Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 68, Issue 9
Displaying 1-9 of 9 articles from this issue
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Opening Article
Program of the 40th Autumn Scientific Congress
Originals
  • Inspection of Dose Reduction in Patients during Percutaneous Coronary Intervention and Catheter Ablation Procedures
    Yoshiyuki Umezu, Kazuhisa Ogawa, Noboru Shigetani, Emi Kinoshita, Hito ...
    2012 Volume 68 Issue 9 Pages 1221-1230
    Published: September 20, 2012
    Released on J-STAGE: September 20, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.9.1221
    JOURNAL FREE ACCESS
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    With an increasing number of interventional radiology (IVR) procedures, it is a critical issue to control and reduce the radiation dose for patients by radiological technologists. In our study, we analyzed the usefulness of a provision for radiation reduction on catheter ablation and percutaneous coronary intervention (PCI) procedures based on the data from radiation information system (RIS). With regard to catheter ablation, 50% reduction was enabled with decreasing fluoroscopic and radiographic conditions regardless of each technique. Radiation reduction enabled a decrease in the fluoroscopic dose during PCI procedure. However, note that excessive radiation reduction does not show positive results of the radiation dose reduction. Moreover it leads to an increase in fluoroscopic time.
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  • Investigation of Radiofrequency Heating for a Closed Conducting Loop Formed in a Part of the Patient’s Body in 1.5 Tesla Magnetic Resonance (MR) Imaging and 3.0 Tesla MR Imaging—Measurement of Temperature by Use of Human Body-equivalent Phantom
    Masaru Yamazaki, Mitsuji Higashida, Sadahiro Kudo, Takahiro Ideta, Mas ...
    2012 Volume 68 Issue 9 Pages 1231-1241
    Published: September 20, 2012
    Released on J-STAGE: September 20, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.9.1231
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    Thermal injuries have been sometimes reported due to a closed conducting loop formed in a part of the patient’s body during magnetic resonance imaging (MRI). In recent years, 3.0 T-MRI scanner has been widely used. However, it is considered that the specific absorption rate (SAR) of 3.0 T-MRI can affect the heat of the loop because its own SAR becomes approximately 4 times as much as that of the1.5 T-MRI scanner. With this, the change in temperature was measured with human body-equivalent loop phantom in both 1.5 T-MRI and 3.0 T-MRI. In the two scanners, the temperature during 20 min of scanning time was measured with three types of sequences such as field echo (FE), spin echo (SE), and turbo SE (TSE) set up with the same scanning condition. It was found from the result that rise in temperature depended on SAR of the scanning condition irrespective of static magnetic field intensity and any pulse sequences. Furthermore, the increase of SAR and rise in temperature were not only in proportion to each other but also were indicated to have good correlation. However, even low SAR can occasionally induce serious thermal injuries. It was found from result that we had to attempt not to form a closed conducting loop with in a part of the patient’s body during MRI.
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  • Comparison of Diffusion Tensor Imaging-Derived Fractional Anisotropy in Multiple Centers for Identical Human Subjects
    Kousaku Saotome, Yoshiyuki Ishimori, Tomonori Isobe,, Eisuke Satou, Ka ...
    2012 Volume 68 Issue 9 Pages 1242-1249
    Published: September 20, 2012
    Released on J-STAGE: September 20, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.9.1242
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    The fractional anisotropy (FA) is calculated by using diffusion tensor imaging (DTI) with multiple motion probing gradients (MPG). While FA has become a widely used tool to detect moderate changes in water diffusion in brain tissue, the measured value is sensitive to scan parameters (e.g. MPG-direction, signal to noise ratio, etc.). Therefore, it is paramount to address the reproducibility of DTI measurements among multiple centers. The purpose of this study was to assess the inter-center variability of FA. We studied five healthy volunteers who underwent DTI brain scanning three times at three different centers (I–III), each with a 1.5 T scanner having a different MPG-schema. Then, we compared the FA and eigenvalue from the three centers measured in seven brain regions: splenium of corpus callosum (CCs), genu of corpus callosum (CCg), putamen, posterior limb of internal capsule, cerebral peduncle, optic radiation, and middle cerebellar peduncle. At the CCs and CCg, there was a statistical difference (p<0.05) between center Iand center IIfor the same MPG-directions. Furthermore, at CCs and CCg, there was a statistical difference (p<0.05) between center II and center III for different MPG-directions. Conversely, no statistical differences were found between center I and center III for the different MPG-directions for all regions. These results indicate that the FA value was affected by the MPG-schema as well as by the MPG-directions.
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Clinical Technology
  • Examination of the Effectiveness of Heart Rate Control Using Intravenous β-blocker in 64-slice Coronary Computed Tomography Angiography
    Takayoshi Yamaguchi, Daichi Takahashi, Shingo Nakagawa, Mari Morita, R ...
    2012 Volume 68 Issue 9 Pages 1250-1260
    Published: September 20, 2012
    Released on J-STAGE: September 20, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.9.1250
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    The purpose of this study is to clarify the effectiveness of the use of β-blocker in coronary computed tomography angiography (CCTA). In 1783 patients, heart rate was controlled by propranolol injection to patients with heart rates of 61 bpm or more. As a result, the scan heart rate (58.8±6.5 bpm) decreased significantly compared with the initial heart rate (72.7±9.4 bpm). Prospective gating method was used by 61.9% including 64.3% of the intravenous β-blocker injection group. Moreover, daily use of oral β-blocker had influence on reduction of the scan heart rate (daily use group: 60.1±6.5 bpm vs. unuse group: 58.5±6.3 bpm p<0.01). When we evaluated the image quality of CCTA by the score, the improvement of the score was obviously admitted by 65 bpm or less of the scan heart rate. The ratio of scan heart rate that was controlled by 65 bpm or less was decreased in the initial heart rate groups that were 81 bpm or more. The incidence of adverse reactions by the propranolol injection was few, and these instances only involved slight symptoms. Therefore, heart rate control with the use of β-blocker is useful for the image quality improvement of CCTA. This form of treatment can be safely enforced.
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Data
  • Summary of Results of the Patient Exposures in Diagnostic Radiography in 2011 Questionnaire—Focus on Radiographic Conditions—
    Yasuki Asada, Syoichi Suzuki, Kenichi Kobayashi, Hideyuki Kato, Takayu ...
    2012 Volume 68 Issue 9 Pages 1261-1268
    Published: September 20, 2012
    Released on J-STAGE: September 20, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.9.1261
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    We carried out a questionnaire survey to research on radiographic conditions in 3000 institutes. We discussed on radiographic conditions to estimate patient exposures. The collection rate was 24.7%. Most of the institutes shifted to the use of high-voltage generator, digital devices, and filmless equipment. We did not see a shift in this survey of radiographic conditions compared with the 2007 survey.
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  • Effects of Region of Interest Settings in Signal-to-Noise Ratio Measurement of Clinical Images Using Arrays of Multiple Receiver Coils
    Yoshihiro Kitoh, Hiroshi Imai, Toshiaki Miyati, Akio Ogura, Yoshio Mac ...
    2012 Volume 68 Issue 9 Pages 1269-1278
    Published: September 20, 2012
    Released on J-STAGE: September 20, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.9.1269
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    In many clinical imaging procedures using arrays of multiple receiver coils, a uniform sensitivity process is performed using the sensitivity distribution from the body coil. This causes the noise to be uneven, and background noise cannot be used when measuring the signal-to-noise ratio (SNR). The SNR of clinical images with sensitivity correction using arrays of multiple receiver coils sets the region of interest (ROI) in the region where the signal is uniform, and is limited to the identical ROI method where measurements are taken with noise from the identical region. When SNR is measured with the identical ROI method, uneven noise caused by sensitivity correction as well as the signal strength distribution within the ROI of the object is reflected in the noise. Therefore, evaluation must be performed in as localized a position as possible. Measurement error becomes small on images with higher resolution, and if ROI larger than 10×10 pixels can be set in a region of even signal, SNR measurement of clinical images with less underestimation may be possible.
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