1. Articles from taner akkin

    1-24 of 24
    1. Glioma cell migration dynamics in brain tissue assessed by multimodal optical imaging

      Glioma cell migration dynamics in brain tissue assessed by multimodal optical imaging

      Glioblastoma is a primary malignant brain tumor characterized by highly infiltrative glioma cells. Vasculature and white matter tracts are considered to be the preferred and fastest routes for glioma invasion through brain tissue. In this study, we systematically quantified the routes and motility of the U251 human glioblastoma cell line in mouse brain slices by multimodal imaging. Specifically, we used polarization-sensitive optical coherence tomography to delineate nerve fiber tracts while confocal fluorescence microscopy was used to image cell migration and brain vasculature. Somewhat surprisingly, we found that in mouse brain slices, U251 glioma cells do not follow white matter tracts ...

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    2. Contrast-enhanced serial optical coherence scanner with deep learning network reveals vasculature and white matter organization of mouse brain

      Contrast-enhanced serial optical coherence scanner with deep learning network reveals vasculature and white matter organization of mouse brain

      Optical coherence tomography provides volumetric reconstruction of brain structure with micrometer resolution. Gray matter and white matter can be highlighted using conventional and polarization-based contrasts; however, vasculature in ex-vivo fixed brain has not been investigated at large scale due to lack of intrinsic contrast. We present contrast enhancement to visualize the vasculature by perfusing titanium dioxide particles transcardially into the mouse vascular system. The brain, after dissection and fixation, is imaged by a serial optical coherence scanner. Accumulation of particles in blood vessels generates distinguishable optical signals. Among these, the cross-polarization images reveal the vasculature organization remarkably well. The conventional ...

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    3. Polarization-sensitive optical coherence tomography reveals gray matter and white matter atrophy in SCA1 mouse models

      Polarization-sensitive optical coherence tomography reveals gray matter and white matter atrophy in SCA1 mouse models

      Spinocerebellar ataxia type 1 (SCA1) is a fatal inherited neurodegenerative disease. In this study, we demonstrate the label-free optical imaging methodology that can detect, with a high degree of sensitivity, discrete areas of degeneration in the cerebellum of the SCA1 mouse models. We used ATXN1[82Q] and ATXN1[30Q]-D776 mice in which the transgene is directed only to Purkinje cells. Molecular layer, granular layer, and white matter regions are analyzed using the intrinsic contrasts provided by polarization-sensitive optical coherence tomography. Cerebellar atrophy in SCA1 mice occurred both in gray matter and white matter. While gray matter atrophy is obvious ...

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    4. White matter atrophy in spinocerebellar ataxia type 1 mouse models revealed by serial optical coherence scanner

      White matter atrophy in spinocerebellar ataxia type 1 mouse models revealed by serial optical coherence scanner

      Spinocerebellar ataxia type 1 (SCA1) is a fatal inherited neurodegenerative disease. Post-mortem studies showed neurodegeneration involving white matter components in the cerebral lobes, the cerebellar peduncles and the more distal cranial nerves in human patients. However, the progression of SCA1 in the brain remains unclear. We present the study of white matter atrophy of SCA1 mouse models using serial optical coherence scanner (SOCS). SOCS consists of a polarization sensitive optical coherence tomography and a tissue slicer (vibratome) with associated controls for serial imaging. The optical system has 5.5 µm axial resolution and utilizes a scan lens or a water-immersion ...

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    5. Visualizing and mapping the cerebellum with serial optical coherence scanner

      Visualizing and mapping the cerebellum with serial optical coherence scanner

      We present the visualization of the mouse cerebellum and adjacent brainstem using a serial optical coherence scanner, which integrates a vibratome slicer and polarization-sensitive optical coherence tomography for ex vivo imaging. The scanner provides intrinsic optical contrasts to distinguish the cerebellar cortical layers and white matter. Images from serial scans reveal the large-scale anatomy in detail and map the nerve fiber pathways in the cerebellum and brainstem. By incorporating a water-immersion microscope objective, we also present high-resolution tiled images that delineate fine structures in the cerebellum and brainstem.

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    6. Quantifying three-dimensional optic axis using polarization-sensitive optical coherence tomography

      Quantifying three-dimensional optic axis using polarization-sensitive optical coherence tomography

      The optic axis of birefringent samples indicates the direction of optical anisotropy, which should be described in three-dimensional (3-D) space. We present a method to quantify the complete 3-D optic axis orientation calculated from in-plane optic axis measurements from a polarization-sensitive optical coherence tomography system. The in-plane axis orientations with different illumination angles allow the calculation of the necessary polar angle. The method then provides the information to produce the actual birefringence. The method and results from a biological sample are presented.

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    7. Polarization sensitive optical coherence microscopy for brain imaging

      Polarization sensitive optical coherence microscopy for brain imaging

      Optical coherence tomography (OCT) and optical coherence microscopy (OCM) have demonstrated the ability to investigate cyto- and myelo-architecture in the brain. Polarization-sensitive OCT provides sensitivity to additional contrast mechanisms, specifically the birefringence of myelination and, therefore, is advantageous for investigating white matter fiber tracts. In this Letter, we developed a polarization-sensitive optical coherence microscope (PS-OCM) with a 3.5 μm axial and 1.3 μm transverse resolution to investigate fiber organization and orientation at a finer scale than previously demonstrated with PS-OCT. In a reconstructed mouse brain section, we showed that at the focal depths of 20–70 μm, the ...

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    8. Polarization-based balanced detection for spectral-domain optical coherence tomography

      Polarization-based balanced detection for spectral-domain optical coherence tomography

      We present a new design for spectral-domain optical coherence tomography that allows balanced detection using a single camera. The design uses polarization optics to encode the light in reference and sample arms. Two parallel and highly aligned spectra, which carry out-of-phase interference signals, in-phase common noise, and auto-interference terms, are focused on the camera, which performs the digital balanced detection for each wavelength. The optical system is characterized and tested for tissue imaging. Results demonstrate consistent signal gains in depth and suppression of DC and sample auto-interference. The design could be further amended for polarization-sensitive imaging and might demonstrate a ...

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    9. Optical coherence tomography for cross-sectional imaging of neural activity

      Optical coherence tomography for cross-sectional imaging of neural activity

      Abstract. We report a functional optical coherence tomography cross-sectional scanner to detect neural activity using unmyelinated nerves dissected from squid. The nerves, unstained or stained with a voltage-sensitive dye, were imaged in a nerve chamber. Transient phase changes from backscattered light were detected during action potential propagation. The results show that the scanner can provide high spatiotemporal resolution cross-sectional images of neural activity ( 15     μ s / A - line ; 0.25     ms / B - scan ; ∼ 8.5 × 5.5     μ m 2 in x z ). The advantage of this method compared to monitoring a single depth profile z is a dramatic increase in the ...

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    10. Marker-Free Tracking of Facet Capsule Motion Using Polarization-Sensitive Optical Coherence Tomography

      Marker-Free Tracking of Facet Capsule Motion Using Polarization-Sensitive Optical Coherence Tomography

      We proposed and tested a method by which surface strains of biological tissues can be captured without the use of fiducial markers by instead, utilizing the inherent structure of the tissue. We used polarization-sensitive optical coherence tomography (PS OCT) to obtain volumetric data through the thickness and across a partial surface of the lumbar facet capsular ligament during three cases of static bending. Reflectivity and phase retardance were calculated from two polarization channels, and a power spectrum analysis was performed on each a-line to extract the dominant banding frequency (a measure of degree of fiber alignment) through the maximum value ...

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    11. Cross-validation of serial optical coherence scanning and diffusion tensor imaging: A study on neural fiber maps in human medulla oblongata

      Cross-validation of serial optical coherence scanning and diffusion tensor imaging: A study on neural fiber maps in human medulla oblongata

      We established a strategy to perform cross-validation of serial optical coherence scanner imaging (SOCS) and diffusion tensor imaging (DTI) on a postmortem human medulla. Following DTI, the sample was serially scanned by SOCS, which integrates a vibratome slicer and a multi-contrast optical coherence tomography rig for large-scale three-dimensional imaging at microscopic resolution. The DTI dataset was registered to the SOCS space. An average correlation coefficient of 0.9 was found between the co-registered fiber maps constructed by fractional anisotropy and retardance contrasts. Pixelwise comparison of fiber orientations demonstrated good agreement between the DTI and SOCS measures. Details of the comparison ...

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    12. Serial optical coherence scanner for large-scale brain imaging at microscopic resolution

      Serial optical coherence scanner for large-scale brain imaging at microscopic resolution

      We describe a serial optical coherence scanner (SOCS) for high resolution imaging of ex-vivo brain. SOCS integrates a multi-contrast optical coherence tomography and a vibratome slicer to establish comprehensive brain anatomy and fiber pathways in three-dimensional space. Rat brain images are demonstrated by utilizing intrinsic optical contrasts including back-scattering, birefringence and optic axis orientation, which are simultaneously generated from the same dataset. Volumetric images from serial scans are combined to realize large scale brain maps. Nerve fiber tracts are globally described in 3D by retardance, and delicately delineated by cross-polarization at the resolution of 15 × 15 × 5.5 μm 3 ...

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    13. Blockface histology with optical coherence tomography: A comparison with Nissl staining

      Blockface histology with optical coherence tomography: A comparison with Nissl staining

      Spectral domain optical coherence tomography (SD-OCT) is a high resolution imaging technique that generates excellent contrast based on intrinsic optical properties of the tissue, such as neurons and fibers. The SD-OCT data acquisition is performed directly on the tissue block, diminishing the need for cutting, mounting and staining. We utilized SD-OCT to visualize the laminar structure of the isocortex and compared cortical cytoarchitecture with the gold standard Nissl staining, both qualitatively and quantitatively. In histological processing, distortions routinely affect registration to the blockface image and prevent accurate 3D reconstruction of regions of tissue. We compared blockface registration to SD-OCT and ...

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    14. Measurement of neural functionality using phase sensitive optical coherence reflectometry

      Measurement of neural functionality using phase sensitive optical coherence reflectometry

      Optical methods, devices, and systems for noninvasively detecting transient surface displacements in a neuron are disclosed. Methods, devices, and systems provided may employ a phase-sensitive optical low coherence reflectometer. In addition, surface displacements due to action potential propagation in neural tissues may be detected in some embodiments using back-reflected light. According to some embodiments, exogenous chemicals or reflect ion coatings are not required. Transient neural surface displacement of less then 1 nm in amplitude and 1 ms in duration may be detected and may be generally coincident with action potential arrival to the optical measurement site. The systems and methods ...

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    15. Visualizing the complex 3D geometry of the perfusion border zone in isolated rabbit heart.

      Visualizing the complex 3D geometry of the perfusion border zone in isolated rabbit heart.

      Myocardial infarction, caused by a major blockage of a coronary artery, creates a border zone (BZ) between perfused and nonperfused tissue, which is believed to be the origin of fatal cardiac arrhythmias. We used a combination of optical clearing and polarization-sensitive optical coherence tomography to visualize a three-dimensional organization of the BZ in isolated rabbit hearts (n=5) at the microscopic level with a high spatial resolution. We found that the BZ has a complex three-dimensional structure with nonperfused areas penetrating into perfused tissue with finger-like projections. These "fingers" may play an important role in the initiation and maintenance of ...

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    16. Reconstructing micrometer-scale fiber pathways in the brain: Multi-contrast optical coherence tomography based tractography

      Reconstructing micrometer-scale fiber pathways in the brain: Multi-contrast optical coherence tomography based tractography
      Comprehensive understanding of connective neural pathways in the brain has put great challenges on the current imaging techniques, for which three-dimensional (3D) visualization of fiber tracts with high spatiotemporal resolution is desirable. Here we present optical imaging and tractography of rat brain ex-vivo using multi-contrast optical coherence tomography (MC-OCT), which is capable of simultaneously generating depth-resolved images of reflectivity, phase retardance, optic axis orientation and, for in-vivo studies, blood flow images. Using the birefringence property of myelin sheath, nerve fiber tracts as small as a few tens of micrometers can be resolved and neighboring fiber tracts with different orientations can ...
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    17. Measurement of neural functionality using phase sensitive optical reflectometry

      Measurement of neural functionality using phase sensitive optical reflectometry
      Optical methods, devices, and systems for non-invasively detecting transient surface displacements in a neuron are disclosed. Methods, devices, and systems provided may employ a phase-sensitive optical low coherence reflectometer. In addition, surface displacements due to action potential propagation in neural tissues may be detected in some embodiments using back-reflected light. According to some embodiments, exogenous chemicals or reflection coatings are not required. Transient neural surface displacement of less than 1 nm in amplitude and 1 ms in duration may be detected and may be generally coincident with action potential arrival to the optical measurement site. The systems and methods may ...
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    18. Swept-source polarization-sensitive
optical coherence tomography based on
polarization-maintaining fiber

      Swept-source polarization-sensitive
optical coherence tomography based on
polarization-maintaining fiber
      We present a swept-source polarization-sensitive optical coherence tomography system based on a polarization-maintaining fiber interferometer. The system produces reflectivity and birefringence information along a depth profile with a single sweep of the optical spectrum. Unlike single-mode fiber systems, retardance and relative optical axis orientation images are calculated without compensation. The source is a 45 mW polygon-based swept-source centered at 1290 nm and tuned at a rate of 28 kHz. The interferometer consists of a single polarization-maintaining coupler that utilizes balanced detection for improved performance. Characterization data shows that this system yields accurate measurements with high sensitivity (106.2 dB) comparable ...
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    19. Polarization-maintaining fiber based polarization-sensitive optical coherence tomography in spectral domain

      Polarization-maintaining fiber based polarization-sensitive optical coherence tomography in spectral domain
      We demonstrate a polarization-sensitive spectral-domain optical coherence tomography system based on polarization-maintaining fiber technology. Using a single-line-scan camera, the system produces reflectivity and retardance information along a depth profile with a single measurement. The relative axis orientation is available as well. System design and characterization and images of a biological tissue are presented.
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    20. Optical Coherence Tomography Phase Measurement of Transient Changes in Squid Giant Axons During Activity

      Noncontact optical measurements reveal that transient changes in squid giant axons are associated with action potential propagation and altered under different environmental (i.e., temperature) and physiological (i.e., ionic concentrations) conditions. Using a spectral-domain optical coherence tomography system, which produces real-time cross-sectional images of the axon in a nerve chamber, axonal surfaces along a depth profile are monitored. Differential phase analyses show transient changes around the membrane on a millisecond timescale, and the response is coincident with the arrival of the action potential at the optical measurement area. Cooling the axon slows the electrical and optical responses and increases ...
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    21. Polarization-maintaining fiber based optical coherence tomography for polarization-sensitive measurements

      We present a polarization-maintaining (PM) fiber based optical coherence tomography system for polarization-sensitive and phase-sensitive measurements. Using a single detector, a single depth scan accurately yields retardance and polarization-insensitive reflectivity information along an A-line. Int ...
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    22. Polarization-sensitive optical coherence tomography based on polarization-maintaining fibers and frequency multiplexing

      Polarization-sensitive optical coherence tomography based on polarization-maintaining fibers and frequency multiplexing
      Muhammad K. Al-Qaisi, Taner Akkin. We report a novel polarization-maintaining fiber based optical coherence tomography for single detector imaging of tissue reflectivity and birefringence. A single depth scan yields quantitative birefringence information along the A-line accurately. Since the orthogonal polarization channels are ... [Opt. Express 16, 13032-13041 (2008)]
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    23. Imaging Depth-Resolved Tissue Birefringence With a Single Detector

      We report a novel frequency multiplexed optical coherence tomography (FM-OCT) system that is capable of measuring depth-resolved tissue birefringence from a single record of a single detector. The FM-OCT system utilizes polarization-maintaining-fiber based components. The orthogonal channels of the polarization-maintaining-fiber and the cross-terms are frequency multiplexed. After recording the interference signal, a set of digital band-pass filters extract the polarization information. A rapid scanning optical delay line in the reference arm compensates for dispersion and allows a real-time display of tissue birefringence. The axial resolution provided by a superluminescent diode working at 855 nm with 28 nm bandwidth is 12 ...
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    24. Fiber-based optical low coherence tomography

      Generally, and in one form of the present invention, is a polarization-maintaining fiber-based polarization sensitive optical low coherence reflectometer for depth resolved birefringence measurement. With the present invention, linear birefringence of a sample may be measured from data recorded in a single A-Scan. In addition, the present invention provides for the simultaneous measurement of retardation and orientation of birefringent axes, wherein measured retardation is insensitive to sample rotation in the plane perpendicular to ranging.
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    1-24 of 24
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    1. (23 articles) Taner Akkin
    2. (20 articles) University of Minnesota
    3. (6 articles) Hui Wang
    4. (5 articles) Muhammad K. Al-Qaisi
    5. (3 articles) University of Texas at Austin
    6. (3 articles) David A. Boas
    7. (3 articles) Thomas E. Milner
    8. (2 articles) Massachusetts General Hospital
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    Polarization-sensitive optical coherence tomography based on polarization-maintaining fibers and frequency multiplexing Polarization-maintaining fiber based polarization-sensitive optical coherence tomography in spectral domain Swept-source polarization-sensitive
optical coherence tomography based on
polarization-maintaining fiber Measurement of neural functionality using phase sensitive optical reflectometry Reconstructing micrometer-scale fiber pathways in the brain: Multi-contrast optical coherence tomography based tractography Blockface histology with optical coherence tomography: A comparison with Nissl staining Conavi Medical and Japan Lifeline Announce MHLW Approval of Novasight Hybrid Intravascular Imaging System for Japanese Market Capsule Endomicroscopy for Visualization of the Small Intestine in EED Population in Pakistan Three-dimensional detection and quantification of defects in SiC by optical coherence tomography University of Illinois at Chicago Receives NIH Grant for Functional Tomography of Neurovascular Coupling Interactions in Healthy and Diseased Retinas Dyad Medical Receives NIH Grant for Software For OCT Analysis of Vascular Stents Oregon Health and Science University Receives NIH Grant for Application of Ultrahigh-Speed Long-Range Wide-Field OCT in Anterior Eye Diseases