US5126673A
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Method for generating a sequence of spin echo signals, the application of this method in nuclear spin tomography, and a devicefor carrying out and/or for applying this method
Assignee: Spectrospin AG
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Filing: 1989-07-05
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Granted: 1992-06-30
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Expires: 2009-07-05
Abstract
Abstract A method and drive for generating spin echo signals by a sequence of equidistant rf pulses of different amplitude and small flip angle α, which pulses follow each other in very rapid succession. By proper selection of the amplitude, it is ensured that the sequence of equidistant echo signals so obtained has of an image without numerous gradient switching steps heretofore required.
Inventors
- 👤 Jurgen Hennig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:56
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/561; G01R33/5615; G01R33/5617
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
140 words
A method for generating a sequence of spin echo signals in NMR Spectroscopy comprising the steps of placing a sample in a homogeneous magnetic field, additionally exposing said sample to a magnetic gradient field and exciting said sample by a sequence of equidistant rf pulse of different amplitude having a flip angle α, said rf pulses following each other in rapid sequence, said flip angle α and amplitude being selected in such a manner that the product of the number of rf pulses and the flip angle of the individual pulses results in an overall flip angle of between 90 degrees and 180 degrees in order that, following said sequence of rf pulses, a train of equidistant echo signals of generally constant amplitude is obtained, said magnetic gradient field being held constant during excitation by the sequence of rf pulses.
Claim 2
Independent Claim
140 words
A method for generating a sequence of spin echo signals in NMR Spectroscopy comprising the steps of placing a sample in a homogeneous magnetic field, additionally exposing said sample to a magnetic gradient field and exciting said sample by a sequence of equidistant rf pulse of different amplitude having a flip angle α, said rf pulses following each other in rapid sequence, said flip angle α and amplitude being selected in such a manner that the product of the number of rf pulses and the flip angle of the individual pulses results in an overall flip angle of between 90 degrees and 180 degrees in order that, following said sequence of rf pulses, a train of equidistant echo signals of generally constant amplitude is obtained, said magnetic gradient field being held constant during excitation by the sequence of rf pulses.
Claim 3
Dependent Claim
33 words
A method according to claim 1, wherein the intensity of the magnetic gradient field is varied during a time interval between the sequence of rf pulses and the beginning of the echo signals.
Claim 4
Dependent Claim
23 words
A method according to claim 1 wherein a sequence of equidistant rf pulses is generated which are interrupted by gaps at predetermined points.
Claim 5
Dependent Claim
89 words
A method according to claim 1 for the generation of the signals characteristic of the points of a two-dimensional image in nuclear spin tomography, further comprising the steps of exposing the sample, after termination of the said sequence of rf pulses and for the duration of the said sequence of the echo signals, to a magnetic phase gradient directed perpendicularly to the said magnetic gradient field, and subjecting the echo signals so obtained to two-dimensional Fourier transformation in order to provide signals characteristic of the points of the image.
Claim 6
Dependent Claim
19 words
A method according to claim 4, wherein the phase gradient is constant during the sequence of the echo signals.
Claim 7
Dependent Claim
26 words
A method according to claim 4, wherein the said phase gradient is switched on in a pulse-like manner in the intervals between the individual echo signals.
Claim 8
Dependent Claim
45 words
A method according to claim 4, wherein the sample is subjected, before irradiation with the sequence of rf pulses, to a disk-selection gradient and a selective excitation pulse, in order that the sequence of the rf pulses will have the effect of a refocusing pulse.
Claim 9
Dependent Claim
41 words
A method according to claim 4, wherein the sample is subjected, prior to irradiation with the sequence of the rf pulses, to a disk-selection gradient and an rf pulse which saturated the area of the sample positioned outside the selected disk.
Claim 10
Dependent Claim
52 words
A method according to claim 4, wherein a disk-selective refocusing pulse in irradiated upon the sample after termination of the sequence of rf pulses and before the beginning of the sequence of echo pulses, and the magnetic gradient field is replaced by the selection gradient for the duration of the refocusing pulse.
Claim 11
Dependent Claim
65 words
A method according to claim 1 for the generation of the signals characteristic of the points of a two-dimensional image in nuclear spin tomography, further comprising the step of subjecting the sample to a disk-selection gradient and a selective excitation pulse for enabling the recording of a third dimension of the sample, said third dimension being perpendicular to the plane of the disk selection gradient.
Claim 12
Independent Claim
128 words
A method for generating a sequence of spin echo signals in NMR Spectroscopy comprising the steps of placing a sample in a homogeneous magnetic field, additionally exposing said sample to a magnetic gradient field and exciting said sample by a sequence of equidistant rf pulses of different amplitude having a flip angle α, said rf pulses being phase-modulated and following each other in rapid sequence, said flip angle α and amplitude being selected in such a manner that the product of the number of rf pulses and the flip angle of the individual pulses results in an overall flip angle of between 90 degrees and 180 degrees in order that, following said sequence of rf pulses a train of equidistant echo signals of generally constant amplitude is obtained.
Claim 13
Independent Claim
128 words
A method for generating a sequence of spin echo signals in NMR Spectroscopy comprising the steps of placing a sample in a homogeneous magnetic field, additionally exposing said sample to a magnetic gradient field and exciting said sample by a sequence of equidistant rf pulses of different amplitude having a flip angle α, said rf pulses being phase-modulated and following each other in rapid sequence, said flip angle α and amplitude being selected in such a manner that the product of the number of rf pulses and the flip angle of the individual pulses results in an overall flip angle of between 90 degrees and 180 degrees in order that, following said sequence of rf pulses a train of equidistant echo signals of generally constant amplitude is obtained.
Claim 14
Dependent Claim
34 words
A method according to claim 11, wherein the phase of a first half of the rf pulses is phase-shifted by 90 degrees relative to the phase of a second half of the rf pulses.
Claim 15
Independent Claim
109 words
A device for generating a sequence of spin echo signals in NMR spectroscopy comprising: means for applying a homogeneous magnetic field to a sample; means for applying a constant magnetic gradient field to said sample during exposure thereof to rf pulses; transmitter means for generating rf pulses and disposed for exposing said sample to the rf pulses, said transmitter means being adapted for generating a rapid sequence of equidistant rf pulses with different amplitudes each having a flip angle α, said amplitudes and flip angles α being selected such that the product of the number of rf pulses and the flip angle is between 90 degrees and 180 degrees.
Claim 16
Independent Claim
109 words
A device for generating a sequence of spin echo signals in NMR spectroscopy comprising: means for applying a homogeneous magnetic field to a sample; means for applying a constant magnetic gradient field to said sample during exposure thereof to rf pulses; transmitter means for generating rf pulses and disposed for exposing said sample to the rf pulses, said transmitter means being adapted for generating a rapid sequence of equidistant rf pulses with different amplitudes each having a flip angle α, said amplitudes and flip angles α being selected such that the product of the number of rf pulses and the flip angle is between 90 degrees and 180 degrees.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-06-30 | 1995-12-30 | 1996-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-06-30 | 1999-12-30 | 2000-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-06-30 | 2003-12-30 | 2004-06-30 | $7700.00 | Window Closed / Lapsed |