著者

藤原 康博 石田 翔太 木村 浩彦

出版者

日本磁気共鳴医学会

雑誌

日本磁気共鳴医学会雑誌 (ISSN:09149457)

巻号頁・発行日

pp.2020-1719, (Released:2020-09-28)

参考文献数

77

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Arterial spin labeling (ASL) is a method for evaluating perfusion that uses magnetically labeled arterial blood water as an endogenous tracer. Although research and technical development have been conducted for a long time, introduction of ASL into clinical practice has been delayed because of its low signal-to-noise ratio (SNR). In recent years, advances in the pulse sequence and hardware, such as high static magnetic fields and high-sensitivity phased array coils, have made it possible to obtain high-SNR ASL images in a clinically acceptable time. In this regard, a consensus paper proposed simple and standard usage, including recommended techniques and parameters, to obtain a consistent image quality. Major MR manufacturers offered ASL pulse sequences based on this study. Hence, ASL has been used in clinical practice, and the effectiveness in measuring perfusion using ASL has been reported for the diagnosis of various neurological disorders. This article will review the technique for perfusion measurement and quantification and the recent technical progress in ASL.

著者

森下 雄太 宮地 利明 上田 丞政 清水 満 濱口 隆史 藤原 康博 林 弘之

出版者

日本放射線技術学会 = Japanese Society of Radiological Technology

雑誌

日本放射線技術學會雜誌 = RADIOLOGICAL TECHNOLOGY (ISSN:03694305)

巻号頁・発行日

vol.64, no.5, pp.587-590, 2008-05-20

参考文献数

13

被引用文献数

2

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The purpose of our study was to assess the mechanical effect on tattoo seals and eye makeup caused by a spatial magnetic gradient in the magnetic resonance imaging (MRI) system. Seven kinds of tattoo seals and three kinds of eye makeup, i.e., mascara, eye shadow, and eyeliner were used. On a 3.0-Tesla MRI, we determined these deflection angles according to a method established by the American Society for Testing and Materials (ASTM) at the position that produced the greatest magnetically induced deflection. Eighty-five percent of the tattoo seals showed deflection angles greater than 45 degrees of the ASTM guidelines, and the mascara and eye shadow showed over 40 degrees. This was because these contained ferromagnetic pigments such as an iron oxide, but those translational forces were very small owing to slight mass. However, it is desirable that these should be removed before MRI examination to prevent secondary problems.

著者

森下 雄太 宮地 利明 上田 丞政 清水 満 濱口 隆史 藤原 康博 林 弘之

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.64, no.5, pp.587-590, 2008-05-20 (Released:2008-05-29)

参考文献数

13

被引用文献数

1 2

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The purpose of our study was to assess the mechanical effect on tattoo seals and eye makeup caused by a spatial magnetic gradient in the magnetic resonance imaging (MRI) system. Seven kinds of tattoo seals and three kinds of eye makeup, i.e., mascara, eye shadow, and eyeliner were used. On a 3.0-Tesla MRI, we determined these deflection angles according to a method established by the American Society for Testing and Materials (ASTM) at the position that produced the greatest magnetically induced deflection. Eighty-five percent of the tattoo seals showed deflection angles greater than 45 degrees of the ASTM guidelines, and the mascara and eye shadow showed over 40 degrees. This was because these contained ferromagnetic pigments such as an iron oxide, but those translational forces were very small owing to slight mass. However, it is desirable that these should be removed before MRI examination to prevent secondary problems.

著者

福永 晃太 藤原 康博 圓崎 将大 小味 昌憲 平井 俊範 東 美菜子

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

pp.2023-1378, (Released:2023-08-07)

参考文献数

24

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【目的】Voxel-based quantification (VBQ) smoothingは,Montreal Neurological Institute標準空間上の定量画像に対する平滑化方法の一つである.VBQ smoothingは,組織境界の定量値の変化を抑制する特徴をもつが,脳の緩和時間マップに適用する際に緩和時間の変化をどの程度抑制できるかは明らかになっていない.本研究の目的は,緩和時間マップに対するVBQ smoothingの有用性を明らかにすることである.【方法】健常者20名を対象に2D multi-dynamic multi-echo sequenceを用いて脳を撮像し,緩和時間(T1値,T2値,プロトン密度)画像を取得した.緩和時間マップのカーネルサイズを1から6 mmまで変化させてVBQ smoothingとGaussian smoothingを適用し,脳組織を対象に平滑化後の緩和時間の変化を評価した.【結果】VBQ smoothingを適用した緩和時間マップは,Gaussian smoothingと比較して平滑化による緩和時間の変化が小さかった.また,カーネルサイズの増加に伴う緩和時間の変化は,Gaussian smoothingと比較して小さかった.そのため,VBQ smoothingは,緩和時間マップに対して平滑化を行う場合,Gaussian smoothingよりも緩和時間の変化を小さくできることが示された.【結語】VBQ smoothingは,平滑化による緩和時間の変化を抑制でき,緩和時間マップに対して有用な平滑化方法である.特に緩和時間が大きく異なる組織が隣接する領域で有用性が高い.

著者

藤原 康博 石田 翔太 木村 浩彦

出版者

日本磁気共鳴医学会

雑誌

日本磁気共鳴医学会雑誌 (ISSN:09149457)

巻号頁・発行日

vol.40, no.4, pp.149-168, 2020-11-15 (Released:2020-12-15)

参考文献数

77

---

Arterial spin labeling (ASL) is a method for evaluating perfusion that uses magnetically labeled arterial blood water as an endogenous tracer. Although research and technical development have been conducted for a long time, introduction of ASL into clinical practice has been delayed because of its low signal-to-noise ratio (SNR). In recent years, advances in the pulse sequence and hardware, such as high static magnetic fields and high-sensitivity phased array coils, have made it possible to obtain high-SNR ASL images in a clinically acceptable time. In this regard, a consensus paper proposed simple and standard usage, including recommended techniques and parameters, to obtain a consistent image quality. Major MR manufacturers offered ASL pulse sequences based on this study. Hence, ASL has been used in clinical practice, and the effectiveness in measuring perfusion using ASL has been reported for the diagnosis of various neurological disorders. This article will review the technique for perfusion measurement and quantification and the recent technical progress in ASL.

著者

福永 晃太 圓﨑 将大 小味 昌憲 東 美菜子 平井 俊範 藤原 康博

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.79, no.7, pp.663-673, 2023 (Released:2023-07-20)

参考文献数

29

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【目的】Three-dimensional (3D) quantification using an interleaved Look-Locker acquisition sequence with T2 preparation pulse(QALAS)は,緩和時間を測定可能なシーケンスの一つである.3D-QALASは短時間に高い空間分解能で撮像可能な特徴があるが,3.0 Tにおける3D-QALASの緩和時間の測定精度や従来法とのバイアスは明らかになっていない.本研究の目的は,3.0 Tにおける3D-QALASの緩和時間を従来法と比較し,明らかにすることである.【方法】3D-QALASでファントムのT1値とT2値を測定し,それらの精度を評価した.次に,健常者の脳組織のT1値,T2値,プロトン密度を2D multi-dynamic multi-echo(MDME)と3D-QALASで測定し,それらの差を評価した.【結果】ファントムによる評価において,3D-QALASのT1値は,inversion recovery spin-echoのT1値より平均8.3%延長した.3D-QALASのT2値は,multi-echo spin-echoのT2値より平均18.4%短縮した.生体による評価では,3D-QALASの平均のT1値とT2値とPDは,2D-MDMEと比較して,それぞれ5.3%延長,9.6%短縮,7.0%増加した.【結語】3.0 Tの3D-QALASはT1値が1000 ms未満では測定精度が高いが,それ以上では過大評価される.また,3D-QALASのT2値は過小評価され,T2値が長いほどその傾向は大きくなる.

著者

芳倉 太郎 西尾 孝之 藤原 康博

出版者

Osaka Urban Living and Health Association

雑誌

生活衛生 (ISSN:05824176)

巻号頁・発行日

vol.52, no.1, pp.33-43, 2008 (Released:2008-02-07)

参考文献数

73

被引用文献数

2

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The present document summarizes the achievements of Osaka City Institute of Public Health and Environmental Sciences in the study of leachate control and management at a sea-based solid waste disposal sites in Osaka City.The document covers investigative research such as analysis of changes in water quality, advanced water treatment for the removal of nitrogen and micropollutans, water treatment using activated charcoal made from wastewood, and microbiological study.

著者

藤原 康博 木村 浩彦

出版者

医用画像情報学会

雑誌

医用画像情報学会雑誌 (ISSN:09101543)

巻号頁・発行日

vol.32, no.4, pp.xxxvii-xli, 2015-12-25 (Released:2015-12-26)

参考文献数

40

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Arterial spin labeling (ASL) is a means of perfusion assessments in magnetic resonance imaging (MRI). Since ASL uses arterial blood water as an endogenous tracer, it is no need to use contrast agent or irradiation. Therefore, these features make ASL complete non‐invasive and easily accepted in routine clinical practice. Recent prevalence of 3T clinical MRI system has dramatically increased the quality of ASL image along together with the development of ASL techniques. In this paper, we have described the overview of ASL techniques such as labeling scheme, post‐label delay, background signal control, and intra vascular signal suppression. Finally, we have presented some clinical cases with ASL application from our own experience.

著者

山口 功 石森 佳幸 藤原 康博 谷内田 拓也 吉岡 千絵

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.68, no.10, pp.1295-1306, 2012-10-20 (Released:2012-10-22)

参考文献数

13

被引用文献数

1 1

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The purpose of this study was to verify the applicability of measurement of slice thickness of magnetic resonance imaging (MRI) by the delta method, and to discuss the measurement precision by the disk diameter and baseline setup of the slice profile of the delta method. The delta method used the phantom which put in the disk made of acrylic plastic. The delta method measured the full width at half maximum (FWHM) and the full width at tenth maximum (FWTM) from the slice profile of the disk signal. Evaluation of the measurement precision of the delta method by the disk diameter and baseline setup were verified by comparison of the FWHM and FWTM. In addition, evaluation of the applicability of the delta method was verified by comparison of the FWHM and FWTM using the wedge method. The baseline setup had the proper signal intensity of an average of 10 slices in the disk images. There were statistically significant difference in the FWHM between disk diameter of 10 mm and disk diameter of 30 mm and 5 mm. The FWHM of the disk diameter of 10 mm was smaller than the disk diameter of 30 mm and 5 mm. There was no statistically significant difference in the FWHM between the delta method and the wedge method. There is no difference in the effective slice thickness of the delta method and the wedge method. The delta method has an advantage in measurement of thin slice thickness.