CAVITY RESONATOR FOR MAGNETIC RESONANCE SYSTEMS

• US 20080024133A1
• Filed: 11/24/2006
• Published: 01/31/2008
• Est. Priority Date: 11/25/2005
• Status: Active Grant

• Current Assignee: MR Instruments, Inc.
• Original Assignee: MR Instruments, Inc.
• Inventors: Watson, Mark A., Bradshaw, Kenneth M., Holwell, Joshua J., Waks, Matthew T., Vaughan, John Thomas
• Granted Patent: US 7,659,719 B2
• Time in Patent Office: Days
• US Class Current: 324/318
• CPC Class Codes: G01R 33/34046 Volume type coils, e.g. bird-cage coils; Quadrature bird-cage coils; Circularly polarised coils
• CPC Class Codes: G01R 33/3453 Transverse electromagnetic [TEM] coils
• CPC Class Codes: G01R 33/3678 involving quadrature drive or detection, e.g. a circularly polarized RF magnetic field

Abstract

An magnetic resonance apparatus in embodiments of the invention may include one or more of the following features: (a) a coil having at least two sections, (b) the at least two sections having a resonant circuit, (c) the at least two sections being reactively coupled or decoupled, (d) the at least two sections being separable, (e) the coil having openings allowing a subject to see or hear and to be accessed through the coil, (f) a cushioned head restraint, and (g) a subject input/output device providing visual data to the subject, the input/output device being selected from the group consisting of mirrors, prisms, video monitors, LCD devices, and optical motion trackers.

Claims

1. A radio frequency (RF) device for magnetic resonance imaging, the RF device comprising:

a resonator coil having two or more separable sections, the sections adapted to be disposed circumferentially about an axis to form the coil, the coil defining a cavity therethrough,

each of the two or more sections including at least one transmission line segment,

the two or more sections being reactively coupled when disposed to form the coil, the reactive coupling configured such that excitation energy applied to any one of the two or more sections causes excitation energy in the remaining sections,

the two or more sections adapted to form an electromagnetic shield when disposed to form the coil.

2. The device of claim 1 wherein the at least one transmission line segment comprises an inner conductor and an outer shield portion, the outer shield portion being formed of a non-magnetic conductive material.

3. The device of claim 2 wherein at least one separable section includes an outer shield portion which overlaps an outer shield portion of an adjacent separable section.

4. The device of claim 3 wherein the outer shield portion includes copper.

5. The device of claim 3 wherein an overlapping outer shield portion is formed between each section to form a continuous shield.

6. The device of claim 3 wherein the inner conductor of the transmission line segment is adapted to carry an electric current, and the outer shield portion is adapted to provide a return path for the electric current.

7. The device of claim 3 wherein the inner conductors and outer shield portions are substantially aligned with the axis of the coil.

8. The device of claim 3 wherein the inner conductors and outer shield portions are separated by a dielectric material.

9. The device of claim 3 wherein the cavity of the coil is open at both ends forming a generally cylindrical structure.

10. The device of claim 9 wherein the cavity is adapted to substantially conform to a portion of a patient limb.

11. The device of claim 9 wherein the cavity is adapted to substantially conform to a knee of a patient.

12. The device of claim 9 wherein the electromagnetic shield is adapted to reduce noise signals from adjacent objects.

13. The device of claim 12 wherein the electromagnetic shield is adapted to reduce noise signals from an adjacent limb.

14. The device of claim 7 wherein the outer shield portions include a radial end portion for providing electrical contact to the inner conductors.

15. The device of claim 3 wherein the overlap between outer shield portions are capacitively coupled to form a substantially continuous electromagnetic shield.

16. A radio frequency (RF) device for magnetic resonance imaging, the RF device comprising:

a TEM coil having a plurality of transmission line segments disposed circumferentially about a cavity; and

a loop array coil adapted to fit within the cavity of the TEM coil, the loop array coil comprising a generally cylindrical support and a plurality of loop elements disposed circumferentially about the support,

the loop array coil adapted to generate field components that are generally orthogonal to a magnetic field formed by the TEM coil.

17. The device of claim 16 wherein the TEM coil is adapted to function as a transmit coil for magnetic resonance imaging.

18. The device of claim 16 wherein the loop array coil is adapted to function as a receive coil for magnetic resonance imaging.

19. The device of claim 18 wherein the TEM coil is adapted to function as both a transmit coil and a receive coil.

20. The device of claim 16 wherein the loop array coil is adapted to mechanically mate with the TEM coil.

21. A radio frequency (RF) device for magnetic resonance imaging, the RF device comprising:

a TEM coil having a plurality of transmission line segments disposed circumferentially about a cavity, the TEM coil adapted to receive a loop array coil within the cavity of the TEM coil, the loop array coil adapted to generate field components that are generally orthogonal to a magnetic field formed by the TEM coil.

22. The device of claim 21 wherein the TEM coil is adapted to receive a plurality of loop array coils within the cavity of the TEM coil.

23. The device of claim 21 wherein the TEM coil is adapted to receive a loop array coil within the cavity of the TEM coil, the loop array coil being selectable from a variety of loop array coils adapted for imaging a particular type of object.

24. The device of claim 23 wherein the TEM coil is adapted to receive a loop array coil adapted for imaging a human body part.