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Article type: Cover
2001 Volume 57 Issue 4 Pages
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Article type: Cover
2001 Volume 57 Issue 4 Pages
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Article type: Index
2001 Volume 57 Issue 4 Pages
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Article type: Index
2001 Volume 57 Issue 4 Pages
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[in Japanese]
Article type: Article
2001 Volume 57 Issue 4 Pages
I-
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
II-IV
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
V-
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
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EITARO NISHIHARA, [in Japanese], [in Japanese]
Article type: Article
2001 Volume 57 Issue 4 Pages
367-371
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YOSHIHISA AKIYAMA, [in Japanese], [in Japanese], [in Japanese], [in Ja ...
Article type: Article
2001 Volume 57 Issue 4 Pages
372-376
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Eishu Shinkai
Article type: Article
2001 Volume 57 Issue 4 Pages
377-387
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Katsutaro Kaneko
Article type: Article
2001 Volume 57 Issue 4 Pages
388-392
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KAZUO AWAI, [in Japanese], [in Japanese], [in Japanese], [in Japanese] ...
Article type: Article
2001 Volume 57 Issue 4 Pages
393-410
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TOSHIHIRO OGURA, [in Japanese], [in Japanese]
Article type: Article
2001 Volume 57 Issue 4 Pages
411-417
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KUNIMASA MIYOSHI
Article type: Article
2001 Volume 57 Issue 4 Pages
418-420
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Planning and Research Division
Article type: Article
2001 Volume 57 Issue 4 Pages
421-424
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TSUTOMU GOMI, FENG LI, TAKASHI ANDOU, NORIAKI YOKOI, SHIGEKIYO SATOH, ...
Article type: Article
2001 Volume 57 Issue 4 Pages
425-432
Published: April 20, 2001
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The aim of this study was to evaluate thoracic computed tomography (CT) images compressed by different joint photographic experts group (JPEG) algorithms at ratios of 10:1, 20:1, 30:1, and 40:1. As a physical evaluation, the modulation transfer function (MTF) of these images was calculated, and, as a clinical evaluation, 24 chest CT images (12 control subjects and 12 with pulmonary nodules) were used. Five radiologists interpreted the presence or absence of nodules and evaluated the quality of images. The detection of nodules was studied by receiver operating characteristic (ROC) and power spectral analyses. MTF was decreased at compression ratios higher than 20:1, owing to the influence of blocking artifacts. There was no significant difference in nodule detection by ROC and power spectral analysis between uncompressed and compressed CT images. The quality of images compressed at ratios higher than 20:1 was inferior. JPEG algorithms allow the compression of CT images without compromising their diagnostic value at a ratio of 20:1.
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HIROSHI SATO, TAKAHITO KATANO, YOSHIFUMI NAKAMURA, YOSHIAKI KITAMURA
Article type: Article
2001 Volume 57 Issue 4 Pages
433-439
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When chest radiographs are obtained using an anti-scatter grid in a mobile x-ray unit by Fuji Computed Radiography (FCR), right lung densities may differ from left lung densities owing to misalignment caused by an oblique x-ray beam. Such misalignment is considered to be caused by factors such as the shape of the bed and angle of the x-ray tube. Misalignment is especially frequent when exposure is carried out in the sitting position. Although a low-ratio grid has been reported to offer improvement, the misalignment is not completely eliminated. Therefore, we used a copper plate without a lattice feature instead of grid, and examined the results. The copper plate was found to have the ability of a grid to eliminate radiation scatter, and, furthermore, to offer the physical capabilities of a grid as determined by Carlin's new grid assessment method. Image quality was demonstrated through contrast manipulation to be equal to that obtained by grid use. Further, optimal conditions were found to be a 95 kV tube voltage and 0.3 mm thick copper plate.
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KOICHI SHIBUYA, KOICHI MIYAKE, TSUGUTO OEDA, TERUMASA FUJI, YOSHITADA ...
Article type: Article
2001 Volume 57 Issue 4 Pages
440-443
Published: April 20, 2001
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Rates of Flow of barium meal into the bowel and ease of swallowing a barium meal and foaming agent were investigated according to the procedure of administration, in order to study the timing of adding the foaming agent. In group medical examinations, the flow rates of barium meals of 100 examinees given a barium meal followed by a foaming agent were compared with those of the same examinees given the foaming agent first. Parasympatholytic agents were not administered in this study. When the foaming agent was given before the barium meal, the flow rate of the barium meal into the bowels was 44.0%. In contrast, when the foaming agent was given after the barium meal, the rate was 78.0%. A total of 67.3% of 101 Volunteers given the foaming agent and the barium meal twice in the reverse order answered that it was easier to swallow the barium meal first. When a parasympatholytic agent is not given, it is better to give the foaming agent first, even though it is more difficult to swallow the barium meal after the foaming agent, because it is most important in examination of the stomach that the barium meal does not flow out into the bowel.
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AKIO OGURA, TAKAHARU HONGOH, HIROSHI INOUE, MASARU YAMAZAKI, MITSUHARU ...
Article type: Article
2001 Volume 57 Issue 4 Pages
444-448
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In MR imaging, the time-varying magnetic field associated with gradients induces electric fields in the human body and may stimulate nerves and even the heart. The time rate of change in gradient magnetic fields on echo planar imaging (EPI) needs to exceed 20 mT/ms. EPI has recently become more widely used in the clinical field, and the protection of patient safety during MR scans has become an issue. However, dB/dt as an index of the time-varying magnetic field is not displayed on the operating monitor. Therefore, dB/dt of various scan techniques was measured using a search coil and storage oscilloscope, according to the IEC standard method. The results demonstrated that dB/dt of EPI, spin-echo, and field-echo techniques are much the same. Thus, the possibility of a risk to health resulting from EPI scanning is the same as that for other scanning techniques that use a high-performance MRI system. Therefore, even with spin-echo scanning, it is necessary to consider biological change in patients.
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
449-452
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
453-
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
454-
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
455-459
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
460-462
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
463-494
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
495-508
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Article type: Appendix
2001 Volume 57 Issue 4 Pages
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Article type: Cover
2001 Volume 57 Issue 4 Pages
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