Systems and Methods For Designing Magnetic Resonance Imaging Radio Frequency Pulses That Are Robust Against Physiological Motion Errors
AssigneeDeere & Company
InventorsSebastian Schmitter, Pierre-Francois van de Moortele, Xiaoping Xu, Kamil Ugurbil
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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.
Claims20
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 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 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 is robust against the physiological motion;
- control the plurality of gradient coils and the RF system to produce an RF field based on the RF pulse waveform to acquire imaging data from the subject;
- and
- reconstruct an image of the subject from the imaging data.
A method for designing a radio frequency (RF) pulse for parallel transmission with a magnetic resonance imaging (MRI) system, the method comprising:
- determining a state of physiological motion including plurality of different states of physiological motion within a region of interest (ROI) of a subject without performing a navigator pulse sequence;
- correlating a B1+ calibration map for each of a selected ones of the plurality of different states of physiological motion in the subject;
- and
- assembling the B1+ calibration maps into groups of virtual slices within the ROI;
- using the B1+ calibration maps grouped into virtual slices and correlated state of the physiological motion in the subject, designing an RF pulse waveform for parallel transmission that is robust against the physiological motion by adjusting pulses in the RF pulse waveform relative to the groups of virtual slices to reduce errors in data acquired using the RF pulse waveform induced by the cyclical physiological motion in the ROI.
A method for designing a radio frequency (RF) pulse for parallel transmission with a magnetic resonance imaging (MRI) system, the method including steps comprising:
- (a) providing a B0 calibration map for each of a plurality of different states of physiological motion in a subject;
- (b) providing a B1+ calibration map for each of the plurality of different states of physiological motion in the subject;
- (c) optimizing an RF pulse waveform that is robust against physiological motion by designing the RF pulse waveform for specific states of physiological motion using the B0 and B1+ calibration maps provided for the specific states of physiological motion;
- and
- (d) directing the MRI system to produce an RF field based on the optimized RF pulse waveform.
Dependencies are inferred from the claim text.