Medical Imaging Technology
Online ISSN : 2185-3193
Print ISSN : 0288-450X
ISSN-L : 0288-450X
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Volume 29, Issue 1
Displaying 1-11 of 11 articles from this issue
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Main Topics/Radiological Technologists who Play a Part of Future Image Science and Technology Research in Clinical Medicine
  • Radiological Technologists who Play a Part of Future Image Science and Technology Research in Clinical Medicine—Introduction—
    Hiroshi FUJITA
    2011 Volume 29 Issue 1 Pages 1
    Published: 2011
    Released on J-STAGE: February 03, 2011
    DOIhttps://doi.org/10.11409/mit.29.1
    JOURNAL FREE ACCESS
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  • The Role of Image Evaluation for Digital Mammography Systems: Physical Imaging Properties and Detectability of Microcalcifications
    Tadamitsu IDEGUCHI, Yoshiharu HIGASHIDA
    2011 Volume 29 Issue 1 Pages 2-9
    Published: 2011
    Released on J-STAGE: February 03, 2011
    DOIhttps://doi.org/10.11409/mit.29.2
    JOURNAL FREE ACCESS
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    We investigated the clinical application of digital mammography systems by evaluating their basic imaging parameters, namely, modulation transfer functions, Wiener spectra, and visual evaluation of contrast-detail phantom images, and by comparing them with those of conventional single-screen/single-film system. Digital systems used in this study were the new (FCR5000MA) and conventional (FCR9000) CR systems and full–field digital mammography (FFDM) system. The new CR system consists of a high-resolution imaging plate with a transparent support and dual-sided reading system. The MTF of FFDM system showed higher than those of new and conventional CR systems, but lower than that of the screen-film system. The FFDM system had a lowest noise level in the digital systems, and new CR system showed lower noise level than that of the conventional CR system. The results of the contrast-detail analyses indicated that the detectability of new CR and FFDM systems comparable to or slightly superior than that of the screen-film system.
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  • Improvement of the CT Image Quality and Operation Support with Image Processing Technique
    Eiji NISHIMARU, Katsuhiro ICHIKAWA
    2011 Volume 29 Issue 1 Pages 10-16
    Published: 2011
    Released on J-STAGE: February 03, 2011
    DOIhttps://doi.org/10.11409/mit.29.10
    JOURNAL FREE ACCESS
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    The present studies were performed to investigate a new noise reduction filter algorithm which can be applicable for pediatric body CT images and a method which automatically detects the scan angle and range in the head CT examination. The filter was based on a three-dimensional post-processing, in which output pixel values are calculated by multi-directional one-dimensional median filters. From results of phantom studies, the proposed algorithm could reduce standard deviation values (SD) as a noise index by up to 30% without affecting on the spatial resolution of all directions. The results of the visual evaluation of the peripheral portal vein branches in clinical abdomen images indicated that the visibility of the portal vein was significantly improved (p = 0.042). The scan angle and range detection method for head CT was based on a Hough transformation and a cross-correlation technique. For the 30 clinical cases, the accuracy of the determined scan angle was 1.0±0.7 degrees, and the determined results were evaluated as "acceptable" by five radiological technologists in 93% of the cases. These studies will be useful for image improvement, dose reduction and operation support in CT.
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  • Z-score Mapping for Extracting Hypoattenuation Regions of Hyper Acute Stroke in Unenhanced CT
    Noriyuki TAKAHASHI, Yongbum LEE, Du-Yih TSAI, Toshibumi KINOSHITA, Kiy ...
    2011 Volume 29 Issue 1 Pages 17-22
    Published: 2011
    Released on J-STAGE: February 03, 2011
    DOIhttps://doi.org/10.11409/mit.29.17
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    This paper described a z-score mapping method on the basis of a voxel-by-voxel analysis to visualize hypoattenuation regions of hyperacute stroke on unenhanced CT images. The algorithm of this method consisted of 5 major steps, i.e., anatomic standardization, construction of a normal reference database, calculation of z score, elimination of false positive areas, and extraction of hypoattenuation areas. The performance of this method in detection of hypoattenuation with a series of 21 patients with infarction (< 3 hours) showed the AUC =0.834 for distinction between hypoattenuation and normal regions. The result of an observer study with five neuroragiologists, also, demonstrated the average AUC for detection oh hypoattenuation regions significantly improved from 0.883 to 0.925 (P< 0.01). Therefore, the z-score mapping method could effectively extract hypoattenuation regions that showed a high z-score value on the z-score map. The use of this method has the potential to help neuroradiolgists detect hypoattenuation regions of hyperacute stroke on unenhanced CT images.
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  • Quantitative Analysis of Diagnostic Information in Brain MRI
    Norio HAYASHI, Shigeru SANADA, Tosiaki MIYATI, Mitsuru Kikuchi, Yoshio ...
    2011 Volume 29 Issue 1 Pages 23-28
    Published: 2011
    Released on J-STAGE: February 03, 2011
    DOIhttps://doi.org/10.11409/mit.29.23
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    The present study was performed to investigate methods of imaging, image evaluation, and quantitative analysis for diagnosis of brain atrophy on brain magnetic resonance imaging (MRI). For quantitative analysis, it is important to obtain optimal MR images by an optimal imaging sequence. Signal-to-noise ratio (SNR) is an excellent index for evaluation of MR image quality. However, it is difficult to measure correct SNR in clinical MR images using parallel imaging (PI) techniques. We developed a method to measure SNR on clinical MR images using the PI technique by the modified identical regions of interest (ROI) method. We developed a semi-automated volumetry method for the cerebrum, cerebellum-brain stem, and temporal lobe on brain MRI using texture and anatomical information on brain MR images. It is possible to evaluate cerebrum volume on images of different qualities obtained by spin echo or gradient echo sequences. Image quality obtained by each imaging sequence was evaluated by our SNR measurement method and the volumetry method consisting of optimal image processing for image quality. It is useful to evaluate MR image quality and to measure volume semi-automatically for diagnosis of brain atrophy in brain MRI.
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  • Estimation of Membrane Permeability of the Brain Using Diffusion Magnetic Resonance Imaging
    Toshikazu IMAE, Masaki SEKINO, Hiroyuki SHINOHARA
    2011 Volume 29 Issue 1 Pages 29-35
    Published: 2011
    Released on J-STAGE: February 03, 2011
    DOIhttps://doi.org/10.11409/mit.29.29
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    Diffusion-weighted imaging (DWI) using magnetic resonance imaging (MRI) reflects the influence of the intra- and extracellular diffusion coefficient of water and cell membrane permeability. Previous diffusion MRI studies have focused mainly on measurement of the effective diffusion coefficient of water molecules in biological tissues, but details of the underlying microscopic structures were not clear. Various models have been proposed for clarifying the relation between diffusion MRI signals and diffusion properties in cells, and numerical simulation of water diffusion provides a useful tool for estimation of cellular variables. The purpose of this study is to evaluate the influence of cellular variables on diffusion MRI signals and to estimate intracellular diffusion coefficient and cell membrane permeability of the normal rat and human brain. By minimizing the difference between signals obtained experimentally and those from numerical simulation, we could estimate intracellular diffusion coefficient (rat: (0.9±0.4) ×10-3mm2/s, human: (1.2±0.2) ×10-3mm2/s) and membrane permeability (rat: 68±6 μm/s, human: 80±13 μm/s). Our method is useful for non-invasively estimating the cell membrane permeability of biological tissues, and is easily applicable to human tissues and other samples.
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Papers
  • Endoscopic Image Matching for Reconstructing the 3-D Structure of the Intestines
    Katsuhiro HIRAI, Yasushi KANAZAWA, Ryusuke SAGAWA, Yasushi YAGI
    2011 Volume 29 Issue 1 Pages 36-46
    Published: 2011
    Released on J-STAGE: February 03, 2011
    DOIhttps://doi.org/10.11409/mit.29.36
    JOURNAL FREE ACCESS
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    We have developed a new method for matching endoscopic image sequences in order to reconstruct the 3-D structure of the intestines. Endoscopic images are among the most difficult images for identifying correspondences due to the lack of textures. It is difficult not only to detect feature points in the images but also to identify correspondences between the images. As a result, conventional interest point detectors and matching methods can obtain few correct correspondences. In this report, we propose a new feature detection and matching method for endoscopic images. This method focuses on the folds of the intestines because these folds are distinct and stable features in endoscopic images. First, the folds are enhanced in the images. Then, points on the folds are determined. By adopting a HOG-based descriptor for the descriptions of the points, the correspondences between the images can be identified. We also demonstrate the effectiveness of our method using examples of actual images.
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