US4752734A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flow imaging by means of nuclear magnetic resonance
Assignee: General Hospital Corp
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Filing: 1987-02-24
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Granted: 1988-06-21
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Expires: 2007-02-24
Abstract
Abstract A nuclear magnetic resonance projection image of fluid flow in a vessel is obtained by generating two data sets encoded with phase information indicative of two different velocity profiles of the fluid (taken at different times), combining the data sets, and displaying the resulting data set as an image.
Inventors
- 👤 Van J. Wedeen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:03
CPC Classifications
G; G01; G01N; G01N24/00; G01N24/08
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
233 words
Nuclear magnetic resonance apparatus for forming an image representative of fluid flow in a vessel situated within a matrix, said fluid flowing with a first velocity profile at a first time and with a second velocity profile, different from said first velocity profile, at a second time, comprising means for stimulating said fluid, vessel, and matrix to produce a magnetic resonance signal, including means for providing a magnetic field gradient, means for deriving data from said magnetic resonance signal, said means for stimulating including means for introducing into said data phase information indicative of said velocity profile of said fluid as of a given time, and for controlling the time variation of said magnetic gradient field to induce phase shifts in said data corresponding to velocity, means for extracting a data set representative of a projection image of said fluid, vessel, and matrix as of said given time, means for causing said apparatus to generate two said data sets corresponding to two projection images respectively as of said first and second times, and means to combine said data sets to form a resulting data set in which the signal is cancelled or not according to whether or not said velocity, and hence said phase shift, changed from said first time to said second time, and means for displaying said resulting data set as said image representative of said fluid flow in said vessel.
Claim 2
Dependent Claim
233 words
Nuclear magnetic resonance apparatus for forming an image representative of fluid flow in a vessel situated within a matrix, said fluid flowing with a first velocity profile at a first time and with a second velocity profile, different from said first velocity profile, at a second time, comprising means for stimulating said fluid, vessel, and matrix to produce a magnetic resonance signal, including means for providing a magnetic field gradient, means for deriving data from said magnetic resonance signal, said means for stimulating including means for introducing into said data phase information indicative of said velocity profile of said fluid as of a given time, and for controlling the time variation of said magnetic gradient field to induce phase shifts in said data corresponding to velocity, means for extracting a data set representative of a projection image of said fluid, vessel, and matrix as of said given time, means for causing said apparatus to generate two said data sets corresponding to two projection images respectively as of said first and second times, and means to combine said data sets to form a resulting data set in which the signal is cancelled or not according to whether or not said velocity, and hence said phase shift, changed from said first time to said second time, and means for displaying said resulting data set as said image representative of said fluid flow in said vessel.
Claim 3
Dependent Claim
51 words
The apparatus of claim 1 wherein said means for stimulating further comprises means for imparting a sequence of RF and magnetic gradient pulses to said fluid, vessel, and matrix beginning at a predetermined time to produce said resonance signal, and said sequences used to generate said two data sets are identical.
Claim 4
Dependent Claim
88 words
The apparatus of claim 1 wherein said first velocity profile includes a first range of velocities, and said second velocity profile includes a second range of velocities higher than said first range, and said means for stimulating includes means for imparting to protons in said fluid with respect to said first velocity profile, phases that are within a predetermined angle of the phases imparted to protons in said vessel and matrix, and for imparting random phases to protons in said fluid with respect to said second velocity profile.
Claim 5
Dependent Claim
66 words
The apparatus of claim 1 wherein said means for stimulating imparts a sequence of RF and magnetic gradient pulses to said fluid, vessel, and matrix that generates a phase shift in protons in said fluid at a rate of 2π radians for a predetermined velocity level of said fluid that is higher than said first range of velocities and lower than said second range of velocities.
Claim 6
Dependent Claim
37 words
The apparatus of claim 4 wherein said fluid is blood, said first range of velocities comprises the velocities of blood flowing in diastole, and said second range of velocities comprises the velocities of blood flowing in systole.
Claim 7
Dependent Claim
55 words
The apparatus of claim 1 wherein said fluid is blood, said first time is diastole, said second time is systole, and said apparatus further comprises means for triggering said means for stimulating at said first time based on the occurrence of said diastole, or at said second time based on the occurrence of said systole.
Claim 8
Dependent Claim
27 words
The apparatus of claim 6 wherein said second time follows said diastole by a predetermined interval based on the location of said vessel relative to the heart.
Claim 9
Dependent Claim
16 words
The apparatus of claim 6 wherein said first time follows a QRS complex by 10 milliseconds.
Claim 10
Dependent Claim
19 words
The apparatus of claim 6 wherein said second time follows said QRS complex by between 100 and 300 milliseconds.
Claim 11
Dependent Claim
17 words
The apparatus of claim 2 wherein said sequence comprises a two-dimensional Fourier transform spin echo pulse sequence.
Claim 12
Dependent Claim
88 words
The apparatus of claim 10 wherein said spin-echo pulse sequence comprises 90° and 180° RF pulses, and a pair of magnetic gradient pulses along an axis of said vessel, said gradient pulses comprising a compensating pulse preceding said 180° RF pulse and a readout pulse following said 180° RF pulse, said two magnetic gradient pulses being of magnitudes and durations such that for static protons the phase shift imposed by one said gradient pulse is exactly canceled by the phase shift imposed by the other said gradient pulse.
Claim 13
Dependent Claim
20 words
The apparatus of claim 10 wherein a spin echo occurs no later than 15 milliseconds after said 90° RF pulse.
Claim 14
Dependent Claim
10 words
The apparatus of claim 1 wherein said fluid is blood.
Claim 15
Dependent Claim
11 words
The apparatus of claim 1 wherein said vessel is an artery.
Claim 16
Dependent Claim
10 words
The apparatus of claim 1 wherein said matrix is tissue.
Claim 17
Dependent Claim
11 words
The apparatus of claim 1 wherein said fluid flow is pulsatile.
Claim 18
Dependent Claim
17 words
The apparatus of claim 1 wherein said data produced from said resonance signal comprises Fourier transformed data.
Claim 19
Independent Claim
204 words
A method for forming an image representative of fluid flow in a vessel situated within a matrix, said fluid flowing with a first velocity profile at a first time and with a second velocity profile, different from said first velocity profile, at a second time, comprising stimulating said fluid, vessel, and matrix to produce a magnetic resonance signal, including generating a magnetic field gradient, deriving data from said magnetic resonance signal, introducing into said data phase information indicative of said velocity profile of said fluid as of a given time controlling the time variation of said magnetic field gradient to induce phase shifts in said data corresponding to the velocity, extracting a data set representative of a projection image of said fluid, vessel, and matrix as of said given time, generating two said data sets corresponding to two projection images respectively as of said first and second times, and combining said data sets to form a resulting data set in which the signal is cancelled or not according to whether or not said velocity, and hence said phase shift, changed from said first time to said second time displaying said resulting data set as said image representative of said fluid flow in said vessel.
Claim 20
Independent Claim
204 words
A method for forming an image representative of fluid flow in a vessel situated within a matrix, said fluid flowing with a first velocity profile at a first time and with a second velocity profile, different from said first velocity profile, at a second time, comprising stimulating said fluid, vessel, and matrix to produce a magnetic resonance signal, including generating a magnetic field gradient, deriving data from said magnetic resonance signal, introducing into said data phase information indicative of said velocity profile of said fluid as of a given time controlling the time variation of said magnetic field gradient to induce phase shifts in said data corresponding to the velocity, extracting a data set representative of a projection image of said fluid, vessel, and matrix as of said given time, generating two said data sets corresponding to two projection images respectively as of said first and second times, and combining said data sets to form a resulting data set in which the signal is cancelled or not according to whether or not said velocity, and hence said phase shift, changed from said first time to said second time displaying said resulting data set as said image representative of said fluid flow in said vessel.
Claim 21
Dependent Claim
27 words
The apparatus of claim 1 wherein said fluid is blood and said phase shifts are cancelled with respect to venous vessels and stationary parts of said matrix.
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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) | 1991-06-21 | 1991-12-21 | 1992-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-21 | 1995-12-21 | 1996-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-21 | 1999-12-21 | 2000-06-21 | $7700.00 | Window Closed / Lapsed |