Efficient multi-slice acquisition with black blood contrast
First Claim
1. A method of multi-slice fast image acquisition with black-blood contrast comprising:
- applying a non-selective inversion pulse;
applying a re-inversion pulse that is slice-selective over a region encompassing a plurality of slice selections;
timing execution of a series of RF excitation pulses with fast spin echo readout such that signal from blood is near a null point; and
acquiring data for the plurality of slice selections.
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Abstract
The invention includes a technique for efficient multi-slice fast spin echo image acquisition with black blood contrast in cardiac imaging. The technique includes applying a non-selective inversion pulse, followed by a re-inversion pulse that is slice-selective over a region encompassing a plurality of slice selections. Execution of a series of RF excitation pulses with fast spin echo readout is timed such that signal from blood is near a null point before acquiring data for each spatial slice. For greater contrast consistency, the flip angles for the excitation pulses occurring before the null point can be reduced, and those occurring after the null point can be increased.
48 Citations
32 Claims
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1. A method of multi-slice fast image acquisition with black-blood contrast comprising:
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applying a non-selective inversion pulse;
applying a re-inversion pulse that is slice-selective over a region encompassing a plurality of slice selections;
timing execution of a series of RF excitation pulses with fast spin echo readout such that signal from blood is near a null point; and
acquiring data for the plurality of slice selections. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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6. The method of claim 5 further comprising creating the re-inversion pulse with a center centered about a midpoint between Z1 and Zn.
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7. The method of claim 1 wherein the timing step includes selecting an inversion time TI such that the null point of the blood occurs near a center of the multi-slice acquisition.
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8. The method of claim 1 further comprising modifying a flip angle of RF excitation pulses executed before and after an occurrence of the null point of the blood to improve blood suppression.
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9. The method of claim 8 further comprising modifying the flip of RF excitation pulses occurring before the null point to slightly less than 90°
- and those occurring after the null point to slightly more than 90°
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- and those occurring after the null point to slightly more than 90°
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10. A computer program for multi-slice coverage in a single acquisition with black-blood T2-weighted magnetic resonance image contrast, the computer program having a set of instructions that when executed by a computer cause the computer to:
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generate and cause application of a non-selective inversion RF pulse to a slab of slices each having a predefined thickness;
generate and cause application of a slice-selective re-inversion RF pulse having a slice thickness greater than the predefined thickness of a single slice;
apply an inversion time so that a null point of blood within the slab occurs in a middle of an acquisition segment;
apply a series of RF excitation pulses; and
acquire MR data for each slice in the slab. - View Dependent Claims (11, 12, 13, 14)
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15. An MR apparatus to produce consistent contrast in MR image acquisition comprising:
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a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing rnagnetic field and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images; and
a computer programmed to apply a pulse sequence having;
a non-selective inversion pulse to invert spins in a longitudinal direction across an entire slab of slices;
a slice-selective re-inversion pulse having width at least as large as that of the non-selective inversion pulse; and
a series of excitation pulses having fast spin echo readout spaced apart from the slice-selective re-inversion pulse by an inversion time to acquire data for each slice in the slab. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A pulse sequence for use in multi-slice MR data acquisition comprising:
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a non-selective inversion pulse applicable to a slab of slices;
a slice-selective re-inversion pulse applicable to at least a number of slices in the slab of slices; and
a series of fast spin echo readout excitation pulses applicable to the at least a number of slices in the slab of slices after an inversion time. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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27. The pulse sequence of claim 26 wherein the slice-selective re-inversion pulse has a center centered about a mid-point between Z1 and Zn.
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28. The pulse sequence of claim 21 wherein the series of fast spin echo readout excitation pulses have varying flip angles.
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29. The pulse sequence of claim 28 wherein excitation pulses that occur before a mid-point of the series have a flip angle of less than 90°
- , those near the mid-point have a flip angle near or at 90°
, and those that occur after the mid-point have a flip angle greater than 90°
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- , those near the mid-point have a flip angle near or at 90°
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30. A method of MR image acquisition comprising:
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applying a non-selective inversion pulse;
applying a re-inversion pulse that is slice-selective over a region encompassing a plurality of slice selections;
timing execution of at least one RF excitation pulse such that signal from blood is near a null point; and
acquiring data for the plurality of slice selections.
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31. A computer program for multi-slice coverage in a single acquisition with black-blood T2-weighted image contrast, the computer program having a set of instructions that when executed by a computer cause the computer to:
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generate and cause application of a non-selective inversion RF pulse to a slab of slices each having a predefined thickness;
generate and cause application of a slice-selective re-inversion RF pulse;
allow an inversion time so that a null point of blood within the slab occurs in a middle of an acquisition segment;
apply an RF excitation pulse; and
acquire MR data.
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32. An MR apparatus to produce consistent contrast in MR image acquisition comprising:
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a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing magnetic field and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images; and
a computer programmed to apply a pulse sequence having;
a non-selective inversion pulse to invert spins in a longitudinal direction across an entire slab of slices;
a slice-selective re-inversion pulse having width at least as large as that of the non-selective inversion pulse; and
a series of excitation pulses spaced apart from the slice-selective re-inversion pulse by an inversion time to acquire data for each slice in the slab.
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Specification