著者

Enrico Tedeschi Sirio Cocozza Pasquale Borrelli Lorenzo Ugga Vincenzo Brescia Morra Giuseppe Palma

出版者

日本磁気共鳴医学会

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.cr.2016-0137, (Released:2017-03-27)

参考文献数

24

被引用文献数

9

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We report the assessment of Dentate Nuclei (DN) R1 (1/T1) and R2* (1/R2*) values in a patient with relapsing-remitting Multiple Sclerosis, exposed to 22 standard (0.1 mmol/kg) doses of gadobutrol, who underwent eight relaxometric magnetic resonance (MR) measurements within two years. DN R1 did not significantly increase nor correlated with cumulative gadobutrol administration, even after a total dose of 130 ml. Likewise, DN R2* relaxometry remained unchanged. In conclusion, massive gadobutrol exposure did not induce significant DN relaxometry changes.

著者

押尾 晃一

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.2021-1752, (Released:2022-03-07)

参考文献数

10

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Gradient echo sequences (GRE sequences) might look simple on the sequence diagram, but understanding their principles is more difficult. In this review, the four main types of GRE sequences are explained. Since GRE sequences rely on spin echoes as well as stimulated echoes, coherence pathways and echo formation are also explained. Moreover, the history of the development of GRE sequences is briefly described.

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.

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.2, pp.72-81, 2020-05-15 (Released:2020-06-15)

参考文献数

18

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Recently, magnetic resonance imaging (MRI) of many medical devices has been allowed. However, risks of MRI of clothes, materials pasted on the body, body art, etc., are unclear. Moreover, the correspondence of the MRI operator with the patient varies. MRI is performed after removing such items that are removable. However, judgments regarding the items that are difficult to remove or cannot be removed are difficult to make. Operators need to correctly understand the risk level of each item to improve patient service and find out the appropriate method for performing MRI. As for dental implants, we need to understand their types, structure, and characteristics. For patients with tattoos, we must explain the risk of heating. Furthermore, we place a spacer between both legs, between a hand and gantry, when performing MRI to reduce the intensity of the induced current. As for nail art, thick gloves are effective for preventing suction and heating. As for thermal clothing, we should compare the risk level and frequency of occurrences of burns due to heating with fractures due to falling. When we perform MRI without removing thermal clothing, we should recognize the possibility of overheating and try to keep the patient from sweating. When we scanned cosmetics containing iron oxide with the upper limit level of the first standard management operation mode, the skin temperature rose by approximately 3℃ in approximately 10 min. When we perform MRI without removing makeup, we should tell the patient to use the emergency call instantly if a heat sensation is felt. When a heating test was performed under the same conditions as those created by cosmetics, the volunteers felt warm immediately after the start of the scan, and the scan had to be stopped within approximately 2 min because of heat. The temperature of hair rose to approximately 42℃. We should remove as much hair powder as possible because the head heats up and distorts the image. We performed MRI with a surgical hair cap on a patient. Risks posed by hair powder are higher than those posed by cosmetics. Furthermore, if hair powder splatters, the MRI scan becomes unusable. However, these items are not contraindications to MRI, and we may be able to perform MRI with adequate knowledge and attention. However, MRI cannot always be performed safely, and the highest risks during MRI are caused by incomplete knowledge and inappropriate techniques.

著者

加々美智 成田浩

出版者

日本磁気共鳴医学会

雑誌

第42回日本磁気共鳴医学会大会

巻号頁・発行日

2014-09-11

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【背景】過去のMRI安全の報告によると、遠赤外性を謳ったインナーにおいて、火傷の報告や画像への影響が報告されている。また、衣服の装飾品や、クリーニング後のホッチキスの芯が画像に影響を及ぼす可能性は知られている。MRI検査時に検査着に着替えさせ検査を行うことが推奨されているが、インナーは身につけたままで検査を行っているケースは多い。2003年に株式会社ユニクロよりヒートテックが発売されて以来、保温インナーは世界中で広がっている。また、各衣服メーカーより類似製品が販売され始め、国内では多くの方がヒートテックや類似製品を着用している。【目的】MRI検査時に患者が着用している保温インナーが、画像や人体に及ぼす影響について基礎検討をすることを目的とした。【使用機器】(株)日立メディコ社製1.5TMRI装置ECHELON OVALを用い、本体付属ファントムとNVコイル、保温インナーや、一般的なインナーなどを用いた。【実験方法】コイル中心にファントムを配置し、SE法、およびGE法において検討を行った。ファントムには温度計を張り付け、何も巻き付けない、一般的な肌着、保温下着、スポーツインナーなど巻き付け素材を変更し、5種類の撮像を行った。また、巻き付け回数を変化させ撮像を行った。撮像開始は、ファントムの流動がなくなるように20分以上待機してから撮像を行った。検討方法は差分法を用いてSNRを測定し、t検定を行った。【結果】肌着の種類や巻き方に応じてGE法ではSNRの低下がみられ、5%以下で優位に差が生じた。【まとめ】検討によりインナーの材質、厚みによってはMRI信号に影響を及ぼし、患者の体温を上昇させる可能性が示唆された。厚生労働省のSARに関する記載では、患者の温度変化に関して、第一次水準管理操作モードで1度以上の変化がないことや、体温の最大値は規定されている。保温インナーはこれらの規格を超える恐れがあり、注意が必要である。

著者

三木 幸雄

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.2020-1715, (Released:2020-09-28)

参考文献数

13

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This article describes how to organize sentences in English papers on magnetic resonance field. In particular, “paragraph writing” and “coherence” are important skills required to logically organize sentences. This article explains them in detail with a number of examples from published papers on magnetic resonance. The ability to write in English may become less important in the near future due to the rapid progress of automatic translation technologies, using artificial intelligence (AI) such as Google Translate and DeepL. However, arranging English sentences and organizing them in a logical manner will continue to be an essential task for authors, even in the age of AI. I hope that this article will be of help to young researchers who plan to write manuscripts in English.

著者

雨宮史織 高橋浩一 美馬達夫 吉岡直紀 大友邦

出版者

日本磁気共鳴医学会

雑誌

第42回日本磁気共鳴医学会大会

巻号頁・発行日

2014-09-11

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【目的】自発的神経活動および認知機能異常とこれの治療による変化を低髄液圧症候群/脳脊髄液減少症患者において縦断的に評価する事。【方法】低髄液圧/脳脊髄液減少症患者の硬膜外ブラッドパッチ術施行直前及び手術一ヶ月後に安静時fMRIおよびworking memory課題を用いた認知機能評価を施行した。安静時fMRIは撮像タイミング補正、体動補正、空間的標準化、平滑化による標準的前処理の後に線形トレンド除去、低周波成分抽出(0.01-0.1 Hz)を行い同帯域での振幅の積分値を各全脳平均値で除して標準化し、自発的神経活動の指標とした(amplitude of low-frequency fluctuations, ALFF)。認知機能指標は2-back課題の正答率とした。これを回帰変数としてALFFの全脳線形回帰分析を行い両者に有意な相関のある領域を同定した。また交互作用検定により両者の相関に有意な縦断的変化があるか評価した。【結果】2-back課題の正答率は術後有意に改善した(p < 0.05)。全脳解析では認知機能指標と楔前部のALFFに正の相関、右内側前頭前皮質/前部帯状回、両側眼窩前頭皮質のALFFに負の相関が見られた(多重比較補正後p < 0.05)。右内側前頭前皮質/前部帯状回、両側眼窩前頭皮質におけるALFFと認知機能指標の負の相関は術後有意に低下した(p < 0.05)。【結論】task-positive networkにおけるALFFと認知機能指標には健常者にて正の相関がある事が知られるが、本術前患者では両者の関係は反転しており、認知機能障害の強い患者でtask-positive networkであるfrontoparietal control systemにおける異常な自発的神経活動の上昇およびdefault mode networkでの神経活動低下が示唆された。認知機能障害とtask-positive networkでの相関は術後の認知機能の回復にともなって減弱ないし反転しており、正常化が示唆された。これらは脳脊髄液減少下における機械的圧排/浮力低下に伴う前頭葉底部での異常神経放電が、可逆性認知機能障害の原因となるという仮説を支持するものである。

著者

対馬 義人

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.2, pp.55-61, 2020-05-15 (Released:2020-06-15)

参考文献数

27

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In the European Society of Urogenital Radiology (ESUR) guidelines 10.0, the usefulness of premedication, such as steroids, which is widely used for patients with risk factors for acute (immediate) adverse effects, has been disproved, and the recommendation of premedication has been scrapped. Certainly, there is no evidence that premedication is effective for preventing the occurrence of adverse effects or reducing the severity. How this change would be applied in the actual clinical setting is controversial. There is no major change in management of acute adverse effects. For this point, however, recommendation no. 3 laid down by the Japan Medical Safety Research Organization in 2019 should be referred to. If anaphylaxis is suspected, 0.3 mg of adrenaline should be administered in the anterolateral thigh muscle without hesitation. Even if you are not convinced of anaphylaxis, an intramuscular injection of adrenaline must be given immediately. Moreover, adverse effects of intramuscular injections of 0.3 mg of adrenaline are not a cause for concern, as the injection route is not intravenous. The knowledge of nephrogenic systemic fibrosis (NSF) is already well established. This disease was first described in the 2018 edition of the Japanese National Examination Standard for Doctors. The use of linear gadolinium-based contrast agents with low chelate stability (except EOB Primovist) is extremely limited, and occurrence probability of NSF is extremely low as long as macrocyclic gadolinium-based contrast agents are used. Patient-related risk factors are eGFR <15 mL/min/1.73 m3 and dialysis. Gadolinium accumulation (retention) in the body and environmental diffusion have recently been described. Although the accumulation of gadolinium in the body is widely known, its clinical significance is unknown. Since gadolinium is an element, once it diffuses in the environment, it is almost impossible to recover it. However, its effect on humans is unknown.

著者

丸山 裕稔

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.2, pp.62-71, 2020-05-15 (Released:2020-06-15)

参考文献数

5

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Optimization of scan parameter is important for acquiring high-quality image during MRI examination. This study describes the method of constructing a human-tissue-equivalent phantom useful in optimizing the scan parameter. The main ingredient of constructing phantom is gadolinium contrast agent. T1 and T2 values can be modulated by varying the concentration of gadolinium contrast agents and composing agarose. The construction of phantom is a time and effort intensive process. However, ample scan data are acquired using phantom scans. Comparing the phantom scans to that of volunteer scans will help objectively evaluate the quality of scanned images. Therefore, it is possible to set optimum scan parameter.

著者

礒田 治夫

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.39, no.4, pp.126-136, 2019-11-15 (Released:2019-12-05)

参考文献数

29

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For larger blood vessels, such as cervical arteries and aortic arteries, 4D-Flow imaging with high signal to noise ratio (SNR) can be used to collect accurate measurements. When the SNR is sufficient and the voxel size is less than 30% of the vessel diameter, the error rate for the cross-sectional average flow velocity obtained by 4D-Flow is less than 10%. When the SNR is sufficient and the voxel size is less than 10% of the vessel diameter, error rate for the maximum flow velocity is also less than 10%. However, for smaller vessels, such as intracranial arteries, 4D-Flow imaging underestimates the flow velocities owing to the low spatial resolution or low SNR. Meanwhile, because of the partial volume phenomenon, the velocity of each voxel is underestimated within the vessel and overestimated near the vessel wall. Thus, the spatial resolution affects the velocity profile in the blood vessels. Higher spatial resolution leads to more accurate velocity profile and more accurate wall shear stress (WSS). However, it should be noted that the WSS determined by 4D-Flow is smaller compared to the true value. We can obtain the 3D velocity vector fields, maximum flow velocity, spatially averaged flow velocity, volume flow rate, streamlines, pathlines, streak lines, and WSS and its derivatives using a flow analysis software. The spatial resolution and SNR of 4D-Flow affects the accuracy of each voxel, velocity profile in blood vessels, and ultimately, the calculated WSS. However, there is a trade-off between the spatial resolution and SNR and hence there are limitations to increase the spatial resolution. Artificial intelligence (AI) may be able to interpolate lower spatial resolution data, and therefore, address this problem in the future. AI may also help us to obtain flow related biomarkers like WSS and its derivatives more easily and quickly in clinical practice. Development of the magnetic resonance fluid dynamics is ongoing and can provide a promising solution.

著者

北尾 梓 松井 修 米田 憲秀 小坂 一斗 小林 聡 香田 渉 井上 大 扇 尚弘 吉田 耕太郎 蒲田 敏文

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.3, pp.102-109, 2020-08-15 (Released:2020-09-26)

参考文献数

26

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Hepatobiliary specific contrast medium Gd-EOB-DTPA-enhanced MRI (EOB-MRI) is excellent for the detection and characterization of nodular lesions and plays an important role in the diagnosis of hepatocellular carcinoma (HCC). Gd-EOB-DTPA is received by normal hepatocytes, and then, excreted into bile ducts, under mediation by hepatocyte membrane transporters. The expression of uptake transporter organic anion transporting polypeptide 1B3 (OATP1B3) correlates with the enhancement ratio in the hepatobiliary phase of HCC. Consequently, OATP1B3 is the main uptake transporter of Gd-EOB-DTPA in HCC. The hepatobiliary phase of EOB-MRI can sensitively detect pathologically early HCC as a hypointense nodule, because the OATP1B3 expression decreases at an early stage of multistep hepatocarcinogenesis. Hypervascular HCC commonly presents hypointensity in the hepatobiliary phase with the decrease in the OATP1B3 expression ; however, approximately 10% of HCC atypically demonstrates hyperintensity, owing to OATP1B3 overexpression. HCC presenting hyperintensity in the hepatobiliary phase is a unique genetic subtype of HCC with a biologically less aggressive nature and mature hepatocyte-like molecular/genetic features. The interaction between β-catenin signaling and hepatocyte nuclear factor (HNF) 4α may plays an important role in the OATP1B3 expression and less aggressive biological nature of the hyperintense HCC in the hepatobiliary phase. Thus, EOB-MRI is crucial for the detection and characterization of HCC as well as for personalized medicine, such as an imaging biomarker.

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

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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

吉田 学誉

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.2, pp.48-54, 2020-05-15 (Released:2020-06-15)

参考文献数

12

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Contrast-enhanced magnetic resonance imaging (CE-MRI) has overcome the drawback of non-CE-MRI of incomplete image information. However, the use of contrast agents requires consideration of the side effects and accident risks during injection, and the ability to respond promptly requires knowledge of treatment and management for the same. Side effects of contrast agents and accidents during contrast injections occur with a fixed probability. Attached documents and manuals describing side effects of contrast agents are provided by pharmaceutical companies, and many hospitals prepare manuals based on such information. However, little is known about puncture accidents during contrast agent injection, and the knowledge of treatment in case of accidents is often obtained from experience. Preventive measures for accidents during contrast media injections are necessary. Here, we elaborate our ideas on these safety measures.

著者

大内 翔平 伊藤 聡志

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.39, no.1, pp.29-32, 2019-02-15 (Released:2019-03-18)

参考文献数

5

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Compressive sensing (CS) is an effective approach for fast magnetic resonance imaging (MRI). To improve the reconstruction accuracy and computational speed, we propose a novel deep architecture using deep learning. Experiments on MR image reconstruction demonstrate that proposed method significantly accelerates the reconstruction time, with image quality comparable to that of traditional iterative reconstruction.

著者

笈田武範 武藤正人 小林哲生

出版者

日本磁気共鳴医学会

雑誌

第42回日本磁気共鳴医学会大会

巻号頁・発行日

2014-09-11

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【背景・目的】近年,他のモダリティとの融合や小型軽量化などの理由から,超低磁場MRIの研究が注目されている.超低磁場MRIを実現するためには,超伝導量子干渉素子(superconducting quantum interference device : SQUID)や光ポンピング原子磁気センサ(optically pumped atomic magnetometer : OPAM)などを用いて,低周波の微弱磁場を検出する必要がある.OPAMはアルカリ金属蒸気を封入したガラスセルにポンプ光・プローブ光2つのレーザを照射し,光ポンピングされたアルカリ金属原子の電子スピン偏極による磁気光学回転により磁場を計測する.OPAMは,SQUIDでは必須の冷媒が不要であり,維持コストなどの面で利点がある.しかしながら,アルカリ金属原子の電子スピン偏極の磁気回転比は,MRIにおいて主に計測対象となるプロトンの約164倍であるため,同一磁場中に試料およびガラスセルを設置すると,共鳴周波数の不一致により計測感度が低下する.この問題に対して,フラックストランスフォーマ(flux transformer : FT)を用いた遠隔計測法が提案されている.先行研究において,単一FTを用いたMR信号計測では,信号対雑音比(signal-to-noise ratio : SNR)が最大となるコイルのパラメータが存在する一方,その感度に限界があることが報告されている.本研究では,直交位相FTを用いることにより,OPAMを用いた遠隔MR信号計測のSNR向上を目指す.【方法】直交位相FTとして,鞍型コイルペアを入出力コイルとするFTをコイルペアの円筒の軸の回りに90°回転した2組のFTを用いた時の間接MR信号計測について,磁場分布の数値解析および擬似MR信号計測を用いてSNRを評価し,OPAMと直交位相FTを用いた間接MR信号計測の有効性を確認した.【結果・結論】数値解析の結果,直交位相FTを用いることにより単一のFTを用いた場合と比較して,約2倍のSNRが得られることが確認された.また,擬似MR信号計測の結果においてもSNRの向上が確認され,直交位相FTを用いることによりOPAMを用いた遠隔MR信号計測のSNR向上が可能である事が示された.

著者

Utaroh Motosugi Diego Hernando Curtis Wiens Peter Bannas Scott. B Reeder

出版者

日本磁気共鳴医学会

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

pp.mp.2016-0081, (Released:2017-02-13)

参考文献数

47

被引用文献数

9

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Purpose: To determine whether high signal-to-noise ratio (SNR) acquisitions improve the repeatability of liver proton density fat fraction (PDFF) measurements using confounder-corrected chemical shift-encoded magnetic resonance (MR) imaging (CSE-MRI).Materials and Methods: Eleven fat-water phantoms were scanned with 8 different protocols with varying SNR. After repositioning the phantoms, the same scans were repeated to evaluate the test-retest repeatability. Next, an in vivo study was performed with 20 volunteers and 28 patients scheduled for liver magnetic resonance imaging (MRI). Two CSE-MRI protocols with standard- and high-SNR were repeated to assess test-retest repeatability. MR spectroscopy (MRS)-based PDFF was acquired as a standard of reference. The standard deviation (SD) of the difference (Δ) of PDFF measured in the two repeated scans was defined to ascertain repeatability. The correlation between PDFF of CSE-MRI and MRS was calculated to assess accuracy. The SD of Δ and correlation coefficients of the two protocols (standard- and high-SNR) were compared using F-test and t-test, respectively. Two reconstruction algorithms (complex-based and magnitude-based) were used for both the phantom and in vivo experiments.Results: The phantom study demonstrated that higher SNR improved the repeatability for both complex- and magnitude-based reconstruction. Similarly, the in vivo study demonstrated that the repeatability of the high-SNR protocol (SD of Δ = 0.53 for complex- and = 0.85 for magnitude-based fit) was significantly higher than using the standard-SNR protocol (0.77 for complex, P < 0.001; and 0.94 for magnitude-based fit, P = 0.003). No significant difference was observed in the accuracy between standard- and high-SNR protocols.Conclusion: Higher SNR improves the repeatability of fat quantification using confounder-corrected CSE-MRI.

著者

Yoshimitsu OHGIYA Hiroshi NOBUSAWA Noritaka SEINO Osamu MIYAGAMI Naomi YAGI Sasamori HIROTO Jiro MUNECHIKA Masanori HIROSE Nobuyuki TAKEYAMA Nobuyuki OHIKE Ryu MATSUOKA Akihiko SEKIZAWA Takehiko GOKAN

出版者

日本磁気共鳴医学会

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

vol.15, no.2, pp.212-219, 2016 (Released:2016-04-11)

参考文献数

23

被引用文献数

15

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Purpose: To evaluate morphological and signal intensity (SI) changes of placental insufficiency on magnetic resonance imaging (MRI) and to assess morphological changes and decreased flow voids (FVs) on T2-weighted rapid acquisition with relaxation enhancement (RARE) images for diagnosing placental insufficiency.Methods: Fifty singleton fetuses underwent MRI using a 1.5-T MR scanner. Placental thickness, area, volume, SI, amniotic fluid SI, and size of FVs between the uterus and the placenta were measured on MR images. Two radiologists reviewed T2-weighted RARE images for globular appearance of the placenta and FVs between the uterus and the placenta. Data were analyzed using t-tests, McNemar’s tests, and areas under the receiver operating characteristic curve (AUCs) at 5% level of significance.Results: Twenty-five of the 50 pregnancies were categorized as having an insufficient placenta. Significant differences were observed between insufficient and normal placentas in mean placental thickness, area, volume, placenta to amniotic fluid SI ratio, and size of FVs (49.0 mm vs. 36.9 mm, 1.62 × 104 mm2 vs. 2.67 × 104 mm2, 5.13 × 105 mm3 vs. 6.56 × 105 mm3, 0.549 vs. 0.685, and 3.4 mm vs. 4.3 mm, respectively). The sensitivity and accuracy using globular appearance plus decreased FVs were greater than those using decreased FVs (P < 0.01). There was no significant difference among AUCs using globular appearance and decreased FVs, and globular appearance plus decreased FVs.Conclusions: Placental insufficiency was associated with placental thickness, area, volume, placenta to amniotic fluid SI ratio, and size of FVs. Evaluating FVs on T2-weighted RARE images can be useful for detecting placental insufficiency, particularly in placentas without globular appearance on MR images.

著者

Kang CHENG

出版者

日本磁気共鳴医学会

雑誌

Magnetic Resonance in Medical Sciences (ISSN:13473182)

巻号頁・発行日

vol.15, no.1, pp.1-10, 2016-01-01 (Released:2016-01-12)

参考文献数

48

被引用文献数

1 3

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This article reviews our exploration of structures and functions of the human visual cortex using high resolution (submillimeter) functional magnetic resonance imaging (fMRI). It discusses factors that restrict the spatial resolution of blood oxygenation-level dependent (BOLD) fMRI–the point-spread function of the BOLD signal, limited by both imaging techniques to be used and neurovascular units to be studied, and the signal-to-noise ratio. I offer personal thoughts regarding optimal solutions for dealing with these issues, summarize techniques we have developed over the years for using high resolution fMRI to visualize functional architectures and explore physiological properties in the primary visual cortex of humans, including choices of imaging hardware and pulse sequences, experimental procedures, and stimulation paradigms, and finally offer my personal opinions regarding the future of high resolution fMRI.

著者

伊藤 憲之 濵﨑 望 堂領 和彦 尾﨑 裕

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.43, no.4, pp.174-181, 2023-11-15 (Released:2023-12-08)

参考文献数

15

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Golden Angle Radial Sparse Parallel-Volumetric Interpolated Breath hold Examination (GRASP-VIBE) using compressed sensing and golden-angle radial sampling is a gradient echo (GRE) sequence that provides an inflow effect. The purpose of this study was to investigate parameters for non-contrast visualization of the renal artery using GRASP-VIBE with respiratory synchronization by the liver gate. We used a flow phantom and a self-made phantom to determine effective fat suppression methods and appropriate settings for repetition time (TR) and flip angle (FA). We also performed imaging on five healthy volunteers and compared the ability to visualize the renal artery. In the phantom study, water excitation showed the highest fat suppression effect ; the flow phantom was well visualized at TR 7.2 ms~9.0 ms and FA 9°~13°. In the volunteer study, the renal artery was best visualized at TR 7.2 ms and FA 13°. The results suggest that GRASP-VIBE can be used to visualize the renal artery without contrast enhancement by using the parameter settings examined in this study.

著者

桑島 成子

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.39, no.2, pp.39-47, 2019-05-15 (Released:2019-06-18)

参考文献数

15

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Fetal magnetic resonance imaging (MRI) is an important diagnostic modality in adjunct with ultrasound (US). The purpose of fetal MRI is to complement an US, either by confirming the US findings or by acquiring additional findings. The use of fetal MRI has been increasing in the prenatal diagnosis of fetal neck, chest, and abdominal malformations, and it is well established in other fields, especially in that of fetal CNS anomalies. This study aimed to review the application and safety of fetal MRI.