Virtual coil emulation in parallel transmission MRI
First Claim
1. A method of performing a magnetic resonance imaging scan for acquiring a magnetic resonance image of an object, wherein the scan is performed using a physical coil arrangement comprising set of individual transmit coils, the coils being adapted for transmission of an RF transmit field to the object for magnetic resonance spin excitation of the object, wherein each coil is associated with a physical transmit channel, the method comprising:
- a) selecting a desired RF transmit field to be generated by the coils, said RF transmit field corresponding to a virtual arrangement of two or more of said coils, wherein virtual transmit channel properties comprising virtual transmit channel weights are assigned to the RF transmit field, said virtual transmit channel weights describing the virtual complex RF field amplitudes with respect to each individual coil of the virtual coil arrangement required to be applied to the physical coils for generating the RF transmit field,b) transforming the virtual transmit channel properties using a channel encoding matrix, the transmit channel encoding matrix describing a transformation of the virtual transmit channel properties of the virtual coil arrangement to physical transmit channel properties of the physical coil arrangement,c) measuring individual virtual coil sensitivities of the two or more virtual coils using the respective transformed individual virtual transmit channel property for each virtual coil, wherein the RF transmit field of each individual virtual coil is given by the combination of the corresponding virtual transmit channel property and the corresponding virtual coil sensitivity,d) optimizing the individual virtual transmit channel properties for each virtual coil using the measured virtual coil sensitivities in order to obtain the desired RF transmit field at higher accuracy,e) transforming the optimized virtual transmit channel properties using the channel encoding matrix, said transformation resulting in physical transmit channel properties comprising physical transmit channel weights, said physical transmit channel weights describing the physical complex RF field amplitudes with respect to each individual coil of the physical coil arrangement,f) performing the magnetic resonance imaging scan using the physical transmit channel properties.
1 Assignment
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Accused Products
Abstract
A virtual coil emulation method is used in a magnetic resonance imaging scan for acquiring a magnetic resonance image of an object (10). The scan is performed by an MR system (1) using a physical coil arrangement (9; 11; 12; 13) including a set of individual transmit coils. The coils are adapted for transmission of a desired RF transmit field to the object (10) for magnetic resonance spin excitation of the object (10). Each coil is associated with a physical transmit channel. The RF transmit field corresponds to a virtual arrangement of two or more of the coils. Virtual transmit channel properties include virtual transmit channel weights are assigned to the RF transmit field which describe the virtual complex RF field amplitudes with respect to each individual coil of the virtual coil arrangement to be applied to the physical coils (9; 11; 12; 13) for generating the RF transmit field.
14 Citations
20 Claims
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1. A method of performing a magnetic resonance imaging scan for acquiring a magnetic resonance image of an object, wherein the scan is performed using a physical coil arrangement comprising set of individual transmit coils, the coils being adapted for transmission of an RF transmit field to the object for magnetic resonance spin excitation of the object, wherein each coil is associated with a physical transmit channel, the method comprising:
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a) selecting a desired RF transmit field to be generated by the coils, said RF transmit field corresponding to a virtual arrangement of two or more of said coils, wherein virtual transmit channel properties comprising virtual transmit channel weights are assigned to the RF transmit field, said virtual transmit channel weights describing the virtual complex RF field amplitudes with respect to each individual coil of the virtual coil arrangement required to be applied to the physical coils for generating the RF transmit field, b) transforming the virtual transmit channel properties using a channel encoding matrix, the transmit channel encoding matrix describing a transformation of the virtual transmit channel properties of the virtual coil arrangement to physical transmit channel properties of the physical coil arrangement, c) measuring individual virtual coil sensitivities of the two or more virtual coils using the respective transformed individual virtual transmit channel property for each virtual coil, wherein the RF transmit field of each individual virtual coil is given by the combination of the corresponding virtual transmit channel property and the corresponding virtual coil sensitivity, d) optimizing the individual virtual transmit channel properties for each virtual coil using the measured virtual coil sensitivities in order to obtain the desired RF transmit field at higher accuracy, e) transforming the optimized virtual transmit channel properties using the channel encoding matrix, said transformation resulting in physical transmit channel properties comprising physical transmit channel weights, said physical transmit channel weights describing the physical complex RF field amplitudes with respect to each individual coil of the physical coil arrangement, f) performing the magnetic resonance imaging scan using the physical transmit channel properties. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A magnetic resonance imaging system adapted for performing a magnetic resonance imaging scan for acquiring a magnetic resonance image of an object, wherein the system comprises a physical coil arrangement comprising set of individual transmit coils adapted to perform the scan, the coils being adapted for transmission of an RF transmit field to the object for magnetic resonance spin excitation of the object, wherein each coil is associated with a physical transmit channel, the system being adapted for:
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a) selecting an desired RF transmit field to be generated by the coils, said RF transmit field corresponding to a virtual arrangement of two or more of said coils, wherein virtual transmit channel properties comprising virtual transmit channel weights are assigned to the RF transmit field, said virtual transmit channel weights describing the virtual complex RF field amplitudes with respect to each individual coil of the virtual coil arrangement required to be applied to the physical coils for generating the RF transmit field, b) transforming the virtual transmit channel properties using a channel encoding matrix, the transmit channel encoding matrix describing a transformation of the virtual transmit channel properties of the virtual coil arrangement to physical transmit channel properties of the physical coil arrangement, c) measuring individual virtual coil sensitivities of the two or more virtual coils using the respective transformed individual virtual transmit channel property for each virtual coil, wherein the RF transmit field of each individual virtual coil is given by the combination of the corresponding virtual transmit channel property and the corresponding virtual coil sensitivity, d) optimizing the individual virtual transmit channel properties for each virtual coil using the measured virtual coil sensitivities in order to obtain the desired RF transmit field at higher accuracy, e) transforming the optimized virtual transmit channel properties using the channel encoding matrix, said transformation resulting in physical transmit channel properties comprising physical transmit channel weights, said physical transmit channel weights describing the physical complex RF field amplitudes with respect to each individual coil of the physical coil arrangement, f) performing the magnetic resonance imaging scan using the physical transmit channel properties. - View Dependent Claims (11)
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12. A virtual coil emulation method to be used in a magnetic resonance imaging scan for acquiring a magnetic resonance image of an object, wherein the scan is performed by an MR system using a physical coil arrangement comprising set of individual transmit coils, the coils being adapted for transmission of a desired RF transmit field to the object for magnetic resonance spin excitation of the object, wherein each coil is associated with a physical transmit channel, wherein the RF transmit field corresponds to a virtual arrangement of two or more of said coils, wherein virtual transmit channel properties comprising virtual transmit channel weights are assigned to the RF transmit field, said virtual transmit channel weights describing the virtual complex RF field amplitudes with respect to each individual coil of the virtual coil arrangement required to be applied to the physical coils for generating the RF transmit field, the method comprising:
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a) receiving the virtual transmit channel properties from the MR system, b) transforming the virtual transmit channel properties using a channel encoding matrix, the transmit channel encoding matrix describing a transformation of the virtual transmit channel properties of the virtual coil arrangement to physical transmit channel properties of the physical coil arrangement, c) receiving optimized virtual transmit channel properties, the optimized virtual transmit channel properties being received from the MR system and resulting from i. measuring by the MR system individual virtual coil sensitivities of the two or more virtual coils using the respective transformed individual virtual transmit channel property for each virtual coil, wherein the RF transmit field of each individual virtual coil is given by the combination of the corresponding virtual transmit channel property and the corresponding virtual coil sensitivity, ii. optimizing by the MR system the individual virtual transmit channel properties for each virtual coil using the measured virtual coil sensitivities resulting in the desired RF transmit field at higher accuracy, d) transforming the optimized virtual transmit channel properties using the channel encoding matrix, said transformation resulting in physical transmit channel properties comprising physical transmit channel weights, said physical transmit channel weights describing the physical complex RF field amplitudes with respect to each individual coil of the physical coil arrangement, e) providing the physical transmit channel properties to the MR system for performing the magnetic resonance imaging scan using the physical transmit channel properties.
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13. A virtual coil emulation system adapted to be used in a magnetic resonance imaging scan for acquiring a magnetic resonance image of an object, wherein the scan is performed by an MR system using a physical coil arrangement comprising set of individual transmit coils, the coils being adapted for transmission of a desired RF transmit field to the object for magnetic resonance spin excitation of the object, wherein each coil is associated with a physical transmit channel, wherein the RF transmit field corresponds to a virtual arrangement of two or more of said coils, wherein virtual transmit channel properties comprising virtual transmit channel weights are assigned to the RF transmit field, said virtual transmit channel weights describing the virtual complex RF field amplitudes with respect to each individual coil of the virtual coil arrangement required to be applied to the physical coils for generating the RF transmit field, the emulation system being adapted for:
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a) receiving the virtual transmit channel properties from the MR system, b) transforming the virtual transmit channel properties using a channel encoding matrix, the transmit channel encoding matrix describing a transformation of the virtual transmit channel properties of the virtual coil arrangement to physical transmit channel properties of the physical coil arrangement, c) receiving optimized virtual transmit channel properties, the optimized virtual transmit channel properties being received from the MR system and resulting from i. measuring by the MR system individual virtual coil sensitivities of the two or more virtual coils using the respective transformed individual virtual transmit channel property for each virtual coil, wherein the RF transmit field of each individual virtual coil is given by the combination of the corresponding virtual transmit channel property and the corresponding virtual coil sensitivity, ii. optimizing by the MR system the individual virtual transmit channel properties for each virtual coil using the measured virtual coil sensitivities resulting in the desired RF transmit field at higher accuracy, d) transforming the optimized virtual transmit channel properties using the channel encoding matrix, said transformation resulting in physical transmit channel properties comprising physical transmit channel weights, said physical transmit channel weights describing the physical complex RF field amplitudes with respect to each individual coil of the physical coil arrangement, e) providing the physical transmit channel properties to the MR system for performing the magnetic resonance imaging scan using the physical transmit channel properties.
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14. A non-transitory computer-readable medium carrying computer executable instructions configured to control one or more computer processors to:
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transform the virtual transmit channel properties using a channel encoding matrix, the transmit channel encoding matrix describing a transformation of a virtual transmit channel properties of a virtual coil arrangement to physical transmit channel properties of a physical magnetic resonance coil arrangement; determine individual virtual coil sensitivities of two or more virtual coils using the respective transformed individual virtual transmit channel property for each virtual coil, wherein the RF transmit field of each individual virtual coil is given by the combination of the corresponding virtual transmit channel property and the corresponding virtual coil sensitivity; optimize the individual virtual transmit channel properties for each virtual coil using the determined virtual coil sensitivities resulting in an accurate RF transmit field; transform the optimized virtual transmit channel properties using the channel encoding matrix, the transformation resulting in physical transmit channel properties including physical transmit channel weights, the physical transmit channel weights describing physical complex RF field amplitudes with respect to each individual coil of the physical coil arrangement. - View Dependent Claims (15, 16, 17)
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18. A magnetic resonance system comprising:
one or more processors configured to; transform the virtual transmit channel properties using a channel encoding matrix, the transmit channel encoding matrix describing a transformation of a virtual transmit channel properties of a virtual coil arrangement to physical transmit channel properties of a physical magnetic resonance coil arrangement; determine individual virtual coil sensitivities of two or more virtual coils using the respective transformed individual virtual transmit channel property for each virtual coil, wherein the RF transmit field of each individual virtual coil is given by the combination of the corresponding virtual transmit channel property and the corresponding virtual coil sensitivity; optimize the individual virtual transmit channel properties for each virtual coil using the determined virtual coil sensitivities resulting in an accurate RF transmit field; transform the optimized virtual transmit channel properties using the channel encoding matrix, the transformation resulting in physical transmit channel properties including physical transmit channel weights, the physical transmit channel weights describing physical complex RF field amplitudes with respect to each individual coil of the physical coil arrangement. - View Dependent Claims (19, 20)
Specification