System and apparatus for compensating for magnetic field distortion in an MRI system

Patent metadata

Field	Value
Publication number	US-9279871-B2
Application number	US-201213690312-A
Country	US
Kind code	B2
Filing date	Nov 30, 2012
Priority date	Dec 20, 2011
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

A magnet apparatus for a magnetic resonance imaging system, the magnet apparatus includes a vacuum vessel, a helium vessel disposed within the vacuum vessel and a thermal shield disposed between the vacuum vessel and the helium vessel. A set of passive compensation coils are disposed within the vacuum vessel or the helium vessel and used to compensate for magnetic field distortion caused by mechanical vibrations within the magnet apparatus.

First claim

We claim:

1. A magnet apparatus for a magnetic resonance imaging system, the magnet apparatus comprising:
a vacuum vessel;
a helium vessel disposed within the vacuum vessel;
a thermal shield disposed between the vacuum vessel and the helium vessel; and
a set of passive compensation coils disposed within the vacuum vessel configured to compensate for magnetic field distortion caused by mechanical vibrations within the magnet apparatus;
wherein the set of passive compensation coils comprises:
a first set of passive compensation coils for a z-axis direction;
a second set of passive compensation coils for a y-axis direction; and
a third set of passive compensation coils for an x-axis direction.

2. A magnet apparatus according to claim 1 , wherein the passive compensation coils are superconducting coils.

3. A magnet apparatus according to claim 2 , wherein the passive compensation coils are constructed from a low temperature superconducting material.

4. A magnet apparatus according to claim 2 , wherein the passive compensation coils are constructed from a high temperature superconducting material.

5. A magnet apparatus according to claim 1 , wherein the helium vessel comprises an outer cylinder and an inner cylinder, the outer cylinder having an outer surface and the set of passive compensation coils disposed on the outer surface of the outer cylinder of the helium vessel.

6. A magnet apparatus according to claim 1 , wherein the helium vessel comprises an outer cylinder and an inner cylinder, the inner cylinder having an outer surface and the set of passive compensation coils disposed on the outer surface of the inner cylinder of the helium vessel.

7. A magnet apparatus according to claim 1 , wherein the thermal shield comprises an outer cylinder and an inner cylinder, the outer cylinder having an outer surface and the set of passive compensation coils disposed on the outer surface of the outer cylinder of the thermal shield.

8. A magnet apparatus according to claim 1 , wherein the thermal shield comprises an outer cylinder and an inner cylinder, the inner cylinder having an outer surface and the set of passive compensation coils disposed on the outer surface of the inner cylinder of the thermal shield.

9. A magnet apparatus for a magnetic resonance imaging system, the magnet apparatus comprising:
a vacuum vessel;
a helium vessel disposed within the vacuum vessel;
a thermal shield disposed between the vacuum vessel and the helium vessel; and
a set of passive compensation coils disposed within the helium vessel configured to compensate for magnetic field distortion caused by mechanical vibrations within the magnet apparatus;
wherein the set of passive compensation coils comprises:
a first set of passive compensation coils for a z-axis direction;
a second set of passive compensation coils for a y-axis direction; and
a third set of passive compensation coils for an x-axis direction.

10. A magnet apparatus according to claim 9 , wherein the passive compensation coils are superconducting coils.

11. A magnet apparatus according to claim 10 , wherein the passive compensation coils are constructed from a low temperature superconducting material.

12. A magnet apparatus according to claim 10 , wherein the passive compensation coils are constructed from a high temperature superconducting material.

13. A magnet apparatus according to claim 9 , further comprising:
a main coil former disposed inside the helium vessel; and
wherein the set of passive compensation coils are positioned inside of the main coil former.

14. A magnet apparatus according to claim 9 , further comprising:
a main coil former disposed inside the helium vessel and having an outer surface; and
wherein the set of passive compensation coils are positioned on the outer surface of the main coil former.

15. A magnate apparatus according to claim 9 , further comprising:
a bucking coil former disposed inside the helium vessel; and
wherein the set of passive compensation coils are positioned inside of the bucking coil former.

16. A magnet apparatus according to claim 9 , further comprising:
a bucking coil former disposed inside the helium vessel and having an outer surface; and
wherein the set of passive compensation coils are positioned on the outer surface of the bucking coil former.

17. A magnet apparatus according to claim 9 , further comprising:
a shim coil former disposed inside the helium vessel and having an outer surface; and
wherein the set of passive compensation coils are positioned on the outer surface of the shim coil former.

18. A magnet apparatus according to claim 9 , further comprising:
a passive compensation coil former disposed inside the helium vessel and having an outer surface; and
wherein the set of passive compensation coils are positioned on the outer surface of the passive compensation coil former.

Assignees

• Gen Electric

Inventors

• Shen Weijun
• Havens Timothy J
• Jiang Longzhi
• Kidane Tesfaye K

Classifications

• G01R33/34092 Primary

  RF coils specially adapted for NMR spectrometers · CPC title

• G01R33/3875

  using correction coil assemblies, e.g. active shimming · CPC title

• G01R33/56518

  due to eddy currents, e.g. caused by switching of the gradient magnetic field · CPC title

• G01R33/389 Primary

  Field stabilisation {, e.g. by field measurements and control means or indirectly by current stabilisation} · CPC title

• G01R33/56509

  due to motion, displacement or flow, e.g. gradient moment nulling (G01R33/567 takes precedence) · CPC title