US4843322A
Expired / Lapsed
US
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Method for producing multi-slice NMR images
Assignee: General Electric Co
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Filing: 1988-08-15
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Granted: 1989-06-27
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Expires: 2008-08-15
Abstract
Abstract In an NMR imaging system spins in a set of slices are simultaneously excited by a composited RF excitation pulse in each NMR pulse sequence of a scan. The composite RF excitation pulse contains a set of terms, each of which excites a separate slice and each of which is modulated by a k y -dependent phase factor. The k y -dependent phase factor causes the iamge of each slice to be offset in the resulting reconstruction so that each slice image can be separated from the others.
Inventors
- 👤 Gary H. Glover
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:19
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/483; G01R33/4833; G01R33/4835
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
150 words
In an NMR system for producing images by Fourier transformation of an NMR data set acquired from a set of NMR pulse sequences in which a phase encoding magnetic field gradient is stepped through a corresponding set of discrete values, the improved method comprising: applying a composite RF excitation pulse during each NMR pulse sequence which contains a plurality of pulse envelope terms multiplied by a sequence number dependent phase factor, and which excites spins in a plurality of slices which are selected by the frequency of a respective one of said plurality of pulse envelope terms in the composite RF excitation pulse; performing a Fourier transform on the NMR data set which is acquired by the set of NMR pulse sequences to produce an image array; and separating the slice imgges contained in the image array to produce a separate image array for each of said plurality of slices.
Claim 2
Dependent Claim
150 words
In an NMR system for producing images by Fourier transformation of an NMR data set acquired from a set of NMR pulse sequences in which a phase encoding magnetic field gradient is stepped through a corresponding set of discrete values, the improved method comprising: applying a composite RF excitation pulse during each NMR pulse sequence which contains a plurality of pulse envelope terms multiplied by a sequence number dependent phase factor, and which excites spins in a plurality of slices which are selected by the frequency of a respective one of said plurality of pulse envelope terms in the composite RF excitation pulse; performing a Fourier transform on the NMR data set which is acquired by the set of NMR pulse sequences to produce an image array; and separating the slice imgges contained in the image array to produce a separate image array for each of said plurality of slices.
Claim 3
Dependent Claim
67 words
The improvement as recited in claim 1 in which the composite RF excitation pulse is expressed as follows: ##EQU2## where: R s (t) is the pulse envelope for each term, N is the number of slices in which spins are simultaneously excited, k y is a sequence number dependent factor, and y s is a desired amount of offset which enables the slice image to be separated.
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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) | 1992-06-26 | 1992-12-26 | 1993-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-26 | 1996-12-26 | 1997-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-26 | 2000-12-26 | 2001-06-27 | $7700.00 | Window Closed / Lapsed |