Browsing by Author "Chu, Woei-Chyn"

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A Web-Based Solution for Viewing Large-Sized Microscopic Images
(2009-06-01)
Lien, Chung-Yueh
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Teng, Hsu-Chih
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Chen, Deng-Ji
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Chu, Woei-Chyn
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Hsiao, Chia-Hung
This paper demonstrates a pure web-based solution enabling the presentation of scanned pathologic microscopic images on the web. For each slide, an entire specimen is scanned, and a high-resolution digital image (in the order of giga-pixels) is reconstructed. These huge images are then tiled into many 256 x 256-pixel blocks with different resolutions, and information about the blocks of each scanned slide is included in an extensible markup language metafile. Based on the data, a virtual microscopy system is created for viewing the scanned pathologic slides on web. The functionalities (changing viewing resolution, location adjustment, and multimedia annotation presentation) of our virtual slide viewing system are accomplished using pure hypertext markup language (HTML) and JavaScript. We show that there is no need to add plug-in components to browsers in order to handle virtual slides on the web. In a heterogeneous healthcare environment, methods using pure HTML and JavaScript to deal with pathologic content are more appropriate than using proprietary technologies supported only by specific browsers.
Concurrent sympathetic activation and vagal withdrawal in hyperthyroidism: Evidence from detrended fluctuation analysis of heart rate variability
(2010-05-01)
Chen, Jin-Long
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Shiau, Yuo-Hsien
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Tseng, Yin-Jiun
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Chiu, Hung-Wen
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Hsiao, Tzu-Chien
Despite many previous Studies on the association between hyperthyroidism and the hyperadrenergic state, controversies still exist. Detrended fluctuation analysis (DFA) is a well recognized method in the nonlinear analysis of heart rate variability (HRV), and it has physiological significance related to the autonomic nervous system. In particular, an increased short-term scaling exponent alpha 1 calculated from DFA is associated with both increased sympathetic activity and decreased vagal activity. No study has investigated the DFA of HRV in hyperthyroidism. This study was designed to assess the sympathovagal balance in hyperthyroidism. We performed the DFA along with the linear analysis of HRV in 36 hyperthyroid Graves' disease patients (32 females and 4 males; age 30 +/- 1 years, means +/- SE) and 36 normal controls matched by sex, age and body mass index. Compared with the normal controls, the hyperthyroid patients revealed a significant increase (P < 0.001) in alpha 1 (hyperthyroid 1.28 +/- 0.04 versus control 0.91 +/- 0.02), long-term scaling exponent alpha 2 (1.05 +/- 0.02 versus 0.90 +/- 0.01), overall scaling exponent alpha (1.11 +/- 0.02 versus 0.89 +/- 0.01), low frequency power in normalized units (LF%) and the ratio of low frequency power to high frequency power (LF/HF); and a significant decrease (P < 0.001) in the standard deviation of the R-R intervals (SDNN) and high frequency power (HF). In conclusion, hyperthyroidism is characterized by concurrent sympathetic activation and vagal withdrawal. This sympathovagal imbalance state in hyperthyroidism helps to explain the higher prevalence of atrial fibrillation and exercise intolerance among hyperthyroid patients. (C) 2010 Elsevier B.V. All rights reserved.
Development of Limited-Angle Iterative Reconstruction Algorithms with Context Encoder-Based Sinogram Completion for Micro-CT Applications
(2018-12-01)
Jin, Shih-Chun
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Hsieh, Chia-Jui
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Chen, Jyh-Cheng
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Tu, Shih-Huan
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Chen, Ya-Chen
Limited-angle iterative reconstruction (LAIR) reduces the radiation dose required for computed tomography (CT) imaging by decreasing the range of the projection angle. We developed an image-quality-based stopping-criteria method with a flexible and innovative instrument design that, when combined with LAIR, provides the image quality of a conventional CT system. This study describes the construction of different scan acquisition protocols for micro-CT system applications. Fully-sampled Feldkamp (FDK)-reconstructed images were used as references for comparison to assess the image quality produced by these tested protocols. The insufficient portions of a sinogram were inpainted by applying a context encoder (CE), a type of generative adversarial network, to the LAIR process. The context image was passed through an encoder to identify features that were connected to the decoder using a channel-wise fully-connected layer. Our results evidence the excellent performance of this novel approach. Even when we reduce the radiation dose by 1/4, the iterative-based LAIR improved the full-width half-maximum, contrast-to-noise and signal-to-noise ratios by 20% to 40% compared to a fully-sampled FDK-based reconstruction. Our data support that this CE-based sinogram completion method enhances the efficacy and efficiency of LAIR and that would allow feasibility of limited angle reconstruction.
Nonlinear analysis of heart rate dynamics in hyperthyroidism
(2007-04-01)
Chen, Jin-Long
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Tseng, Yin-Jiun
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Chiu, Hung-Wen
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Hsiao, Tzu-Chien
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Chu, Woei-Chyn
Studies on the physiology of the cardiovascular system suggested that the generation of the heart rate signal is governed by nonlinear chaotic dynamics. No study investigated the nonlinear dynamics of heart rate in hyperthyroidism. We examined whether the heart rate dynamics of hyperthyroid patients is different from normal controls by the nonlinear analysis of heart rate variability (HRV) with correlation dimension (CD). Thirty-three hyperthyroid Graves' disease patients (30 females and 3 males; age 31 +/- 1 years, means +/- SE) and 33 sex-, age-, and body mass index-matched normal controls were recruited to receive one-channel electrocardiogram recording for 30 min. The CD, an index of complexity, was computed from the sequence of normal R-R intervals by the Grassberger and Procaccia algorithm. Compared to the normal controls, the hyperthyroid patients showed significant reductions (P < 0.001) in the mean R-R interval (hyperthyroid 616 +/- 15 versus control 868 +/- 16 ms), the standard deviation of R-R intervals (25 +/- 2 versus 54 +/- 4 ms) and CD (5.02 +/- 0.11 versus 6.42 +/- 0.16). Our study demonstrated for the first time that hyperthyroid patients and normal controls could be distinguished by CD analysis of HRV. In addition, the decreased CD in hyperthyroid patients implies reduced complexity and impaired tolerance to cardiovascular stresses in hyperthyroidism. This finding helps to explain exercise intolerance and irritability manifested by the hyperthyroid patients.