Patent US3944564A successfully refreshed from Google Patents.
Patent US4954779A successfully refreshed from Google Patents.
US4954779A
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Correction for eddy current caused phase degradation
Assignee: General Electric Co
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Filing: 1989-04-28
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Granted: 1990-09-04
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Expires: 2009-04-28
Abstract
Abstract A system corrects for phase angles degradation due, for example to eddy currents, and uses the corrected phase angles to determine flow. The system acquires flow compensated low resolution images and uncompensated low and normal resolution images of a flowing fluid. The images include phase angle data. The phase angle data of the low resolution images are subtracted from the corresponding phase angle data of the normal resolution images to obtain phase angle corrected compensated and uncompensated images. The phase angle corrected compensated images are subtracted from the phase angle corrected uncompensated images to obtain flow images with minimized phase angle distortion. Reliable and accurate flow velocity for each pixel is thereby obtained using the minimized phase angle distortion flow images.
Inventors
- 👤 Yuval Zur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:14
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/563; G01R33/56308; G01R33/565; G01R33/56518; G01R33/56316
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
101 words
A method of correcting for eddy current caused phase distortions in the magnetic resonance images, said method comprising the steps of: acquiring normal resolution time domain magnetic resonance imaging (MRI) data, acquiring low resolution time domain magnetic resonance imaging (MRI) data, Fourier transforming the normal resolution time domain MRI data, Fourier transforming low resolution MRI data, obtaining the phase images in the frequency domain after the steps of Fourier transforming, and subtracting the phase image of the low resolution data from the phase image of the normal resolution data to provide a phase image corrected for eddy current caused phase distortion.
Claim 2
Independent Claim
101 words
A method of correcting for eddy current caused phase distortions in the magnetic resonance images, said method comprising the steps of: acquiring normal resolution time domain magnetic resonance imaging (MRI) data, acquiring low resolution time domain magnetic resonance imaging (MRI) data, Fourier transforming the normal resolution time domain MRI data, Fourier transforming low resolution MRI data, obtaining the phase images in the frequency domain after the steps of Fourier transforming, and subtracting the phase image of the low resolution data from the phase image of the normal resolution data to provide a phase image corrected for eddy current caused phase distortion.
Claim 3
Dependent Claim
68 words
The method of correcting for eddy current caused phase distortions of claim 1 wherein the steps of acquiring normal resolution time domain MRI data comprises using a normal data acquisition sequence to obtain original time domain MRI data, and wherein the step of acquiring the low resolution MRI data comprises the step of operating on said normal resolution MRI data to obtain data of only low spatial frequency.
Claim 4
Dependent Claim
27 words
The method of claim 2 wherein said step of operating on said normal resolution MRI data comprises spatial frequency filtering of said original time domain MRI data.
Claim 5
Dependent Claim
34 words
The method of claim 2 wherein said step of operating on said normal resolution MRI data comprises windowing said original MRI data with a function that will obtain data of only low spatial frequency.
Claim 6
Independent Claim
150 words
A method of correcting for eddy current caused phase distortion and using the corrected measured phase angles to determine flow, said method comprising the steps of: acquiring an uncompensated low resolution image of a flowing fluid, acquiring a flow compensated low resolution image of said flowing fluid, obtaining a normal resolution uncompensated image of said flowing fluid, obtaining a normal resolution flow compensated image of said flowing fluid, said images, including phase angle data, subtracting the phase angle data of the low resolution image from the corresponding phase angle data of the normal resolution image to provide phase angle corrected compensated and uncompensated images, subtracting the said phase angle corrected compensated and uncompensated images to obtain a flow image with minimized phase angle distortion, and using the phase angle of said flow image with minimized phase angle distortion to obtain the flow velocity for each pixel of said flow image.
Claim 7
Independent Claim
150 words
A method of correcting for eddy current caused phase distortion and using the corrected measured phase angles to determine flow, said method comprising the steps of: acquiring an uncompensated low resolution image of a flowing fluid, acquiring a flow compensated low resolution image of said flowing fluid, obtaining a normal resolution uncompensated image of said flowing fluid, obtaining a normal resolution flow compensated image of said flowing fluid, said images, including phase angle data, subtracting the phase angle data of the low resolution image from the corresponding phase angle data of the normal resolution image to provide phase angle corrected compensated and uncompensated images, subtracting the said phase angle corrected compensated and uncompensated images to obtain a flow image with minimized phase angle distortion, and using the phase angle of said flow image with minimized phase angle distortion to obtain the flow velocity for each pixel of said flow image.
Claim 8
Dependent Claim
37 words
The method of claim 5 wherein the velocity is determined by obtained solution for V in the following equation: ##EQU2## where: Z o is spin position at time t=0(t o ), and V is the spin velocity.
Claim 9
Independent Claim
110 words
A system for correcting for eddy current caused phase distortions in magnetic resonance images, said system comprising: means for acquiring normal resolution time domain magnetic resonance imaging (MRI) data, means for acquiring low resolution time domain magnetic resonance imaging (MRI) data, means for Fourier transforming the normal resolution time domain MRI data, means for Fourier transforming the low resolution MRI data, means for obtaining the phase images in the frequency domain after the steps of Fourier transforming, and means for subtracting the phase image of the low resolution data from the phase image of the normal resolution data to provide a phase image corrected for eddy current caused phase distortion.
Claim 10
Independent Claim
110 words
A system for correcting for eddy current caused phase distortions in magnetic resonance images, said system comprising: means for acquiring normal resolution time domain magnetic resonance imaging (MRI) data, means for acquiring low resolution time domain magnetic resonance imaging (MRI) data, means for Fourier transforming the normal resolution time domain MRI data, means for Fourier transforming the low resolution MRI data, means for obtaining the phase images in the frequency domain after the steps of Fourier transforming, and means for subtracting the phase image of the low resolution data from the phase image of the normal resolution data to provide a phase image corrected for eddy current caused phase distortion.
Claim 11
Dependent Claim
68 words
The system of correcting for eddy current caused phase distortions of claim 7 wherein the means for acquiring normal resolution time domain MRI data comprises means for using a normal data acquisition sequence to obtain original time domain MRI data, and wherein the means for acquiring the low resolution MRI data comprises means for operating on said original MRI data to obtain data of only low spatial frequency.
Claim 12
Dependent Claim
29 words
The system of claim 8 wherein said means for operating on said original MRI data comprises filter means for spatial frequency filtering of said original time domain MRI data.
Claim 13
Dependent Claim
36 words
The system of claim 8 wherein said means for operating on said original MRI data comprises windowing means for windowing said original MRI data with a function that will obtain data of only low spatial frequency.
Claim 14
Independent Claim
161 words
A system for correcting for eddy current caused phase distortion and for using the corrected measured phase angles to determine flow, said system comprising: means for acquiring an uncompensated low resolution image of a flowing fluid, means for acquiring a flow compensated low resolution image of said flowing fluid, means for obtaining a normal resolution uncompensated image of said flowing fluid, means for obtaining a normal resolution flow compensated image of said flowing fluid, said images, including phase angle data, means for subtracting the phase angle data of the low resolution image from the corresponding phase angle data of the normal resolution image to provide phase angle corrected compensated and uncompensated images, means for subtracting the said phase angle corrected compensated and uncompensated images to obtain a flow image with minimized phase angle distortion, and means using the phase angle of said flow image with minimized phase angle distortion to obtain the flow velocity for each pixel of said flow image.
Claim 15
Independent Claim
161 words
A system for correcting for eddy current caused phase distortion and for using the corrected measured phase angles to determine flow, said system comprising: means for acquiring an uncompensated low resolution image of a flowing fluid, means for acquiring a flow compensated low resolution image of said flowing fluid, means for obtaining a normal resolution uncompensated image of said flowing fluid, means for obtaining a normal resolution flow compensated image of said flowing fluid, said images, including phase angle data, means for subtracting the phase angle data of the low resolution image from the corresponding phase angle data of the normal resolution image to provide phase angle corrected compensated and uncompensated images, means for subtracting the said phase angle corrected compensated and uncompensated images to obtain a flow image with minimized phase angle distortion, and means using the phase angle of said flow image with minimized phase angle distortion to obtain the flow velocity for each pixel of said flow image.
Claim 16
Dependent Claim
40 words
The system of claim 11 wherein the velocity is determined by means for obtaining a solution for V in the following equation: ##EQU3## where: Z o is spin position at time t=0(t o ), and V is the spin velocity.
References Cited (Backward Citations)
US4683431A
Cited
US4870361A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-03 | 1994-03-05 | 1994-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-03 | 1998-03-05 | 1998-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-03 | 2002-03-05 | 2002-09-04 | $7700.00 | Window Closed / Lapsed |