MAGNETIC RESONANCE COIL SYSTEM

• US 20080204028A1
• Filed: 04/28/2008
• Published: 08/28/2008
• Est. Priority Date: 05/05/2006
• Status: Active Grant

• Current Assignee: Polarean Imaging Ltd.
• Original Assignee: M2M Imaging Corp. (Polarean Imaging Plc)
• Inventors: Gao, Erzhen, James, Timothy W., DeVries, Jon T., Kunimoto, Wallace Y., Hullihen, C. Richard
• Granted Patent: US 7,777,491 B2
• Time in Patent Office: Days
• US Class Current: 324/322
• CPC Class Codes: G01R 33/307 specially adapted for moving the sample relative to the MR system, e.g. spinning mechanisms, flow cells or means for positioning the sample inside a spectrometer
• CPC Class Codes: G01R 33/34023 Superconducting RF coils
• CPC Class Codes: G01R 33/34046 Volume type coils, e.g. bird-cage coils; Quadrature bird-cage coils; Circularly polarised coils

Abstract

A magnetic resonance coil system 18 allows for the use of modular components and which in one embodiment is particularly well-suited for use with small animals and includes an animal receiving apparatus 202, a transmit coil module 204, and a receive coil module 206. The receive coil module 206 includes a cryogenic receive coil. The coil system 18 is selectively insertable in the bore of the gradient coil of a magnetic resonance examination system.

Claims

1. A modular coil system for use with a magnetic resonance imaging device, comprising:

a radio frequency cryogenic receive coil that receives a magnetic resonance signal from excited nuclei when the receive coil is operated at a cryogenic temperature during a magnetic resonance procedure; and

a sample receiving region that supports a sample being imaged during the magnetic resonance procedure;

wherein the radio frequency cryogenic receive coil and the sample receiving region are selectively removably assembleable to form the modular coil system.

2. The system of claim 1, further including a cooling system that maintains a temperature of the radio frequency cryogenic receive coil within a cryogenic temperature range.

3. The system of claim 2, wherein the cooling system includes a cryocooler.

4. The system of claim 2, wherein the cooling system includes a cold head in thermal communication with the radio frequency cryogenic receive coil.

5. The system of claim 1, wherein the magnetic resonance system is a small animal magnetic resonance scanner.

6. The system of claim 1, wherein the radio frequency cryogenic receive coil comprises electrical circuitry that includes at least one of decoupling circuitry, a quadrature combiner, and a preamplifier.

7. The system of claim 1, further including an openable cover that closes to cover the sample receiving region, thereby mitigating contamination of an animal sample supported by the sample receiving region.

8. The system of claim 1, wherein the radio frequency cryogenic receive coil generates a signal that includes sample noise and coil noise, and the sample noise predominates over the coil noise.

9. The system of claim 1, wherein the radio frequency cryogenic receive coil includes:

a cryogenic region;

a thermally reflective radiation barrier disposed between the cryogenic region and the ambient environment, wherein the thermally reflective radiation barrier is substantially RF transparent;

an evacuated region; and

a hermetically sealed, non-magnetic electrical feedthrough extending between the evacuated region and the ambient environment.

10. The system of claim 1, further including:

a transmit coil that transmits a signal that excites the nuclei to emit the magnetic resonance signal, wherein the radio frequency cryogenic receive coil and the transmit coil are configured to engage to form a unitary radio frequency coil module.

11. The system of claim 10, wherein the module includes a variable reactor, a rotating shaft operatively connected to the variable reactor for varying reactance, and a clutch operatively connected to the rod, wherein the clutch slips when the variable rector reaches an end of travel, and wherein the variable reactor tunes the transmit coil.

12. A method, comprising:

transmitting, by a transmit coil, an excitation radio frequency signal to excite nuclei in a subject during a magnetic resonance examination of the subject with a small animal magnetic resonance imaging system; and

receiving, by the cryogenic receive coil operating within a cryogenic temperature range, a magnetic resonance signal emitted by the excited nuclei;

wherein the transmit coil and the cryogenic receive coil are removable components of a modular coil system that inserts into an examination region of a magnetic resonance scanner.

13. The method of claim 12, further including cooling the cryogenic receive coil to the cryogenic temperature by introducing a cryogen into a dewar in thermal communication with the cryogenic receive coil.

14. The method of claim 12, further including cooling the cryogenic receive coil to the cryogenic temperature using a cryocooler

15. The method of claim 12, wherein the cryogenic receive coil and the transmit coil are independent and distinct components of the modular coil system and are separately removable from the modular coil system.

16. The method of claim 12, wherein the modular coil system includes a subject support that supports the subject during the examination, and the modular coil system is configured to be removed from the small animal magnetic resonance imaging system for insertion and removal of the subject from the subject support.

17. The method of claim 12, further including tuning the transmit coil to a desired frequency range.

18. The method of claim 12, further including heating a subject receiving region supporting the subject during the examination.

20. The modular magnetic resonance radio frequency coil module of claims 17, further including means for removably attaching the means for transmitting and the cryogenic means for receiving together to form a single module.

19. A modular magnetic resonance radio frequency coil module, comprising:

means for supporting a sample in the module;

means for transmitting an excitation radio frequency signal to excite nuclei in the sample;

cryogenic means for receiving a magnetic resonance signal emitted from the excited nuclei; and

means for cryogenically cooling the cryogenic means for receiving to a cryogenic temperature.