JPWO2020163892A5

JPWO2020163892A5 -

Info

Publication number: JPWO2020163892A5
Application number: JP2021546704A
Authority: JP
Publication date: 2022-10-18

Description

ヒトの研究のための診断画像を生成するための典型的な磁気共鳴システムの基本的な構成要素は、主磁石 (通常、DSV内に実質的に均一な静磁場(B ₀ 磁場)を生成する超伝導磁石) 、1以上のシムコイルのセット、1の傾斜磁場コイルのセット、および1以上のRFコイルを含む。MRIの議論は、例えば、Haacke et al., Magnetic Resonance Imaging: Physical Principles and Sequence Design, John Wiley & Sons, Inc., New York, 1999に見出すことができる。Crozier et al.、米国特許第5,818,319号、Crozier et al.、米国特許第6,140,900号、Crozier et al.、米国特許第6,700,468号、Dorri et al.、米国特許第5,396,207号、Dorriet al.、米国特許第5,416,415号、Knuttel et al.、米国特許第5,646,532号、およびLaskaris et al.、米国特許第5,801,609号も参照されたい。これらの内容は、その全体がここに組み込まれる。 A basic component of a typical magnetic resonance system for producing diagnostic images for human research is the generation of a substantially uniform static magnetic field ( _B0 magnetic field) within the main magnet, usually the DSV. superconducting magnet), including one or more sets of shim coils, one set of gradient coils, and one or more RF coils. A discussion of MRI can be found, for example, in Haacke et al., Magnetic Resonance Imaging: Physical Principles and Sequence Design, John Wiley & Sons, Inc., New York, 1999. Crozier et al., U.S. Patent No. 5,818,319; Crozier et al., U.S. Patent No. 6,140,900; Crozier et al., U.S. Patent No. 6,700,468; See also 5,416,415, Knuttel et al., US Patent 5,646,532, and Laskaris et al., US Patent 5,801,609. The contents of these are incorporated herein in their entirety.

補助的な構成要素 (傾斜磁場及び高周波コイル) を追加した後の従来のMRI装置の典型的な開口部は、約0.6～0.8メートルの直径、すなわち、対象者の肩を受け入れるのにちょうど十分な大きさを有し、約2.0メートル以上の長さを有する円筒形の空間である。驚くことではないが、多くの人がこのような空間に置かれると閉所恐怖症に苦しむ。また、撮像される対象者の身体の部分と磁石システムの端部との間の距離が大きいことは、医師がMRI の手順の間に対象者を容易に補助したり、個人的にモニターしたりすることができないことを意味する。従って、臨床応用においては、短い又はコンパクトな磁石システムが必要である。 A typical opening in a conventional MRI machine after adding ancillary components ( gradients and radio frequency coils) is about 0.6 to 0.8 meters in diameter, ie just enough to receive the subject's shoulder. A cylindrical space with a length of about 2.0 meters or more. Not surprisingly, many people suffer from claustrophobia when placed in such a space. Also, the large distance between the part of the subject's body being imaged and the end of the magnet system makes it easier for the physician to assist or personally monitor the subject during the MRI procedure. means that you cannot Therefore, short or compact magnet systems are needed in clinical applications.

第1の態様では、本発明は、人間の被験者を移動させることによって磁気共鳴画像を生成する磁気共鳴イメージングシステムに関する。このシステムは、ディスクタイプ均一磁場領域を生成する磁石、傾斜磁場コイル及び高周波 (Radio Frequency; RF) コイルを含む。 In a first aspect, the invention relates to a magnetic resonance imaging system for generating magnetic resonance images by moving a human subject. The system includes magnets, gradient coils and Radio Frequency (RF) coils that generate a disk-type homogeneous magnetic field region.

好ましくは、磁石またはMRIシステムは、一次コイルレイヤおよびシールドコイルレイヤを含む傾斜磁場コイル構造をさらに備える。好ましくは、傾斜磁場コイル構造の一次コイルレイヤの長さは、傾斜磁場コイル構造のシールドコイルレイヤの長さよりも短い。より好ましくは、傾斜磁場コイル構造の一次コイルレイヤの長さは、傾斜磁場コイル構造のシールドコイルレイヤの長さよりも著しく短い。有利には、シールドコイルレイヤは、良好な遮蔽性能を維持しながら傾斜磁場コイル厚さを減少させるために、一次コイルレイヤにより近い位置に配置することができる。 Preferably, the magnet or MRI system further comprises a gradient coil structure comprising a primary coil layer and a shield coil layer. Preferably, the length of the primary coil layer of the gradient coil structure is shorter than the length of the shield coil layer of the gradient coil structure. More preferably, the length of the primary coil layer of the gradient coil structure is significantly shorter than the length of the shield coil layer of the gradient coil structure. Advantageously, the shield coil layer can be placed closer to the primary coil layer to reduce the gradient coil thickness while maintaining good shielding performance.

好ましくは、傾斜磁場コイル構造は、磁石内に配置された傾斜体内に配置される。好ましくは、傾斜体は、ボアと磁石本体との間に配置される。 Preferably, the gradient coil structure is arranged within a gradient body arranged within the magnet. Preferably, the ramp is arranged between the bore and the magnet body.

好ましくは、磁石またはMRIシステムは、傾斜磁場コイル構造とボアとの間に配置された1以上の高周波 (RF) コイルをさらに含む。好ましくは、RFコイルは、円錐台状および/または円筒形であり、ボアの形状に適合する。好ましくは、RFコイルは、ボアを取り囲む傾斜体の内面に配置される。 Preferably, the magnet or MRI system further includes one or more radio frequency (RF) coils positioned between the gradient coil structure and the bore. Preferably, the RF coil is frusto-conical and/or cylindrical and conforms to the shape of the bore. Preferably, the RF coil is arranged on the inner surface of the ramp surrounding the bore.

好ましくは、システムは、1以上のシムポケットをさらに含む。好ましくは、シムポケットは円錐台状および/または円筒形である。好ましくは、シム部は、各シムポケット内に配置される。好ましくは、シム部は、鉄系または強磁性材料を含む。好ましくは、各一次コイルは、磁石本体および/またはボアの形状に適合する形状を有する付属のシムポケットおよびシム部を有する。好ましくは、シム部は、好ましい磁場(B₀) 均一性レベルを達成するために、受動的に撮像領域にシムを入れる。好ましくは、シム部は、一次コイル構造とシールドコイル構造との間に配置される。いくつかの実施形態では、シム部は、シールドコイル構造の外側に配置される。好ましくは、シム部は、磁石と傾斜磁場コイルとの間に配置される。 Preferably, the system further includes one or more shim pockets. Preferably, the shim pocket is frusto-conical and/or cylindrical. Preferably, a shim portion is positioned within each shim pocket. Preferably, the shim portion comprises a ferrous or ferromagnetic material. Preferably, each primary coil has an associated shim pocket and shim section with a shape that matches the shape of the magnet body and/or bore. Preferably, the shimming section passively shims the imaging region to achieve a preferred magnetic field (B ₀ ) uniformity level. Preferably, the shim portion is positioned between the primary coil structure and the shield coil structure. In some embodiments, the shim portion is located outside the shield coil structure. Preferably , the shims are arranged between the magnets and the gradient coils.

好ましくは、ボアの長さは250mmから1000mmである。いくつかの好ましい実施態様において、ボアの長さは、300mm、570mm、600mm、800mm又は900mmである。 Preferably, the bore length is between 250mm and 1000mm. In some preferred embodiments, the length of the bore is 300mm, 570mm , 600mm, 800mm or 900mm.

好ましくは、磁気共鳴イメージングシステムは、患者を支持するように構成された可動プラットフォームまたは部分を含む。好ましくは、可動プラットフォームまたは可動部分は、磁気共鳴イメージングシステムのボアを通過するように構成される。 Preferably, the magnetic resonance imaging system includes a moveable platform or portion configured to support the patient. Preferably, the movable platform or movable portion is configured to pass through a bore of the magnetic resonance imaging system.

別の形態では、本発明は、磁気共鳴イメージングスキャンの方法に関し、この方法は、以下のステップを含む。
磁気共鳴イメージングシステムを通して、患者を支持するプラットフォームを移動させるものであり、磁気共鳴イメージングシステムは上記のような磁石を有する。 In another form, the invention relates to a method of magnetic resonance imaging scanning, the method comprising the following steps.
A platform for supporting a patient is moved through a magnetic resonance imaging system, the magnetic resonance imaging system having magnets as described above.

磁石101内には傾斜体102が配置されている。傾斜体102の内部には、一次傾斜磁場コイルレイヤ121およびシールド傾斜磁場コイルレイヤ122が配置され、３本の直交z、xおよびy軸において３つの直交傾斜磁場を生成する。 A tilting body 102 is arranged in the magnet 101 . Inside the gradient body 102, a primary gradient coil layer 121 and a shield gradient coil layer 122 are arranged to generate three orthogonal magnetic field gradients in three orthogonal z, x and y axes.

シールド傾斜磁場コイルレイヤ122のシールド傾斜磁場コイルにおける電流方向は、一次傾斜磁場コイルレイヤ121の該当する一次傾斜磁場コイルにおける電流方向と反対である。一次傾斜磁場コイルレイヤ121の長さ(Lp)は、シールド傾斜磁場コイルレイヤ122の長さ (Ls) よりも著しく短く、良好な遮蔽性能を維持しながら、一次レイヤとシールドレイヤとの間の半径方向距離をより近くすることが可能となる。RFコイル104も短いので、DSVが短いことにより効率的である。

The current direction in the shield gradient coils of the shield gradient coil layer 122 is opposite to the current direction in the corresponding primary gradient coils of the primary gradient coil layer 121 . The length (Lp) of the primary gradient coil layer 121 is significantly shorter than the length (Ls) of the shield gradient coil layer 122, maintaining good shielding performance while maintaining a radius between the primary and shield layers. It is possible to make the directional distance closer. Since the RF coil 104 is also short, it is efficient due to the short DSV.

Claims

A magnet suitable for use in a magnetic resonance imaging (MRI) system, said magnet having a magnet body, said magnet body having a bore extending therethrough along an axis of said magnet body, The magnet is
arranged along the axis including a first end coil adjacent a first end of the magnet bore and a second end coil adjacent a second end of the magnet having a primary coil structure with at least four primary coils;
the maximum inner diameter of the primary coil structure is greater than 700 mm;
the distance between the first end coil and the second end coil is 1000 mm or less;
The imaging area generated by the primary coil is of disk type ,
The disk-type imaging area has an axial diameter and a radial diameter, wherein the axial diameter is less than the radial diameter and the radial diameter is greater than 200 mm;
wherein the ratio of the axial diameter to the radial diameter of the disk-type imaging area is 0.60 or less.
magnet.

the diameter of the imaging area along the x -axis is between 200 mm and 500 mm;
the diameter of the imaging area along the y-axis is between 200 mm and 500 mm;
the diameter of the imaging area along the z-axis is between 20mm and 350mm;
A magnet according to claim 1.

The imaging area is 250 mm (x-) × 250 mm (y-) × 40 mm (z-) , 320 mm (x-) × 320 mm (y-) × 100 mm (z-), 450 mm (x-) × 450 mm (y -) x 100 mm (z-) or 300 mm (x-) x 300 mm (y-) x 100 mm (z-) ,
A magnet according to claim 1 or 2 .

The distance between the first end coil and the second end coil is between 300 mm and 1000 mm , the inner diameter of the bore is between 700 mm and 1100 mm, and the length of the bore is between 300 mm. is between 1000mm,
A magnet according to any one of claims 1 to 3 .

The primary coil structure has 4 to 8 primary coils ,
Each of the primary coils has the same current polarity, or one of the four to eight primary coils adjacent to the second end coil is opposite the second end coil. with a current polarity of
A magnet according to any one of claims 1 to 4 .

at least one of said magnet body and bore being cylindrical, conical, frustoconical or stepped ; and said primary coil being cylindrical, conical, frustoconical or stepped. There is
the magnet body and bore include at least one cylindrical portion;
The cylindrical portion is adjacent to a frusto-conical portion, or the first cylindrical portion is adjacent to a second cylindrical portion having a diameter smaller than the diameter of the first cylindrical portion.
A magnet according to any one of claims 1 to 5 .

at least one of the plurality of frusto-conical portions and the plurality of cylindrical portions define a stepped diameter bore ;
at least one of the primary coils of the primary coil structure is disposed about a first step of the stepped diameter bore;
at least one of the primary coils of the primary coil structure is positioned about a second step of the stepped diameter bore;
A magnet according to any one of claims 1 to 5 .

said magnet is capable of producing a magnetic field of at least 1.0 Tesla , said magnetic field being substantially uniform over a predetermined imaging area;
The imaging region has an exterior surface defined by a calculated variation of the longitudinal magnetic field relative to the longitudinal magnetic field at the center of imaging of less than 20 ppm peak-to-peak.
A magnet according to any one of claims 1 to 7 .

said magnet further comprising a shield coil structure, said shield coil structure disposed around said primary coil structure ;
the shield coil structure includes at least two shield coils having a diameter larger than the primary coil;
The shield coil structure is arranged radially outward of the primary coil structure,
each of the shield coils conducts current in a direction opposite to the direction of current in the first and second end coils of the primary coil structure;
each of the shield coils is superconducting or ferromagnetic;
9. A magnet according to any one of claims 1-8 .

the magnet further comprising a gradient coil structure including a primary coil layer and a shield coil layer ;
the length of the primary coil layer of the gradient coil structure is shorter than the length of the shield coil layer of the gradient coil structure;
the gradient coil structure disposed within a gradient body disposed within the magnet body;
the tilting body is positioned between the bore and the magnet body;
the magnet further comprises one or more radio frequency (RF) coils positioned between the gradient coil structure and the bore;
the one or more RF coils are frusto-conical or cylindrical to match the shape of the bore and are disposed on the inner surface of the ramp surrounding the bore;
10. A magnet according to any one of claims 1-9 .

the magnet further comprises a shielded coil structure and one or more shim pockets;
the shield coil structure includes at least one shield coil disposed around the primary coil structure and having a diameter larger than the primary coil;
each said shim pocket having a shim portion of ferrous or ferromagnetic material disposed therein;
the shim pocket is frusto-conical or cylindrical;
Each said primary coil has an associated shim pocket and shims having a shape that matches the shape of the magnet body and/or the bore, one or more of said shims having a desired magnetic field (B ₀ ) uniformity. passively shimming the imaging region to achieve a sexual level;
The shim portion is arranged between the primary coil structure and the shield coil structure,
The shim portion is arranged outside the shield coil structure,
A magnet according to any one of claims 1 to 10 .

The dimension of the 5 Gauss line is between 1.5 m and 6 m radially and between 2.5 m and 9 m axially , or the dimension of said 5 Gauss line is
3m radially, 5m axially;
4.6m radially, 7.9m axially;
4.8m radially, 7.0m axially; or
4.3m radially, 6.5m axially.
is either
12. A magnet according to any one of claims 1-11 .

A magnetic resonance imaging (MRI) system having a magnet, the magnet having a bore extending along the axis of the magnet, the magnet comprising:
positioned along the axis including a first end coil adjacent a first end of the bore of the magnet and a second end coil adjacent a second end of the magnet; a primary coil structure having at least four primary coils;
the maximum inner diameter of the primary coil structure is greater than 700 mm;
the distance between the first end coil and the second end coil is 1000 mm or less;
The imaging area generated by the primary coil is of disk type ,
The disk-type imaging area has an axial diameter and a radial diameter, wherein the axial diameter is less than the radial diameter and the radial diameter is greater than 200 mm;
wherein the ratio of the axial diameter to the radial diameter of the disk-type imaging area is 0.60 or less.
Magnetic resonance imaging system.

said magnetic resonance imaging system comprising a movable platform or portion configured to support a patient ;
the movable platform or portion is configured to pass through the bore of the magnetic resonance imaging system;
14. The magnetic resonance imaging system of claim 13 .

A method of magnetic resonance imaging scanning, comprising:
13. A method comprising moving a platform supporting a patient through a magnetic resonance imaging system having a magnet according to any one of claims 1-12 .