Eddy current mitigation systems and methods
AssigneeHyperfine Operations, Inc.
InventorsHadrien A. Dyvorne, Cedric Hugon, Rafael O'Halloran, Laura Sacolick
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Abstract
Techniques for compensating for presence of eddy currents during the operation of a magnetic resonance imaging (MRI) system in accordance with a pulse sequence, the pulse sequence comprising a gradient waveform associated with a target gradient field. The techniques include: compensating for presence of eddy currents during operation of the MRI system at least in part by correcting the gradient waveform using a nonlinear function of a characteristic of the gradient waveform to obtain a corrected gradient waveform; and operating the MRI system in accordance with the corrected gradient waveform to generate the target gradient field.
Claims23
A method for operating a magnetic resonance imaging (MRI) system by generating a target gradient field in accordance with a pulse sequence, the pulse sequence comprising a gradient waveform associated with the target gradient field, the method comprising:
- compensating for presence of eddy currents during operation of the MRI system at least in part by correcting the gradient waveform using a first nonlinear function of a characteristic of the gradient waveform to obtain a corrected gradient waveform;
- determining a shifted B0 magnetic field strength waveform using the corrected gradient waveform and a second nonlinear function describing effects of an amplitude of the gradient waveform on a B0 magnetic field of the MRI system;
- determining information indicative of variation of an operating frequency of an RF coil of the MRI system over a duration of the pulse sequence based on the shifted B0 magnetic field strength waveform, the information configured to govern a transmit and/or receive frequency of the RF coil while the MRI system is operated in accordance with the pulse sequence;
- and
- operating the MRI system in accordance with the corrected gradient waveform to generate the target gradient field.
A magnetic resonance imaging (MRI) system, comprising:
- a magnetics system comprising a plurality of magnetics components configured to produce magnetic fields for performing MRI, the plurality of magnetics components including at least one gradient coil for producing a gradient magnetic field;
- and
- at least one controller configured to operate one or more of the plurality of magnetics components in accordance with a pulse sequence, the pulse sequence comprising a gradient waveform associated with a target gradient field, wherein the at least one controller is configured to:
- compensate for presence of eddy currents during operation of the MRI system at least in part by correcting the gradient waveform using a nonlinear function of a characteristic of the gradient waveform to obtain a corrected gradient waveform;
- determine a shifted B0 magnetic field strength waveform using the corrected gradient waveform and a second nonlinear function describing effects of an amplitude of the gradient waveform on a B0 magnetic field of the MRI system;
- determine information indicative of variation of an operating frequency of an RF coil of the MRI system over a duration of the pulse sequence based on the shifted B0 magnetic field strength waveform, the information configured to govern a transmit and/or receive frequency of the RF coil while the MRI system is operated in accordance with the pulse sequence;
- and
- operate the MRI system in accordance with the corrected gradient waveform to generate the target gradient field.
At least one non-transitory computer-readable storage medium storing processor-executable instructions that, when executed by a magnetic resonance imaging (MRI) system, cause the MRI system to perform a method of operating the MRI system by applying a plurality of gradient fields in accordance with a pulse sequence, the pulse sequence comprising a gradient waveform associated with a target gradient field, the method comprising:
- compensating for presence of eddy currents during operation of the MRI system at least in part by correcting the gradient waveform using a nonlinear function of a characteristic of the gradient waveform to obtain a corrected gradient waveform;
- determining a shifted B0 magnetic field strength waveform using the corrected gradient waveform and a second nonlinear function describing effects of an amplitude of the gradient waveform on a B0 magnetic field of the MRI system;
- determining information indicative of variation of an operating frequency of an RF coil of the MRI system over a duration of the pulse sequence based on the shifted B0 magnetic field strength waveform, the information configured to govern a transmit and/or receive frequency of the RF coil while the MRI system is operated in accordance with the pulse sequence;
- and
- operating the MRI system in accordance with the corrected gradient waveform to generate the target gradient field.
Dependencies are inferred from the claim text.