JPH0424019A - High frequency probe for magnetic resonance apparatus - Google Patents
High frequency probe for magnetic resonance apparatusInfo
- Publication number
- JPH0424019A JPH0424019A JP2130891A JP13089190A JPH0424019A JP H0424019 A JPH0424019 A JP H0424019A JP 2130891 A JP2130891 A JP 2130891A JP 13089190 A JP13089190 A JP 13089190A JP H0424019 A JPH0424019 A JP H0424019A
- Authority
- JP
- Japan
- Prior art keywords
- high frequency
- frequency
- frequency coil
- magnetic resonance
- coil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000523 sample Substances 0.000 title claims abstract description 27
- 239000003990 capacitor Substances 0.000 claims description 20
- 230000008878 coupling Effects 0.000 abstract description 7
- 238000010168 coupling process Methods 0.000 abstract description 7
- 238000005859 coupling reaction Methods 0.000 abstract description 7
- 230000001939 inductive effect Effects 0.000 abstract description 2
- 239000004020 conductor Substances 0.000 description 4
- 230000003068 static effect Effects 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000002595 magnetic resonance imaging Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】
［発明の目的］
（産業上の利用分野）
この発明は、磁気共鳴装置において高周波磁場の発生や
磁気共鳴信号の検出に用いられる高周波プローブに係り
、特に高周波磁場分布を乱さずに簡便に同調をとること
かできる高周波プローブに関する。[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a high-frequency probe used for generating a high-frequency magnetic field and detecting a magnetic resonance signal in a magnetic resonance apparatus, and particularly relates to a high-frequency probe used for generating a high-frequency magnetic field and detecting a magnetic resonance signal in a magnetic resonance apparatus. This invention relates to a high frequency probe that can be easily tuned without disturbance.
（従来の技術）
磁気共鳴装置は固有の磁気モーメントを持つ原子核の集
団が−様な静磁場中に置かれた時に、特定の周波数で回
転する高周波磁場のエネルギーを共鳴的に吸収する現象
を利用して、物質の化学的および微視的な情報を映像化
したり、あるいは化学シフトスペクトルを観測する装置
である。このような磁気共鳴装置においては、被検体の
関心領域に高周波磁場を照射したり、それによって生じ
る磁気共鳴信号を検出するための高周波プローブか不可
欠である。(Prior art) Magnetic resonance devices utilize the phenomenon that when a group of atomic nuclei with a unique magnetic moment are placed in a static magnetic field, they resonantly absorb the energy of a high-frequency magnetic field that rotates at a specific frequency. This is a device that visualizes the chemical and microscopic information of substances or observes chemical shift spectra. In such a magnetic resonance apparatus, a high-frequency probe is essential for irradiating a region of interest of a subject with a high-frequency magnetic field and for detecting magnetic resonance signals generated thereby.
高周波プローブで検出される磁気共鳴信号は、観測対象
の核種の原子核か十分に多ければそのＳ／Ｎも高くなる
が、実際にはそうでない場合か多い。例えば診断用磁気
共鳴装置における観測対象の一つとして３１Ｐ（リン）
の化学シフトスペクトルかあるか、生体内に存在する３
１ｐは極めて微量であり、十分なＳ／Ｎの磁気共鳴信号
は得られない。このような場合には、磁気共鳴信号を積
算して観測することが行われている。The S/N of a magnetic resonance signal detected by a high-frequency probe will be high if there are a sufficient number of nuclei of the nuclide to be observed, but in reality this is often not the case. For example, 31P (phosphorus) is one of the observation targets in diagnostic magnetic resonance equipment.
Is there a chemical shift spectrum of 3 that exists in living organisms?
1p is an extremely small amount, and a magnetic resonance signal with sufficient S/N cannot be obtained. In such cases, magnetic resonance signals are integrated and observed.
しかし、この方法では必然的に観測に時間がかかってし
まうという問題かある。However, the problem with this method is that observation inevitably takes time.
時間を掛けずにＳ／Ｎ良く磁気共鳴信号を観測するため
には、静磁場強度を高くすればよい。In order to observe magnetic resonance signals with a good S/N ratio without taking much time, it is sufficient to increase the static magnetic field strength.
静磁場強度を上げると磁気共鳴周波数か高くなるため、
高周波プローブとしてはソレノイドコイル（または鞍型
コイル）キャパシタを用いた単純な共振回路構成のもの
に代えて、キャパシタによる分割型コイルやスロッティ
ッドチューブレゾネータ（Ｒｅｖ、Ｓｃｉ、Ｉｎｓｔｒ
ｕｍ、、Ｖｏｌ、４８．Ｎｏ。Increasing the static magnetic field strength increases the magnetic resonance frequency, so
Instead of a simple resonant circuit configuration using a solenoid coil (or saddle coil) capacitor as a high frequency probe, a split coil using a capacitor or a slotted tube resonator (Rev, Sci, Instr.
um,, Vol, 48. No.
１、Ｊａｎ、、１９７７、Ｐａｌ！ 〜参照）、分布定
数型コイル（鳥籠型コイル） （Ｊ、Ｍａｇｎ、Ｒｅ
５ｏｎａｎｃｅ、８３，６２２−６２８．１９８５参照
）などが使われている。1, Jan, 1977, Pal! ), distributed constant coil (birdcage coil) (J, Magn, Re
5onance, 83, 622-628.1985) are used.
これらの高周波プローブは、いずれも複数個のインダク
タと複数個のキャパシタで構成され、それらのキャパシ
タの値を等しくしないと高周波磁場の空間的均一性が損
なわれるという性質を持つ。実際に高周波プローブを使
うときには、被検体によって所定の周波数に同調をとる
だめの調整が必要であり、複数個のキャパシタの容量値
を同時に、同じたけ変化させて調整するのは非常に難し
い。このため１個所のキャパシタの容量値を変化させて
調整をしているのが現状であり、高周波磁場の均一性を
悪化させていた。All of these high-frequency probes are composed of a plurality of inductors and a plurality of capacitors, and have the property that if the values of these capacitors are not equal, the spatial uniformity of the high-frequency magnetic field will be impaired. When actually using a high-frequency probe, it is necessary to make adjustments to tune to a predetermined frequency depending on the subject being tested, and it is extremely difficult to adjust the capacitance values of multiple capacitors by changing them by the same amount at the same time. For this reason, at present, adjustment is made by changing the capacitance value of a capacitor at one location, which deteriorates the uniformity of the high frequency magnetic field.
（発明が解決しようとする課題）
上述したように、従来の高周波プローブでは複数個のキ
ャパシタの容量値を同時に調整するのは非常に難しいた
め、１個所のキャパシタの容量値を調整しており、それ
によって高周波磁場の均一性を悪化させるという問題が
あった。(Problems to be Solved by the Invention) As mentioned above, with conventional high-frequency probes, it is very difficult to adjust the capacitance values of multiple capacitors at the same time, so the capacitance value of a single capacitor is adjusted. There was a problem in that this deteriorated the uniformity of the high frequency magnetic field.
本発明は、高周波磁場の均一性を悪化させること無く同
調を容易にとることができる磁気共鳴装置用高周波プロ
ーブを提供することを目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide a high-frequency probe for a magnetic resonance apparatus that can be easily tuned without deteriorating the uniformity of a high-frequency magnetic field.
［発明の構成コ
（課題を解決するための手段）
本発明の磁気共鳴装置用高周波プローブは、高周波コイ
ルの外周側に、この高周波コイルに対して相対的に移動
可能に構成された導電性部材を配置したことを特徴とす
る。[Configuration of the Invention (Means for Solving the Problem) The high-frequency probe for a magnetic resonance apparatus of the present invention includes a conductive member configured to be movable relative to the high-frequency coil on the outer circumferential side of the high-frequency coil. It is characterized by having been placed.
（作用）
導電性部材は主として誘導的に高周波コイルと結合する
。従って、導電性部材を高周波コイルに対し相対的に移
動させると、両者の結合の程度が変わる。これは高周波
コイルのインダクタンスを等価的に変化させることにな
るから、高周波プローブの共振周波数、すなわち共振す
る磁気共鳴周波数が変化することになる。(Function) The conductive member is mainly inductively coupled to the high frequency coil. Therefore, when the conductive member is moved relative to the high-frequency coil, the degree of coupling between the two changes. Since this equivalently changes the inductance of the high frequency coil, the resonant frequency of the high frequency probe, that is, the resonant magnetic resonance frequency changes.
ここで、高周波コイルと導電性部材はほぼ同心円筒状に
、かつ軸対称に構成すれば、高周波磁場分布が不均一と
なって悪化することはほとんどない。Here, if the high frequency coil and the conductive member are configured in a substantially concentric cylindrical shape and axially symmetrical, the high frequency magnetic field distribution will hardly become uneven and deteriorate.
また、特に磁気共鳴映像装置では画像化のために勾配磁
場を利用するので、勾配磁場によって導電性部材に渦電
流が発生し、これにより新たな磁場が生じてしまう可能
性がある。これは導電性部材を複数の部分に分割し、そ
の分割した各部分を高周波的に結合することにより回避
される。Further, in particular, since a magnetic resonance imaging apparatus uses a gradient magnetic field for imaging, there is a possibility that an eddy current is generated in the conductive member due to the gradient magnetic field, and a new magnetic field is thereby generated. This can be avoided by dividing the conductive member into a plurality of parts and coupling the divided parts using high frequency.
（実施例） 以下、図面を参照して本発明の詳細な説明する。(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.
第１図は本発明の一実施例に係る磁気共鳴装置用高周波
プローブの分解斜視図である。この高周波プローブは、
高周波コイル１ｏと高周波コイル１０の外周側に所定の
距離隔てて配置された導電性部材２０とからなる。高周
波コイル１０は、この例ではインダクタ１１とキャパシ
タ１２を６エレメント用いてほぼ円筒状に構成された公
知の低域通過型の円筒状鳥籠型コイルである。FIG. 1 is an exploded perspective view of a high-frequency probe for a magnetic resonance apparatus according to an embodiment of the present invention. This high frequency probe
It consists of a high-frequency coil 1o and a conductive member 20 arranged on the outer circumferential side of the high-frequency coil 10 at a predetermined distance apart. In this example, the high-frequency coil 10 is a known low-pass cylindrical birdcage coil configured in a substantially cylindrical shape using six elements of an inductor 11 and a capacitor 12.
導電性部材２０は高周波コイル１ｏと同様にほぼ円筒状
に構成され、高周波コイル１０と同軸的に、かつ軸対称
に配置され、高周波コイル１０に対して軸方向に移動可
能となっている。The conductive member 20 has a substantially cylindrical shape similar to the high frequency coil 1o, is arranged coaxially and axially symmetrically with the high frequency coil 10, and is movable in the axial direction with respect to the high frequency coil 10.
この導電性部材２０は高周波電流の良導体、例えば銅ま
たはアルミニウムにより作製される。This conductive member 20 is made of a good conductor of high frequency current, such as copper or aluminum.
また、導電性部材２０は図示しない勾配コイルから発生
される勾配磁場の鎖交することにより渦電流が生じるの
を避けるため、軸方向に沿って切断されることにより円
周方向に複数（この例では４個）の部分２１〜２４に分
割され、その分割された各部分２１〜２４は結合用キャ
パシタ２５によって高周波的に結合されている。Furthermore, in order to avoid the generation of eddy currents due to the interlinkage of gradient magnetic fields generated from gradient coils (not shown), the conductive member 20 is cut along the axial direction so that a plurality of conductive members (in this example, In this case, it is divided into four parts 21 to 24, and each of the divided parts 21 to 24 is coupled at high frequency by a coupling capacitor 25.
このように構成された高周波プローブでは、導電性部材
２０を高周波コイル１０に対して軸方向に相対的に移動
させると、両者の誘導的結合の程度が変化することによ
り、高周波コイル１０のインダクタンスが等価的に変化
する。従って、高周波プローブの共振周波数、すなわち
共振する磁気共鳴周波数か変化するので、導電性部材２
０の位置を適切に調整することで同調をとることができ
る。また、高周波コイル１０に接続された可変容量の同
調用キャパシタ１３を用いて高周波プローブと送受信回
路（図示せず）との整合をとることができる。In the high-frequency probe configured in this way, when the conductive member 20 is moved relative to the high-frequency coil 10 in the axial direction, the degree of inductive coupling between the two changes, so that the inductance of the high-frequency coil 10 changes. change equivalently. Therefore, since the resonant frequency of the high-frequency probe, that is, the resonant magnetic resonance frequency, changes, the conductive member 2
Tuning can be achieved by appropriately adjusting the 0 position. Further, a variable capacitance tuning capacitor 13 connected to the high frequency coil 10 can be used to match the high frequency probe and a transmitting/receiving circuit (not shown).
さらに、導電性部材２０は高周波コイル１０を高周波シ
ールドするので、高周波コイル１０か高周波プローブの
外側に設置される勾配コイルや静磁場調整用シムコイル
（図示せず）と結合して磁気共鳴信号のＳ／Ｎを低下さ
せるのを防ぐ効果も期待できる。Furthermore, since the conductive member 20 shields the high-frequency coil 10 from high-frequency waves, it is coupled with a gradient coil or a static magnetic field adjustment shim coil (not shown) installed outside the high-frequency coil 10 or the high-frequency probe, and the S of the magnetic resonance signal is The effect of preventing a decrease in /N can also be expected.
第２図、第３図および第４図に、本発明の他の実施例に
おける導電性部材を示す。第２図では、分割された各部
分２１を導線２６（または導体板）により短絡して結合
し、さらに導電性部材２０全体を接地している。この実
施例によれば、被検体に対する高周波の誘電損失を低減
することができ、磁気共鳴信号のＳ／Ｎを更に向上させ
ることか可能である。2, 3, and 4 show conductive members in other embodiments of the present invention. In FIG. 2, each divided portion 21 is short-circuited and connected by a conductive wire 26 (or a conductive plate), and furthermore, the entire conductive member 20 is grounded. According to this embodiment, it is possible to reduce the high frequency dielectric loss to the subject, and it is possible to further improve the S/N of the magnetic resonance signal.
第３図に示す導電性部材３０は、軸方向と、軸方向の中
心で軸方向に垂直な面で４つの部分３１〜３４に分割し
、隣接するもの同士を結合用キャパシタ３５により高周
波的に結合している。この場合、高周波磁場の均一性を
良好にするため、導電性部材３０は軸対称、または軸方
向の中心を含み軸に垂直な面に対して面対称となるよう
に分割することが望ましく、またキャパシタ３５の取付
は位置は、これらの軸や面に対称の位置が好ましい。The electrically conductive member 30 shown in FIG. are combined. In this case, in order to improve the uniformity of the high-frequency magnetic field, it is preferable that the conductive member 30 be divided so as to be axially symmetrical or symmetrical to a plane that includes the axial center and is perpendicular to the axis. The capacitor 35 is preferably mounted at a position symmetrical to these axes and planes.
第４図に示す導電性部材４０は、断面半弧状の導体板４
１〜４８を少しずつ重ねで二重筒構造とし、外筒を構成
する導体板４１〜４４と内筒を構成する導体板４５〜４
８との間に、フッ素樹脂やポリメチルメタクリレートな
どの誘電体材料からなる誘電体板４９を介在させている
。The conductive member 40 shown in FIG.
1 to 48 are overlapped little by little to form a double cylinder structure, with conductor plates 41 to 44 forming the outer cylinder and conductor plates 45 to 4 forming the inner cylinder.
A dielectric plate 49 made of a dielectric material such as fluororesin or polymethyl methacrylate is interposed between the base plate 8 and the base plate 8 .
これら誘電体板４９とその両側の導体板により結合用キ
ャパシタが構成されている。従ってキャパシタを接続す
る工程が不要となり、製造が容易となる。These dielectric plates 49 and the conductor plates on both sides constitute a coupling capacitor. Therefore, the process of connecting the capacitors is not necessary, and manufacturing becomes easy.
上記実施例では高周波コイル１０として低域通過型の鳥
籠型コイルを用いたが、第５図に示すような高域通過型
の鳥籠型コイルや、第６図に示すような分割型の鞍型コ
イル、第７図に示すようなスロティッドチューブレゾネ
ータを用いても良い。第５図、第６図、第７図に示す高
周波コイル５０．６０．７０において、５１゜６１．７
１はインダクタ、５２，６２．７２はキャパシタ、５３
．６３．７３は整合用の可変容量キャパシタである。In the above embodiment, a low-pass type birdcage-type coil was used as the high-frequency coil 10, but a high-pass type birdcage-type coil as shown in FIG. 5 or a split type coil as shown in FIG. A saddle-shaped coil or a slotted tube resonator as shown in FIG. 7 may also be used. In the high frequency coil 50.60.70 shown in Fig. 5, Fig. 6, Fig. 7, 51°61.7
1 is an inductor, 52, 62.72 is a capacitor, 53
．． 63 and 73 are variable capacitors for matching.
［発明の効果］
本発明によれば、高周波磁場の均一性を劣化させること
なく、同調が容易な構造の磁気共鳴装置用高周波プロー
ブを提供することができる。[Effects of the Invention] According to the present invention, it is possible to provide a high-frequency probe for a magnetic resonance apparatus having a structure that allows easy tuning without deteriorating the uniformity of the high-frequency magnetic field.
第１図は本発明の一実施例に係る磁気共鳴装置用高周波
プローブの分解斜視図、第２図および第３図はそれぞれ
本発明の他の実施例における導電性部材の斜視図、第４
図（ａ）（ｂ）は本発明の更に別の実施例における導電
性部材の斜視図および断面図、第５図、第６図および第
７図は本発明における高周波コイルの他の例を示す図で
ある。
１０，５０．６０．７０・・・高周波コイル１１．５１
，６１．７１・・・インダクタ１２．５２□ ６２．７
２・・・キャパシタ１３．５３．６３．７３・・・整合
用キャパシタ２０．３０．４０・・・導電性部材
２１〜２４．３１〜３４・・・分割された部分２５．３
５・・・結合用キャパシタ
４１〜４８・・・分割された部分
４９・・・誘電体板FIG. 1 is an exploded perspective view of a high-frequency probe for a magnetic resonance apparatus according to one embodiment of the present invention, FIGS. 2 and 3 are perspective views of a conductive member in another embodiment of the present invention, and FIG.
Figures (a) and (b) are perspective views and cross-sectional views of a conductive member in yet another embodiment of the present invention, and Figures 5, 6, and 7 show other examples of the high-frequency coil in the present invention. It is a diagram. 10,50.60.70...High frequency coil 11.51
, 61.71...Inductor 12.52□ 62.7
2... Capacitor 13.53.63.73... Matching capacitor 20.30.40... Conductive members 21-24. 31-34... Divided portion 25.3
5... Coupling capacitors 41 to 48... Divided portion 49... Dielectric plate
Claims (3)
構成され、特定の磁気共鳴周波数で共振する高周波コイ
ルと、 前記高周波コイルの外周側に配置され、前記高周波コイ
ルに対して相対的に移動可能に構成された導電性部材と を具備することを特徴とする磁気共鳴装置用高周波プロ
ーブ。(1) A high-frequency coil configured by combining a plurality of inductors and capacitors and resonating at a specific magnetic resonance frequency; and a high-frequency coil arranged on the outer circumferential side of the high-frequency coil and configured to be movable relative to the high-frequency coil. 1. A high-frequency probe for a magnetic resonance apparatus, comprising a conductive member.
に、かつ軸対称に構成されることを特徴とする請求項１
に記載の磁気共鳴装置用高周波プローブ。(2) Claim 1 characterized in that the high-frequency coil and the conductive member are constructed in a substantially concentric cylindrical shape and axially symmetrical.
A high frequency probe for a magnetic resonance apparatus described in .
れた各部分は高周波的に結合されていることを特徴とす
る請求項１に記載の磁気共鳴装置用高周波プローブ。(3) The high-frequency probe for a magnetic resonance apparatus according to claim 1, wherein the conductive member is divided into a plurality of parts, and each divided part is coupled in a high-frequency manner.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2130891A JP2953745B2 (en) | 1990-05-21 | 1990-05-21 | High frequency probe for magnetic resonance equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2130891A JP2953745B2 (en) | 1990-05-21 | 1990-05-21 | High frequency probe for magnetic resonance equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0424019A true JPH0424019A (en) | 1992-01-28 |
| JP2953745B2 JP2953745B2 (en) | 1999-09-27 |
Family
ID=15045129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2130891A Expired - Fee Related JP2953745B2 (en) | 1990-05-21 | 1990-05-21 | High frequency probe for magnetic resonance equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2953745B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003180659A (en) * | 2001-11-21 | 2003-07-02 | Koninkl Philips Electronics Nv | Rf coil system for magnetic resonance imaging device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101171526B (en) * | 2005-05-06 | 2012-07-18 | 皇家飞利浦电子股份有限公司 | Electromagnetic shielding for high field MRI coils |
-
1990
- 1990-05-21 JP JP2130891A patent/JP2953745B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003180659A (en) * | 2001-11-21 | 2003-07-02 | Koninkl Philips Electronics Nv | Rf coil system for magnetic resonance imaging device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2953745B2 (en) | 1999-09-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |