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33 巻 (2016)
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33 巻, 1 号
選択された号の論文の7件中1～7を表示しています
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MRI特集号2「MRI先端技術の“今”に迫る！」
原著論文
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Eiichi SATO, Osahiko HAGIWARA, Hiroshi MATSUKIYO, Manabu WATANABE, Shi ...2016 年 33 巻 1 号 p. i-vi
発行日: 2016/03/25
公開日: 2016/03/26
ジャーナル フリーCancerous‐region enhancement using gadolinium‐oxide（Gd2O3）suspension and 7.0‐T magnetic resonance imaging is described. The suspension consists of the saline and the Gd2O3 nanoparticles with an average diameter of less than 15nm. Six glass vials are filled with six‐different Gd densities of 0, 10, 20, 50, 100 and 200μg/ml. Utilizing T1‐weighted imaging（T1WI）, the signal intensity（image density）of Gd media seldom varied with changes in the Gd density. However, the signal intensity decreased with increasing Gd density utilizing T2*‐weighted imaging（T2*WI）. The minimum‐detectable Gd density was approximately 20μg/ml, and the minimum‐detectable Gd molar density of approximately 120 n mol/ml was higher than that of Fe in ferucarbotran colloid for liver‐cancer imaging. Subsequently, the signal intensity of the VX2‐cancer region around the cancerous milk in a rabbit thigh decreased by the femoral‐vein injection of the Gd2O3 suspension utilizing T2*WI. The VX2 is a popular rabbit cancer sold at laboratory‐animal breeding companies. After seven days from the injection, we observed the Gd2O3 nanoparticles remained in the cancerous region.抄録全体を表示PDF形式でダウンロード (8983K) -
Akihiro KITANAKA, Tosiaki MIYATI, Naoki OHNO, Hirohito KAN, Mitsuhito ...2016 年 33 巻 1 号 p. vii-xi
発行日: 2016/03/25
公開日: 2016/03/26
ジャーナル フリーThe apparent diffusion coefficient （ADC）obtained by diffusion MRI in the cerebral white matter changes significantly during the cardiac cycle even when minimizing the bulk motion effect of the brain parenchyma. However, these changes（ΔADC）depend on the hemodynamic state, including cerebral blood flow（CBF）. Here we evaluated regional hemodynamic‐independent biomechanical information on the brain and clarified the relationship between ΔADC and regional CBF（rCBF）by using diffusion and perfusion MRI. Using 3.0‐T MRI, ΔADC images were obtained using the maximum‐minus‐minimum ADC values of all cardiac phase images on a pixel‐by‐pixel basis. Moreover, the pseudo‐continuous arterial spin labeling method was used to obtain the CBF map on the same slice. We obtained a hemodynamic‐independent ΔADC map defined as ΔADC divided by rCBF, and assessed the hemodynamic‐independent ΔADC in the cerebral white matter in healthy volunteers（N＝9）. There was a good correlation between ΔADC and rCBF（R2＝0.65, P ＜0.01）, showing that ΔADC depends on rCBF, and therefore ΔADC should be normalized by rCBF. We revealed that ΔADC depends on CBF, and this analysis enabled the generation of hemodynamic‐independent biomechanical information on the degree of water molecule fluctuation in the brain.抄録全体を表示PDF形式でダウンロード (1793K) -
深田 大輝, 山本 悦治2016 年 33 巻 1 号 p. xii-xvii
発行日: 2016/03/25
公開日: 2016/03/26
ジャーナル フリーEddy currents induced by switching of gradient magnetic fields generate eddy current fields, which create undesired distortions or artifacts in images. Such image quality deteriorations are significantly amplified with diffusion‐weighted imaging or echo planar imaging. To resolve this problem, it is necessary to precisely measure the eddy current fields and understand the relationship between eddy current fields and image quality deteriorations. However, high precision measurements are time‐consuming and the relationships are complicated, as the amount of eddy current generated during MR signal acquisition varies with pulse sequence. We introduced eddy current fields to an MRI simulator, and evaluated their effects on the diffusion‐weighted images. The results revealed that there are two types of image quality degradations, which depend on the source of the eddy current fields. We applied these results to estimate the errors in diffusion coefficient images due to the eddy current fields, and proposed an error reduction method that utilizes a combination of b‐value and motion probing gradient （MPG）. With this approach, the amounts of eddy current fields got close each other so that the errors in the diffusion coefficient images decreased.抄録全体を表示PDF形式でダウンロード (2839K)
依頼総説
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－可視化は常に有効か？－水田 正弘2016 年 33 巻 1 号 p. 1-3
発行日: 2016/03/25
公開日: 2016/03/26
ジャーナル フリーWe deal with a question whether visualization is always effective for big data? “Big data" is an important key word for business, academic, medical and so on. Many persons insist “In a Big Data World we need visualization" or “What we need to deal with big data is only visualization!!" We discuss a mechanism and a limitation of visualization and generalize the visualization approach to the mini data approach.抄録全体を表示PDF形式でダウンロード (757K)
依頼総説
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神島 保2016 年 33 巻 1 号 p. 4-7
発行日: 2016/03/25
公開日: 2016/03/26
ジャーナル フリーCurrent magnetic resonance imaging （MRI） techniques and high‐quality coil system can provide exquisite anatomic detail of the wrist and fingers. They present a valuable tool for assessment and characterization of traumatic injuries to small structures, various arthropathies, and neoplastic processes. As imaging quality continues to improve, the clinical significance of MRI of this field becomes more apparent in the evaluation and management of these entities.抄録全体を表示PDF形式でダウンロード (2025K)
原著論文
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山之内 雅幸, 有村 秀孝2016 年 33 巻 1 号 p. 8-15
発行日: 2016/03/25
公開日: 2016/03/26
ジャーナル フリーIt is time‐consuming to check couch‐gantry and patient‐gantry collisions on an actual radiotherapy machine when using couch rotations for non‐coplanar beam angles. The aim of this study was to develop a computer‐graphics（CG）‐based radiation therapy simulator with physical modeling for detection of collisions between gantry and couch or patient on the radiotherapy machine. The radiation therapy simulator was three‐dimensionally reconstructed with a radiotherapy machine, couch, and radiation treatment room according to their designs by using a physical‐modeling‐based computer graphics software. An anthropomorphic chest phantom was modeled by applying a surface rendering technique to their treatment planning computed tomography（CT）images acquired from a 16‐slice CT scanner. The CG‐based radiation therapy simulator could make it possible to estimate the collision angle between gantry and couch or patient on the radiotherapy machine without verifying the collision angles in the actual radiation treatment room.抄録全体を表示PDF形式でダウンロード (1935K) -
李 鎔範, 高橋 規之, 長谷川 晃2016 年 33 巻 1 号 p. 16-21
発行日: 2016/03/25
公開日: 2016/03/26
ジャーナル フリーThe purpose of this study is to develop an automated selection method for cross‐sectional images with basal ganglia from brain CT scan. The proposed method includes binarization, morphological operation and labeling techniques. Area was calculated from the labeled region inside the cranial bones. The cross‐sectional images with basal ganglia were automatically selected using the calculated area. The method was applied to 22 cases each with 20 slices. As a result, the sensitivity and the specificity were 0.95 and 0.98 respectively. The proposed method would be a fundamental technique for the development of computer‐aided diagnosis（CAD）system.抄録全体を表示PDF形式でダウンロード (1996K)
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