitive optical frequency domain imaging system for endobronchial imaging

      Polarization sensitive optical frequency domain imaging system for endobronchial imaging

      A polarization sensitive endoscopic optical frequency domain imaging (PS-OFDI) system with a motorized distal scanning catheter is demonstrated. It employs a passive polarization delay unit to multiplex two orthogonal probing polarization states in depth, and a polarization diverse detection unit to detect interference signal in two orthogonal polarization channels. Per depth location four electro-magnetic field components are measured that can be represented in a complex 2x2 field matrix. A Jones matrix of the sample is derived and the sample birefringence is extracted by eigenvalue decomposition. The condition of balanced detection and the polarization mode dispersion are quantified. A complex field ...

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    13. Direct Blood Flow Measurements in a Free RPE-Choroid Graft with Phase-Resolved Doppler OCT

      Direct Blood Flow Measurements in a Free RPE-Choroid Graft with Phase-Resolved Doppler OCT

      Purpose: We directly demonstrated the revascularization in a free retinal pigment epithelium (RPE)-choroid graft with direct blood flow detection by experimental phase-resolved Doppler optical coherence tomography (PRD-OCT). Methods: Seven patients with age-related macular degeneration underwent an RPE-choroid graft translocation in a prospective institutional cohort study. Spectral domain optical coherence tomography (SD-OCT) was used to measure the revascularization stage. With PRD-OCT the presence of flow was imaged postoperatively. Results: The PRD-OCT confirmed flow in three patients when SD-OCT indicated the afferent vessel ingrowth stage, and in all seven patients when the SD-OCT indicated the efferent vessel ingrowth stage. Conclusions: The ...

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    14. Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions

      Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions

      In polarization-sensitive optical coherence tomography (PS-OCT) the use of single-mode fibers causes unpredictable polarization distortions which can result in increased noise levels and erroneous changes in calculated polarization parameters. In the current paper this problem is addressed by a new Jones matrix analysis method that measures and corrects system polarization distortions as a function of wavenumber by spectral analysis of the sample surface polarization state and deeper located birefringent tissue structures. This method was implemented on a passive-component depth-multiplexed swept-source PS-OCT system at 1040 nm which was theoretically modeled using Jones matrix calculus. High-resolution B-scan images are presented of the ...

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    15. Feature Of The Week 7/21/13: VU University Amsterdam Demonstrates Focus-Extension by Depth-Encoded Synthetic Aperture in Optical Coherence Tomography

      Feature Of The Week 7/21/13: VU University Amsterdam Demonstrates Focus-Extension by Depth-Encoded Synthetic Aperture in Optical Coherence Tomography

      Optical coherence tomography (OCT) is an interferometric technique that provides cross-sectional images of biological tissue. It has become an essential tool for clinical diagnosis and disease monitoring in ophthalmology and it shows great potential in other clinical areas such as dermatology, cardiology and gastroenterology. The axial resolution in OCT is provided by the coherence gate and is invariant over the full image depth. The lateral resolution is determined by the beam parameters such as wavelength and numerical aperture. The Rayleigh range determines the depth range over which the lateral resolution can be maintained. The depth of focus is generally defined ...

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    16. High speed 3D endoscopic optical frequency domain imaging probe for lung cancer diagnosis

      High speed 3D endoscopic optical frequency domain imaging probe for lung cancer diagnosis

      We present a miniature motorized endoscopic probe for Optical Frequency Domain Imaging with an outer diameter of 1.65 mm and a rotation speed of 3,000 – 12,500 rpm. The probe has a motorized distal end which provides a significant advantage over proximally driven probes since it does not require a drive shaft to transfer the rotational torque to the distal end of the probe and functions without a fiber rotary junction. The probe has a focal Full Width at Half Maximum of 9.6 μm and a working distance of 0.47 mm. We analyzed the non-uniform rotation ...

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    17. Collecting optical coherence elastography depth profiles with a micromachined cantilever probe

      Collecting optical coherence elastography depth profiles with a micromachined cantilever probe

      We present an experimental setup that combines optical coherence elastography depth sensing with atomic force microscope indentation. The instrument relies on a miniaturized cantilever probe that compresses a sample with a small footprint force and simultaneously collects an optical coherence tomography (OCT) depth profile underneath the indenting point. The deflection of the cantilever can be monitored via optical fiber interferometry with a resolution of 2 nm. The OCT readout then provides depth profiles of the subsurface layer deformation with 15 nm resolution and depth range of a few millimeters.

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    18. Focus-extension by depth-encoded synthetic aperture in Optical Coherence Tomography

      Focus-extension by depth-encoded synthetic aperture in Optical Coherence Tomography

      We present a novel method to extend the depth-of-focus of Optical Coherence Tomography (OCT). OCT is an interferometric imaging technique that provides depth-resolved scattering information. The axial resolution in OCT is provided by the coherence gate and is invariant over the full image depth. The lateral resolution is determined by the beam parameters such as wavelength and numerical aperture. The Rayleigh range determines the depth range over which the lateral resolution can be maintained. The lateral resolution is often sacrificed to maintain relatively long Rayleigh range. In this study, we propose to use a depth-encoded synthetic aperture detection scheme to ...

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    19. Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans

      Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans

      In conventional phase-resolved OCT blood flow is detected from phase changes between successive A-scans. Especially in high-speed OCT systems this results in a short evaluation time interval. This method is therefore often unable to visualize complete vascular networks since low flow velocities cause insufficient phase changes. This problem was solved by comparing B-scans instead of successive A-scans to enlarge the time interval. In this paper a detailed phase-noise analysis of our OCT system is presented in order to calculate the optimal time intervals for visualization of the vasculature of the human retina and choroid. High-resolution images of the vasculature of ...

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    20. Real-time eye motion correction in phase-resolved OCT angiography with tracking SLO

      Real-time eye motion correction in phase-resolved OCT angiography with tracking SLO

      In phase-resolved OCT angiography blood flow is detected from phase changes in between A-scans that are obtained from the same location. In ophthalmology, this technique is vulnerable to eye motion. We address this problem by combining inter-B-scan phase-resolved OCT angiography with real-time eye tracking. A tracking scanning laser ophthalmoscope (TSLO) at 840 nm provided eye tracking functionality and was combined with a phase-stabilized optical frequency domain imaging (OFDI) system at 1040 nm. Real-time eye tracking corrected eye drift and prevented discontinuity artifacts from (micro)saccadic eye motion in OCT angiograms. This improved the OCT spot stability on the retina and ...

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    21. Means For Determining DEPTH-RESOLVED Physical AND/OR Optical Properties Of Scattering Media

      Means For Determining DEPTH-RESOLVED Physical AND/OR Optical Properties Of Scattering Media

      In depth-resolved imaging of scattering media, incident light interacts with tissue in a complex way before the signal reaches the detector: Light interacts with media between the light source and a specific depth, then scatters at that depth and the back scattered light again interacts with media, on its way to the detector. The resulting depth-resolved signal therefore likely does not directly represent a physical or optical property of the media at those depths. According to an exemplary embodiment of the present disclosure, systems, methods and computer-accessible medium can be provided to determine physical or optical properties based on such ...

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    22. Real-time eye motion compensation for OCT imaging with tracking SLO

      Real-time eye motion compensation for OCT imaging with tracking SLO

      Fixational eye movements remain a major cause of artifacts in optical coherence tomography (OCT) images despite the increases in acquisition speeds. One approach to eliminate the eye motion is to stabilize the ophthalmic imaging system in real-time. This paper describes and quantifies the performance of a tracking OCT system, which combines a phase-stabilized optical frequency domain imaging (OFDI) system and an eye tracking scanning laser ophthalmoscope (TSLO). We show that active eye tracking minimizes artifacts caused by eye drift and micro saccades. The remaining tracking lock failures caused by blinks and large saccades generate a trigger signal which signals the ...

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    23. High speed miniature motorized endoscopic probe for optical frequency domain imaging

      High speed miniature motorized endoscopic probe for optical frequency domain imaging

      We present a miniature motorized endoscopic probe for Optical Coherence Tomography with an outer diameter of 1.65 mm and a rotation speed of 3,000–12,500 rpm. This is the smallest motorized high speed OCT probe to our knowledge. The probe has a motorized distal end which provides a significant advantage over proximally driven probes since it does not require a drive shaft to transfer the rotational torque to the distal end of the probe and functions without a fiber rotary junction. The probe has a focal Full Width at Half Maximum of 9.6 µm and a ...

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    24. RPE-normalized RNFL attenuation coefficient maps derived from volumetric OCT imaging for glaucoma

      RPE-normalized RNFL attenuation coefficient maps derived from volumetric OCT imaging for glaucoma

      Purpose: We present spatial retinal nerve fiber layer (RNFL) attenuation coefficient maps for healthy and glaucomatous eyes based on optical coherence tomography (OCT) measurements. Quantitative analyses of differences between healthy and glaucomatous eyes were performed. Methods: Peripapillary volumetric images of 10 healthy and 8 glaucomatous eyes were acquired by a Spectralis OCT system (Heidelberg Engineering, Germany). Per A-line, the RNFL's attenuation coefficient was determined based on a method that utilizes the retinal pigment epithelium as a reference layer. The attenuation coefficient describes the attenuation of light in tissue due to scattering and absorption. En-face maps were constructed and visually ...

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    1-24 of 63 1 2 3 »
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    1. (61 articles) Johannes F. de Boer
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    In vitro ovarian tumor growth and treatment response dynamics visualized with time-lapse OCT imaging Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics In vivo 3D human vocal fold imaging with polarization sensitive optical coherence tomography and a MEMS scanning catheter Optical coherence tomography in multiple sclerosis: a systematic review and meta-analysis Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography Postdoctoral Fellow, In Vivo Ophthalmology at Roche in Basel, Switzerland RETINOCYTOMA WITH VITREOUS SEEDING: NEW INSIGHTS FROM ENHANCED DEPTH IMAGING OPTICAL COHERENCE TOMOGRAPHY AND HIGH-RESOLUTION POSTERIOR SEGMENT ULTRASONOGRAPHY Optical Coherence Tomography Angiography In ADULT-ONSET Foveomacular Vitelliform Dystrophy A Study Using Optical Coherence Tomography Angiography Spectral Domain Optical Coherence Tomography Versus Swept-Source Optical Coherence Tomography Postdoctoral Fellow: Biophotonics Stanford University / Vanderbilt University 'Girl with Pearl Earring' to undergo examination