研究者詳細 - 大久保　真樹

論文 - 大久保　真樹

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Validation of the blurring of a small object on CT images calculated on the basis of three-dimensional spatial resolution 査読

Ohkubo M, Wada S, Saito M

Igaku Butsuri 25 ( 3 ) 132 - 140 2005年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本医学物理学会

We determine three-dimensional (3D) blurring of a small object on computed tomography (CT) images calculated on the basis of 3D spatial resolution. The images were characterized by point spread function (PSF), line spread function (LSF) and slice sensitivity profile (SSP). In advance, we systematically arranged expressions in the model for the imaging system to calculate 3D images under various conditions of spatial resolution. As a small object, we made a blood vessel phantom in which the direction of the vessel was not parallel to either the xy scan-plane or the z-axis perpendicular to the scan-plane. Therefore, when scanning the phantom, non-sharpness must be induced in all axes of the image. To predict the image blurring of the phantom,3D spatial resolution is essential. The LSF and SSP were measured on our scanner, and two-dimensional (2D) PSF in the scan-plane was derived from the LSF by solving an integral equation. We obtained 3D images by convolving the 3D object-function of the phantom with both 2D PSF and SSP, corresponding to the 3D convolution. Calculated images showed good agreement with scanned images. Our technique of determining 3D blurring offers an accuracy advantage in 3D shape (size) and density measurements of small objects.

DOI： 10.11323/jjmp2000.25.3_132

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High-resolution magnetic resonance of the extracranial facial nerve and parotid duct: demonstration of the branches of the intraparotid facial nerve and its relation to parotid tumours by MRI with a surface coil 査読

N Takahashi, K Okamoto, M Ohkubo, M Kawana

CLINICAL RADIOLOGY 60 ( 3 ) 349 - 354 2005年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：W B SAUNDERS CO LTD

AIM: To investigate the usefulness of high-resolution MR imaging in the evaluation of the extracranial. facial nerve, compared with surgical findings.
MATERIALS AND METHODS: Thirteen patients with benign parotid tumours were studied on a 1.5-T MR system with a 3 in circular surface coil. High-resolution T1-weighted spin-echo, T2-weighted fast spin-echo, and three-dimensional gradient-recalled acquisition in the steady state (GRASS) images were obtained in the axial planes. Oblique reformatted images were generated. Tumours, parotid ducts and facial nerves were identified on these images. The relationship of the tumours to the facial nerves was confirmed at surgery.
RESULTS: Facial nerves appeared as linear structures of low intensity on all pulse sequences. The main trunks and cervicofacial and temporofacial divisions of the facial nerves were identified in 100%, 84.1% and 53.8% of GRASS images, respectively. Parotid ducts appeared as structures of low intensity on T1-weighted (66.6%) and GRASS images (81.8%), and as structures of very high intensity on T2-weighted images (91.7%). The relationships of the tumours to the facial nerves were correctly diagnosed in 11 (91.7%) of 12 cases.
CONCLUSION: High-resolution MR imaging depicts the extracranial facial nerve and the parotid duct, and is useful for preoperative evaluation of parotid gland tumours. (C) 2005 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.crad.2004.06.018

Web of Science

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Endorectal Coil の特性評価 MRS での使用を目的とした検討査読

八木下裕子, 内藤健一, 太田絢子, 岡純子, 大越幸和, 大久保真樹

日本放射線技術学会東北部会雑誌 14 ( 14 ) 149 - 151 2005年1月

肝臓 dynamic MRI における 3D VIBE の有用性査読

内藤健一, 八木下裕子, 岡純子, 太田絢子, 大越幸和, 大久保真樹

日本放射線技術学会東北部会雑誌 14 ( 14 ) 139 - 141 2005年1月

Measurements and precisions of point spread function of multi-slice CT 査読

S Wada, M Ohkubo, T Matsumoto

Medical Imaging 2005: Physics of Medical Imaging, Pts 1 and 2 5745 ( 22 ) 1209 - 1216 2005年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING

The determination of point spread function (PSF) is essential for the assessment of the performance of multi-slice CT corresponding to particular scanning or reconstruction condition. We studied the accuracy of the method for determination of PSF. The precision were evaluated with use of special made phantom and computer simulations. The PSF of some kinds of multi-slice CT were evaluated under the several scanning or reconstruction conditions. The performances were compared with each other and discussed. The PSF (x, y, z) was measured with separate components of PSF (x, y)) and LSF(z). In the measurement of PSF(x, y) and LSF(z), we used Boone phantom and delta phantom respectively. The PSF(x,y) was calculated from LSF(x) and LSF(y). The LSF(z) obtained from delta phantom was added for the calculation of PSF(x,y,z) with use of the following formula..
PSF(x, y, z) = PSF(x, y) (.) LSF(Z) = LSF(x) (.) LSF(y) (.) LSF(z)
The precision for the obtained LSF and PSF were evaluated by phantom experiment with computer simulation using following equations.
I (x) = LSF(x) * O(x)
I(x, y, z) = integral(infinity)(-infinity)integral(infinity)(-infinity)integral O-infinity(-infinity)(x, y, z) (.) PSF(x - x', y - y', z - z') dx dy dz
The precision of the measured PSF(x, y) was evaluated to be a good approximation for the image of the blood-vessel phantom. The results propose the method for the evaluation of the precision of measured point spread function.. At the same time this results suggests the method of the calculation of the CT image affected by spatial resolution.

DOI： 10.1117/12.596683

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CT画像系におけるline spread function(LSF)およびslice sensitivity profile(SSP)とpoint spread function(PSF)の関連査読

大久保真樹, 和田真一, 小林悌二, 李鎔範, 蔡篤儀

医学物理 24 ( 3 ) 115 - 122 2004年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：(公社)日本医学物理学会

多列Multi-slice CTの開発に伴い,これまでのline spread function(LSF)やslice sensitivity profile(SSP)を用いた1次元での検討から,2次元や3次元に拡張しての検討が重要になるが,LSFやSSPとpoint spread function(PSF)の関係について詳細に論ずる報告はみあたらない.そこで,LSFおよびSSPとPSFの関係について理論的に考察し,シミュレーションを加えて,それらの関連を明らか場合,その系のPSF'(x,y,z)はLSSFx(X)とLSFy(Y)およびSSP(z)の積で表すことができ,PSF(x,y)はLSFx(X)とLSFy(Y)の積で表すことができた

DOI： 10.11323/jjmp2000.24.3_115

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Medical image classification using genetic-algorithm based fuzzy-logic approach 査読

DY Tsai, Y Lee, M Sekiya, M Ohkubo

JOURNAL OF ELECTRONIC IMAGING 13 ( 4 ) 780 - 788 2004年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：I S & T - SOC IMAGING SCIENCE TECHNOLOGY

In this paper we present a genetic-algorithm-based fuzzy-logic approach for computer-aided diagnosis scheme in medical imaging. The scheme is applied to discriminate myocardial heart disease from echocardiographic images and to detect and classify clustered microcalcifications from mammograms. Unlike the conventional types of membership functions such as trapezoid, triangle, S curve, and singleton used in fuzzy reasoning, Gaussian-distributed fuzzy membership functions (GDMFs) are employed in the present study. The GDMFs are initially generated using various texture-based features obtained from reference images. Subsequently the shapes of GDMFs are optimized by a genetic-algorithm learning process. After optimization, the classifier is used for disease discrimination. The results of our experiments are very promising. We achieve an average accuracy of 96% for myocardial heart disease and accuracy of 88.5% at 100% sensitivity level for micro-calcification on mammograms. The results demonstrated that our proposed genetic-algorithm-based fuzzy-logic approach is an effective method for computer-aided diagnosis in disease classification. 2004, SPIE and IST.

DOI： 10.1117/1.1786607

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CT angiographyの血管描出能とpoint spread functionの関係査読

和田真一, 大久保真樹, 田中孝, 吉村宣彦, 笹井啓資, 松本徹

胸部CT検診 10 ( 2 ) 200 - 209 2004年4月

spiral SPGR法の基礎的検討査読

八木下裕子, 大越幸和, 内藤健一, 柴木充朗, 大久保真樹

日本放射線技術学会東北部会雑誌 13 112 - 115 2004年1月

Elliptical Centric法を用いた造影三次元MR Angiographyにおける造影効果持続時間および撮像タイミングに関する検討査読

八木下裕子, 大越幸和, 大久保真樹, 内藤健一, 井上智子, 蔡篤儀

日本放射線技術学会雑誌 59 ( 12 ) 1555 - 1560 2003年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：(公社)日本放射線技術学会

elliptical centric法において描出される血管の信号強度が,造影効果持続時間や撮像タイミングにより,どのように変化するかを定量的に評価した.ファントム実験を行い,centric法との比較を交えて検討した.elliptical centric法を用いた造影三次元(3D)MR angiography(MRA)において,造影効果持続時間及び撮像タイミングと,描出される血管の信号強度との関連を定量的にとらえることができた.elliptical centric法は,スラブ分割数が少ない場合にはcentric法と大きな差異はみられないが,高分解能撮像等においてスラブ分割数が多くなると,造影効果持続時間の短縮や撮像タイミングの遅れに対してcentric法よりも有利であることが明らかとなった

DOI： 10.6009/jjrt.KJ00000921687

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Fast RecoveryパルスによるFast Spin Echo画像の信号強度の増加に関する検討査読

大久保真樹, 大越幸和, 内藤健一, 八木下裕子, 蔡篤儀

日本放射線技術学会雑誌 59 ( 7 ) 879 - 882 2003年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：(公社)日本放射線技術学会

種々のT2値を持つファントムを用いて,fast recovery fast spin echo(PR-PSB)法で撮像した画像の信号強度をfast spin echo(PSE)法と比較し,fast recovery(PR)パルスによる信号強度の増加を定量的に評価した.PR-PSE法による画像の信号強度をPSE法と比較し,PRパルスによる信号強度の増加を定量的に評価できた.PRパルスの効果は,対象物のT2が長い,TRが短い,ETLが少ない,場合に大きくなる傾向がみられる

DOI： 10.6009/jjrt.KJ00003174218

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An integrated fuzzy-GA-based CAD system for disease discriminations 査読

Tsai D-Y, Lee Y, Sekiya M, Ohkubo M, Kojima K, Yamada I

Proceedings of the IASTED International Conference on BIOMEDICAL ENGINEERING 166 - 171 2003年6月

3D FIESTA法の基礎的検討査読

内藤健一, 大越幸和, 八木下裕子, 柴木充朗, 大久保真樹

日本放射線技術学会東北部会雑誌 12 124 - 127 2003年1月

造影三次元MR angiography における撮像タイミングに関するシミュレーション査読

大久保真樹, 大越幸和, 井上智子, 内藤健一, 八木下裕子, 蔡篤儀

日本放射線技術学会雑誌 58 ( 5 ) 705 - 710 2002年5月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：(公社)日本放射線技術学会

標題のシミュレーション手法を考案し,撮像のタイミングと血管描出能との関連を評価する試みを行った.その結果,撮像タイミングの変化に伴う血管の信号強度の変化を定量的に評価することができた.太い血管の描出には適切な撮像タイミングの設定が重要であり,細い血管の描出には長い造影効果持続時間(或いは撮像時間の短縮を要することが明らかになった

DOI： 10.6009/jjrt.KJ00001364431

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Evaluation of efficacy of an automated single-voxel proton MRS algorithm on a 3T system 査読

Masaki Ohkubo, Teruo Kimura, Hitoshi Matsuzawa, Tsuyoshi Matsuda, Ingrid L. Kwee, Tsutomu Nakada

Magnetic Resonance in Medical Sciences 1 ( 2 ) 121 - 124 2002年

記述言語：英語掲載種別：研究論文（学術雑誌）

Purpose: To evaluate the efficacy of a fully automatic, single-voxel, proton MR spectroscopy algorithm on a 3.0T MR system. Methods: The PROBE/SVQ algorithm (GE Medical Systems) was evaluated on a General Electric (GE) Signa LX-3T system. Ten normal volunteers (female, 21.1±2.0 years old) participated in the study. Nine representative regions of interest were examined, namely, right and left frontal white matter
right and left parietal white matter
right and left basal ganglia
right and left dentate nucleus
and pons. Results: The mean coefficients of variation in all regions for the N-acetyl-aspartate to creatine ratio (NAA/Cr), choline to creatine ratio (Cho/Cr), and choline to N-acetyl-aspartate ratio (Cho/NAA) were 10.2±2.4%, 11.4±3.2% and 12.6±1.4%, respectively. Conclusion: A fully automated spectroscopic examination under clinical setting utilizing the PROBE/SVQ algorithm appears to be a reliable method, extending the window of routine clinical assessment of brain metabolism. © 2002 by Japanese Society for Magnetic Resonance in Medicine.

DOI： 10.2463/mrms.1.121

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PubMed

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GE社製MRI装置Signaの頭頚部用Neurovascular Array Coilの評価査読

内藤健一, 大越幸和, 井上智子, 大久保真樹, 八木下裕子

新大医保紀要 7 ( 3 ) 357 - 361 2001年12月

造影三次元 MR angiography における造影効果の持続時間に関するシミュレーション査読

大久保真樹, 大越幸和, 井上智子, 内藤健一, 鈴木清隆

日本磁気共鳴医学会雑誌 21 ( 5 ) 186 - 192 2001年7月

A Morphology-Based Method for Automated Detection of Clustered Microcalcifications 査読

Tsai D-Y, Sekiya M, Lee Y, Yamazaki Y, Ohkubo M, Kojima K, Yamaada I

Proceedings of the IASTED International Conference SIGNAL PROCESSING, PATTERN RECOGNITION & APPLICATIONS 159 - 162 2001年7月

造影3次元MR angiographyに関する基礎的検討ー造影効果持続時間および撮像のタイミングについてー査読

井上智子, 大越幸和, 大久保真樹, 内藤健一

新大医保紀要 7 ( 2 ) 265 - 270 2000年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：新潟大学医学部保健学科

造影三次元MRアンギオグラフィーの造影効果持続時間と撮像のタイミングが画像に及ぼす影響について検討した.造影剤を封入した血管ファントムを用いて造影効果の有無を模擬実験した.その結果,造影時間が長くなるに従い,画像のコントラストは対数関数的に高くなった.造影効果の中心時刻がk-space中央となるデータ収集時刻と一致すれば,造影効果持続時間が多少短くなった場合でもコントラストは大きく低下することはなかった.又,造影効果中心時刻がk-space中央の時刻からずれた場合,コントラストが低下することが確認された.ただしある程度の長さの造影効果持続時間があれば,造影効果中心時刻がk-space中央から多少ずれた場合でもコントラストが大きく低下することはなかった

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超高磁場MR装置を用いたプロトンスペクトロスコピーに関する基礎研究招待査読

大久保真樹, 中田力, 松沢等, 松田豪

INNERVISION 15 ( 8 ) 66 2000年8月

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