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学位論文 |
学位
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笠井, 治昌 ; Kasai, Harumasa
概要:
博士論文要旨Abstract 要約Outline 以下に掲載：Radiological Physics and Technology 7(2) Springer. 共著者：Harumasa Kasai, Tosiaki Miyati, Tatsuya Kawai, Hirohito Kan, Makoto kawano, Yuta Shibamoto
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論文 |
論文
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上田, 優 ; 宮地, 利明 ; 澤, 健太郎 ; 笠井, 治昌 ; 川野, 誠 ; 原, 眞咲 ; 芝本, 雄太 ; 大野, 直樹
概要:
金沢大学医薬保健研究域保健学系<br />The purpose of our study is to evaluate restricted diffusion of the water molecules caused by the t
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rabecular bone structure of the vertebra using a phantom. On a 1.5-T MRI, single shot diffusion echo planar imaging was used with b factors of 0, 500, and 1000s/mm2, effective TE of 80 ms, and TR of 2000ms. We determined ADC values with an original phantom, which consists of sponges with different space diameters and dry vertebral bone into the container filled with pure water We assessed the effects of values (0, 500, 1000s/mm2) and acquisition matrix (64×64, 128×128, 256×256) . ADC of the sponge increased as space diameter due to change in restricted diffusion of the water molecules, and was the same level of the dry vertebral bone. Moreover, ADC varied with b values and matrix sizes. Our original phantom enables to analyze restricted diffusion, and ADC is affected by the trabecular bone structure.
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| 3.
論文 |
論文
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大野, 直樹 ; 宮地, 利明 ; 間瀬, 光人 ; 笠井, 治昌 ; 菅, 博人 ; 朝日, 美幸 ; 川野, 誠 ; 原, 眞咲 ; 芝本, 雄太 ; 上田, 優
概要:
金沢大学附属病院放射線部<br />We evaluated regional apparent diffusion coefficient (ADC) change of the brain during the cardiac cycl
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e (ΔADC) . On a 1.5-T MRI, ECG-triggered single-shot diffusion echo planar imaging was used with sensitivity encoding, half scan and rectangular FOV techniques to minimize the bulk motion such as brain pulsation, i.e., data-sampling window of 3ms. ΔADC image was calculated from maximum minus minimum ADC value of all cardiac phase images on a pixel-by-pixel basis. We determined ΔADC in regions of parietal, frontal, temporal and occipital white matters (WM) in twelve healthy volunteers. Moreover, we assessed influences of scan parameters on ΔADC. ΔADC was affected by b-values, but unaffected by voxel size. There was no significant correlation between ΔADC and ADC. The ΔADC values in parietal WM at centrum semiovale level were significantly higher than those in temporal WM at basal ganglia level, although there was no significant difference in ADC values between among WM regions. ΔADC analysis using appropriate scan parameter makes it possible to noninvasively obtain new and more detailed information on the regional brain condition.
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論文 |
論文
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笠井, 治昌 ; 宮地, 利明 ; 朝日, 美幸 ; 加藤, 勝也
概要:
医薬保健研究域保健学系<br />The aim of our study was to compare between fat-suppression method with adiabatic pulse and that withou
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t adiabatic pulse, i.e., spectral presaturation with inversion recovery (SPIR) , when radio frequency (RF) penetration affected degree of fat-suppression. We determined the signal change and image uniformity in fat-suppressed area under varying the coil loading with sodium chloride solutions. The adiabatic pulse method showed greater degree of fat-suppression and image uniformity more than SPIR under especially higher density of sodium chloride solutions or a big body if inversion time of the adiabatic pulse method was appropriately set. The adiabatic pulse method makes it possible to evenly suppress the fat signal without affecting the RF penetration.
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| 5.
論文 |
論文
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小野, 絵理 ; 宮地, 利明 ; 大野, 直樹 ; 笠井, 治昌 ; 原, 真咲 ; 芝本, 雄太 ; 川野, 誠 ; 朝日, 美幸
概要:
金沢大学医薬保健研究域保健学系<br />We evaluated the R2* (iron content) and fat fraction of the liver tissue simultaneously using modul
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us and real multiple gradient-echo (MRM-GRE) sequence. On a 1.5-T MRI, modulus images of 7-9 gradient-echoes were obtained by MRM-GRE sequence at a time. A real part of the first echo image was also reconstructed to differentiate below and above the 50 percent fat fraction. The fat fraction and R2* were obtained from the parameters of a theoretically fitted formula with each echo signal. R2* and fat fraction were measured with MRM-GRE in the phantom and the liver in normal volunteers (n=6) and patients with fatty liver (n=4) . MRI-derived fat fraction of the phantom was in good agreement with the actual value, and R2* of the phantom showed a strongly positive correlation with the actual iron content. MRI-derived fat fraction in fatty liver was significantly higher than that in the normal volunteers. However, no significant difference in R2* was found between fatty liver and normal volunteers. These results show that the MRM-GRE enables to differentiate the causes of signal reduction whether increasing R2*or increasing fat fraction. The MRM-GRE method makes it possible to simply and accurately assess the fat content and the iron content.
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論文
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菅, 博人 ; 宮地, 利明 ; 櫻井, 亮介 ; 笠井, 治昌 ; 川野, 誠 ; 依光, 里沙 ; 北中, 章博 ; 三平, 佐弓 ; Kan, Hirohito ; Miyati, Toshiaki ; Sakurai, Ryosuke ; Kasai, Harumasa ; Kawano, Makoto ; Yorimitsu, Risa ; Kitanaka, Akihiro ; Mihira, Sayumi
概要:
Fast spin echo(FSE)sequence has been widely recognized that the contrast of T2 weighted image was affected by multi-refocusing pulses. The contrasts have never been investigated in case of echo space(ES)below 20msec although magnetic
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resonance imaging(MRI)developed such that the ES of multi-refocusing pulses could set at 5msec. To evaluate the contrasts of fat with short ES, we determined the signal intensities of the brain tissues and bottle phantom which consists of lard, water and bean oil. The signal intensities of all regions increased with decreasing echo spaces, due to the decoupling of J-coupling, excepting water signal intensity. In addition, the contrasts between the white matter and each region decreased with decreasing ES until 10ms and, however, did not change with decreasing ES over 10ms. The contrast between white and gray matter is also discussed. It is concluded that the contrast does not change in case of the echo space below 10ms.
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| 7.
論文 |
論文
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上田, 優 ; 宮地, 利明 ; 澤, 健太郎 ; 笠井, 治昌 ; 川野, 誠 ; 原, 眞咲 ; 芝本, 雄太 ; 大野, 直樹
概要:
The purpose of our study is to evaluate restricted diffusion of the water molecules caused by the trabecular bone struct
…
ure of the vertebra using a phantom. On a 1.5-T MRI, single shot diffusion echo planar imaging was used with b factors of 0, 500, and 1000s/mm2, effective TE of 80 ms, and TR of 2000ms. We determined ADC values with an original phantom, which consists of sponges with different space diameters and dry vertebral bone into the container filled with pure water We assessed the effects of values (0, 500, 1000s/mm2) and acquisition matrix (64×64, 128×128, 256×256) . ADC of the sponge increased as space diameter due to change in restricted diffusion of the water molecules, and was the same level of the dry vertebral bone. Moreover, ADC varied with b values and matrix sizes. Our original phantom enables to analyze restricted diffusion, and ADC is affected by the trabecular bone structure.
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| 8.
論文 |
論文
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今井, 広 ; 春日, 敏夫 ; 宮地, 利明 ; 笠井, 治昌 ; 川野, 誠 ; 杉山, 雅之
概要:
Parallel imaging in magnetic resonance imaging (MRI) is a method to reduce the acquisition time by using phased array coils. However, there are a small number of commercial diagnostic MR imagers which could be used that method. Therefore,
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we developed a parallel imaging program for sensitivity encoding (SENSE). We produced sensitivity maps calculated from phantom images which was obtained with each coil element. Next, we eliminated wrap-around artifacts by using the sensitivity maps. Parallel imaging with SENSE made it possible to achieve fast scan or remove wrap-around artifacts.
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