Anatomically conformal quadrature MRI surface coil

• US 5,196,796 A
• Filed: 08/06/1991
• Issued: 03/23/1993
• Est. Priority Date: 08/06/1991
• Status: Expired due to Term

• Current Assignee: Medrad Incorporated (Bayer AG)
• Original Assignee: Medrad Incorporated (Bayer AG)
• Inventors: Reid, Eric D., Misic, George J.
• Primary Examiner(s): Tokar, Michael J.
• Application Number:
  US07/740,920
• Time in Patent Office: 595 Days
• Field of Search: 324/300, 324/307, 324/309, 324/312, 324/318, 324/322, 364/413, 333/26, 128/653.5, 128/653.2
• US Class Current: 324/322
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: G01R 33/34084 implantable coils or coils being geometrically adaptable to the sample, e.g. flexible coils or coils comprising mutually movable parts
• CPC Class Codes: G01R 33/341 comprising surface coils
• CPC Class Codes: G01R 33/3678 involving quadrature drive or detection, e.g. a circularly polarized RF magnetic field

Abstract

A quadrature surface probe comprising two individual mirror image coil loops arranged so that the magnetic field vectors of the respective coil loops are substantially perpendicular. An area of overlap between the first and second coil loops is adjusted to minimize the mutual coupling between the individual coils. Also disclosed is the method of manufacturing the quadrature surface probe.

Claims

1. A magnetic resonance quadrature surface probe for detecting magnetic resonance signals comprising:

a first coil loop having a first net magnetic field vector;

a second coil loop having a second net magnetic field vector;

said first and second coil loops being shaped to be mirror images of each other and oriented relative to each other so that said first and second net magnetic field vectors are substantially perpendicular to one another.

2. The probe of claim 1, wherein a region of overlap between the first and second coil loops is provided for obtaining a desired level of isolation between the first coil loop and the second coil loop.

3. The probe of claim and further comprising a housing for enclosing said first and second coil loops, said housing being shaped to conform with the anatomical configuration of the human cervical spine.

4. A magnetic resonance quadrature surface probe for detecting magnetic resonance signals, said quadrature surface probe comprising:

a first non-planar coil loop having a first net magnetic field vector;

a second non-planar coil loop having a second net magnetic field vector;

said first and second coil loops being shaped so as to be mirror images of each other and oriented so that the first and second net magnetic field vectors are substantially perpendicular to each other; and

a region of overlap being provided between the first coil loop and the second coil loop.

5. The magnetic resonance system of claim 4, wherein said first and second coil loops are bent and positioned with respect to each other so as to form a cradle into which the body part to be imaged is received.

6. The magnetic resonance system of claim 4, and further comprising a conductive strip attached to one of said first and second coil loops to alter the current path therein for adjusting isolation between the first and second coil loops.

7. A method for constructing a quadrature MRI surface probe comprising the steps of:

bending first and second electrically conductive loops into non-planar orientations whereby the first and second loops are mirror images of one another;

adjusting the orientation, curvature and shape of the first and second loops so that a first net magnetic field vector of the first loop is substantially perpendicular to a second magnetic field vector of the second loop;

determining the degree of isolation between the first and second loops; and

adjusting an overlap between the first and second loops to obtain a desired degree of isolation.

8. The method of claim 7, and further comprising the step of repeating the steps of adjusting curvature and adjusting the overlap to minimize isolation and ensure the perpendicular relationship of the magnetic vectors of the first and second loops.

9. The magnetic resonance system of claim 7, and further comprising the step of attaching a conductive strip to one of said first and second loops to adjust the isolation therebetween.

10. A magnetic resonance imaging system comprising:

means for generating a static magnetic field about a patient;

means for generating an oscillating magnetic field and applying said oscillating field to a region of interest of a patient; and

a quadrature surface probe for detecting magnetic resonance signals from said region of interest, said probe comprising;

a first coil loop having a first net magnetic field vector;

a second coil loop having a second net magnetic field vector;

said first and second coil loops being shaped to be mirror images of each other and oriented relative to each other so that said first and second net magnetic field vectors are substantially perpendicular to one another;

receiving circuitry for amplifying the detected magnetic resonance signals; and

display means for displaying a magnetic resonance image of said region of interest on the basis of said detected magnetic resonance signals.

11. The system of claim 10, wherein a region of overlap between the first and second coil loops of said quadrature surface probe is provided for obtaining a desired level of isolation between the first coil loop and the second coil loop.