Method and apparatus for performing neuroimaging

• US 6,711,430 B1
• Filed: 10/20/2000
• Issued: 03/23/2004
• Est. Priority Date: 10/09/1998
• Status: Expired due to Fees

• Current Assignee: Ekam Imaging Inc.
• Original Assignee: Insight Neuroimaging Systems, Inc.
• Inventors: Bogdanov, Gene, Ferris, Craig F., Allard, Arthur C., King, Jean A, Ludwig, Reinhold
• Primary Examiner(s): SHAW, SHAWNA JEANNINE
• Application Number:
  US09/694,087
• Time in Patent Office: 1,250 Days
• Field of Search: 600/415, 600/417, 600/421, 600/422, 324/318, 324/322, 606/130
• US Class Current: 600/417
• CPC Class Codes: A61B 2503/40 Animals
• CPC Class Codes: A61B 5/0042 for the brain
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging

Abstract

The present invention relates to systems and methods of performing magnetic resonance imaging (MRI) in awake animals. The invention utilizes head and body restrainers to position an awake animal relative to a radio frequency dual coil system operating in a high field magnetic resonance imaging system to provide images of high resolution without motion artifact.

Claims

1. A restraining assembly for an awake animal within a magnetic resonance imaging (MRI) device comprising:

a head restrainer that restrains a head of an awake animal;

a body restrainer that holds a body of the awake animal;

a support frame positioned in a cavity of the MRI device, the support frame carrying the head restrainer and the body restrainer;

a volume coil mounted on the support frame, the volume coil extending around the body restrainer such that the assembly can be inserted in the MRI device, the volume coil surrounding the head restrainer; and

an RF surface coil disposed within the an interior of the head restrainer for placement proximate the animal'"'"'s head.

2. The restraining assembly of claim 1 wherein the head restrainer comprises:

a head holder having a channel that receives and restrains the head, the head holder being disposed within the volume coil and having a surface coil positionable within the volume coil;

a position tube carried by a support mount that retains the head holder, the head holder having an aperture in the position tube, a bite bar within the aperture and a plurality of lateral ear clamping members to secure an animal'"'"'s head.

3. The restraining assembly of claim 2 wherein the body restrainer comprises:

an elongated body tube carried by a mounting unit; and

a shoulder positioning device carried by the elongated body tube that positions the shoulders of the animal.

4. The restraining assembly of claim 1 wherein the frame comprises:

a front mounting plate having an access hole extending through the plate, the front mounting plate adapted to be secured into the bore of the MRI device;

a rear mounting plate parallel and spaced from the front mounting plate and having an access hole extending through the plate, the rear mounting plate adapted to be secured into the bore of the MRI device; and

a plurality of support rods extending between the mounting plates to space and support the mounting plates in relative position, the support rods including a damping structure for reducing transmission of movement of the body restrainer to the head retainer.

5. The restraining assembly of claim 4 wherein the damping structure of the frame further comprises gaskets interposed between the support rods and the mounting plates for reducing transmission of movement of the body restrainer to the head restrainer.

6. The restraining assembly of claim 4 wherein the damping structure further comprises a gasket interposed between the front mounting plate and the position tube of the head restrainer for reducing transmission of movement of the body restrainer to the head restrainer.

7. A non-magnetic restraining system to immobilize an awake animal for insertion into a bore of a magnetic resonance imaging (MRI) device comprising:

a support frame adapted to be slidably mounted in the bore of the MRI device, the frame including;

a front mounting plate having an access hole extending through the plate;

a rear mounting plate parallel and spaced from the front mounting plate; and

a plurality of support rods extending between the mounting plates to space and support the mounting plates in relative position;

a body restrainer for holding the body of the awake animal, the body restrainer including;

an elongated body tube carried by the frame; and

a shoulder restrainer carried by the elongated body tube; and

a head restrainer for immobilizing the head of the awake animal, the head restrainer including;

a head holder having an opening to receive and restrain the head of an animal, the head holder receiving an RF surface coil in the opening; and

a position tube carried by the frame for retaining the head holder, the head holder having an aperture extending from the opening to communicate with an aperture in the position tube.

8. The restraining assembly of claim 7 further comprising a volume coil to generate an excitation RF signal, the volume coil having a cylindrical non-magnetic core module having an outer shield and a longitudinal axis, a cylindrical bore extending through the core module along the longitudinal axis and defining an inner surface, a plurality of bores extending parallel to, and spaced from, the longitudinal axis, each bore receiving one of the support rods for lateral movement of the volume coil relative to the head restrainer.

9. The restraining system of claim 8 wherein the head holder further comprises a pair of lateral ear clamping screws extending horizontally through the sides of the head holder into the bore of the aperture and perpendicular to the axis and above a horizontal bite bar to abut and limit the horizontal movement of the animal.

10. The restraining system of claim 9 wherein the head holder further comprises a nose clamping screw extending inward through the top of the head holder into the bore of the aperture that abuts the nose of an animal above the bite bar and secures the animal'"'"'s jaw thereon.

11. The restraining system of claim 9 wherein the head holder further comprises a pair of jaw anchor screws extending inward through the head holder into the bore of the aperture and a head clamping screw located at the top of the head holder and extending inward through the head holder into the bore of the aperture.

12. The restraining system of claim 9 further comprising a restraining jacket that restrains the body of the animal.

13. The restraining system of claim 12 wherein the head holder further comprises a nose clamping screw extending inward through the top of the head holder into the bore of the aperture and adapted to abut the nose of an animal above the bite bar and secure the animal'"'"'s jaw thereon.

14. The restraining system of claim 13 wherein the head holder further comprises a pair of jaw anchor screws extending inward through the head holder into the bore of the aperture.

15. The restraining system of claim 14 further comprising ear pads wherein the ear pads are placed under a protective ear piece.

16. The restraining system of claim 15 wherein the head holder further comprises a head clamping screw located at the top of the head holder and extending inward through the head holder into the bore of the aperture.

17. The restraining system of claim 8 wherein the RF surface coil detects the MRI signal and is carried by the head holder.

18. The restraining system of claim 17 wherein the volume coil further comprises:

a plurality of conductive strip lines, the strip lines extending parallel to the longitudinal axis on the inner surface of the core module;

a pair of circuit boards carried by the ends surfaces of the core module;

a plurality of shielding strips extending parallel to the longitudinal axis on the outer surface;

a resonating element having strip lines, a shielding strip, and at least one tuneable, variable capacitor;

a detuning circuit carried on the circuit board for detuning the resonating element; and

a RF decoupling circuit carried on the circuit boards for reducing interference between a DC detuning signal and an RF signal.

19. The retraining system of claim 18 further comprising a transceiver unit having a RF transmitter and a RF receiver, the transceiver unit connected to the surface coil and the volume coil.

20. A volume coil for a magnetic resonance system, the volume coil comprising:

a cylindrical non-magnetic core module having an outer surface and a longitudinal axis, a cylindrical bore extending through the core module along the longitudinal axis and defining an inner surface;

a plurality of conductive strip lines fixedly attached to the inner surface of the core module, the strip lines extending parallel to the longitudinal axis of the core module;

a pair of circuit boards carried by the ends of the core module;

a plurality of shielding strips extending parallel to the longitudinal axis on the outer surface of the core module;

a resonating element having strip lines, shielding strips and at least one tuneable capacitor;

a detuning circuit formed as part of the circuit board for detuning the resonating element; and

an RF decoupling circuit formed as part of the circuit board for reducing interference between a DC detuning signal and an RF signal.

21. The volume coil of claim 20 wherein the core module is formed of Teflon or nylon.

22. The volume coil of claim 20 wherein the strip lines are electroplated on the core module.

23. The volume coil of claim 20 wherein the adjacent shielding strips are coupled by at least one capacitor attaching adjacent shielding strips at alternative ends of the shielding strips.

24. The volume coil of claim 23 further comprising:

a matching circuit for adjusting the impedance of the resonating elements to that of the RF source and

a filter for separating the high frequency RF signal from interfering the DC detuning signal.

25. The volume coil of claim 24 wherein the detuning circuit has a pair of pin diodes.

26. The volume coil of claim 24 wherein the RF decoupling circuit has a plurality of high frequency inductors.

27. A restraining assembly to immobilize an awake animal for insertion into a magnetic resonance imaging (MRI) device, the assembly comprising:

a support frame configured for placement within a bore of the MRI device;

a volume coil slidably displaceable along a longitudinal axis of the support frame;

an elongated body member coupled to the support frame for holding the body of the awake animal;

a head restrainer coupled to the elongated body member such that the volume coil surrounds the head restrainer when the volume coil is in an operating position; and

a surface coil adjustably mounted relative to the head restrainer such that the volume coil surrounds the surface coil in the operating position.

28. The assembly of claim 27, wherein the surface coil is received through an aperture formed in the head restrainer so that the surface coil is disposed within an interior of the head restrainer in the operating position.

29. The assembly of claim 27, wherein the frame includes a front mounting plate and a rear mounting plate spaced therefrom and a plurality of support rods extending therebetween, the volume coil having a plurality of complementary bores formed therein to receive the support rods to permit the volume coil to be slidably displaceable relative to the frame.

30. The assembly of claim 27, wherein the head restrainer includes a plurality of restraining features for locating and restraining the head of the animal within the head restrainer so that horizontal movement of the animal is restricted.

31. The assembly of claim 27, wherein the elongated member has a cut-out formed therein for receiving and positioning the head restrainer.