Method and Apparatus for Compensating for B1 Inhomogeneity in Magnetic Resonance Imaging by Nonselective Tailored RF Pulses
First Claim
1. A method of exciting nuclear spins in a body, the method comprising the steps of:
- (a) immerging said body (PB) in a static magnetic field (B0) for aligning nuclear spins along a magnetization axis (z), said static magnetic field being substantially uniform over at least a volume of interest (VOI) of said body;
(b) exposing said body, or at least said volume of interest, to a time-varying magnetic field gradient having components (Gx, Gy, Gz) directed along at least three non-coplanar directions (x, y, z) and to a radio-frequency non-selective pulse having a transverse polarization (B1), whereby said time-varying magnetic field gradient defines a three-dimensional trajectory in k-space constituted by straight segments linking discrete points (kT1-kT9), and said radio-frequency non-selective pulse having a transverse polarization deposits radio-frequency energy along at least part of said trajectory;
the positions of said discrete points in k-space being determined, and the radio-frequency non-selective pulse having a transverse polarization being designed, for flipping said nuclear spins by a same predetermined flip angle, independently from their position within said volume of interest.
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Accused Products
Abstract
A method of exciting nuclear spins in a body, the method comprising the steps of: (a) immerging said body (PB) in a static magnetic field (B0) for aligning nuclear spins along a magnetization axis (z), said static magnetic field being substantially uniform over at least a volume of interest (VOI) of said body; (b) exposing said body, or at least said volume of interest, to a time-varying magnetic field gradient having components (Gx, Gy, Gz) directed along at least three non-coplanar directions (x, y, z) and to a transverse radio-frequency field (B1), whereby said time-varying magnetic field gradient defines a three-dimensional trajectory in k-space constituted by segments linking discrete points (kT1−kT9), and said transverse radio-frequency field deposits radio-frequency energy along at least part of said trajectory for flipping said nuclear spins by a same predetermined flip angle, independently from their position within said volume of interest. A method of performing magnetic resonance imaging comprising a step of exciting nuclear spins in a body to be imaged, characterized in that said step is performed by carrying out a method. A magnetic resonance imaging scanner for carrying out such a method.
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Citations
15 Claims
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1. A method of exciting nuclear spins in a body, the method comprising the steps of:
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(a) immerging said body (PB) in a static magnetic field (B0) for aligning nuclear spins along a magnetization axis (z), said static magnetic field being substantially uniform over at least a volume of interest (VOI) of said body; (b) exposing said body, or at least said volume of interest, to a time-varying magnetic field gradient having components (Gx, Gy, Gz) directed along at least three non-coplanar directions (x, y, z) and to a radio-frequency non-selective pulse having a transverse polarization (B1), whereby said time-varying magnetic field gradient defines a three-dimensional trajectory in k-space constituted by straight segments linking discrete points (kT1-kT9), and said radio-frequency non-selective pulse having a transverse polarization deposits radio-frequency energy along at least part of said trajectory;
the positions of said discrete points in k-space being determined, and the radio-frequency non-selective pulse having a transverse polarization being designed, for flipping said nuclear spins by a same predetermined flip angle, independently from their position within said volume of interest. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of exciting nuclear spins in a human head, the method comprising the steps of:
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(a) immerging said human head, or a portion thereof, in a static magnetic field for aligning nuclear spins along a magnetization axis substantially parallel to a cranio-caudal direction of said human head, said static magnetic field being substantially uniform over at least a volume of interest (VOI) of said human head; (b) exposing at least said volume of interest, to a time-varying magnetic field gradient defining a bi-dimensional trajectory in k-space constituted by straight segments linking discrete points, and said radio-frequency non-selective pulse having a transverse polarization deposits radio-frequency energy along at least part of said trajectory;
the positions of said discrete points in k-space being determined, and the radio-frequency non-selective pulse having a transverse polarization being designed, for flipping said nuclear spins by a same predetermined flip angle, independently from their position within said volume of interest. - View Dependent Claims (15)
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Specification