Method and apparatus for B.sub.0 eddy current compensation by B.sub.1 phase modulation
AssigneeThe Board of Trustees of the Leland Stanford Junior University
InventorsWalter F. Block, Adam B. Kerr, John M. Pauly
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Abstract
In accordance with the invention, spatially invariant B.sub.0 eddy currents induced by a slice-selection gradient, G.sub.Z in an MRI system, are compensated by phase modulating the RF excitation pulse with a compensating function. In one embodiment, the compensating function is based on a measure of the integral of the B.sub.0 eddy current. In another embodiment, a scaled copy of the excitation gradient can be used as an approximation of the compensating function.
Claims3
A method of improving spectral-spatial excitation in magnetic resonance imaging comprising the steps of:
- a) placing an object to be imaged in a static magnetic field (B.sub.0),
- b) applying a phase modulated RF excitation pulse to said object, the phase modulation being based on an empirically adjusted scaled copy of a slice-selection gradient whereby said RF excitation pulse providing spectral-spatial excitation to image tissue which suppresses fat, the phases modulation compensation for B.sub.0 eddy current phase modulation of the RF excitation pulse, and
- c) detecting signals emitted from said object.
Apparatus for use in providing improved spectral-spatial excitation in magnetic resonance imaging of an object comprising
- a) means for establishing a static magnetic field (B.sub.0 through the object,
- b) means for applying a phase modulated RF excitation pulse to said object, the phase modulation being based on an empirically adjusted scaled copy of a slice-selection gradient whereby said RF excitation pulse providing spectral-spatial excitation to image tissue which suppresses fat, the phases modulation compensation for B.sub.0 eddy current phase modulation of the RF excitation pulse, and
- c) detecting signals emitted from said object.
Dependencies are inferred from the claim text.