1. Articles from Sherif Sherif

    1-11 of 11
    1. Scaled nonuniform Fourier transform for image reconstruction in swept source optical coherence tomography

      Scaled nonuniform Fourier transform for image reconstruction in swept source optical coherence tomography

      Swept Source optical coherence tomography (SS-OCT) is an important imaging modality for both medical and industrial diagnostic applications. A cross-sectional SS-OCT image is obtained by applying an inverse discrete Fourier transform (DFT) to axial interferograms measured in the frequency domain (k-space). This inverse DFT is typically implemented as a fast Fourier transform (FFT) that requires the data samples to be equidistant in k-space. As the frequency of light produced by a typical wavelength-swept laser is nonlinear in time, the recorded interferogram samples will not be uniformly spaced in k-space. Many image reconstruction methods have been proposed to overcome this problem ...

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    2. Texture based segmentation method to detect atherosclerotic plaque from optical tomography images

      Texture based segmentation method to detect atherosclerotic plaque from optical tomography images

      Optical coherence tomography (OCT) imaging has been widely employed in assessing cardiovascular disease. Atherosclerosis is one of the major cause cardio vascular diseases. However visual detection of atherosclerotic plaque from OCT images is often limited and further complicated by high frame rates. We developed a texture based segmentation method to automatically detect plaque and non plaque regions from OCT images. To verify our results we compared them to photographs of the vascular tissue with atherosclerotic plaque that we used to generate the OCT images. Our results show a close match with photographs of vascular tissue with atherosclerotic plaque. Our texture ...

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    3. Detection of atherosclerotic vascular tissue from optical coherence tomography images

      Detection of atherosclerotic vascular tissue from optical coherence tomography images

      Atherosclerotic coronary artery disease continues to be one of the major causes of mortality. Prevention, diagnosis and treatment of atherosclerotic coronary artery disease are dependent on the detection of high risk atherosclerotic plaque. As age is one of the most important risk factors, atherosclerosis worsens steadily with increasing age. Automatic characterization of atherosclerotic plaque using the optical coherence tomography (OCT) images provides a powerful tool to classify patients with high risk plaque. In this study we develop an automatic classifier to detect atherosclerotic plaque in young and old Watanabe heritable hyperlipidemic (WHHL) rabbits, using OCT images without reliance on visual ...

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    4. Optical coherence tomography: fundamental principles, instrumental designs and biomedical applications

      Optical coherence tomography: fundamental principles, instrumental designs and biomedical applications
      The advances made in the last two decades in interference technologies, optical instrumentation, catheter technology, optical detectors, speed of data acquisition and processing as well as light sources have facilitated the transformation of optical coherence tomography from an optical method used mainly in research laboratories into a valuable tool applied in various areas of medicine and health sciences. This review paper highlights the place occupied by optical coherence tomography in relation to other imaging methods that are used in medical and life science areas such as ophthalmology, cardiology, dentistry and gastrointestinal endoscopy. Together with the basic principles that lay behind ...
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    5. Dispersion compensation for optical coherence tomography

      Dispersion compensation for optical coherence tomography
      Optical coherence tomography (OCT) is an imaging technique widely used in various applications especially in biomedical field. It constructs a high resolution 3-D image using multiple cross-sectional views. The axial resolution can be degraded if the sample is dispersive, which is usually true as most of the samples are living tissues. For time-domain OCT, this dispersion is minimized numerically by introducing a compensation filter, which is applied to the obtained signal in Wigner domain, a time-frequency domain. The filter is designed using simulated annealing optimization technique. This paper shows the design of the filter and the results of dispersion compensation.
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    6. High-power 1300 nm FDML swept laser using polygon-based narrowband optical scanning filter

      Swept-source optical coherence tomography (SS-OCT) has received much attention in recent years because of its higher sensitivity in high speed imaging. A fast and high powered wavelength-swept laser is important for SS-OCT since its speed and sensitivity directly rely on the sweeping rate and the ou ... [Proc. SPIE 7168, 716822 (2009)] published Fri Feb 20, 2009.
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    7. Optical coherence tomography: technology and applications

      Optical coherence tomography (OCT) has recently emerged as a powerful optical imaging instrument and technology. OCT performs high resolution, cross-sectional tomographic imaging of the internal structure in 3D materials including biological tissues. Advantages of OCT vs. other imaging systems are: 1) High resolution: enables greater visualization of defects. (OCT: 5-10 microns, ultrasound: 150 microns. High resolution CT: 300 microns. MRI: 1,000 microns). 2) Noninvasive, non-contact: increase ease of use. 3) Fiber-optics delivery: allows OCT to be used in catheters and endoscopes. (Fiber diameter is normally 125 microns). 4) High speed: enables high-resolution 3D imaging. 5) Potential for additional information ...
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    8. 3×3 MZI with unbalanced differential detection for full range swept-source optical coherence tomography

      Quadrature interferometry based on 3×3 fiber couplers could be used to double the effective imaging depth in Swept- Source Optical Coherence Tomography. This is due to its ability to suppress the complex conjugate artifact naturally. We present theoretical and experimental results for a 3×3 Mach-Zehnder interferometer using a new unbalanced differential optical detection method. The new interferometer provides simultaneous access to complementary phase components of the complex interferometric signal. No calculations by trigonometric relationships are needed. We demonstrate a complex conjugate artifact suppression of 27 dB obtained in a swept-source optical coherence tomography using our unbalanced differential detection ...
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    9. Fiber probes used in optical coherence tomography

      Quality and parameters of probing optical beams are extremely important in optical coherence tomography (OCT) systems both for image quality and light coupling efficiency considerations. For example, the shape, size, focal position, and focal range of such beams could have a great impact on the lateral resolution, penetration depth, and signal-to-noise ratio of the image. We present a design, construction and characterization of different variations of GRIN and ball fiber lenses, for ultra-small OCT probes. Those fiber probes are made of a single mode fiber and a GRIN or ball fiber lens with or without a fiber spacer between them ...
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    10. 3×3 Mach-Zehnder interferometer with unbalanced differential detection for full-range swept-source optical coherence tomography

      Youxin Mao, Sherif Sherif, Costel Flueraru, Shoude Chang. Quadrature interferometry based on 3×3 fiber couplers could be used to double the effective imaging depth in swept-source optical coherence tomography. This is due to its ability to suppress the complex conjugate artifact naturally. We present theoretical and experimental results for a ... [Appl. Opt. 47, 2004-2010 (2008)]
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    11. Design and implementation of fiber lenses for ultra-small probes used in biomedical imaging

      Quality and parameters of probing optical beams are extremely important in biomedical imaging systems both for image quality and light coupling efficiency considerations. For example, the shape, size, focal position, and focal range of such beams could have a great impact on the lateral resolution, ... [Proc. SPIE Int. Soc. Opt. Eng. 6826, 68261A (2008)] published Tue Jan 8, 2008.
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    1-11 of 11
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  2. Topics in the News

    1. (11 articles) Sherif S. Sherif
    2. (9 articles) University of Manitoba
    3. (9 articles) National Research Council Canada
    4. (7 articles) Shoude Chang
    5. (7 articles) Youxin Mao
    6. (7 articles) Costel Flueraru
    7. (3 articles) Michael G. Sowa
    8. (2 articles) Mark D. Hewko
    9. (2 articles) Ammu Prakash
    10. (1 articles) Lin-P'ing Choo-Smith
    11. (1 articles) British Columbia Cancer Agency
    12. (1 articles) Shanghai Jiao Tong University
    13. (1 articles) Singapore Eye Research Institute
    14. (1 articles) Simon Fraser University
    15. (1 articles) Columbia University
    16. (1 articles) Stephen Lam
    17. (1 articles) Pierre M. Lane
    18. (1 articles) Tien Yin Wong
    19. (1 articles) Giuseppe Querques
    20. (1 articles) Francesco Bandello
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    Dispersion compensation for optical coherence tomography Optical coherence tomography: fundamental principles, instrumental designs and biomedical applications Detection of atherosclerotic vascular tissue from optical coherence tomography images Texture based segmentation method to detect atherosclerotic plaque from optical tomography images Line-field confocal optical coherence tomography-Practical applications in dermatology and comparison with established imaging methods Optical coherence tomography detection of changes in inner retinal and choroidal thicknesses in patients with early retinitis pigmentosa Feasibility of combined optical coherence tomography and autofluorescence imaging for visualization of needle biopsy placement Characterization of microvascular tortuosity in retinal vein occlusion utilizing optical coherence tomography angiography Evaluation of retinochoroidal tissues in third trimester pregnants: An optical coherence tomography angiography study Evaluation of retinal and choroidal variations in thyroid-associated ophthalmopathy using optical coherence tomography angiography OCTA Study: Retinal Vascular Changes in COVID19 Patients DIABETIC MACULAR ISCHEMIA: Correlation of Retinal Vasculature Changes by Optical Coherence Tomography Angiography and Functional Deficit