PARALLEL TRANSMISSION RF PULSE DESIGN WITH LOCAL SAR CONSTRAINTS
First Claim
1. A method of designing a parallel transmission radio frequency (RF) pulse for a magnetic resonance imaging (MRI) system, the method comprising:
- compressing a model for a subject to be scanned by the MRI system into a plurality of voxel clusters, each voxel cluster defining a virtual observation point with a peak sensitivity to local specific absorption rate (SAR) for the voxel cluster; and
defining the parallel transmission RF pulse based on an approximation of a minimization criterion having a local SAR component based on the peak sensitivity of each virtual observation point, the approximation comprising a weighted sum of local SAR values for the virtual observation points.
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Abstract
A method of designing a parallel transmission radio frequency (RF) pulse for a magnetic resonance imaging (MRI) system includes compressing a model for a subject to be scanned by the MRI system into a plurality of voxel clusters, each voxel cluster defining a virtual observation point with a peak sensitivity to local specific absorption rate (SAR) for the voxel cluster, and defining the parallel transmission RF pulse based on an approximation of a minimization criterion having a local SAR component based on the peak sensitivity of each virtual observation point, the approximation comprising a weighted sum of the local SAR values for each virtual observation point.
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Citations
26 Claims
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1. A method of designing a parallel transmission radio frequency (RF) pulse for a magnetic resonance imaging (MRI) system, the method comprising:
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compressing a model for a subject to be scanned by the MRI system into a plurality of voxel clusters, each voxel cluster defining a virtual observation point with a peak sensitivity to local specific absorption rate (SAR) for the voxel cluster; and defining the parallel transmission RF pulse based on an approximation of a minimization criterion having a local SAR component based on the peak sensitivity of each virtual observation point, the approximation comprising a weighted sum of local SAR values for the virtual observation points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of designing a parallel transmission radio frequency (RF) pulse for a magnetic resonance imaging (MRI) system and a model for a subject to be scanned by the MRI system, the model being defined via a number of voxels, the method comprising:
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calculating a spatial matrix for each voxel of the model, the spatial matrix being indicative of absorption sensitivity; defining a plurality of clusters of the voxels in the model, each cluster having a virtual observation point representing a maximum sensitivity to local specific absorption rate (SAR) for each voxel in the cluster; and selecting the parallel transmission RF pulse that minimizes an approximation of a design criterion having a local SAR component based on the peak sensitivity of each virtual observation point, the approximation comprising a weighted sum of local SAR values for the virtual observation points. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A magnetic resonance imaging (MRI) system comprising:
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a data storage unit to store calibration data for a model for a subject to be scanned, the model having a number of voxels; a coil array for transmitting a parallel transmission radio frequency (RF) pulse to the subject; and a control system in communication with the data storage unit and the coil array; wherein the control system is configured to design the parallel transmission RF pulse to control local specific absorption rate (SAR) based on the model, a model compression in which the model is compressed into a plurality of clusters of the voxels of the model, each cluster defining a virtual observation point with a peak sensitivity to local SAR for the voxel cluster, and an approximation of a design criterion having a local SAR component based on the peak sensitivity of each virtual observation point, the approximation comprising a weighted sum of local SAR values for the virtual observation points. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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Specification