US5448170A
Expired / Lapsed
US
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Method for exciting transverse magnetization in magnetic resonance
Assignee: Spectrospin AG
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Filing: 1993-12-08
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Granted: 1995-09-05
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Expires: 2013-12-08
Abstract
Abstract A method for exciting transverse magnetization by irradiating a nuclear spin system subjected to a constant magnetic field with a frequency-modulated rf-pulse ("chirp"-pulse) and with a further frequency-modulated rf-pulse (further chirp-pulse) for refocusing the magnetization, is characterized in that the rf-pulse-(P1) and the further rf-pulse (P2) overlap each other in time at least partially. Thus, the duration of the pulses can be reduced.
Inventors
- 👤 Geoffrey Bodenhausen
- 👤 Vladimir I. Ermakov
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:34
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/46; G01R33/4616
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
55 words
A method for exciting transverse magnetization by irradiating a nuclear spin system, subjected to a constant magnetic field, with a first frequency-modulated rf-pulse (first "chirp"-pulse) and with a second frequency-modulated rf-pulse (second chirp-pulse) for refocusing the magnetization, wherein said first rf-pulse (P1) and said second rf-pulse (P2) at least partially overlap each other in time.
Claim 2
Independent Claim
55 words
A method for exciting transverse magnetization by irradiating a nuclear spin system, subjected to a constant magnetic field, with a first frequency-modulated rf-pulse (first "chirp"-pulse) and with a second frequency-modulated rf-pulse (second chirp-pulse) for refocusing the magnetization, wherein said first rf-pulse (P1) and said second rf-pulse (P2) at least partially overlap each other in time.
Claim 3
Dependent Claim
14 words
The method of claim 1, wherein the rf-pulses end approximately at the same time.
Claim 4
Dependent Claim
14 words
The method of claim 1, wherein the second rf-pulse ends after the first rf-pulse.
Claim 5
Dependent Claim
29 words
The method of claim 1, wherein a speed of variation of the frequency of the second chirp-pulse is greater than a speed of variation of the first chirp pulse.
Claim 6
Dependent Claim
29 words
The method of claim 4, wherein the speed of variation of frequency of the second chirp-pulse is approximately twice the speed of variation of frequency of the first chirp-pulse.
Claim 7
Dependent Claim
23 words
The method of claim 1, wherein a second amplitude of the second chirp-pulse is greater than a first amplitude of the first chirp-pulse.
Claim 8
Dependent Claim
27 words
The method of claim 6, wherein the second amplitude of the second chirp-pulse is approximately three to four times the first amplitude of the first chirp pulse.
Claim 9
Dependent Claim
35 words
The method of claim 1, wherein the edge of at least one of the first chirp-pulse and the second chirp-pulse, in a time-amplitude-diagram, has a shape different from a rectangle with respect to the time-coordinate.
Claim 10
Dependent Claim
43 words
The method of claim 8, wherein an edge of at least one of the first and the second chirp pulses rises with the dependence of a first quarter of a sine-wave and falls with the dependence of a second quarter of a sine-wave.
Claim 11
Dependent Claim
15 words
The method of claim 1, wherein a phase-cycling is performed according to an EXORCYCLE method.
Claim 12
Dependent Claim
37 words
The method of claim 1, wherein a sweep rate, that is the change in frequency per unit time, of at least one of the first and the second chirp pulses is varied as a function of time.
References Cited (Backward Citations)
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Cited
US5126671A
Cited
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Cited
US5280245A
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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) | 1998-09-04 | 1999-03-06 | 1999-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-09-04 | 2003-03-06 | 2003-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-09-04 | 2007-03-06 | 2007-09-05 | $7700.00 | Window Closed / Lapsed |