Method, system storage medium and software arrangement for homogenizing a magnetic field in a magnetic resonance imaging system

• US 20050248348A1
• Filed: 05/04/2005
• Published: 11/10/2005
• Est. Priority Date: 05/05/2004
• Status: Active Grant

• Current Assignee: New York University
• Original Assignee: New York University
• Inventors: Axel, Leon
• Granted Patent: US 7,215,123 B2
• Time in Patent Office: Days
• US Class Current: 324/320
• CPC Class Codes: G01R 33/3875 using correction coil assemblies, e.g. active shimming

Abstract

A method and system for homogenizing a main magnetic field of a magnetic resonance imaging (“MRI”) system includes obtaining a main magnetic field distribution generated by the MRI system, obtaining at least one shim magnetic field distribution generated by at least one shim coil of the MRI system, and determining a corresponding shim current based on a relationship between the main magnetic field distribution and the at least one shim magnetic field distribution.

Claims

1. A method for homogenizing a main magnetic field of a magnetic resonance imaging (“

MRI”

) system, comprising;

(a) obtaining a distribution of the main magnetic field generated by the MRI system;

(b) obtaining at least one shim magnetic field distribution generated by at least one shim coil of the MRI system; and

(c) determining information associated with a shim current of the MRI system based on a relationship between the main magnetic field distribution and the at least one shim magnetic field distribution.

2. The method of claim 1, further comprising the step of:

(d) providing a variation of the shim current to the at least one shim coil to homogenize the main magnetic field of the MRI system.

3. The method of claim 2, wherein the variation of the shim current is the negative of the shim current.

4. The method of claim 1, wherein step (c) comprises calculating a dot product of the distribution of the main magnetic field and the at least one shim magnetic field distribution.

5. The method of claim 1 further comprising the step of:

(e) determining at least one orthogonalized shim field using the at least one shim magnetic field distribution.

6. The method of claim 5, wherein step (e) comprises calculating a dot product of the distribution of the main magnetic field and the at least one orthogonalized shim field.

7. The method of claim 6, further comprising the step of:

(f) providing a variation of the shim current to the at least one shim coil to homogenize the main magnetic field of the MRI system.

8. The method of claim 7, wherein the variation of the shim current is the negative of the shim current.

9. A system for homogenizing a main magnetic field of an MRI system, comprising a processing arrangement configurable to:

(a) obtain a distribution of the main magnetic field generated by the MRI system;

(b) obtain at least one shim magnetic field distribution generated by at least one shim coil of the MRI system; and

(c) determine information associated with a shim current of the MRI system based on a relationship between the main magnetic field distribution and the at least one shim magnetic field distribution.

10. The system of claim 9, wherein the processing arrangement is further configurable to provide a variation of the shim current to the at least one shim coil to homogenize the main magnetic field of the MRI system.

11. The system of claim 10, wherein the variation of the shim current is the negative of the shim current.

12. The system of claim 9, wherein the processing arrangement determines the information by calculating a dot product of the distribution of the main magnetic field and the at least one shim magnetic field distribution.

13. The system of claim 9, wherein the processing arrangement is further configurable to perform the step of (e) determining at least one orthogonalized shim field using the at least one shim magnetic field distribution.

14. The system of claim 13, wherein step (e) comprises calculating a dot product of the distribution of the main magnetic field and the at least one orthogonalized shim field.

15. The system of claim 14, wherein the processing arrangement is further configurable to provide a variation of the shim current to the at least one shim coil to homogenize the main magnetic field of the MRI system.

16. The system of claim 15, wherein the variation of the shim current is the negative of the shim current.

17. A computer-readable medium for operating an MRI system having a set of instructions which are operable to direct a processing arrangement to perform the steps comprising of:

(a) obtaining a distribution of the main magnetic field generated by the MRI system;

(b) obtaining at least one shim magnetic field distribution generated by at least one shim coil of the MRI system; and

(c) determining information associated with a shim current of the MRI system based on a relationship between the main magnetic field distribution and the at least one shim magnetic field distribution.

18. The computer-readable medium of claim 17, wherein the set of instructions are further operable to direct the processing arrangement to provide a variation of the shim current to the at least one shim coil to homogenize the main magnetic field of the MRI system.

19. The computer-readable medium of claim 18, wherein the variation of the shim current is the negative of the shim current.

20. The computer-readable medium of claim 17, wherein the information is determined by calculating a dot product of the distribution of the main magnetic field and the at least one shim magnetic field distribution.

21. The computer-readable medium of claim 17, wherein the set of instructions are further operable to direct the processing arrangement to determine at least one orthogonalized shim field using the at least one shim magnetic field distribution.

22. The computer-readable medium of claim 21, wherein the shin field is determined by calculating a dot product of the distribution of the main magnetic field and the at least one orthogonalized shim field.

23. The computer-readable medium of claim 22, wherein the set of instructions are further operable to direct the processing arrangement to provide a variation of the shim current to the at least one shim coil to homogenize the main magnetic field of the MRI system.

24. The computer-readable medium of claim 23, wherein the variation of the shim current is the negative of the shim current.

25. A software arrangement which, when executed by a processing arrangement, configures the processing arrangement to operate an MRI system having a set of instructions which are operable to direct a processing arrangement, the software arrangement comprising:

(a) a first set of instructions which are capable of configuring the processing arrangement to obtain a distribution of the main magnetic field generated by the MRI system;

(b) a second set of instructions which are capable of configuring the processing arrangement to obtain at least one shim magnetic field distribution generated by at least one shim coil of the MRI system; and

(c) a third set of instructions which are capable of configuring the processing arrangement to determine information associated with a shim current of the MRI system based on a relationship between the main magnetic field distribution and the at least one shim magnetic field distribution.