1. Articles from chih-chung yang

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    1. Mirror image suppression method

      Mirror image suppression method

      A mirror image suppression method adapted to an optical coherence tomography (OCT) system is provided. The mirror image suppression method includes the following steps: obtaining a tomography image of an object to be tested by using the OCT system; calculating one real image signal obtained from an n.sup.th specific-mode scan for a specific pixel of the tomography image based on image signals obtained from an (n-1).sup.th and the n.sup.th specific-mode scans; obtaining one real image signal of each of a plurality of pixels in the tomography image based on the calculation in the step ...

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    2. Motion-insensitive optical coherence tomography based micro-angiography

      Motion-insensitive optical coherence tomography based micro-angiography
      An improved image processing procedure for suppressing the phase noise due to a motion artifact acquired during optical coherence tomography scanning and effectively illustrating the blood vessel distribution in a living tissue is demonstrated. This new processing procedure and the widely used procedure for micro-angiography application are based on the selection of high-frequency components in the spatial-frequency spectrum of B-mode scanning (x-space), which are contributed from the image portions of moving objects. However, by switching the processing order between the x-space and k-space, the new processing procedure shows the superior function of effectively suppressing the phase noise due to a ...
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    3. Method for analyzing mucosa samples with optical coherence tomography

      Method for analyzing mucosa samples with optical coherence tomography

      A method for analyzing mucosa structure with optical coherence tomography (OCT) is provided, and includes: (a) scanning a mucosa sample with optical coherence tomography; (b) choosing a lateral range from a two- or three-dimensional OCT image and analyzing all the A-scan intensity profiles in the lateral range; (c) calculating three indicators in each A-scan intensity profile, including the standard deviation for a certain depth range below the sample surface, the exponential decay constant of the spatial-frequency spectrum and the epithelium thickness under the condition that the basement membrane is identifiable; and (d) using the three indicators of each A-scan intensity ...

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    4. Microvascular Imaging Using Swept-Source Optical Coherence Tomography with Single-Channel Acquisition

      Microvascular Imaging Using Swept-Source Optical Coherence Tomography with Single-Channel Acquisition
      This study proposes a new approach to improve the phase stability for swept-source optical coherence tomography (SS-OCT) with single-channel acquisition. This approach can improve the phase instability due to the A-scan trigger jitter from the swept source, or the asynchronization between the A-scan trigger and high-speed digitizer, which enables the visualization of vascular structures by SS-OCT. Aside from reducing the phase noise of the OCT system, only one channel is required for the A-scan trigger, data storage, and wavelength calibration by implementing the proposed approach. Finally, human skin was scanned in vivo to demonstrate the vascular images.
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    5. Method for suppressing the mirror image in Fourier-domain optical coherence tomography

      Method for suppressing the mirror image in Fourier-domain optical coherence tomography
      A method, novel to our knowledge, for effective mirror image suppression in Fourier-domain optical coherence tomography based on a phase shift between neighboring A-mode scans is demonstrated. By realizing that the phase shifts of the real and mirror images are mutually reversed and assuming that the real image intensities of the two successive A-mode scans are the same, we can solve a set of two coupled equations to obtain the real image signals. The images based on the scanning of a high-resolution spectral-domain optical coherence tomography system are processed to show effective mirror image suppression results. Compared with a similar ...
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    6. Feature Of The Week 10/24/10: Optical Coherence Tomography Research at National Taiwan University

      Feature Of The Week 10/24/10: Optical Coherence Tomography Research at National Taiwan University

      Feature Of The Week 10/24/10: This week OCT News features OCT research of Professor Chih-Chung Yang's group at National Taiwan University. Show here includes the following topics:1. Real-time diagnosis of oral cancer and precancer with OCT: We have built a swept-source OCT system and a probe to scan oral cavities of patients at the University Hospital for early diagnosis of oral cancer and precancer. In particular, we have identified several image parameters as effective diagnosis indicators and built certain golden rules for differentiating different stages of oral cancer and precancer. We further prepared a computer code ...

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    7. Differentiating oral lesions in different carcinogenesis stages with optical coherence tomography

      A swept-source optical coherence tomography (SS-OCT) system is used to clinically scan oral lesions in different oral carcinogenesis stages, including normal oral mucosa control, mild dysplasia (MiD), moderate dysplasia (MoD), early-stage squamous cell carcinoma (ES-SCC), and well-developed SCC (WD-SCC), for diagnosis purpose. On the basis of the analyses of the SS-OCT images, the stages of dysplasia (MiD and MoD), and SCC (ES-SCC and WD-SCC) can be differentiated from normal control by evaluating the depth-dependent standard deviation (SD) values of lateral variations. In the dysplasia stage, the boundary between the epithelium (EP) and lamina propria (LP) layers can still be identified ...

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    8. Delineation of an oral cancer lesion with swept-source optical coherence tomography

      We demonstrate the ex vivo imaging of an oral cancerous sample with a swept-source optical coherence tomography (SS-OCT) system. With the axial resolution of 8μm in free space and system sensitivity of 108dB, we can well distinguish the normal and abnormal tissue portions in a sample. In particular, we analyze the lateral variation of A-scan profiles to show two parameters of SS-OCT signal for delineating an oral cancer lesion. One of the parameters is the decay constant in the exponential fitting of the SS-OCT signal intensity along depth. This decay constant decreases as the A-scan point moves laterally ...

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    1-8 of 8
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    1. (8 articles) National Taiwan University
    2. (4 articles) Chang Gung University
    3. (2 articles) National Yang-Ming University
    4. (2 articles) Sun Yat-Sen University
    5. (2 articles) Tokyo Medical & Dental University
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    Feature Of The Week 10/24/10: Optical Coherence Tomography Research at National Taiwan University Method for suppressing the mirror image in Fourier-domain optical coherence tomography Microvascular Imaging Using Swept-Source Optical Coherence Tomography with Single-Channel Acquisition Method for analyzing mucosa samples with optical coherence tomography Motion-insensitive optical coherence tomography based micro-angiography Mirror image suppression method Prognostic Features of Preoperative Optical Coherence Tomography in Retinal Detachments: A systematic review and meta-analysis Automatic assessment of calcified plaque and nodule by optical coherence tomography adopting deep learning model Coronary plaque characterization assessed by delayed enhancement dual-layer spectral CT angiography and optical coherence tomography Use of multimodal dataset in AI for detecting glaucoma based on fundus photographs assessed with OCT: focus group study on high prevalence of myopia Distinctive Morphological Patterns of Complicated Coronary Plaques in Acute Coronary Syndromes: Insights from an Optical Coherence Tomography Study Characterization of Hyperreflective Dots by Structural and Angiographic Optical Coherence Tomography in Patients with Diabetic Retinopathy and Healthy Subjects