Method for magnetic resonance imaging using sequential excitation and refocusing
First Claim
1. A method of multi-slice magnetic resonance imaging comprising:
- turning on a selection gradient using a magnetic resonance system;
applying an excitation pulse in the presence of the selection gradient, the excitation pulse exciting magnetization sequentially along one spatial axis;
turning on a phase-encoding gradient;
applying a first refocusing pulse;
turning on a refocusing gradient;
applying a second refocusing pulse;
turning on an acquisition gradient;
turning on an alternating frequency encoding gradient in a different direction to the acquisition gradient;
acquiring a signal in the presence of the acquisition gradient and the alternating frequency encoding gradient, the signal being time-encoded and frequency-encoded;
wherein the acquisition gradient sums to zero with the selection gradient and the refocusing gradient for sequential points in space; and
wherein a plurality of slices are acquired.
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Abstract
A method of magnetic resonance imaging based on rapid acquisition by sequential excitation and refocusing is provided. The method comprises turning on a first time-encoding gradient and applying an excitation pulse in the presence of the first time-encoding gradient. The excitation pulse excites magnetization sequentially along one spatial axis. Thereafter, a first refocusing pulse is applied. A second time-encoding gradient is turned on followed by a second refocusing pulse. A third time-encoding gradient is turned on and a signal is acquired in the presence of the third time-encoding gradient. The third time-encoding gradient sums to zero with the first time-encoding gradient and the second time-encoding gradient for sequential points in space.
38 Citations
33 Claims
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1. A method of multi-slice magnetic resonance imaging comprising:
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turning on a selection gradient using a magnetic resonance system; applying an excitation pulse in the presence of the selection gradient, the excitation pulse exciting magnetization sequentially along one spatial axis; turning on a phase-encoding gradient; applying a first refocusing pulse; turning on a refocusing gradient; applying a second refocusing pulse; turning on an acquisition gradient; turning on an alternating frequency encoding gradient in a different direction to the acquisition gradient; acquiring a signal in the presence of the acquisition gradient and the alternating frequency encoding gradient, the signal being time-encoded and frequency-encoded; wherein the acquisition gradient sums to zero with the selection gradient and the refocusing gradient for sequential points in space; and wherein a plurality of slices are acquired. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of multi-slice magnetic resonance imaging comprising:
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turning on a time-encoding selection gradient using a magnetic resonance system; applying a frequency-swept chirp pulse in the presence of the time-encoding selection gradient, the excitation pulse exciting magnetization sequentially along one spatial axis; turning on a phase-encoding gradient; applying a first refocusing pulse; turning on a time-encoding refocusing gradient; applying a second refocusing pulse; turning on a time-encoding acquisition gradient; turning on an alternating frequency encoding gradient in an orthogonal direction to the acquisition gradient acquiring a signal in the presence of the acquisition gradient and the alternating frequency encoding gradient, the signal being time-encoded and frequency-encoded; wherein the acquisition gradient sums to zero with the selection gradient and the refocusing gradient for sequential points in space; and wherein a plurality of slices are acquired. - View Dependent Claims (16, 17, 18, 19)
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20. A method of single-shot magnetic resonance imaging comprising:
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turning on a selection gradient using a magnetic resonance system; applying an excitation pulse in the presence of the selection gradient, the excitation pulse exciting magnetization sequentially along one spatial axis; applying a first refocusing pulse; turning on a first slice selection gradient approximately concurrently with the first refocusing pulse; turning on a refocusing gradient; applying a second refocusing pulse; turning on a second slice selection gradient approximately concurrently with the second refocusing pulse; turning on an acquisition gradient; turning on an alternating frequency encoding gradient in a different direction to the acquisition gradient; acquiring a signal in the presence of the acquisition gradient and the alternating frequency encoding gradient, the signal being time-encoded and frequency-encoded; wherein the acquisition gradient sums to zero with the selection gradient and the refocusing gradient for sequential points in space. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method of single-shot magnetic resonance imaging comprising:
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turning on a time-encoding selection gradient using a magnetic resonance system; applying a 90°
frequency-swept excitation pulse in the presence of the time-encoding selection gradient, the excitation pulse exciting magnetization sequentially along one spatial axis;applying a first 180°
refocusing pulse;turning on a first slice selection gradient approximately concurrently with the first refocusing pulse; turning on a time-encoding refocusing gradient; applying a second 180°
refocusing pulse;turning on a second slice selection gradient approximately concurrently with the second refocusing pulse; turning on a time-encoding acquisition gradient; turning on an alternating frequency encoding gradient in an orthogonal direction to the acquisition gradient; acquiring a signal in the presence of the time-encoding acquisition gradient and the alternating frequency encoding gradient, the signal being time-encoded and frequency-encoded; wherein the acquisition gradient sums to zero with the selection gradient and the refocusing gradient for sequential points in space. - View Dependent Claims (32, 33)
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Specification