DOUBLY RESONANT HIGH FIELD RADIO FREQUENCY SURFACE COILS FOR MAGNETIC RESONANCE

• US 20100026303A1
• Filed: 01/30/2008
• Published: 02/04/2010
• Est. Priority Date: 02/26/2007
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Morich, Michael A., Zhai, Zhiyong, Demeester, Gordon D.
• Granted Patent: US 8,089,281 B2
• Time in Patent Office: Days
• US Class Current: 324/318
• CPC Class Codes: G01R 33/34007 Manufacture of RF coils, e.g. using printed circuit board technology; additional hardware for providing mechanical support to the RF coil assembly or to part thereof, e.g. a support for moving the coil assembly relative to the remainder of the MR system
• CPC Class Codes: G01R 33/341 comprising surface coils
• CPC Class Codes: G01R 33/3635 Multi-frequency operation
• CPC Class Codes: G01R 33/3678 involving quadrature drive or detection, e.g. a circularly polarized RF magnetic field

Abstract

A radio frequency coil comprises an annular conductor or parallel annular conductors (22, 22c, 22d) configured to support: (i) a uniform electrical current distribution generating a first B₁ field (B_1,uniform) at a first magnetic resonance frequency directed out of a plane of the annular conductor or conductors; and (ii) a sinusoidal electrical current distribution generating a second B₁ field (B_1,sine) at a second magnetic resonance frequency directed parallel with the plane of the annular conductor or conductors. A magnetic resonance scanner comprises: a magnet (10) generating a static magnetic field (B₀); a magnetic field gradient system (14) configured to superimpose selected magnetic field gradients on the static magnetic field; and said radio frequency coil including said annular conductor or parallel annular conductors (22, 22c, 22d).

Claims

1. A generally planar radio frequency coil comprising:

one or two annular conductors (22, 22c, 22d) arranged generally parallel with a coil plane of the generally planar radio frequency coil and configured to support (i) a uniform electrical current distribution generating a first B₁ field (B_1,uniform) at a first magnetic resonance frequency directed out of the coil plane and (ii) a sinusoidal electrical current distribution generating a second B₁ field (B_1,sine) at a second magnetic resonance frequency directed parallel with the coil plane.

2. The radio frequency coil as set forth in claim 1, wherein the one or two annular conductors comprise a single annular conductor (22) configured to support both the uniform current distribution and the sinusoidal current distribution, and second magnetic resonance frequency is higher than the first magnetic resonance frequency.

3. The radio frequency coil as set forth in claim 1, wherein the one or two annular conductors include two annular conductors (22c, 22d), one of which is configured to support the uniform current distribution and the other of which is configured to support the sinusoidal current distribution.

4. The radio frequency coil as set forth in claim 3, wherein the second magnetic resonance frequency is higher than the first magnetic resonance frequency.

5. The radio frequency coil as set forth in claim 3, wherein the first magnetic resonance frequency and the second magnetic frequency are the same, and the two annual conductors (22c, 22d) define a quadrature surface coil.

6. The radio frequency coil as set forth in claim 3, wherein the two annular conductors (22c, 22d) are concentric and co-planar.

7. The radio frequency coil as set forth in claim 1, further including:

a generally planar radio frequency shield (26, 36a) arranged parallel with the one or two annular conductors (22, 22c, 22d).

8. The radio frequency coil as set forth in claim 7, wherein the generally planar radio frequency shield (26, 36a) is one of disk-shaped and annular.

9. The radio frequency coil as set forth in claim 7, further including:

a transverse annular radio frequency shield portion (36b) extending transverse to the generally planar radio frequency shield (36a) and surrounding at least an outer perimeter of the one or two annular conductors (22, 22c, 22d).

10. A magnetic resonance scanner incorporating at least one generally planar radio frequency coil set forth in claim 1.

11. A radio frequency coil comprising:

an annular conductor (22) configured to support;

(i) a uniform electrical current distribution generating a first B₁ field (B_1,uniform) at a first magnetic resonance frequency directed out of a plane of the annular conductor, and

(ii) a sinusoidal electrical current distribution generating a second B₁ field (B_1,sine) at a second magnetic resonance frequency directed parallel with the plane of the annular conductor.

12. The radio frequency coil as set forth in claim 11, wherein the second magnetic resonance frequency is higher than the first magnetic resonance frequency.

13. The radio frequency coil as set forth in claim 12, wherein the first magnetic resonance frequency corresponds to magnetic resonance of a first nuclear species in a selected static magnetic field (B₀), and the second magnetic resonance frequency corresponds to magnetic resonance of a second nuclear species in the selected static magnetic field (B₀).

14. The radio frequency coil as set forth in claim 13, wherein the second magnetic resonance frequency corresponds to the ¹H magnetic resonance in the selected static magnetic field (B₀).

15. The radio frequency coil as set forth in claim 14, wherein the first magnetic resonance frequency corresponds to the magnetic resonance of a nuclear species selected from the group consisting of ¹⁹F, ¹³C, ²³Na, and ³¹P in the selected static magnetic field (B₀).

16. The radio frequency coil as set forth in claim 13, wherein the selected static magnetic field (B₀) is greater than 3 Tesla.

17. The radio frequency coil as set forth in claim 11, wherein the annular conductor (22) includes:

one or more elements (30) having capacitance effective to tune the annular conductor (22b, 22c) to support a uniform electrical current distribution generating a first B₁ field (B_1,uniform) at the first magnetic resonance frequency directed out of the plane of the annular conductor; and

one or more elements (32) having inductance effective to tune the annular conductor (22c) to support a sinusoidal electrical current distribution generating a second B₁ field (B_1,sine) at the second magnetic resonance frequency directed parallel with the plane of the annular conductor.

18. The radio frequency coil as set forth in claim 11, wherein the annular conductor (22) has a width and annular diameter and is spaced apart from a ground plane by a dielectric layer of dielectric width and dielectric constant, and further includes one or more capacitive elements (30), wherein the width, annular diameter, dielectric width, dielectric constant, and capacitive elements are effective to tune the annular conductor (22) to support the uniform and sinusoidal electrical current distributions at selected respective first and second magnetic resonance frequencies.

19. The radio frequency coil as set forth in claim 11, wherein the annular conductor (22) includes an annular microstrip transmission line.

20. The radio frequency coil as set forth in claim 19, wherein the microstrip annular microstrip transmission line includes one or more gaps (30) defining capacitances effective to tune the annular conductor (22b, 22c) to support a uniform electrical current distribution generating a first B₁ field (B_1,uniform) at the first magnetic resonance frequency directed out of the plane of the annular conductor.

21. The radio frequency coil as set forth in claim 11, further including:

a dielectric substrate (24, 34) on which the annular conductor (22) is disposed; and

a ground plane (26, 36a) disposed on a side of the dielectric substrate (24, 34) opposite the annular conductor (22).

22. A magnetic resonance scanner incorporating the radio frequency coil set forth in claim 11.

23. A magnetic resonance scanner comprising:

a magnet (10) generating a static magnetic field (B₀);

a magnetic field gradient system (14) configured to superimpose selected magnetic field gradients on the static magnetic field; and

an annular conductor (22) configured to support a sinusoidal electrical current distribution generating or induced by a B₁ field (B_1,sine) at a magnetic resonance frequency directed parallel with the plane of the annular conductor.

24. The magnetic resonance scanner as set forth in claim 23, wherein the annular conductor (22) is further configured to support a uniform electrical current distribution generating or induced by a B₁ field (B_1,uniform) at a magnetic resonance frequency directed out of a plane of the annular conductor.

25. The magnetic resonance scanner as set forth in claim 24, wherein a plane of the annular conductor (22) is arranged generally parallel with the static magnetic field (B₀).

26. The magnetic resonance scanner as set forth in claim 23, wherein the annular conductor includes:

two parallel annular conductors (22c, 22d) one of which is configured to support the sinusoidal electrical current distribution directed parallel with the two parallel planar annular conductors and the other of which is configured to support a uniform electrical current distribution generating or induced by a B₁ field (B_1,uniform) at a magnetic resonance frequency directed transverse to the two parallel planar annular conductors.