Method for simultaneous multi-slice magnetic resonance imaging
First Claim
1. A method for producing a plurality of images of a subject with a magnetic resonance imaging (MRI) system, the steps of the method comprising:
- a) applying, with the MRI system, a radio frequency (RF) excitation field to a portion of a subject that includes a plurality of slice locations, the plurality of slice locations including a current slice location and at least one adjacent slice location;
b) establishing, with the MRI system, at least one readout magnetic field gradient along a frequency-encoding direction following the application of the RF excitation field in order to form echo signals;
c) sequentially producing a plurality of slice-encoding magnetic field gradient blips along a slice-encoding direction while the at least one readout magnetic field gradient is established in order to impart a phase shift to the formed echo signals such that image data corresponding to the at least one adjacent slice location is shifted by a selected percentage of a field-of-view (FOV) of the current slice location;
d) acquiring, with an array of RF receiver coils that forms a part of the MRI system, image data indicative of the formed echo signals; and
e) reconstructing a plurality of images of the subject from the acquired image data, each of the plurality of images depicting the subject at a corresponding one of the plurality of slice locations.
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Accused Products
Abstract
A method for multi-slice magnetic resonance imaging, in which image data is acquired simultaneously from multiple slice locations using a radio frequency coil array, is provided. By way of example, a modified EPI pulse sequence is provided, and includes a series of magnetic gradient field “blips” that are applied along a slice-encoding direction contemporaneously with phase-encoding blips common to EPI sequences. The slice-encoding blips are designed such that phase accruals along the phase-encoding direction are substantially mitigated, while providing that signal information for each sequentially adjacent slice location is cumulatively shifted by a percentage of the imaging FOV. This percentage FOV shift in the image domain provides for more reliable separation of the aliased signal information using parallel image reconstruction methods such as SENSE. In addition, the mitigation of phase accruals in the phase-encoding direction provides for the substantial suppression of pixel tilt and blurring in the reconstructed images.
51 Citations
20 Claims
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1. A method for producing a plurality of images of a subject with a magnetic resonance imaging (MRI) system, the steps of the method comprising:
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a) applying, with the MRI system, a radio frequency (RF) excitation field to a portion of a subject that includes a plurality of slice locations, the plurality of slice locations including a current slice location and at least one adjacent slice location; b) establishing, with the MRI system, at least one readout magnetic field gradient along a frequency-encoding direction following the application of the RF excitation field in order to form echo signals; c) sequentially producing a plurality of slice-encoding magnetic field gradient blips along a slice-encoding direction while the at least one readout magnetic field gradient is established in order to impart a phase shift to the formed echo signals such that image data corresponding to the at least one adjacent slice location is shifted by a selected percentage of a field-of-view (FOV) of the current slice location; d) acquiring, with an array of RF receiver coils that forms a part of the MRI system, image data indicative of the formed echo signals; and e) reconstructing a plurality of images of the subject from the acquired image data, each of the plurality of images depicting the subject at a corresponding one of the plurality of slice locations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for directing a magnetic resonance imaging (MRI) system to sample k-space, the steps of the method comprising:
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a) applying a radio frequency pulse in the presence of a spatially selective magnetic field gradient pulse, such that transverse magnetization is established in a spatial region including at least two slice locations; b) applying an alternating readout magnetic field gradient along a frequency encoding direction, such that a plurality of echo signals are formed; c) repeatedly applying a set of slice encoding magnetic field gradient blips that includes at least two slice encoding magnetic field gradient blips having opposite polarity, the set of slice encoding magnetic field gradient blips having a zero time integral; and d) acquiring k-space data from the plurality of formed echo signals using an array of RF receiver coils. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification