Patent US5541513A successfully refreshed from Google Patents.
US5541513A
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MRI center point artifact elimination using realtime receiver phase control
Assignee: General Electric Co
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Filing: 1995-04-14
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Granted: 1996-07-30
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Expires: 2015-04-14
Abstract
Abstract A method and apparatus for eliminating baseline error artifacts in NMR images produced using ultrafast pulse sequences including alternating the phase of a reference signal during the reception of NMR echo signals to invert alternate views in the acquisition. The inverted views are re-inverted prior to image reconstruction such that any dc levels introduced during acquisition are converted to a high spacial frequency which moves the resulting artifacts to the borders of the image reconstructed using a Fourier transformation.
Inventors
- 👤 Joseph K. Maier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:22
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/565; G01R33/56554
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
142 words
A method for eliminating baseline error artifacts in NMR images produced during a scan using an ultrafast pulse sequence, the steps comprising: performing an ultrafast pulse sequence in which a series of separately phase encoded NMR echo signals are produced in response to transverse magnetization produced by a single RF excitation pulse; acquiring the series of separately phase encoded NMR echo signals and inverting the polarity of alternate phase encoded ones of the separately phase encoded NMR echo signals as they are acquired; storing an NMR data set comprised of successive phase encoded ones of the separately phase encoded NMR echo signals acquired during the scan; inverting the polarity of alternate phase encoded ones of the separately phase encoded NMR echo signals stored in the NMR data set; and reconstructing an image by performing a Fourier transformation on the NMR data set.
Claim 2
Independent Claim
142 words
A method for eliminating baseline error artifacts in NMR images produced during a scan using an ultrafast pulse sequence, the steps comprising: performing an ultrafast pulse sequence in which a series of separately phase encoded NMR echo signals are produced in response to transverse magnetization produced by a single RF excitation pulse; acquiring the series of separately phase encoded NMR echo signals and inverting the polarity of alternate phase encoded ones of the separately phase encoded NMR echo signals as they are acquired; storing an NMR data set comprised of successive phase encoded ones of the separately phase encoded NMR echo signals acquired during the scan; inverting the polarity of alternate phase encoded ones of the separately phase encoded NMR echo signals stored in the NMR data set; and reconstructing an image by performing a Fourier transformation on the NMR data set.
Claim 3
Dependent Claim
20 words
The method as recited in claim 1 in which the scan is completed by performing a single ultrafast pulse sequence.
Claim 4
Dependent Claim
18 words
The method as recited in claim 1 in which the ultrafast pulse sequence is an echo-planar pulse sequence.
Claim 5
Dependent Claim
26 words
The method as recited in claim 3 in which the separately phase encoded NMR echo signals scan a set of phase encoding values in monotonic order.
Claim 6
Dependent Claim
61 words
The method as recited in claim 1 in which the series of separately phase encoded NMR echo signals are acquired with a receiver that mixes each NMR echo signal with a reference frequency signal, and the polarity of alternate phase encoded ones of the separately phase encoded NMR echo signals is inverted by inverting the polarity of the reference frequency signal.
Claim 7
Dependent Claim
23 words
The method as recited in claim 5 in which the polarity of the reference frequency signal is inverted by shifting its phase 180°.
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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) | 1999-07-30 | 2000-01-29 | 2000-07-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-07-30 | 2004-01-29 | 2004-07-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-07-30 | 2008-01-29 | 2008-07-30 | $7700.00 | Window Closed / Lapsed |