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Article type: Cover
2005 Volume 61 Issue 8 Pages
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Article type: Index
2005 Volume 61 Issue 8 Pages
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Article type: Index
2005 Volume 61 Issue 8 Pages
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[in Japanese]
Article type: Article
2005 Volume 61 Issue 8 Pages
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
2-4
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2005 Volume 61 Issue 8 Pages
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
5-6
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
6-7
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2005 Volume 61 Issue 8 Pages
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2005 Volume 61 Issue 8 Pages
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2005 Volume 61 Issue 8 Pages
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
8-9
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
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2005 Volume 61 Issue 8 Pages
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ISAO YAMAGUCHI
Article type: Article
2005 Volume 61 Issue 8 Pages
1059-1072
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TSUKASA DOI
Article type: Article
2005 Volume 61 Issue 8 Pages
1073-1079
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HIDENORI SHINODA
Article type: Article
2005 Volume 61 Issue 8 Pages
1080-1086
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MASAHARU HOSHI, [in Japanese]
Article type: Article
2005 Volume 61 Issue 8 Pages
1087-1093
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YOSHIHISA MURAMATSU, [in Japanese], [in Japanese], [in Japanese], [in ...
Article type: Article
2005 Volume 61 Issue 8 Pages
1094-1103
Published: August 20, 2005
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TOSHIO ITOU, [in Japanese], [in Japanese], [in Japanese], [in Japanese ...
Article type: Article
2005 Volume 61 Issue 8 Pages
1104-1105
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HIDEMICHI KAWATA
Article type: Article
2005 Volume 61 Issue 8 Pages
1106-1110
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SHINSUKE YANO
Article type: Article
2005 Volume 61 Issue 8 Pages
1111-1115
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MASAO KIGUCHI
Article type: Article
2005 Volume 61 Issue 8 Pages
1116-1117
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Purpose : The purpose of the study is to evaluate the detection of simulated interstitial lung lesions on dual energy subtraction radiography method using a flat panel detector. Methods : Images were obtained using a flat panel detector system on dual energy technique with the exposure of 60kV and 130kV. Three types of interstitial lung lesions; micro-nodule, ground-glass and honeycomb patterns were simulated by using a chest phantom. The ROC analysis was performed, and P-values<0.05 were considered to identify significant differences. Results : The area under the ROC curve Az values on standard vs subtraction methods were 0.768 vs 0.963, 0.670 vs 0.917 and 0.768 vs 0.996 on micro-nodule, ground-glass, and honeycomb patterns, respectively. Significant differences were observed on all patterns. Conclusion : Dual energy subtraction radiography method using flat panel detector is a promising tool in the detection of interstitial lung lesions with an improved diagnostic accuracy.
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HIROYUKI KOBAYASHI
Article type: Article
2005 Volume 61 Issue 8 Pages
1118-1119
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We highly evaluate the effectiveness of Rh/Rh in Digital Mammography. Although the combination of the target/filter in digital mammography is computed based on the model formulated by Boone et al, the clinical validity of Rh/Rh, highly effective in reducing average glandular dose (AGD), is not clear. In Digital Mammography, contrast and density can be adjusted by the window width and levels of the display. Therefore, in clinical digital Mammography, Rh/Rh can be used more widely than Screen-Film Mammography (SFM). We measured the effective range of Rh/Rh and its peak kilo-voltage, changing the breast thickness and maintaining the quality of image. Then we compared Rh/Rh and Automatic Optimization Parameters (AOP) mode. Rh/Rh is equal or superior to AOP mode in any breast thickness. Especially, Rh/Rh was effective in thin breast. We can also reduce exposure dose in this case.
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HISAYA SATO
Article type: Article
2005 Volume 61 Issue 8 Pages
1120-1121
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A cardiac phantom, in which the heart rate could be changed at constant EDV and ESV, was imaged in the RAO 30° projection. To determine the effect on EDV, ESV, and SV, images were obtained at heart rates from 40 to 150 beats/min (in 10-beat increments) and frame rates of 6.3, 8.3, 12.5, and 25 frames/sec. In addition, another phantom and clinical images were used to determine changes of EDV, ESV, and SV at reduced frame rates of 12.5 and 8.3 frames/sec. At frame rates of 12.5 and 25, no changes of EDV or ESV occurred, even when there was an increase of heart rate. Errors and variations of EDV and ESV became marked at a frame rate of 8.3 frames/sec with a heart rate of 120 beats/min or more and at 6.3 frames/sec with a heart rate of 80 beats/min or more. This was probably because the maximum diastolic or systolic excursion was not reached by the left ventricle.
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MASARU NITTA
Article type: Article
2005 Volume 61 Issue 8 Pages
1121-1122
Published: August 20, 2005
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Conventional RIS terminals are fixed onto desks etc. so that the operator have to be at the terminal when retrieving information. The RIS can not be used when radiographies are obtained in the patient room and written orders are used for operation. We have devised a mobile RIS unit using portable PCs equipped with bar-code readers and wireless LAN modules to address these problems. By implementing mobile RIS terminals, general radiology staffs were able to perform the procedures more efficiently since their movement were not restricted by the position of the RIS terminals. Also in the wards, written requests were abolished and the imaging parameters could be obtained instantaneously via wireless LAN. Bar-code readers were used to read information on the patient wrist-tags to prevent misidentification.
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KIYOSHI INOUE
Article type: Article
2005 Volume 61 Issue 8 Pages
1123-1124
Published: August 20, 2005
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MASARU YAMAZAKI, EIJI YAMADA, SADAHIRO KUDOU, MITSUJI HIGASHIDA
Article type: Article
2005 Volume 61 Issue 8 Pages
1125-1132
Published: August 20, 2005
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Cases have been reported of a local rise in temperature at the patient's skin and of burns occurring during MR imaging. To verify this phenomenon, we created a phantom from agarose, saline, and preservative, and measured the increase in local temperature. In addition, phantoms of limbs of the human body shaped such that a closed loop was formed were also used. The temperature of the phantom was measured for 50 minutes in each state, i.e., where a closed loop was formed and where the loop was incomplete. Moreover, the radio frequency (RF) and gradient fields were set as respectively independent states, and the temperature of the phantom was measured. Results of the experiment showed that temperature changed from approximately 6 degrees to 11.5 degrees in the closed loop part of the phantom, whereas there was no significant change when the loop was incomplete. In addition, with exposure to RF, a significant rise in temperature occurred where the loop was closed, whereas there was no significant increase in temperature in gradient fields. This experiment demonstrated that the increase in temperature as a result of RF irradiation occurred in the closed part of the loop phantom. Consequently, a loop formed in the human body may be subject to burns in the area of contact.
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NAOKI KODAMA, TOMOYUKI KANEKO
Article type: Article
2005 Volume 61 Issue 8 Pages
1133-1139
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We examined the objective diagnosis of dementia based on changes in the corpus callosum. We examined midsagittal head MR images of 17 early dementia patients (2 men and 15 women; mean age, 77.2±3.3 years) and 18 healthy elderly controls (2 men and 16 women; mean age, 73.8±6.5 years), 35 subjects altogether. First, the corpus callosum was automatically extracted from the MR images. Next, early dementia was compared with the healthy elderly individuals using 5 features of the straight-line methods, 5 features of the Run-Length Matrix, and 6 features of the Co-occurrence Matrix from the corpus callosum. Automatic extraction of the corpus callosum showed an accuracy rate of 84.1±3.7%. A statistically significant difference was found in 6 of the 16 features between early dementia patients and healthy elderly controls. Discriminant analysis using the 6 features demonstrated a sensitivity of 88.2% and specificity of 77.8%, with an overall accuracy of 82.9%. These results indicate that feature analysis based on changes in the corpus callosum can be used as an objective diagnostic technique for early dementia.
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AKIO OGURA, FUMIE MAEDA, AKIRA MIYAI, RIKIYA KIKUMOTO
Article type: Article
2005 Volume 61 Issue 8 Pages
1140-1143
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High-resolution MRI with increased matrix size is becoming widely used. When matrix size is increased, the signal-to-noise ratio (SNR) decreases. To compensate for a poor SNR, a thick slice is often used. The purpose of this study was to assess whether slice thickness affects the signal detectability of MR images. Signal detectability was evaluated for various slice thicknesses using a contrast-detail phantom. The results showed that thinning slices led to increased signal detection but to decreased SNR because of higher contrast in the partial volume effect. In addition, increasing matrix size and slice thickness for high-resolution imaging led to a decrease in signal detection. It is necessary to consider voxel form for two-dimensional MR images and to recognize that cuboid voxels lead to increased signal detection.
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TAKASHI KAWAI, SHOJI HORIUCHI, MASUO HAYASHI, KEIICHI SUGIBAYASHI, YOS ...
Article type: Article
2005 Volume 61 Issue 8 Pages
1144-1150
Published: August 20, 2005
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Because SPECT images are acquired under normal respiration, the respiratory motion induces artifacts and decreases resolution. In this study we developed a novel method of acquiring SPECT data during deep inhalation breath-hold (BrST) and assessed its efficacy in reducing motion artifacts and improving resolution. Reproducibility studies found that variations in SPECT image homogeneity were reduced using the BrST method to within a clinically non-problematic range. An experiment using a custom-built respiration phantom showed almost complete elimination of motion artifacts and significant improvement in resolution using the BrST method. Clinical assessment confirmed a significant reduction in motion artifacts along with the improvement in resolution. The BrST method enabled visualization of lesions that previously had been impossible to detect by standard acquisition under normal respiration. The BrST method is expected to both significantly reduce motion artifacts and improve resolution.
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YOKO ARAKI, SHIGERU SANADA, TAKESHI KOBAYASHI, NORIYUKI HASHIMOTO, SHI ...
Article type: Article
2005 Volume 61 Issue 8 Pages
1151-1157
Published: August 20, 2005
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With the recent great advances in technology, the use of flat panel displays (FPD) is tending to increase. However, there is concern that the physical properties are not understood well enough by physicians to take advantage of the improved physical properties to assist them with diagnosis. Because displays of differing physical properties are being used in clinics, we have not seen enough research about the relationship between diagnostic ability and the physical properties of displays. The purpose of this study was to evaluate radiologists' performance in the diagnosis of nodules in chest radiographs with three kinds of flat panel displays : 3M-and 5M-pixel monochrome flat panel displays, and a 3M-pixel color flat panel display. Nine radiologists participated in this observer study. Sixty chest radiographs were used. Thirty-five images depicted malignant nodules, and 25 images were normal. We set for an 8-bit gray scale in advance. The radiologists' performance was evaluated with receiver operating characteristic (ROC) analysis by using a computer program (ROCKIT; Charles E. Metz, University of Chicago). Observer performance for the diagnosis of nodules in chest radiographs was not significantly different using 3M- and 5M-pixel monochrome, and 3M-pixel color flat panel displays. Further investigation of frequent spatial patterns requiring higher resolutions such as the interstitial infiltrate pattern in chest images and the microcalcifications in mammographs will be needed.
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MOTOAKI KATO, SACHIE NISHIMURA, TAKAHIDE OKAMOTO, RICHARD L. VANMETTER ...
Article type: Article
2005 Volume 61 Issue 8 Pages
1158-1169
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In projection radiography, stationary grids are indispensable accessories to the improvement of diagnostic imaging. On the other hand, they are becoming one of the issues facing digital image processing. The lead foil that composes the grid can produce moire on printed films and monitors according to the sampling interval at which the image is read by computed radiography (CR), creating a major obstacle to diagnosing images. The subject of this study on Grid Detection and Suppression (GDS) was the development of comprehensive image-processing software to detect and suppress grid lines automatically. Our results showed that applying GDS parameters 3〜5 could provide a sufficient effect on suppression with little impact on images through the use of a multi-purpose grid (grid ratio 8:1, density 34lp/cm) for general purposes. In projection radiography, it is expected that soft copy diagnosis will increase because the digital transition is proceeding, and the establishment of high-speed networks is becoming easier. Therefore, the digital environment is expected to improve and the choice of grids and monitors to expand, by using software such as GDS that does not require special skills.
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MASAO AOKI, [in Japanese], [in Japanese]
Article type: Article
2005 Volume 61 Issue 8 Pages
1170-1171
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
1172-1175
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2005 Volume 61 Issue 8 Pages
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2005 Volume 61 Issue 8 Pages
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
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2005 Volume 61 Issue 8 Pages
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2005 Volume 61 Issue 8 Pages
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Article type: Appendix
2005 Volume 61 Issue 8 Pages
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2005 Volume 61 Issue 8 Pages
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2005 Volume 61 Issue 8 Pages
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Article type: Cover
2005 Volume 61 Issue 8 Pages
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