MRI with motion correction using navigators acquired using a dixon technique
First Claim
1. A method of magnetic resonance (MR) imaging of at least a portion of a body placed in a main magnetic field B0 within an examination volume of a MR device, the method comprising:
- subjecting the portion of the body to an imaging sequence comprising one or more RF pulses and switched magnetic field gradients for acquiring imaging signals;
subjecting the portion of the body to a navigator sequence applied at least once before, during, or after the imaging sequence, the navigator sequence including one or more radio frequency (RF) pulses and switched magnetic field gradients controlled so that separate water navigator signals and fat navigator signals are acquired by means of a single-point or multi-point Dixon technique from a navigator volume of the navigator sequence when motion data indicative of motion occurring within the body exceeds a preselected threshold, the motion data being monitored by k-space navigators or one or more external sensors;
deriving translation and/or rotation and/or shear data from the water navigator signals and the fat navigator signals, wherein the translation and/or rotation and/or shear data reflect the motion occurring within the body;
reconstructing MR images from the imaging signals,wherein the translation and/or rotation and/or shear data are used for adapting the imaging sequence and/or for motion correction during reconstruction of the MR images.
1 Assignment
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Accused Products
Abstract
At least a portion of a body (10) is placed in a main magnetic field Bo within the examination volume of a MR device. The portion of the body (10) is subject to an imaging sequence including one or more RF pulses and switched magnetic field gradients to acquire imaging signals. The portion of the body (10) is subject to a navigator sequence applied at least once before, during, or after the imaging sequence. The navigator sequence includes one or more RF pulses and switched magnetic field gradients controlled to acquire navigator signals with a single-point or multi-point Dixon technique. Translation and/or rotation and/or shear data reflecting motion of the body are derived from the navigator signals during the acquisition of the imaging signals. The translation and/or rotation and/or shear data are used for adapting the imaging sequence and/or for motion correction during reconstruction of an MR image.
14 Citations
11 Claims
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1. A method of magnetic resonance (MR) imaging of at least a portion of a body placed in a main magnetic field B0 within an examination volume of a MR device, the method comprising:
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subjecting the portion of the body to an imaging sequence comprising one or more RF pulses and switched magnetic field gradients for acquiring imaging signals; subjecting the portion of the body to a navigator sequence applied at least once before, during, or after the imaging sequence, the navigator sequence including one or more radio frequency (RF) pulses and switched magnetic field gradients controlled so that separate water navigator signals and fat navigator signals are acquired by means of a single-point or multi-point Dixon technique from a navigator volume of the navigator sequence when motion data indicative of motion occurring within the body exceeds a preselected threshold, the motion data being monitored by k-space navigators or one or more external sensors; deriving translation and/or rotation and/or shear data from the water navigator signals and the fat navigator signals, wherein the translation and/or rotation and/or shear data reflect the motion occurring within the body; reconstructing MR images from the imaging signals, wherein the translation and/or rotation and/or shear data are used for adapting the imaging sequence and/or for motion correction during reconstruction of the MR images. - View Dependent Claims (2, 3, 4, 5)
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6. A magnetic resonance (MR) device comprising at least one main magnet coil configured to generate a main magnetic field B0 within an examination volume, a plurality of gradient coils configured to generate switched magnetic field gradients in different spatial directions within the examination volume, at least one radio frequency (RF) coil configured to generate RF pulses within the examination volume and to receive MR signals from a body of a patient positioned in the examination volume, a reconstruction processor configured to reconstruct MR images from the received MR signals, and a control processor configured to:
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control the gradient coils and the at least one RF coil to subject a portion of the body to an imaging sequence comprising one or more RF pulses and switched magnetic field gradients for acquiring imaging signals; control the gradient coils and the at least one RF coil to subject the portion of the body to a navigator sequence applied at least once before, during, or after the imaging sequence, the navigator sequence comprising one or more RF pulses and switched magnetic field gradients used to acquire Dixon water navigator signals and Dixon fat navigator signals by a single-point or multi-point Dixon technique and to acquire non-Dixon k-space navigator signals when motion data indicative of motion occurring within the body exceeds a preselected threshold, the motion data being monitored by k-space navigators or one or more external sensors; derive translation and/or rotation and/or shear data from the Dixon water and fat navigator signals, wherein the translation and/or rotation and/or shear data reflect the motion occurring within the body; reconstruct MR images from the imaging signals; and use the translation and/or rotation and/or shear data for adapting the imaging sequence and/or for motion correction during the reconstruction of the MR images.
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7. A non-transitory computer-readable medium carrying a computer program which controls one or more computers of a magnetic resonance (MR) device to control the MR device to:
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generate an imaging sequence comprising one or more RF pulses and switched magnetic field gradients for acquiring imaging signals; generate a Dixon navigator sequence and a non-Dixon k-space navigator sequence in an interleaved manner, the navigator sequences being applied at least once before, during, or after the imaging sequence; derive translation and/or rotation and/or shear data from water navigator signals and fat navigator signals acquired by applying the Dixon navigator sequence, wherein the translation and/or rotation and/or shear data reflect motion occurring within a body; wherein the water navigator signals and the fat navigator signals are acquired when motion data indicative of the motion occurring within the body exceeds a threshold, the motion data being monitored by non-Dixon k-space navigator signals acquired by applying the non-Dixon k-space navigator sequence or by one or more external sensors; reconstruct a MR image from the imaging signals; and use the translation and/or rotation and/or shear data for adapting the imaging sequence and/or for motion correction during reconstruction of the MR image. - View Dependent Claims (8)
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9. A magnetic resonance (MR) device comprising at least one main magnet coil configured to generate a main magnetic field B0 within an examination volume, a plurality of gradient coils configured to generate switched magnetic field gradients in different spatial directions within the examination volume, at least one radio frequency (RF) coil configured to generate RF pulses within the examination volume and to receive MR signals from a body of a patient positioned in the examination volume, a reconstruction processor configured to reconstruct MR images from the received MR signals, and a control processor configured to:
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control the gradient coils and the at least one RF coil to subject a portion of the body to an imaging sequence comprising one or more RF pulses and switched magnetic field gradients for acquiring imaging signals; control the gradient coils and the at least one RF coil to generate non-Dixon k-space navigator sequences and Dixon navigator sequences, at least one of the non-Dixon and Dixon navigator sequences being generated at least once before, during, or after the imaging sequence, each Dixon navigator sequence comprising one or more RF pulses and switched magnetic field gradients controlled to acquire Dixon water navigator signals and Dixon fat navigator signals by a single-point or multi-point Dixon technique when motion data indicative of motion occurring within the body exceeds a preselected threshold, the motion data being monitored by k-space navigators or one or more external sensors; and derive translation and/or rotation and/or shear data from the Dixon water and fat navigator signals, wherein the translation and/or rotation and/or shear data reflect the motion occurring within the body. - View Dependent Claims (10)
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11. A method of magnetic resonance (MR) imaging of at least a portion of a body placed in a main magnetic field B0 within an examination volume of an MR device, the method comprising:
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subjecting the portion of the body to an imaging sequence comprising one or more RF pulses and switched magnetic field gradients for acquiring imaging signals; subjecting the portion of the body to a navigator sequence applied at least once before, during, or after the imaging sequence, the navigator sequence comprising one or more RF pulses and switched magnetic field gradients controlled in such a manner that non-Dixon k-space navigator signals and Dixon navigator signals are acquired from a navigator volume, the Dixon navigator signals being acquired using a single-point or multi-point Dixon technique when motion data indicative of motion occurring within the body exceeds a preselected threshold, the motion data being monitored by k-space navigators or one or more external sensors, wherein the Dixon navigator signals include separate water navigator signals and fat navigator signals; deriving translation and/or rotation and/or shear data from the water navigator signals and fat navigator signals of the Dixon navigator signals, wherein the translation and/or rotation and/or shear data reflect motion occurring within the body; reconstructing MR images from the imaging signals, wherein the translation and/or rotation and/or shear data are used for adapting the imaging sequence and/or for motion correction during the reconstruction of the MR images.
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Specification