Method and apparatus for SAR reduction using B0 specific RF excitation
First Claim
1. A method for generation of a radio-frequency (RF) pulse using a magnetic resonance imaging device for excitation of nuclear spins in a predetermined measuring volume for magnetic resonance imaging, wherein the magnetic resonance imaging device comprises a supply unit and a magnet unit, and wherein the supply unit comprises a controller and an RF pulse generating unit, the method comprising:
- determining, with the controller, a spatial variation of a magnetic field strength of a magnetic field in the predetermined measuring volume;
defining, with the controller, a spectral frequency distribution of the RF pulse under a boundary condition of a substantially minimum energy content of the RF pulse, wherein the spectral frequency distribution only encompasses a previously determined frequency range of the spatial variation of the magnetic field strength of the magnetic field in the predetermined measuring volume, and wherein the RF pulse with the spectral frequency distribution is configured to excite nuclear spins in a specimen in the magnetic field in the predetermined measuring volume at a predetermined flip angle with a predetermined variance of the flip angle;
generating, with the RF pulse generating unit, the RF pulse with the defined spectral frequency distribution; and
imaging, with the magnetic resonance imaging device, the specimen using the generated RF pulse.
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Accused Products
Abstract
A method for generation of a radio-frequency (RF) pulse for excitation of nuclear spins in a predetermined layer of a specimen for magnetic resonance imaging and a magnetic resonance imaging device for performing the method are provided. The method includes determining a variation of a magnetic field in a measuring volume, and defining a spectral frequency distribution of the RF pulse. The RF pulse with the spectral frequency distribution is configured to excite nuclear spins in the specimen. The nuclear spins are polarized by the magnetic field at a predetermined flip angle in the measuring volume under a boundary condition of a substantially minimum energy content. The method also includes generating the RF pulse with the defined spectral frequency distribution.
13 Citations
16 Claims
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1. A method for generation of a radio-frequency (RF) pulse using a magnetic resonance imaging device for excitation of nuclear spins in a predetermined measuring volume for magnetic resonance imaging, wherein the magnetic resonance imaging device comprises a supply unit and a magnet unit, and wherein the supply unit comprises a controller and an RF pulse generating unit, the method comprising:
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determining, with the controller, a spatial variation of a magnetic field strength of a magnetic field in the predetermined measuring volume; defining, with the controller, a spectral frequency distribution of the RF pulse under a boundary condition of a substantially minimum energy content of the RF pulse, wherein the spectral frequency distribution only encompasses a previously determined frequency range of the spatial variation of the magnetic field strength of the magnetic field in the predetermined measuring volume, and wherein the RF pulse with the spectral frequency distribution is configured to excite nuclear spins in a specimen in the magnetic field in the predetermined measuring volume at a predetermined flip angle with a predetermined variance of the flip angle; generating, with the RF pulse generating unit, the RF pulse with the defined spectral frequency distribution; and imaging, with the magnetic resonance imaging device, the specimen using the generated RF pulse. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A magnetic resonance imaging device comprising:
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a magnet unit operable to generate a magnetic field that has a variation of the magnetic field in a predetermined measuring volume; and a supply unit comprising a control unit and a radio-frequency (RF) pulse generating unit, wherein the control unit is configured to; determine a spatial variation of a magnetic field strength of the magnetic field in the predetermined measuring volume; determine a spectral frequency distribution for an RF pulse under a boundary condition of a substantially minimum energy content of the RF pulse, wherein the spectral frequency distribution only encompasses a previously determined frequency range of the spatial variation of the magnetic field strength of the magnetic field in the predetermined measuring volume, and wherein the RF pulse is suitable to excite nuclear spins in a specimen in the magnetic field in the predetermined measuring volume at a predetermined flip angle with a predetermined variance of the flip angle, wherein the RF pulse generating unit is configured to generate the RF pulse with the spectral frequency distribution, and wherein the magnetic resonance imaging device is configured to image the specimen using the generated RF pulse. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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Specification