Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 64, Issue 5
Displaying 1-14 of 14 articles from this issue
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Opening Article
Original
  • Adaptive Wiener Filter based on Gaussian Mixture Distribution Model for Denoising Chest X-ray CT Image
    Motohiro Tabuchi, Nobumoto Yamane, Yoshitaka Morikawa
    2008 Volume 64 Issue 5 Pages 563-572
    Published: May 20, 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.563
    JOURNAL FREE ACCESS
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    In recent decades, X-ray CT imaging has become more important as a result of its high-resolution performance. However, it is well known that the X-ray dose is insufficient in the techniques that use low-dose imaging in health screening or thin-slice imaging in work-up. Therefore, the degradation of CT images caused by the streak artifact frequently becomes problematic. In this study, we applied a Wiener filter (WF) using the universal Gaussian mixture distribution model (UNI-GMM) as a statistical model to remove streak artifact. In designing the WF, it is necessary to estimate the statistical model and the precise co-variances of the original image. In the proposed method, we obtained a variety of chest X-ray CT images using a phantom simulating a chest organ, and we estimated the statistical information using the images for training. The results of simulation showed that it is possible to fit the UNI-GMM to the chest X-ray CT images and reduce the specific noise. (Article in Japanese)
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Clinical Technology
  • Elimination of Bowel Fluid Artifact on Abdominal DWI Using Oral Contrast Agent Ferric Ammonium Citrate
    Toshiyuki Takahashi, Kyoichi Kato, Takeshi Nishizawa, Yasuo Nakazawa
    2008 Volume 64 Issue 5 Pages 573-578
    Published: May 20, 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.573
    JOURNAL FREE ACCESS
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    The clinical usefulness, as well as the advantages and limitations of DWI in the abdomen and pelvis, currently are under discussion. One of the limitations is the artifact from bowel fluid that may obscure lesion signals or make it difficult to detect them. The purpose of this study was to examine evidence as to whether an oral contrast agent of ferric ammonium citrate could eliminate this artifact from the bowel loop. The study consisted of a phantom study and clinical study. The density of the phantom compounded it to 1-6 times, 8 times and 12 times. We changed the density with ferric ammonium citrate to find the best density. The pulse sequence used SE-PEI and, variable parameter changed TE and b value. The signal intensity of the phantoms was visually analyzed. We took the results to an outside observer as a clinical study and confirmed the effect visually. When a signal of ferric ammonium citrate extended TE time and increased b value, it fell. As it thickened the density of phantom, it was the result that the signal deteriorated, and was good. However, an artifact from ferric ammonium citrate appeared when we exceeded 5× density. The signal of the bowel fluid artifact disappeared by having a normal person take the 4× density as in the clinical study. Elimination of bowel fluid artifact on abdominal DWI was able to suggest the possibility of taking the ferric ammonium citrate solution at 4× density. (Article in Japanese)
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  • Examination of R-L Shunt Ratio Mensuration Using Dynamic Images in Lung Perfusion Scintigraphy
    Hajime Ichikawa, Sayaka Yamada, Chiho Yoshioka, Toyoshi Tamaoki, Syuni ...
    2008 Volume 64 Issue 5 Pages 579-586
    Published: May 20, 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.579
    JOURNAL FREE ACCESS
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    Objective: We examined a method of quantitative analysis that used dynamic and static images to measure the Right-left (R-L) shunt ratio in lung perfusion scintigraphy. Methods: A total of 18 patients suspected of having R-L shunt brought on by congenital heart disease were referred for lung perfusion scintigraphy from November 2005 to February 2007 at our hospital. We acquired anterior dynamic images, set ROIs in all fields of view, and measured the highest count. We acquired anterior and posterior static images of the chest and measured lung counts. We considered the highest count on dynamic images to be the total injection dose per one second, normalized the acquisition time of static images, and calculated the R-L shunt ratio. We weighed the measurement results of the R-L shunt ratio obtained by the dynamic method against that of the whole-body method by t-test and the least-squares method. Results: When we used a posterior static image in the dynamic method, we found that the coefficient of correlation (r) was 0.9831. The result of the t-test was that there was no significant difference at a level of significance of 1%. Discussion: We think the use of the dynamic method is possible in R-L shunt ratio measurement and can shorten the examination time. (Article in Japanese)
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Work in Progress
  • Influence of Mechanical Effect Due to MRI-magnet on Tattoo Seal and Eye Makeup
    Yuta Morishita, Tosiaki Miyati, Jousei Ueda, Mitsuru Shimizu, Takashi ...
    2008 Volume 64 Issue 5 Pages 587-590
    Published: May 20, 2008
    Released on J-STAGE: May 29, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.587
    JOURNAL FREE ACCESS
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    The purpose of our study was to assess the mechanical effect on tattoo seals and eye makeup caused by a spatial magnetic gradient in the magnetic resonance imaging (MRI) system. Seven kinds of tattoo seals and three kinds of eye makeup, i.e., mascara, eye shadow, and eyeliner were used. On a 3.0-Tesla MRI, we determined these deflection angles according to a method established by the American Society for Testing and Materials (ASTM) at the position that produced the greatest magnetically induced deflection. Eighty-five percent of the tattoo seals showed deflection angles greater than 45 degrees of the ASTM guidelines, and the mascara and eye shadow showed over 40 degrees. This was because these contained ferromagnetic pigments such as an iron oxide, but those translational forces were very small owing to slight mass. However, it is desirable that these should be removed before MRI examination to prevent secondary problems. (Article in Japanese)
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The 63rd Annual Scientific Congress
The 63rd Annual Scientific Congress
Educational Lecture—Interpreting Medical Images for Radiological Technologists
Basic Lectures—The Image Processing Technology that You Should Learn on Examination
Clinical Technology Cource
Series—Law and Medicine (10)
JIRA Topics
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