Magnetic resonance imaging (MRI) diagnostic apparatus capable of optimally controlling radio-frequency magnetic field by providing flexible material interposed between RF coil and body

• US 5,865,177 A
• Filed: 01/24/1996
• Issued: 02/02/1999
• Est. Priority Date: 06/24/1993
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Segawa, Toru
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US08/590,619
• Time in Patent Office: 1,105 Days
• Field of Search: 128/653.2, 128/653.5, 324/318, 324/322
• US Class Current: 600/410
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: G01R 33/341 comprising surface coils

Abstract

A magnetic resonance imaging (MRI) diagnostic apparatus capable of eliminating density inhomogeneity of the tomographic images obtained thereby. The MRI diagnostic apparatus includes a gantry for defining a space for a MRI diagnosis; an RF shield, disposed inside the gantry and outside an RF coil; and material for correcting a distribution of an RF magnetic field at the time of RF transmitting or receiving by the RF coil, wherein the field correcting material is interposed between the biological body lying inside the shield and the RF coil. Preferably, the field correcting material includes an aqueous high-molecular gel sheet which is flexibly deformable along the shape of the biological body.

Claims

1. A magnetic resonance imaging (MRI) diagnostic apparatus for applying a radiofrequency (RF) pulse to a biological body, and for acquiring nuclear magnetic resonance (NMR) signals therefrom to be reconstructed to obtain an MRI image, the apparatus comprising:

an RF coil for applying the RF pulse directed to the biological body; and

a field correcting means of a sheet material filled with a high molecular gel with a dielectric constant greater than 30 and having a magnetic susceptibility approximately within +150% of the biological body, said sheet material interposed between the RF coil and a position where the biological body is to be placed, said sheet material of a deformable material, and having a contact surface, capable of supporting the biological body to create a contiguous and direct contact between the contact surface and the biological body, and for correcting a distribution of an RF magnetic field at the time of RF transmitting or receiving by the RF coil.

2. The apparatus of claim 1, wherein the field correcting means changes a phase of the RF magnetic field.

3. The apparatus of claim 1, wherein the field correcting means is provided on a part of or around the entire RF coil.

4. The apparatus of claim 1, wherein the field correcting means includes a heat dissipation means for dissipating heat applied to the biological body caused by the applied RF pulse thereto.

5. The apparatus of claim 1, wherein the sheet material filled with the high-molecular gel contains a water content therein.