Patent US5309102A successfully refreshed from Google Patents.
US5309102A
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Frequency calibration for MRI scanner
Assignee: General Electric Co
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Filing: 1993-05-07
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Granted: 1994-05-03
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Expires: 2013-05-07
Abstract
Abstract An NMR scanner performs a prescan before each NMR scan sequence in which the optimal RF excitation frequency is automatically determined and applied to the scanner's transceiver. The prescan sequence includes a pair of NMR measurements which provide data that allows the precise RF excitation frequency to be determined.
Inventors
- 👤 Todd W. Deckard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:09
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/58; G01R33/583
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
147 words
A method for automatically adjusting the RF frequency of a transceiver in an NMR system, which comprises: performing an NMR measurement in which an NMR signal is produced and acquired; transforming the acquired NMR signal to the frequency domain; defining a correlation model which depicts expected fat and water peaks; correlating the correlation model with the transformed NMR signal to produce a correlation frequency (f cor ); locating the peaks in the transformed NMR signal; selecting one of the located peaks positioned to one side of the correlation frequency (f cor ) as the Larmor frequency of water; selecting one of the located peaks positioned to the other side of the correlation frequency (f cor ) as the Larmor frequency of fat; and outputting to the transceiver on the NMR system an RF frequency command (CF) which is based on the determined water or fat Larmor frequency.
Claim 2
Independent Claim
147 words
A method for automatically adjusting the RF frequency of a transceiver in an NMR system, which comprises: performing an NMR measurement in which an NMR signal is produced and acquired; transforming the acquired NMR signal to the frequency domain; defining a correlation model which depicts expected fat and water peaks; correlating the correlation model with the transformed NMR signal to produce a correlation frequency (f cor ); locating the peaks in the transformed NMR signal; selecting one of the located peaks positioned to one side of the correlation frequency (f cor ) as the Larmor frequency of water; selecting one of the located peaks positioned to the other side of the correlation frequency (f cor ) as the Larmor frequency of fat; and outputting to the transceiver on the NMR system an RF frequency command (CF) which is based on the determined water or fat Larmor frequency.
Claim 3
Dependent Claim
14 words
The method as recited in claim 1 which includes filtering the acquired NMR signal.
Claim 4
Dependent Claim
30 words
The method as recited in claim 1 in which the correlation model depicts two pulses separated by the chemical shift frequency of fat and water expected on the NMR system.
Claim 5
Dependent Claim
35 words
The method as recited in claim 1 in which the two selected peaks are located within predetermined regions spaced one-half the chemical shift frequency of fat and water to either side of the correlation frequency.
Claim 6
Dependent Claim
32 words
The method as recited in claim 4 in which one of the selected peaks is located by calculating the center of mass of the transformed NMR signal within one of said regions.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-05-02 | 1997-11-01 | 1998-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-02 | 2001-11-01 | 2002-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-02 | 2005-11-01 | 2006-05-03 | $7700.00 | Window Closed / Lapsed |