EP0142343A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Nuclear magnetic resonance imaging with reduced sensitivity to motional effects
Assignee: Siemens AG
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Filing: 1984-11-09
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Granted: —
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Expires: 2004-11-09
Abstract
Abstract The effects of motion in a given direction of particles being imaged in an NMR imaging system are substantially reduced by using gradients in the given direction produced by gradient pulse sequences which exhibit a zero value first moment relative to the point in time at which phase determination of the particles occurs. This point in time is generally taken at the time at which the longitudinal magnetization is translated to the transverse plane, as that is the phase reference for the NMR signals produced by the particles.
Inventors
- 👤 Russell Allen Compton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 01:25
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/561; G01R33/563
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
96 words
In an NMR imaging system, a method for acquiring NMR signals which are substantially insensitive to motional effects in a given direction in a sample being imaged comprising the steps of: a) applying an r.f. excitation signal to said sample; b) applying spatially encoding gradients to said sample, with the gradient in said given direction being produced in response to a gradient pulse sequence which exhibits a zero value first moment relative to a point in time at which phase determination occurs; and c) acquiring NMR signals resulting from said excitation signal and spatially encoding gradients.
Claim 2
Dependent Claim
96 words
In an NMR imaging system, a method for acquiring NMR signals which are substantially insensitive to motional effects in a given direction in a sample being imaged comprising the steps of: a) applying an r.f. excitation signal to said sample; b) applying spatially encoding gradients to said sample, with the gradient in said given direction being produced in response to a gradient pulse sequence which exhibits a zero value first moment relative to a point in time at which phase determination occurs; and c) acquiring NMR signals resulting from said excitation signal and spatially encoding gradients.
Claim 3
Dependent Claim
60 words
The method of Claim 1, wherein step b) comprises the step of: b) applying spatially encoding gradients to said sample, with the gradient in said given direction being produced in response to a gradient pulse sequence which exhibits a zero value first moment relative to the point in time at which the longitudinal magnetization is translated to the transverse plane.
Claim 4
Dependent Claim
26 words
The method of claim 1 or claim 2, wherein said gradient pulse sequence also exhibits a zero value zeroth moment relative to said point in time.
Claim 5
Dependent Claim
110 words
In an NMR imaging system, a method for producing NMR spin-echo signals which are substantially insensitive to the effects of motion in a given direction in a sample being imaged comprising the steps of: a) applying an r.f. excitation pulse sequence to said sample; b) applying spatially encoding gradients to said sample, with the gradient in said given direction beinq a frequency-encoding gradient produced in response to a gradient pulse sequence which exhibits a zero value first moment relative to a point in time at which phase determination occurs for pulses occurring during the time interval between said point in time and a second time occurring during said spin-echo signal.
Claim 6
Dependent Claim
110 words
In an NMR imaging system, a method for producing NMR spin-echo signals which are substantially insensitive to the effects of motion in a given direction in a sample being imaged comprising the steps of: a) applying an r.f. excitation pulse sequence to said sample; b) applying spatially encoding gradients to said sample, with the gradient in said given direction beinq a frequency-encoding gradient produced in response to a gradient pulse sequence which exhibits a zero value first moment relative to a point in time at which phase determination occurs for pulses occurring during the time interval between said point in time and a second time occurring during said spin-echo signal.
Claim 7
Dependent Claim
23 words
The method of Claim 4, wherein said gradient pulse sequence includes a pulse occurring during the time of occurrence of said spin-echo signal.
Claim 8
Dependent Claim
28 words
S. The method of claim 4 or claim 5, wherein said point of time is the time at which the longitudinal magnetization is translated to the transverse plane.
Claim 9
Independent Claim
29 words
The method of any one of claims 4 to 6, wherein said second time is substantially equal to the time of occurrence of the peak of said spin-echo signal.
Claim 10
Independent Claim
29 words
The method of any one of claims 4 to 7, wherein the portion of said gradient pulse sequence occurring during said time interval exhibits a zero value zeroth moment.
Claim 11
Dependent Claim
106 words
In an NMR imaging system, a method for acquiring NMR signals which are substantially insensitive to motional effects in a given direction in a sample being imaged comprising the steps of: a) applying an r.f. excitation signal to said sample; b) applying spatially encoding gradients to said sample, with the gradient in said given direction being a phase-encoding gradient produced in response to a gradient pulse sequence which exhibits a zero value first moment relative to a point in time at which phase determination occurs, and a non-zero value zero moment; and c) acquiring N MR signals resulting from said excitation signal and spatially encoding gradients.
Claim 12
Dependent Claim
106 words
In an NMR imaging system, a method for acquiring NMR signals which are substantially insensitive to motional effects in a given direction in a sample being imaged comprising the steps of: a) applying an r.f. excitation signal to said sample; b) applying spatially encoding gradients to said sample, with the gradient in said given direction being a phase-encoding gradient produced in response to a gradient pulse sequence which exhibits a zero value first moment relative to a point in time at which phase determination occurs, and a non-zero value zero moment; and c) acquiring N MR signals resulting from said excitation signal and spatially encoding gradients.
Claim 13
Dependent Claim
24 words
The method of Claim 9, wherein said point in time is the time at which the longitudinal magnetization is translated to the transverse plane.
Claim 14
Independent Claim
109 words
A method for preconditioning spatially encoding N M R signals of a moving particle in an NMR sample to substantially eliminate the effects of motion, comprising the steps of: a) subjecting said particle to at least a first gradient field which provides said particle with position encoding and a first encoded component in a first sense which is due to motion; and b) subjecting said particle to at least a second gradient field which provides said particle with a second encoded component in a second sense which is due to motion, wherein substantially no net encoded component results from the combined effect of said first and second encoded components.
Claim 15
Independent Claim
109 words
A method for preconditioning spatially encoding N M R signals of a moving particle in an NMR sample to substantially eliminate the effects of motion, comprising the steps of: a) subjecting said particle to at least a first gradient field which provides said particle with position encoding and a first encoded component in a first sense which is due to motion; and b) subjecting said particle to at least a second gradient field which provides said particle with a second encoded component in a second sense which is due to motion, wherein substantially no net encoded component results from the combined effect of said first and second encoded components.
Claim 16
Dependent Claim
44 words
The method of Claim 11, wherein step a) is preceded by the step of: c) applying an r.f. excitation signal to said sample; and step b) is succeeded by the step of: d) acquiring the NMR signal produced in response to the preceding steps.
Claim 17
Dependent Claim
19 words
1 3. The method of claim 11 or claim 12. wherein said first and second components are phase-encoding components.
Claim 18
Dependent Claim
20 words
The method of claim 11, or claim 12 wherein said first and second gradient fields are in the same direction.
References Cited (Backward Citations)
No citation records indexed.
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