巻号一覧
19 巻 (2002)
- 3 号 p. 122-
- 2 号 p. 50-
- 1 号 p. 2-
19 巻, 1 号
選択された号の論文の5件中1～5を表示しています
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長尾 充展2002 年 19 巻 1 号 p. 2-5
発行日: 2002/01/05
公開日: 2012/08/27
ジャーナル フリーWe introduce three-dimensional fractal analysis (3D-FA) to quantify the spatial heterogeneity of radioisotope on nuclear medicine images. We delineated SPECT images using four cut-off levels, ( % of the maximal voxel radioactivity), and measured the total number of voxels in the areas surrounded by the contours obtained with each cut-off level. We calculated fractal dimensions from the relationship between the total number of voxels and the cut-off levels transformed into natural logarithms. The fractal dimensions obtained from ventilation and cerebral blood flow SPECT images were well correlated with the obstructive impairment in pulmonary function tests and the cognitive impairment in neuropsychological tests.3D-FA may be an useful method for evaluating objectively the progression of emphysema and Alzheimer'disease.3D-FA is applicable for routine clinical use because it is simple and because the fractal dimensions can be calculated easily without using special software.抄録全体を表示PDF形式でダウンロード (3575K) -
大石 茂雄2002 年 19 巻 1 号 p. 6-9
発行日: 2002/01/05
公開日: 2012/08/27
ジャーナル フリーPDF形式でダウンロード (4576K) -
妹尾 淳史, 伊藤 彰義2002 年 19 巻 1 号 p. 10-17
発行日: 2002/01/05
公開日: 2012/08/27
ジャーナル フリーIn recent years, the new SPECT data acquisition system equipped with three-head scinticameras improves the image scanning time significantly and the quality of images is improved by employing the new technetium-99m myocardial agents. QGS(Quantitative Gated SPECT)is the important method as an algorithm of the dynamic analysis of the heart. However, it is impossible to estimate the direction of the myocardium wall rotation. In order to solve this issue, we developed a new optical flow algorithm expanded to four dimensions. The application of the algorithm to QGS images accomplishes the tracing of 3-dimensional myocardium movement. The sufficient times of iteration in the algorithm for getting the stable images, is as small as 10 times. Calculated three-dimensional movement vectors of the myocardium wall were displayed with a Bull's eye displaying method. With the combination of 4-dimensional optical flow algorithm and the Bull's eye displaying method, it would be a powerful tool for showing myocardium wall motions in detail including its rotaion.抄録全体を表示PDF形式でダウンロード (5613K) -
安田 成臣, 山口 弘次郎, 梅沢 栄三, 武藤 晃一, 小原 健2002 年 19 巻 1 号 p. 18-21
発行日: 2002/01/05
公開日: 2012/08/27
ジャーナル フリーWe improve the waveform of the Radiofrequency (RF) pulse for the purpose of reducing the Specific Absorption Rate (SAR) of MRI equipments. Two RF waveforms are examined: the standard ±2π sinc function muldplied by a double exponendal function (sincDE), and the sincDE multiplied by a correctional function (sincDEF). We simulate the RF excitations of magnetization resulting from our RF pulses by solving the Bloch equation numerically, and evaluate the slice characteristics and the phase diagram of the magnetization. The results for our RF pulses are comparable to those for the standard ±2π sinc function. The areas (integrations with respect to time) of sincDE and sincDEF are 65.8% and 87.0% that of the standard ±2π sinc function, respectively. Both rectangle ratios of the frequency characteristics of sincDE and sincDEF are 115.5% that of the standard ±2π sinc function, which can be considered to be comparable to that of the standard ±2π sinc function. It is thought that the reductions of the areas of RF pulses decrease SAR.抄録全体を表示PDF形式でダウンロード (1766K) -
松原 友子, 山崎 大輔, 加藤 雅大, 原 武史, 藤田 広志, 笠井 聡, 岩瀬 拓士, 遠藤 登喜子2002 年 19 巻 1 号 p. 22-27
発行日: 2002/01/05
公開日: 2012/08/27
ジャーナル フリーit is very important to assess fibroglandular breast tissue density to define the degree of the risk that the lesions are obscured by normal breast tissue. We developed an automated classification method, in which the mammograms were divided into three regions by both the variance histogram analysis and discriminant analysis and were classified into four categories based on the ratios of each of three regions. The classification results by the normal images showed the high agreement rate between physicians and computer. In this study, we applied this scheme to abnormal cases. The assessment of fibroglandular breast tissue density was not influenced by calcifications. As a result of malignant images' classification, the influence of existence of mass regions to classification results is dependent on not only mass sizes but also these positions. Because the rate of different classifications of right and left images in malignant massdatabase is larger than that in normal one, it may be possible to apply this scheme for potential indication of the detection of mass lesions.抄録全体を表示PDF形式でダウンロード (4679K)
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