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US5363036A
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Echo-volumar imaging using 180 degree RF pulses
Assignee: BTG International Ltd
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Filing: 1991-07-30
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Granted: 1994-11-08
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Expires: 2011-07-30
Abstract
Abstract A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process including subjecting the object to an initial selection process to select a thick slice within the object to produce an active volume of spin magnetisation subjecting the active volume so defined to a combination of 180° RF pulses and suitably modulated x, y and z gradients to produce an echo volumar image.
Inventors
- 👤 Peter Mansfield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:44
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/561; G01R33/5615; F; F02; F02G; F02G1/00; F02G1/04; F02G1/043; F02G1/044; F02G1/0445; F02G2250/00; F02G2250/18; G01R33/4818; G01R33/482; G01R33/4822; G01R33/5618
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
78 words
A method of producing a magnetic resonance three-dimensional image of a defined region of an object by an echo volumar imaging process, comprising the steps of: subjecting the object to an initial selection process to select a thick slice within the object to produce an active volume of spin magnetisation; and subjecting the active volume so defined to a combination of 180° RF pulses and modulated x, y and z gradients to produce an echo volumar three-dimensional image.
Claim 2
Independent Claim
78 words
A method of producing a magnetic resonance three-dimensional image of a defined region of an object by an echo volumar imaging process, comprising the steps of: subjecting the object to an initial selection process to select a thick slice within the object to produce an active volume of spin magnetisation; and subjecting the active volume so defined to a combination of 180° RF pulses and modulated x, y and z gradients to produce an echo volumar three-dimensional image.
Claim 3
Dependent Claim
91 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 1 in which the combination of the modulated x, y and z gradients (G x , G y , G z ) and the 180° RF pulses produces a complex trajectory in k-space which ensures that signal data obtained in such a sequence is ordered such that a Fourier transform is able to reconstitute a three dimensional image set from the three dimensional k-space data set.
Claim 4
Dependent Claim
48 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 2 in which the x gradient (G x ) is monopolar with small gaps (or windows) within which the RF pulses are applied.
Claim 5
Dependent Claim
59 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 3 in which the modulated y gradient (G y ) comprises a series of short blips which are arranged to fall in alternate G x gaps but not to coincide with the RF pulses.
Claim 6
Dependent Claim
41 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 4 in which the G y blips precede the RF pulses within the G x gaps.
Claim 7
Dependent Claim
58 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 5 in which the modulated z gradient (G z ) is applied as a series of blipped pulses at predetermined intervals the G z pulses being less frequent than the G y pulses.
Claim 8
Dependent Claim
44 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 6 in which the G z pulses precede the RF pulses within the gaps in the G x pulses.
Claim 9
Dependent Claim
72 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 2 in which the x gradient (G x ) is modulated for a short period to provide spatial encoding along the x-axis and in which the y gradient (G y ) is applied in short blips at points corresponding to the zero crossings of G x .
Claim 10
Dependent Claim
61 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 8 in which the modulated z gradient (G z ) pulses are applied during periods in which the G x gradient is zero; the G z pulses being applied less frequently than the G y pulses.
Claim 11
Dependent Claim
67 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 2 in which the modulated y gradient G y is applied in the form of a square or trapezoidally modulated waveform and in which the modulated z gradient (G z ) is applied in the form of a constant low level waveform.
Claim 12
Dependent Claim
65 words
A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process as claimed in claim 2 in which the modulated y gradient (G y ) is applied in the form of a low level waveform and in which the modulated z gradient G z is applied in the form of a constant low level waveform.
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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) | 1997-11-07 | 1998-05-09 | 1998-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-11-07 | 2002-05-09 | 2002-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-11-07 | 2006-05-09 | 2006-11-08 | $7700.00 | Window Closed / Lapsed |