US5471141A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for regulating radio frequency pulse
Assignee: Hitachi Ltd
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Filing: 1995-01-20
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Granted: 1995-11-28
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Expires: 2015-01-20
Abstract
Abstract When image information obtained on the basis of an NMR signal, e.g. MRI, is acquired, a radio frequency pulse is set so that a strong signal can be obtained particularly from a portion of interest among the sample. To accomplish this object, the occurrence of signals from portions of the sample other than the selected portion of interest is inhibited in advance of obtaining information (an image) of the sample. Various radio frequency pulses are then irradiated to the sample and a suitable radio frequency pulse is determined on the basis of the resulting signal.
Inventors
- 👤 Makoto Yoshida
- 👤 Naoki Satoh
- 👤 Hidehiko Asoh
- 👤 Tuyosi Shudo
- 👤 Ryuzaburo Takeda
- 👤 Jun'ichi Taguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:40
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/58; G01R33/583
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
258 words
For a sample placed inside a static magnetic field in which a radio frequency pulse is irradiated to said sample and an image on the status of said sample is obtained on the basis of a nuclear magnetic resonance signal obtained thereby from said sample, a method of regulating said radio frequency pulse to be executed for obtaining the image, associated with said sample, comprising the steps of: inhibiting occurrence of nuclear magnetic resonance signals from portions in a slice of said sample other than a selected portion of said slice including when said selected portion is associated with a relatively weaker NMR signal than NMR signals from other than said selected portion of said slice, said slice corresponding to a selected cross-section of said sample, wherein said selected portion of said slice is defined by a grid portion thereof corresponding to a plan view area of said slice surrounded by rectangular grid portions of said slice disposed to become saturated such that when said radio frequency pulse is irradiated to said sample the image to be formed is comprised from said selected portion in said slice; generating said nuclear magnetic resonance signal from the selected portion in the slice of said sample under such a signal occurrence inhibition state; and regulating at least one of the irradiation time and amplitude of said radio frequency pulse so as to set a flip angle of a spin of said selected portion to a desired angle on the basis of said nuclear magnetic resonance signal generated from said selected portion.
Claim 2
Dependent Claim
258 words
For a sample placed inside a static magnetic field in which a radio frequency pulse is irradiated to said sample and an image on the status of said sample is obtained on the basis of a nuclear magnetic resonance signal obtained thereby from said sample, a method of regulating said radio frequency pulse to be executed for obtaining the image, associated with said sample, comprising the steps of: inhibiting occurrence of nuclear magnetic resonance signals from portions in a slice of said sample other than a selected portion of said slice including when said selected portion is associated with a relatively weaker NMR signal than NMR signals from other than said selected portion of said slice, said slice corresponding to a selected cross-section of said sample, wherein said selected portion of said slice is defined by a grid portion thereof corresponding to a plan view area of said slice surrounded by rectangular grid portions of said slice disposed to become saturated such that when said radio frequency pulse is irradiated to said sample the image to be formed is comprised from said selected portion in said slice; generating said nuclear magnetic resonance signal from the selected portion in the slice of said sample under such a signal occurrence inhibition state; and regulating at least one of the irradiation time and amplitude of said radio frequency pulse so as to set a flip angle of a spin of said selected portion to a desired angle on the basis of said nuclear magnetic resonance signal generated from said selected portion.
Claim 3
Dependent Claim
53 words
A method of regulating a radio frequency pulse according to claim 1, wherein said nuclear magnetic resonance signal comprises an echo signal and at least one of the irradiation time and amplitude of said radio frequency pulse is regulated so as to obtain the same flip angle of a spin in the sample.
Claim 4
Dependent Claim
30 words
A method of regulating a radio frequency pulse according to claim 1, wherein said nuclear magnetic resonance signal comprises a relatively high order echo signal from among multiple echo signals.
Claim 5
Dependent Claim
60 words
A method of regulating a radio frequency pulse according to claim 1, wherein said nuclear magnetic resonance signal comprises a relatively high order echo signal from among multiple echo signals and at least one of the irradiation time and amplitude of said radio frequency pulse is regulated so that said relatively high order echo signal is substantially at maximum magnitude.
Claim 6
Dependent Claim
24 words
A method of regulating a radio frequency pulse according to claim 3, wherein said multiple echo signals are respectively generated at different timing intervals.
Claim 7
Dependent Claim
31 words
A method of regulating a radio frequency pulse according to claim 5, wherein said multiple echo signals are generated by irradiating said radio frequency pulses to said sample at irregular intervals.
Claim 8
Dependent Claim
35 words
A method of regulating a radio frequency pulse according to claim 5, wherein a field gradient is applied with said radio frequency pulse and the application timing of said field gradient is made different therefrom.
Claim 9
Dependent Claim
239 words
In an apparatus for obtaining image information on a sample placed in a static magnetic field by irradiating a radio frequency pulse to said sample, in which the apparatus regulates said radio frequency pulse on the basis of a nuclear magnetic resonance signal obtained thereby from said sample, said apparatus comprising: means for inhibiting occurrence of nuclear magnetic resonance signals from portions in a slice of said sample other than from a selected portion in said slice including when said selected portion is associated with a relatively weaker NMR signal than NMR signals from other than said selected portion of said slice, said slice corresponding to a selected cross-section of said sample, wherein said selected portion of said slice is defined by a grid portion corresponding to a plan view area of said slice surrounded by rectangular grid portions of said slice disposed to become saturated such that when said radio frequency pulse is irradiated to said sample the image to be formed is comprised from said selected portion in said slice; means for generating said nuclear magnetic resonance signal from said selected portion in said slice under such a signal occurrence inhibition state; and means for regulating at least one of the irradiation time and amplitude of said radio frequency pulse on the basis of said nuclear magnetic resonance signal so as to set a flip angle of a spin of said selected portion to a desired angle.
Claim 10
Dependent Claim
239 words
In an apparatus for obtaining image information on a sample placed in a static magnetic field by irradiating a radio frequency pulse to said sample, in which the apparatus regulates said radio frequency pulse on the basis of a nuclear magnetic resonance signal obtained thereby from said sample, said apparatus comprising: means for inhibiting occurrence of nuclear magnetic resonance signals from portions in a slice of said sample other than from a selected portion in said slice including when said selected portion is associated with a relatively weaker NMR signal than NMR signals from other than said selected portion of said slice, said slice corresponding to a selected cross-section of said sample, wherein said selected portion of said slice is defined by a grid portion corresponding to a plan view area of said slice surrounded by rectangular grid portions of said slice disposed to become saturated such that when said radio frequency pulse is irradiated to said sample the image to be formed is comprised from said selected portion in said slice; means for generating said nuclear magnetic resonance signal from said selected portion in said slice under such a signal occurrence inhibition state; and means for regulating at least one of the irradiation time and amplitude of said radio frequency pulse on the basis of said nuclear magnetic resonance signal so as to set a flip angle of a spin of said selected portion to a desired angle.
Claim 11
Dependent Claim
53 words
An apparatus for regulating a radio frequency pulse according to claim 8, wherein said nuclear magnetic resonance signal comprises an echo signal and at least one of the irradiation time and amplitude of said radio frequency pulse is regulated so as to obtain the same flip angle of a spin in the sample.
Claim 12
Dependent Claim
30 words
An apparatus for regulating a radio frequency pulse according to claim 8, wherein said nuclear magnetic resonance signal comprises a relatively high order echo signal from among multiple echo signals.
Claim 13
Dependent Claim
60 words
An apparatus for regulating a radio frequency pulse according to claim 8, wherein said nuclear magnetic resonance signal comprises a relatively high order echo signal from among multiple echo signals and at least one of the irradiation time and amplitude of said radio frequency pulse is regulated so that said relatively high order echo signal is substantially at maximum magnitude.
Claim 14
Dependent Claim
24 words
An apparatus for regulating a radio frequency pulse according to claim 10, wherein said multiple echo signals are respectively generated at different timing intervals.
Claim 15
Dependent Claim
31 words
An apparatus for regulating a radio frequency pulse according to claim 12, wherein said multiple echo signals are generated by irradiating said radio frequency pulses to said sample at irregular intervals.
Claim 16
Dependent Claim
35 words
An apparatus for regulating a radio frequency pulse according to claim 12, wherein a field gradient is applied with said radio frequency pulse and the application timing of said field gradient is made different therefrom.
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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) | 1998-11-27 | 1999-05-29 | 1999-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-11-27 | 2003-05-29 | 2003-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-11-27 | 2007-05-29 | 2007-11-28 | $7700.00 | Window Closed / Lapsed |