Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 63, Issue 2
Displaying 1-8 of 8 articles from this issue
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The 62nd Annual Scientific Congress
The 62nd Annual Scientific Congress
Science Exchanges Committee Report
JIRA Topics
Scientific Papers
Originals
  • Usefulness of Low- and Medium-energy Collimators in 123I-MIBG Myocardial Scintigraphy
    Ryoko Sakashita, Katsuya Sugimoto, Yuko Fukuya, Hiroshi Fujibuchi, Tom ...
    2007 Volume 63 Issue 2 Pages 241-246
    Published: February 20, 2007
    Released on J-STAGE: March 14, 2007
    DOIhttps://doi.org/10.6009/jjrt.63.241
    JOURNAL FREE ACCESS
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    The heart-to-mediastinum (H/M) ratio on myocardial scintigraphy with 123I-metaiodobenzylguanidine (MIBG) is used as a semi-quantitative index. However, the scatter from a photopeak of 529 keV on 123I is thought to affect the H/M ratio, and collimator selection is important as well. We attempted to determine the usefulness of low- and medium-energy general purpose (LME) collimators by comparing them with low-energy high-resolution (LEHR) and medium-energy low-penetration (MELP) collimators in phantom and clinical studies. In the phantom study, we used a thoracic phantom and plastic bottles filled with 123I-MIBG solution as upper limbs. Phantom images were acquired with LEHR, LME, and MELP collimators. Regions of interest were placed on the lung, mediastinum, heart, and liver. The average counts in the lung, coefficient of variation (CV%) in the heart, mediastinum, and liver, and H/M ratio were calculated. The H/M ratios obtained with the LEHR collimator and LME collimator were compared in a clinical study. We found that the average count in the lung measured with the LME collimator was reduced to about 30% of that obtained with the LEHR collimator in the phantom study. CV% measured with the LME collimator improved about 10% compared with that determined with the MELP collimator. The H/M ratio measured with the LME collimator was close to that measured with the MELP collimator. In the clinical study, the H/M ratios measured with the LEHR and LME collimators showed a positive relationship (y=2.1x-1.3, x; H/M with LEHR, y; H/M with LME) . LME collimators provided improved contrast and signal-to-noise ratio in evaluation of the H/M ratio on 123I-MIBG myocardial scintigraphy.
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  • Development of the Automated Patlak Plot Method and Its Verification in Clinical Examples
    Kesato Yano, Tadashi Miyasaka, Makoto Sato
    2007 Volume 63 Issue 2 Pages 247-256
    Published: February 20, 2007
    Released on J-STAGE: March 14, 2007
    DOIhttps://doi.org/10.6009/jjrt.63.247
    JOURNAL FREE ACCESS
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    The Patlak plot method is widely used in general clinical practice to calculate mean cerebral blood flow (mCBF) because it does not require arterial blood sampling and the procedure used is relatively simple. However, it has been pointed out that the calculation is affected by operator subjectivity and experience, and reproducibility is poor when the operator changes. The Patlak plot method consists of the following three procedures: (1) a region of interest (ROI) in the normal cerebral hemisphere is chosen to obtain the time-activity curve; (2) an ROI in the aortic arch is determined to obtain the time-activity curve; and (3) graphic analysis of the two time-activity curves is performed, and mCBF is determined from the slope of the graph. In this study, we automated all three of the above procedures, enabling analysis that is not affected by operator subjectivity or experience. Considering the verification result shown below: (1) automation of an ROI setup of a cerebral hemisphere and an aortic arch was possible in all examples; (2) the point of graphic analysis was set in the error range of 1% - 2% of straight line domains; (3) in comparison with the conventional method in 55 cases, the mean of absolute percentage error was 3.1±2.5%; (4) in 17 cases that did not accept a right-and-left difference in SPECT, the mean of absolute percentage error of right and left mCBF was 1.3±0.9%. It was thought that the processing algorithm was appropriate. Moreover, it was thought that the technique of graphic analysis proposed for this study served as an aid to dissolution of the “ambiguity” of the Patlak plot method.
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Work in Progress
  • Technical Aspects of X-ray Micro-computed Tomography
    Initial Experience of 27-μm Resolution Using Feldkamp Cone-beam Reconstruction
    Shuji Yamamoto, Masahiro Suzuki, Kazushi Kohara, Gen Iinuma, Noriyuki ...
    2007 Volume 63 Issue 2 Pages 257-260
    Published: February 20, 2007
    Released on J-STAGE: March 14, 2007
    DOIhttps://doi.org/10.6009/jjrt.63.257
    JOURNAL FREE ACCESS
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    The objective of this study was to introduce the technical utility of micro-computed tomography (CT) with 27-μm resolution by cone-beam CT algorithm. Whole-body micro-CT scans were performed to honeybee. Two- and three-dimensional image analyses were performed by originally developed and available open-source software for acquired images. The original contribution of this work is to describe the technical characteristics of the X-ray micro-CT system, keeping a small experimental insect in a unique condition. Micro-CT may be used as a rapid prototyping tool to research and understand the high-resolution system with Feldkamp cone-beam reconstruction.
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