Magnetic resonance imaging apparatus

Patent metadata

Field	Value
Publication number	US-12025685-B2
Application number	US-202217840252-A
Country	US
Kind code	B2
Filing date	Jun 14, 2022
Priority date	Jun 29, 2021
Publication date	Jul 2, 2024
Grant date	Jul 2, 2024

Abstract

An MRI apparatus equipped with a magnetic shield structure to reduce flux leakage. The MRI apparatus includes: a pair of static magnetic magnets that are disposed on opposite sides of an imaging space; and a pair of gradient coils that are disposed on opposite sides of the imaging space. Each static magnetic magnet has a disk-shaped magnetic material pole 201 and a ring-shaped magnetic material pole 202 . Each gradient coil has a first coil 204 that applies a magnetic field gradient in a Z axis direction in an imaging region, and a laminate 301 that shields the disk-shaped magnetic material pole from magnetic flux produced in the first coil. The laminate has a smaller thickness in the Z axis direction on the ring-shaped magnetic material pole side than that in a center portion of the imaging space. A vertical lowest portion of a laminate end portion on the ring-shaped magnetic material pole side of the laminate is in a higher position than a position of a lowest portion of a laminate central portion on the imaging region side of the laminate.

First claim

What is claimed is:

1. A magnetic resonance imaging apparatus, comprising:
a pair of static magnetic magnets that are disposed on opposite sides of an imaging space; and
a pair of gradient coils that are disposed on opposite sides of the imaging space,
wherein each of the pair of static magnetic magnets has a disk-shaped magnetic material pole and a ring-shaped magnetic material pole,
each of the pair of gradient coils has
a first coil that applies a magnetic field gradient in a Z axis direction in an imaging region, and
a laminate that shields the disk-shaped magnetic material pole from magnetic flux produced in the first coil, and

the laminate has a smaller thickness in the Z axis direction on the ring-shaped magnetic material pole side than that in a center portion of the imaging space, and a vertical lowest portion of a laminate end portion on the ring-shaped magnetic material pole side of the laminate is in a higher position than a position of a lowest portion of a laminate central portion on the imaging region side of the laminate.

2. The magnetic resonance imaging apparatus according to claim 1 , wherein the laminate has a thickness of 20 mm or greater.

3. The magnetic resonance imaging apparatus according to claim 2 , wherein the laminate is formed by stacking thin film materials having a diameter of 100 mm or less on top of another, and all the thin film materials are approximately equal in terms of shape to each other.

4. The magnetic resonance imaging apparatus according to claim 1 , wherein the gradient coil is disposed within a diameter of the static magnetic magnet.

5. The magnetic resonance imaging apparatus according to claim 1 , wherein the laminate end portion is placed in a middle in the Z axis direction of the laminate central portion.

6. A magnetic resonance imaging apparatus, comprising:
a pair of static magnetic magnets that are disposed on opposite sides of an imaging space; and
a pair of gradient coils that are disposed on opposite sides of the imaging space,
wherein each of the pair of static magnetic magnets has a disk-shaped magnetic material pole and a ring-shaped magnetic material pole,
each of the pair of gradient coils has
a first coil that applies a magnetic field gradient in a Z axis direction in an imaging region, and
a laminate that shields the disk-shaped magnetic material pole from magnetic flux produced in the first coil, and

the laminate has a greater thickness in the Z axis direction on the ring-shaped magnetic material pole side than that in a center portion of the imaging space, and a vertical lowest portion of a laminate end portion on the ring-shaped magnetic material pole side of the laminate is disposed in a lower position than a position of a lowest portion of a laminate central portion.

7. The magnetic resonance imaging apparatus according to claim 6 , wherein the laminate has a thickness of 20 mm or greater.

8. The magnetic resonance imaging apparatus according to claim 7 , wherein the laminate is formed by stacking thin film materials having a diameter of 100 mm or less on top of another, and all the thin film materials are approximately equal in terms of shape to each other.

9. The magnetic resonance imaging apparatus according to claim 6 , wherein the gradient coil is disposed within a diameter of the static magnetic magnet.

Assignees

• Fujifilm Healthcare Corp

Inventors

• Goto Kengo
• Aoki Manabu
• Takayanagi Taisuke
• Hoshino Shin
• Imamura Yukinobu
• Takeuchi Hiroyuki
• Nakayama Takeshi

Classifications

• H01F6/00

  Superconducting magnets; Superconducting coils {(magnetic resonance assemblies using superconducting coil systems G01R33/3815)} · CPC title

• G01R33/3802

  Manufacture or installation of magnet assemblies; Additional hardware for transportation or installation of the magnet assembly or for providing mechanical support to components of the magnet assembly · CPC title

• G01R33/3806

  Open magnet assemblies for improved access to the sample, e.g. C-type or U-type magnets · CPC title

• G01R33/38

  Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field · CPC title

• G01R33/4215 Primary

  of the gradient magnetic field, e.g. using passive or active shielding of the gradient magnetic field · CPC title