US4891595A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Restricted volume imaging
Assignee: GE Medical Systems Israel Ltd
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Filing: 1987-05-26
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Granted: 1990-01-02
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Expires: 2007-05-26
Abstract
Abstract A method of using a stimulated echo sequence for acquiring imaging data of spatially localized volumes with a magnetic resonance system.
Inventors
- 👤 Joseph Granot
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:30
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/4818; G01R33/482; G01R33/54; G01R33/56
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
219 words
A method for performing restricted volume magnetic resonance (MR) imaging comprising the steps of: aligning spins in a subject by positioning the subject in a strong static magnetic field, irradiating said subject with a first RF pulse in the presence of a first magnetic gradient so as to nutate the aligned spins in a first selected volume of said subject, irradiating said subject with a second RF pulse in the presence of a second magnetic gradient normal to said first magnetic gradient so as to further nutate the nutated spins in a portion of said first selected volume of said subject, irradiating said subject with a third RF pulse in the presence of a third magnetic gradient normal to said first and second magnetic gradients to still further nutate the further nutated spins in a section of said portion of said first selected volume, to thereby select a particular volume of the subject, selecting said first, second and third RF pulses to generate stimulated echo signals from said still further nutated spins at a time after the third RF pulse equal to the time between said first and said second RF pulses, applying encoding gradient pulses to provide image data, and sampling the stimulated echo signals for use as the image data in presence of a view gradient pulse.
Claim 2
Independent Claim
219 words
A method for performing restricted volume magnetic resonance (MR) imaging comprising the steps of: aligning spins in a subject by positioning the subject in a strong static magnetic field, irradiating said subject with a first RF pulse in the presence of a first magnetic gradient so as to nutate the aligned spins in a first selected volume of said subject, irradiating said subject with a second RF pulse in the presence of a second magnetic gradient normal to said first magnetic gradient so as to further nutate the nutated spins in a portion of said first selected volume of said subject, irradiating said subject with a third RF pulse in the presence of a third magnetic gradient normal to said first and second magnetic gradients to still further nutate the further nutated spins in a section of said portion of said first selected volume, to thereby select a particular volume of the subject, selecting said first, second and third RF pulses to generate stimulated echo signals from said still further nutated spins at a time after the third RF pulse equal to the time between said first and said second RF pulses, applying encoding gradient pulses to provide image data, and sampling the stimulated echo signals for use as the image data in presence of a view gradient pulse.
Claim 3
Dependent Claim
54 words
The method of claim 1 wherein each of said first, second and third magnetic gradients are along first, second and third axes of a Cartesian coordinate system and wherein the step of applying encoding gradient pulses comprises applying said encoding gradient pulses along one of said axes to obtain a two dimensional projection image.
Claim 4
Dependent Claim
54 words
The method of claim 1 wherein each of said first, second, and third magnetic gradients are along first, second, and third axes of a Cartesian coordinate system and wherein the step of applying said encoding gradient pulses comprises applying said encoding gradient pulses along two of said axes to obtain a three dimensional image.
Claim 5
Dependent Claim
18 words
The method of claim 1 wherein the first, second and third RF pulses are nominal 90 degree pulses.
Claim 6
Dependent Claim
11 words
The method of claim 1 wherein said pulses are shaped pulses.
Claim 7
Dependent Claim
20 words
The method claim 1 including the step of applying rephasing gradient pulses to compensate for unwanted selection gradient pulse dephasing.
Claim 8
Dependent Claim
41 words
The method claim 6 wherein one of said dephasing gradient pulses is a negative pulse applied between the first and the second RF pulses along the same axis as the axis of the selection gradient pulse for the first RF pulse.
Claim 9
Dependent Claim
39 words
The method of claim 6 wherein one of the rephasing gradient pulses is a negative pulse applied after the second RF pulse along the same axis as the axis of the selection gradient pulse for the second RF pulse.
Claim 10
Dependent Claim
38 words
The method claim 6 wherein one of said dephasing gradient pulses is a negative pulse applied after the third RF pulse along the same axis as the axis of the selection gradient pulse for the third RF pulse.
Claim 11
Dependent Claim
39 words
The method of claim 1 including the step of applying an extra gradient pulse along the same axis as the view gradient pulse to assure that the stimulated echo signals occur within the span of the view gradient pulse.
Claim 12
Dependent Claim
23 words
The method of claim 1 including the step of applying spoiler gradients in the time interval between the second and third RF pulses.
Claim 13
Dependent Claim
22 words
The method of claim 1 including the step of extending said second magnetic gradient beyond the second RF pulse to destroy coherence.
Claim 14
Dependent Claim
49 words
The method of claim 1 including the steps of: applying the stimulated echo sequence at least twice, inverting the phase of the first RF pulse for the second application of the sequence, and subtracting the signal acquired using the inverted phase from the signal acquired with the non-inverted phase.
Claim 15
Dependent Claim
16 words
The method of claim 1 and selecting the positions and the sizes of the selected volumes.
Claim 16
Dependent Claim
51 words
The method of claim 1 including the steps of: selecting the position of each of the selected volumes by selecting the frequency of the RF pulses; selecting the sizes of each of the selected volumes by selecting the bandwidth of the RF pulses, and selecting the amplitudes of the field gradients.
Claim 17
Dependent Claim
16 words
The method of claim 1 including the step of simultaneously acquiring signals from multiple localized volumes.
Claim 18
Dependent Claim
19 words
The method of claim 1 wherein said encoding gradient pulses are applied between said first and second RF pulses.
Claim 19
Dependent Claim
17 words
The method of claim 1 wherein said encoding gradient pulses are applied after said third RF pulse.
Claim 20
Dependent Claim
24 words
The method of claim 16 wherein said step of simultaneously acquiring signals from multiple localized volumes comprises applying a series of third RF pulses.
Claim 21
Dependent Claim
60 words
The method of claim 16 wherein said step of simultaneously acquiring signals from multiple localized volumes comprises applying the steps of selecting a localized volume a number of times during the repetition time of a scan but choosing a different volume each time with all of the chosen volumes having independant planes different than the planes of the other volumes.
References Cited (Backward Citations)
US4510449A
Cited
US4563647A
Cited
US4520828A
Cited
US4587488A
Cited
US4480228A
Cited
US4551680A
Cited
US4532473A
Cited
US4684892A
Cited
US4647858A
Cited
US4698592A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-01 | 1993-07-03 | 1994-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-01 | 1997-07-03 | 1998-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-01 | 2001-07-03 | 2002-01-02 | $7700.00 | Window Closed / Lapsed |