RF COIL FOR USE IN AN MR IMAGING SYSTEM

• US 20100039111A1
• Filed: 12/18/2007
• Published: 02/18/2010
• Est. Priority Date: 12/22/2006
• 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: Luekeke, Kai-michael, Leussler, Christoph
• Granted Patent: US 8,159,223 B2
• Time in Patent Office: Days
• US Class Current: 324/318
• CPC Class Codes: G01R 33/341 comprising surface coils
• CPC Class Codes: G01R 33/422 of the radio frequency field
• CPC Class Codes: H01Q 15/0086 said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials
• CPC Class Codes: H01Q 21/065 Patch antenna array

Abstract

An RF coil is proposed for use as an RF antenna for a MR imaging system, for transmitting RF excitation signals and for receiving MR relaxation signals, The RF coil of the invention includes an array of patches (1) which are capacitively coupled with each other. The array of patches forms a resonant surface on which surface currents can be resonantly excited for generating at least one field modus.

Claims

1. An RF coil for an MR imaging system, for transmitting RF excitation signals and/or for receiving MR relaxation signals, in combination with or comprising a metamaterial which operates in the RF/MR frequency band like a magnetic conductor or a magnetic wall.

2. The RF coil according to claim 1, in which the metamaterial is an AMC material.

3. The RF coil according to claim 1, in which the metamaterial is positioned for replacing a PEC screen and/or is positioned in front of a PEC screen and/or combined with a PEC screen of the RF coil.

4. The RF coil according to claim 1, in which the metamaterial is provided in the form of a tuned resonant periodic structure built from dielectrics, wires and metal patches on a metallic ground plane.

5. The RF coil according to claim 4, in which the metamaterial comprises an array of patches which are capacitively coupled with each other for forming a resonant surface on which surface currents can be resonantly excited for generating at least one field modus.

6. The RF coil according to claim 5, in which the patches are capacitively coupled with each other by means of switchable capacitors so that by switching the capacitors the resonant frequency of the metamaterial can be controlled.

7. The RF coil according to claim 4, having a rectangular form and/or comprising patches having a rectangular shape.

8. The RF coil according to claim 4, having a circular form and/or comprising patches have a ring sector shape.

9. The RF coil according to claim 4, wherein a conductor is arranged above or below the array of patches for exciting the resonant surface currents.

10. The RF coil according to claim 9, wherein the conductor is a provided in the form of a loop.

11. The RF coil according to claim 9, wherein the conductor is a provided in the form of a strip line crossing the array of patches.

12. The RF coil according to claim 11, having a rectangular form, wherein the conductor is a provided in the form of a line running diagonal across the array of patches.

13. The RF coil according to claim 5, wherein the patches are connected by means of posts with a ground plane.

14. The RF coil according to claim 1, wherein the array of patches forms a plane or a curved surface.

15. The RF coil according to claim 1, wherein the array of patches is arranged on one side of a dielectric substrate having a ground plane on its other side.

16. The RF coil according to claim 1, which is tuned by selecting the sizes of the patches and/or the values of the coupling capacitors for exciting three orthogonal fundamental field modes at substantially the same resonant frequency.

17. An RF antenna for a MR imaging system comprising at least one RF coil according to claim 1.

18. A magnetic resonance imaging system comprising an RF/MR coil or antenna according to claim 1 for transmitting RF excitation signals and/or for receiving MR relaxation signals.