Method and RF transmitter arrangement for generating RF fields

• US 8,390,288 B2
• Filed: 04/24/2008
• Issued: 03/05/2013
• Est. Priority Date: 05/04/2007
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Graesslin, Ingmar, Boernert, Peter, Vernickel, Peter, Katscher, Ulrich
• Primary Examiner(s): ARANA, LOUIS M
• Application Number:
  US12/598,451
• Publication Number:
  US 20100141259A1
• Time in Patent Office: 1,776 Days
• Field of Search: 324/318, 324/322, 324/312, 324/314
• US Class Current: 324/318
• CPC Class Codes: G01R 33/288 Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room
• 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 33/3415 comprising arrays of sub-coils , i.e. phased-array coils with flexible receiver channels
• CPC Class Codes: G01R 33/543 Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription G01R33/546 takes precedence
• CPC Class Codes: G01R 33/5604 Microscopy; Zooming
• CPC Class Codes: G01R 33/5611 Parallel magnetic resonance imaging, e.g. sensitivity encoding [SENSE], simultaneous acquisition of spatial harmonics [SMASH], unaliasing by Fourier encoding of the overlaps using the temporal dimension [UNFOLD], k-t-broad-use linear acquisition speed-up technique [k-t-BLAST], k-t-SENSE structural details of arrays of sub-coils G01R33/3415
• CPC Class Codes: G01R 33/5659 caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field G01R33/56509, G01R33/56518, G01R33/56536 take precedence

Abstract

A multi-channel RF transmitter arrangement comprising a plurality of RF transmitter elements like RE antennas, antenna elements, coils or coil elements, for generating an RF field, especially for use in a magnetic resonance imaging system for exciting nuclear magnetic resonances, and a method for generating such an RF field wherein the RF transmitter elements are segmented in a plurality of segments at least along the direction of one or more of the main magnetic field of the MRI system, the z-direction or the longitudinal direction.

Claims

1. An RF transmitter arrangement comprising:

a plurality of RF transmitter elements for generating an RF field for exciting nuclear magnetic resonances in an MRI system; and

a plurality of segments formed from the plurality of RF transmitter elements in at least two spatial directions selected from a direction of a main magnetic field of the MRI system, a z-direction, and a longitudinal direction.

2. The RF transmitter arrangement according to claim 1, wherein the RF transmitter elements are arranged in the form of a cylindrical RF coil, providing the plurality of segments in the longitudinal direction of the cylindrical coils.

3. The RF transmitter arrangement according to claim 2, wherein the segments are shifted with respect to one another in the z-direction of the cylindrical coil.

4. The RF transmitter arrangement according to claim 2, wherein the segments are rotated with respect to one another in a circumferential direction of the cylindrical coil.

5. The RF transmitter arrangement according to claim 2, wherein the segments are shifted with respect to one another in the z-direction and rotated with respect to one another in a circumferential direction of the cylindrical coil.

6. A Multi-channel RE transmit system comprising:

an RF transmitter arrangement having a plurality of RF transmitter elements for generating an RF field for exciting nuclear magnetic resonances in an MRI system; and

a plurality of segments formed from the plurality of RF transmitter elements in at least two spatial directions selected from a direction of a main magnetic field of the MRI system, a z-direction, and a longitudinal direction;

a plurality of RF waveform generators and RF amplifiers for generating RF transmit signals for individually feeding the RF transmitter elements and/or segments.

7. The multi-channel RF transmit system according to claim 6, wherein the multi-channel RF transmit system is configured as a magnetic resonance imaging system.

8. A method for generating an RF field comprising acts of:

generating an RF field with an RF transmitter arrangement having a plurality of RF transmitter elements with a plurality of segments formed from the plurality of RF transmitter elements in at least two spatial directions selected from a direction of a main magnetic field of an MRI system, a z-direction, and a longitudinal direction for exciting nuclear magnetic resonances in the MRI system; and

generating a desired pattern of the RF field by individually controlling one or more of the transmitter elements and/or one or more of the segments.

9. A computer program comprising a computer program code stored on a computer readable non-transitory medium adapted to perform a method when said program is run on a programmable microcomputer, the method comprising acts of:

generating an RF field with an RF transmitter arrangement having a plurality of RF transmitter elements with a plurality of segments formed from the plurality of RF transmitter elements in at least two spatial directions selected from a direction of a main magnetic field of an MRI system, a z-direction, and a longitudinal direction for exciting nuclear magnetic resonances in the MRI system; and

generating a desired pattern of the RF field by individually controlling one or more of the transmitter elements and/or one or more of the segments.