Method of and device for magnetic resonance imaging
First Claim
1. A method of forming magnetic resonance images of a moving part of a body, which part is arranged in a substantially uniform, steady magnetic field, said method comprising generating MR signals in the body by application of pulse sequences including RF pulses and temporary magnetic gradient fields, and subsequently reconstructing an image from position-dependent information in said MR signals, which method also comprises the following steps:
- 1) determining a position of the moving part,2) adjusting a position of an image slice to be excited in the body within the uniform magnetic field in conformity with the position determined for the moving part,3) exciting the image slice at the adjusted position to generate MR signals,4) receiving and demodulating the MR signals generated in said image slice, and5) processing the received and demodulated MR signals so as to form an image,wherein in order to determine the position of the moving part the following sub-steps are executed;
a) separately exciting a part of the body indicative of a movement of the moving part to generate a navigator signal,b) receiving the navigator signal, andc) determining the position of the moving part from the received navigator signal.
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Accused Products
Abstract
In a magnetic resonance method for imaging of a moving part of a body (106) temporary magnetic gradient fields (230) are applied and a echo signal (641, 642) is obtained after an excitation pulse (201). An image of the moving part is reconstructed from the received echo signals (240). The moving part introduces artefacts in the reconstructed image. These artefacts could be reduced when the instantaneous position of the moving part is known and the region of the moving part to be excited is adjusted according to this instantaneous position. This instantaneous position is derived from navigator signals (640). These navigator signals (640) could be generated independently from the other echo signals (641, 642) in the moving part of the body. A further reduction of artefacts in the image could be obtained by deriving a phase correction and a frequency correction from the navigator signals (640) and to apply the derived corrections to the received echo signals (641, 642). Also this method could be combined with ECG-triggering and respiratory gating.
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Citations
18 Claims
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1. A method of forming magnetic resonance images of a moving part of a body, which part is arranged in a substantially uniform, steady magnetic field, said method comprising generating MR signals in the body by application of pulse sequences including RF pulses and temporary magnetic gradient fields, and subsequently reconstructing an image from position-dependent information in said MR signals, which method also comprises the following steps:
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1) determining a position of the moving part, 2) adjusting a position of an image slice to be excited in the body within the uniform magnetic field in conformity with the position determined for the moving part, 3) exciting the image slice at the adjusted position to generate MR signals, 4) receiving and demodulating the MR signals generated in said image slice, and 5) processing the received and demodulated MR signals so as to form an image, wherein in order to determine the position of the moving part the following sub-steps are executed; a) separately exciting a part of the body indicative of a movement of the moving part to generate a navigator signal, b) receiving the navigator signal, and c) determining the position of the moving part from the received navigator signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of forming magnetic resonance images of a moving part of a body, which part is arranged in a substantially uniform, steady magnetic field, said method comprising generating MR signals in the body by application of pulse sequences including RF pulses and temporary magnetic gradient fields, and subsequently reconstructing an image from position-dependent information in said MR signals, which method also comprises the following steps:
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1) generating MR signals in an image slice in the body within the uniform magnetic field, 2) receiving and demodulating the MR signals generated in the image slice, and, 3) processing the received and demodulated MR signals so as to form an image, wherein in order to compensate for motion artifacts due to a component of movement of the moving part directed in the plane of the image slice the following sub-steps are executed; a) generating a navigator signal in a part of the body indicative of a movement of the moving part, b) receiving the navigator signal, c) determining at least one of a phase correction and a frequency correction from the navigator signal received, and d) executing the at least one of a phase correction and a frequency correction on the received MR signals during the demodulating. - View Dependent Claims (10, 11, 12)
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13. An MRI device for forming magnetic resonance images of a moving part of a body which is arranged in a substantially uniform, steady magnetic field, the device comprising:
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a) means for sustaining the steady magnetic field, b) means for generating RF electromagnetic signals, c) means for generating temporary magnetic gradient fields, d) means for receiving, demodulating and sampling the MR signals, e) means for determining a position of a moving part of the body, f) a reconstruction unit for processing the sampled MR signals to form an image, and g) a control unit configured for generating control signals for said means for generating RF electromagnetic signals, said means for generating temporary magnetic gradient fields, and said means for determining position in order to cause execution of the following steps; 1) separately exciting a part of the body indicative of a movement of the moving part to generate a navigator signal, 2) receiving the navigator signal, 3) determining the position of the moving part from the received navigator signal, 4) adjusting a position of an image slice to be excited within the uniform magnetic field in conformity with the position determined for the moving part, 5) exciting the image slice at the adjusted position to generate MR signals and receiving the MR signals, and 6) processing the received MR signals so as to form an image. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification