Frequency swept excitation for magnetic resonance
First Claim
Patent Images
1. 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.
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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.
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Citations
35 Claims
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1. 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
- applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies;
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29. 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.
- applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies;
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30. 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. - View Dependent Claims (31, 32, 33)
- applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies;
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34. 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.
- applying a sweeping frequency excitation having a duration, the sweeping frequency excitation being configured to sequentially excite isochromats having different resonant frequencies;
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35. 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.
- 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;
Specification