Ferromagnetic augmentation for magnetic resonance imaging

Patent metadata

Field	Value
Publication number	US-9625544-B2
Application number	US-201615091971-A
Country	US
Kind code	B2
Filing date	Apr 6, 2016
Priority date	Sep 5, 2014
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

In some aspects, a magnetic system for use in a low-field MRI system. The magnetic system comprises at least one electromagnet configured to, when operated, generate a magnetic field to contribute to a B 0 field for the low-field MRI system, and at least one permanent magnet to produce a magnetic field to contribute to the B 0 field.

First claim

What is claimed is:

1. A magnetic system for use in a magnetic resonance imaging system, the magnetic system comprising:
a B 0 magnet configured to generate a magnetic field to contribute to a B 0 magnetic field for the magnetic resonance imaging system; and
at least one ferromagnetic component configured to capture and direct at least some of the magnetic field generated by the B 0 magnet to increase the magnetic flux density within an imaging region of the magnetic resonance imaging system,
wherein the B 0 magnet and the at least one ferromagnetic component are configured to produce the B 0 magnetic field at a strength equal to or less than approximately 0.2 T.

2. The magnetic system of claim 1 , wherein the B 0 magnet comprises at least one electromagnet configured to, when operated, generate a magnetic field to contribute to the B 0 magnetic field for the magnetic resonance imaging system.

3. The magnetic system of claim 1 , wherein the magnetic system is configured to produce the B 0 magnetic field at a strength equal to or less than approximately 0.2 T and greater than or equal to approximately 0.1 T.

4. The magnetic system of claim 1 , wherein the magnetic system is configured to produce the B 0 magnetic field at a strength equal to or less than approximately 0.1 T and greater than or equal to approximately 50 mT.

5. The magnetic system of claim 1 , wherein the magnetic system is configured to produce the B 0 magnetic field at a strength equal to or less than approximately 50 mT and greater than or equal to approximately 20 mT.

6. The magnetic system of claim 1 , wherein the magnetic system is configured to produce the B 0 magnetic field at a strength equal to or less than approximately 20 mT and greater than or equal to approximately 10 mT.

7. The magnetic system of claim 1 , wherein the at least one electromagnet comprises at least one electromagnetic coil wound using a copper or aluminum conductor to generate the magnetic field, and wherein the magnetic system is configured to produce the B 0 magnetic field at a strength equal to or less than approximately 0.1 T and greater than or equal to approximately 20 mT.

8. The magnetic system of claim 2 , wherein the at least one electromagnet comprises a pair of B 0 coils including a first B 0 coil and a second B 0 coil arranged in a bi-planar configuration, and wherein the at least one ferromagnetic component is configured to increase the field strength and/or alter the homogeneity of the B 0 field in the imaging region between the first B 0 coil and the second B 0 coil.

9. The magnetic system of claim 8 , wherein the at least one ferromagnetic component comprises a ferromagnetic structure connected to the first B 0 coil and the second B 0 coil to form a magnetic circuit that provides at least one return path for magnetic flux generated by the first B 0 coil and the second B 0 coil through the ferromagnetic structure.

10. The magnetic system of claim 9 , wherein the ferromagnetic structure provides the at least one return path for magnetic flux along at least one side of the ferromagnetic structure.

11. The magnetic system of claim 10 , wherein the ferromagnetic structure provides a plurality of return paths for magnetic flux along sides of the ferromagnetic structure.

12. The magnetic system of claim 10 , wherein the ferromagnetic structure comprises a C-shaped ferromagnetic structure that provides a return path for magnetic flux along only one side of the ferromagnetic structure.

13. The magnetic system of claim 9 , wherein the ferromagnetic structure comprises at least one beveled corner to reduce a magnetic reluctance around the at least one beveled corner.

14. The magnetic system of claim 9 , wherein the ferromagnetic structure comprises a plurality of ferromagnetic posts configured to provide the at least one return path for magnetic flux.

15. The magnetic system of claim 14 , wherein at least one of the plurality of ferromagnetic posts is removable from the magnetic resonance imaging system.

16. The magnetic system of claim 9 , wherein the at least one ferromagnetic component further comprises at least one first ferromagnetic component located adjacent to the first B 0 coil and/or the second B 0 coil to alter where the magnetic flux exits the ferromagnetic structure.

17. The magnetic system of claim 16 , wherein the ferromagnetic structure comprises a first ferromagnetic material and wherein the at least one first ferromagnetic component located adjacent to the first B 0 coil and/or the second B 0 coil comprises a second ferromagnetic material different than the first ferromagnetic material.

18. The magnetic system of claim 8 , wherein the at least one ferromagnetic component comprises one or more solid ferromagnetic components.

19. The magnetic system of claim 8 , wherein the magnetic system comprises at least one laminate panel having at least one electromagnetic component fabricated thereon.

20. The magnetic system of claim 19 , wherein the at least one laminate panel comprises at least one B 0 coil, at least one shim coil and/or at least one gradient coil formed thereon.

21. The magnetic system of claim 8 , wherein the at least one ferromagnetic component comprises at least one shim ring located adjacent to the first B 0 coil and/or the second B 0 coil.

22. The magnetic system of claim 8 , wherein the at least one ferromagnetic component comprises a plurality of ferromagnetic shim pieces located adjacent to the first B 0 coil and/or the second B 0 coil.

23. The magnetic system of claim 8 , wherein the at least one ferromagnetic component comprises at least one ferromagnetic pole piece located adjacent to the first B 0 coil and/or the second B 0 coil.

24. The magnetic system of claim 23 , wherein the at least one ferromagnetic pole piece comprises a pole piece having a non-rectangular shape.

25. The magnetic system of claim 8 , wherein the at least one ferromagnetic component is configured to provide a support structure that provides support for the first B 0 coil and/or the second B 0 coil.

26. The magnetic system of claim 8 , wherein the at least one ferromagnetic component comprises a plurality of electrically isolated segments to reduce eddy currents generated in the at least one ferromagnetic component.

27. The magnetic system of claim 8 , wherein the at least one ferromagnetic component has a non-uniform thickness to reduce a weight of the at least one ferromagnetic component.

28. The magnetic system of claim 1 , wherein the B 0 magnet comprises at least one permanent magnet that generates a magnetic field to contribute to the B 0 magnetic field of the magnetic resonance imaging system.

29. The magnetic system of claim 20 , wherein the at least one laminate panel comprises at least one x-gradient coil, at least one y-gradient coil, and at least one z-gradient coil to provide spatial encoding in x, y, and z directions, respectively.

30. The magnetic system of claim 29 , wherein the at least one laminate panel comprises at least one B 0 coil configured to contribute to the B 0 magnetic field, and wherein the at least one laminate panel comprises a first laminate panel and a second laminate panel arranged in a bi-planar configuration.

Assignees

• Hyperfine Res Inc

Inventors

• Poole Michael Stephen
• Rearick Todd
• Rothberg Jonathan M

Classifications

• G01R33/56518

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

• H01F7/02

  Permanent magnets {[PM]} · CPC title

• G01R33/3614

  RF power amplifiers · CPC title

• G01R33/3854

  means for active and/or passive vibration damping or acoustical noise suppression in gradient magnet coil systems · CPC title

• G01R33/383

  using permanent magnets · CPC title