US7425828B2
Expired / Lapsed
US
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Frequency swept excitation for magnetic resonance
Assignee: University of Minnesota System
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Filing: 2006-10-11
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Granted: 2008-09-16
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Expires: 2026-10-11
Abstract
Abstract A method of magnetic resonance is provided that uses a frequency swept excitation wherein the acquired signal is a time domain signal is provided. In one embodiment, the method comprises, applying a sweeping frequency excitation and acquiring a time domain signal. The sweeping frequency excitation has a duration and is configured to sequentially excite isochromats having different resonant frequencies. Acquisition of the time domain signal is done during the duration of the sweeping frequency excitation. The time domain signal is based on evolution of the isochromats.
Inventors
- 👤 Michael Garwood
- 👤 Djaudat S. Idiyatullin
- 👤 Curt Corum
- 👤 Steen Moeller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:30
CPC Classifications
G; G01; G01N; G01N24/00; G01N24/10; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/441; G01R33/446; G01R33/46; G01R33/4616; G01R33/48; G01R33/4816; G01R33/54; G01N24/08; G01N24/081
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
88 words
A method comprising: applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats; and; achieving a steady, oscillating, or pseudo-steady state; calculating a projection angle or plane using a gradient shape and frequency sweep; and using the acquired time domain signal to create a magnetic resonance image.
Claim 2
Independent Claim
88 words
A method comprising: applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats; and; achieving a steady, oscillating, or pseudo-steady state; calculating a projection angle or plane using a gradient shape and frequency sweep; and using the acquired time domain signal to create a magnetic resonance image.
Claim 3
Dependent Claim
12 words
The method of claim 1 , wherein the first gradient is constant.
Claim 4
Dependent Claim
12 words
The method of claim 1 , wherein the first gradient is shaped.
Claim 5
Dependent Claim
22 words
The method of claim 1 , further comprising calculating a projection angle trajectory or plane using a gradient shape and frequency sweep.
Claim 6
Dependent Claim
15 words
The method of claim 1 , further comprising changing an orientation of the first gradient.
Claim 7
Dependent Claim
23 words
The method of claim 5 , further comprising separating a fluctuation of an off-resonance isochromat with a consistent location of an on-resonance isochromat.
Claim 8
Dependent Claim
22 words
The method of claim 1 , further comprising jittering at least one of the sweeping frequency excitation and the time domain signal.
Claim 9
Dependent Claim
26 words
The method of claim 7 , further comprising unjittering the at least one of the sweeping frequency excitation and the time domain signal that was jittered.
Claim 10
Dependent Claim
21 words
The method of claim 1 , wherein applying a sweeping frequency excitation is done to coincide with a motion of interest.
Claim 11
Dependent Claim
22 words
The method of claim 1 , wherein achieving a steady, oscillating, or pseudo-steady state is done before applying a sweeping frequency excitation.
Claim 12
Dependent Claim
19 words
The method of claim 10 , wherein achieving a steady, oscillating, or pseudo-steady state comprises applying a preparation pulse.
Claim 13
Dependent Claim
16 words
The method of claim 11 , further comprising acquiring a plurality of preparation time domain signals.
Claim 14
Dependent Claim
12 words
The method of claim 11 , further comprising applying a preparation gradient.
Claim 15
Dependent Claim
31 words
The method of claim 13 , further comprising acquiring a preparation plurality of time domain signals wherein acquiring the plurality of preparation time domain signals is done with sequential gradient orientations.
Claim 16
Dependent Claim
33 words
The method of claim 13 , further comprising acquiring a plurality of preparation time domain signals wherein acquiring the plurality of preparation time domain signals is done with random or pseudo-random gradient orientations.
Claim 17
Dependent Claim
16 words
The method of claim 13 , wherein the preparation gradient is reversed during the preparation pulse.
Claim 18
Dependent Claim
15 words
The method of claim 11 , wherein the preparation pulse is a radio frequency pulse.
Claim 19
Dependent Claim
16 words
The method of claim 11 , further comprising varying radio frequency power during the preparation pulse.
Claim 20
Dependent Claim
23 words
The method of claim 1 , further comprising using a digital filter while acquiring a time domain signal to limit the acquired signal.
Claim 21
Dependent Claim
13 words
The method of claim 1 , wherein the sweeping frequency excitation is asymmetrical.
Claim 22
Dependent Claim
14 words
The method of claim 1 , further comprising processing the acquired time domain signal.
Claim 23
Dependent Claim
19 words
The method of claim 1 , further comprising applying a magnetic field during applying the sweeping radio frequency excitation.
Claim 24
Dependent Claim
36 words
The method of claim 1 , further comprising generating a first spectra based on a correlation of a Fourier transform of the applied sweeping frequency excitation and a Fourier transform of the acquired time domain signal.
Claim 25
Dependent Claim
34 words
The method of claim 23 , further comprising generating a second spectra based on processing the acquired time domain signal as a frequency domain signal and further comprising averaging the first and second spectra.
Claim 26
Dependent Claim
37 words
The method of claim 1 , further comprising generating a first spectra based on deconvoluting the applied sweeping frequency excitation and the acquired time domain signal to generate a deconvoluted signal and Fourier transforming the deconvoluted signal.
Claim 27
Dependent Claim
34 words
The method of claim 25 , further comprising generating a second spectra based on processing the acquired time domain signal as a frequency domain signal and further comprising averaging the first and second spectra.
Claim 28
Dependent Claim
17 words
The method of claim 1 , wherein applying the sweeping frequency excitation comprises applying a phase modulation.
Claim 29
Dependent Claim
17 words
The method of claim 1 , wherein applying the sweeping frequency excitation comprises applying a frequency modulation.
Claim 30
Independent Claim
92 words
A method comprising: applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats wherein acquiring a time domain signal comprises capturing or freezing motion along a direction of the first gradient; achieving a steady, oscillating, or pseudo-steady state; and using the acquired time domain signal to create a magnetic resonance image.
Claim 31
Independent Claim
92 words
A method comprising: applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats wherein acquiring a time domain signal comprises capturing or freezing motion along a direction of the first gradient; achieving a steady, oscillating, or pseudo-steady state; and using the acquired time domain signal to create a magnetic resonance image.
Claim 32
Independent Claim
110 words
A method comprising: applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats; and; achieving a steady, oscillating, or pseudo-steady state; applying a second gradient and acquiring a second time domain signal, the second time domain signal being based on evolution of the isochromats, wherein the second gradient is opposite the first gradient; and using the acquired first and second time domain signals to create a magnetic resonance image.
Claim 33
Independent Claim
110 words
A method comprising: applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats; and; achieving a steady, oscillating, or pseudo-steady state; applying a second gradient and acquiring a second time domain signal, the second time domain signal being based on evolution of the isochromats, wherein the second gradient is opposite the first gradient; and using the acquired first and second time domain signals to create a magnetic resonance image.
Claim 34
Dependent Claim
16 words
The method of claim 30 , further comprising creating a gradient-echo, a spin-echo, or a simulated-echo.
Claim 35
Dependent Claim
49 words
The method of claim 31 , further applying a second sweeping frequency excitation having a duration wherein the first sweeping frequency excitation results in a first sequence and the second sweeping frequency excitation results in a second sequence, and further comprising subtracting the second sequence from the first sequence.
Claim 36
Dependent Claim
20 words
The method of claim 30 , further comprising filtering spin-spin relaxation times based on the created gradient-echo, spin-echo, or simulated-echo.
Claim 37
Independent Claim
109 words
A method comprising: applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats; and; achieving a steady, oscillating, or pseudo-steady state; and processing the acquired time domain signal; wherein achieving a steady, oscillating, or pseudo-steady state includes correcting for a lack of a steady state and is done during processing the acquired time domain signal; and using the acquired time domain signal to create a magnetic resonance image.
Claim 38
Independent Claim
109 words
A method comprising: applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats; and; achieving a steady, oscillating, or pseudo-steady state; and processing the acquired time domain signal; wherein achieving a steady, oscillating, or pseudo-steady state includes correcting for a lack of a steady state and is done during processing the acquired time domain signal; and using the acquired time domain signal to create a magnetic resonance image.
Claim 39
Independent Claim
95 words
A method comprising: applying a sweeping frequency excitation having a duration by applying a plurality of discrete excitation pulses, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats; and; achieving a steady, oscillating, or pseudo-steady state; and wherein acquiring the time domain signal includes sampling between excitation pulses; and using the acquired time domain signal to create a magnetic resonance image.
Claim 40
Independent Claim
95 words
A method comprising: applying a sweeping frequency excitation having a duration by applying a plurality of discrete excitation pulses, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies; applying a first gradient while applying the sweeping frequency excitation; acquiring a time domain signal during the duration, the time domain signal being based on evolution of the isochromats; and; achieving a steady, oscillating, or pseudo-steady state; and wherein acquiring the time domain signal includes sampling between excitation pulses; and using the acquired time domain signal to create a magnetic resonance image.
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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) | 2011-09-16 | 2012-03-17 | 2012-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2015-09-16 | 2016-03-17 | 2016-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2019-09-16 | 2020-03-17 | 2020-09-16 | $7700.00 | Window Closed / Lapsed |