US4991586A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for monitoring vascular flow using magnetic resonance signals
Assignee: Siemens AG
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Filing: 1989-08-15
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Granted: 1991-02-12
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Expires: 2009-08-15
Abstract
Abstract A pulse sequence is disclosed for operating a magnetic resonance system wherein a slice of the examination subject disposed perpendicularly to the flow in a vessel under examination is first selectively excited. A nuclear magnetic resonance signal is read out as an echo signal under the influence of a read-gradient disposed perpendicularly to the slice selection gradient. The signals acquired in successive steps are displayed on a time axis. In contrast to a conventional spin warp sequence, the phase coding gradient, and thus a topical resolution in one direction, are foregone, and instead a chronological resolution of the flow is achieved.
Inventors
- 👤 Edgar Mueller
- 👤 Gerhard Laub
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:36
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/704; G01F1/708; G01F1/716; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/563; G01R33/56308; G01R33/56316
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
148 words
A method for monitoring the chronological course of a flow in a vessel of an examination subject using the phenomena of nuclear magnetic resonance, comprising the steps of: selectively exciting nuclear spins in a slice, containing a vessel in which flow is to be monitored, of an examination subject by simultaneously applying a frequency-selective, radio frequency pulse and a slice selection gradient, thereby generating a nuclear magnetic resonant signal; generating an echo signal of said nuclear magnetic resonant signal; reading out said echo signal while applying a read-out gradient disposed perpendicularly relatively to said slice selection gradient; repeating the above steps n times in succession thereby obtaining raw data signals for each repetition; conducting a Fourier transformation of the raw data signals; and and generating a display of said Fourier transformed raw data signals with respect to time as a representation of the chronological course of said flow.
Claim 2
Independent Claim
148 words
A method for monitoring the chronological course of a flow in a vessel of an examination subject using the phenomena of nuclear magnetic resonance, comprising the steps of: selectively exciting nuclear spins in a slice, containing a vessel in which flow is to be monitored, of an examination subject by simultaneously applying a frequency-selective, radio frequency pulse and a slice selection gradient, thereby generating a nuclear magnetic resonant signal; generating an echo signal of said nuclear magnetic resonant signal; reading out said echo signal while applying a read-out gradient disposed perpendicularly relatively to said slice selection gradient; repeating the above steps n times in succession thereby obtaining raw data signals for each repetition; conducting a Fourier transformation of the raw data signals; and and generating a display of said Fourier transformed raw data signals with respect to time as a representation of the chronological course of said flow.
Claim 3
Dependent Claim
36 words
A method as claimed in claim 1, wherein the step of generating an echo signal is defined by generating a pre-dephasing gradient preceding said read-out gradient and oriented in an opposite direction from said read-out gradient.
Claim 4
Dependent Claim
30 words
A method as claimed in claim 2, wherein the step of generating an echo signal is further defined by generating a bipolar gradient for flow rephasing preceeding said pre-dephasing gradient.
Claim 5
Dependent Claim
53 words
A method as claimed in claim 2, wherein said patient is disposed in a static magnetic field, comprising an additional step of generating a dephasing gradient disposed perpendicularly to said slice selection gradient and perpendicularly to said read-out gradient, and the dephasing gradient being zero within a region of interest containing said vessel.
Claim 6
Dependent Claim
27 words
A method as claimed in claim 4, wherein the step of generating a dephasing gradient is further defined by generating a dephasing gradient before said pre-dephasing gradient.
Claim 7
Dependent Claim
24 words
A method as claimed in claim 4, wherein the step of generating a dephasing gradient is further defined by generating an oscillating dephasing gradient.
Claim 8
Dependent Claim
34 words
A method as claimed in claim 4, wherein the step of generating said dephasing gradient is further defined by generating a dephasing gradient having a course defined by a second order or higher equation.
Claim 9
Dependent Claim
31 words
A method as claimed in claim 1, comprising the additional step of generating a rephasing gradient following said slice selection gradient and oriented in a direction opposite said slice selection gradient.
Claim 10
Dependent Claim
31 words
A method as claimed in claim 8, comprising the additional step of generating a bipolar flow rephasing gradient following said rephasing gradient in at least one repetition of said n repetitions.
Claim 11
Dependent Claim
36 words
A method as claimed in claim 1, comprising the additional step of selectively saturating regions of said examination subject outside of said vessel prior to the step of selectively exciting a slice of the examination subject.
Claim 12
Dependent Claim
52 words
A method as claimed in claim 1, comprising additional steps of disposing said patient in a static magnetic field, and applying a plurality of ferromagnetic elements to said patient during said n repetitions to distort said static field outside of said vessel to attenuate nuclear magnetic resonance signals outside of said vessel.
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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) | 1994-02-11 | 1994-08-13 | 1995-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-11 | 1998-08-13 | 1999-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-11 | 2002-08-13 | 2003-02-12 | $7700.00 | Window Closed / Lapsed |