Flexible and curved radio frequency (RF) coil for the human shoulder for magnetic resonance imaging apparatus

• US 5,143,068 A
• Filed: 11/26/1990
• Issued: 09/01/1992
• Est. Priority Date: 11/26/1990
• Status: Expired due to Fees

• Current Assignee: Resonex Technology Group LLC
• Original Assignee: Resonex, Inc.
• Inventors: Bell, Rodney, Muennemann, Frank
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US07/617,902
• Time in Patent Office: 645 Days
• Field of Search: 128/653 SC, 128/653.5, 324/318, 324/322
• US Class Current: 600/422
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• 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 33/34084 implantable coils or coils being geometrically adaptable to the sample, e.g. flexible coils or coils comprising mutually movable parts
• CPC Class Codes: G01R 33/3628 Tuning/matching of the transmit/receive coil

Abstract

A flexible, conformally fitted coil for imaging of the human shoulder and topologically similar specimens is in the form of a band of flexible conductive foil covered by a soft flexible insulating material. The geometry of the coil is such that it can pass under the arm and over the top of the shoulder, providing high sensitivity for magnetic resonance imaging (MRI) studies of the shoulder in MRI apparatus having either a vertical or horizontal axial magnetic field. The flexibility of the coil and the generality of its geometry makes it suitable for examination of patients in a wide variety of sizes. Radio Frequency (RF) Power is delivered to and/or received from the coil via a matching network. The matching network may include a transformer to reduce the necessary current delivered to the coil, or RF current may be injected directly into and extracted directly from the coil. In the case where a transformer is used, the secondary winding is incorporated into the coil in such a fashion as to make the flexible coil removable and replaceable without direct electrical contacts.

Claims

1. A shoulder coil assembly having a predetermined magnetic axis for transmitting and/or receiving signals from a human shoulder produced in a magnetic resonance imaging apparatus comprising:

inductive pickup coil means for substantially surrounding said human shoulder including a thin flexible, unitary, continuous band of conductive material substantially entirely covered with a flexible protective material, the central portion of said band being shaped to conform to the side of the human thorax and pass around the base of the arm, including when the band is laid out flat in substantially a single plane, a substantially 180 degree turn in said central portion around an axis perpendicular to said plane, the ends of the band terminating in connectors for connection to a radio frequency cable for injection and/or extraction of the signals, said protective cover having facing interiors provided with mutually adhering surfaces which, when fastened together provide a conforming fit of the band to the top of the shoulder being imaged.

2. An assembly as in claim 1 including sufficient padding integral to the protective cover to place the conducting band a distance from the shoulder appropriate for good RF magnetic field uniformity.

3. An assembly as in claim 2 where said protective material is cloth, and said padding material is flexible foam.

4. An assembly as in claim 1 where said connectors include secondary coil means through which said signals may locally be injected or extracted.

5. An assembly as in claim 4 including means for adjusting the mutual inductance between a primary coil and the secondary coil means for matching the impedance of said band to that of the transmitting/receiving RF cable.

6. An assembly as in claim 1 where the ends of said band are joined by a clip means for locally assuring adherence of said band near said ends.