Systems and methods for designing magnetic resonance imaging radio frequency pulses that are robust against physiological motion errors
First Claim
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1. A magnetic resonance imaging (MRI) system comprising:
- a magnet system configured to generate a polarizing magnetic field about at least a region of interest (ROI) of a subject arranged in the MRI system, the ROI being subject to cyclical physiological motion including a plurality of different states of physiological motion;
a plurality of gradient coils configured to apply a gradient field with respect to the polarizing magnetic field;
a radio frequency (RF) system configured to apply RF excitation fields to the subject and acquire MR image data therefrom; and
a computer programmed to;
acquire a B1+ calibration map for each of a plurality of selected ones of the plurality of different states of physiological motion in the subject, wherein each B1+ calibration map is correlated with a state of the physiological motion in the subject during acquisition of the B1+ calibration map;
using the B1+ calibration maps and correlated state of the physiological motion in the subject, design an RF pulse waveform that reduces B1+ inhomogeneity at each correlated state of physiological motion;
control the plurality of gradient coils and the RF system to produce an RF field based on a portion of the RF pulse waveform to acquire the image data from the subject, wherein the portion of the RF pulse waveform is correlated with a state of physiological motion of the subject during acquisition of the image data; and
reconstruct an image of the subject from the image data.
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Abstract
Systems and methods for designing and/or using radio frequency (“RF”) pulses for in-vivo MRI applications, where the RF pulses are robust against errors due to physiological motion of organs during the respiratory cycle. For example, RF pulses are designed based on multi-channel B1+ maps correlated to different positions of the respiratory cycle.
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Citations
7 Claims
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1. A magnetic resonance imaging (MRI) system comprising:
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a magnet system configured to generate a polarizing magnetic field about at least a region of interest (ROI) of a subject arranged in the MRI system, the ROI being subject to cyclical physiological motion including a plurality of different states of physiological motion; a plurality of gradient coils configured to apply a gradient field with respect to the polarizing magnetic field; a radio frequency (RF) system configured to apply RF excitation fields to the subject and acquire MR image data therefrom; and a computer programmed to; acquire a B1+ calibration map for each of a plurality of selected ones of the plurality of different states of physiological motion in the subject, wherein each B1+ calibration map is correlated with a state of the physiological motion in the subject during acquisition of the B1+ calibration map; using the B1+ calibration maps and correlated state of the physiological motion in the subject, design an RF pulse waveform that reduces B1+ inhomogeneity at each correlated state of physiological motion; control the plurality of gradient coils and the RF system to produce an RF field based on a portion of the RF pulse waveform to acquire the image data from the subject, wherein the portion of the RF pulse waveform is correlated with a state of physiological motion of the subject during acquisition of the image data; and reconstruct an image of the subject from the image data. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification