MR imaging method and apparatus with water signal supression
First Claim
1. An MR imaging method using NMR phenomenon, comprising the steps of:
- (a) emitting a first group of RF pulses including a first inversion RF pulse having a frequency band for inverting proton spins included in a plurality of slices, and first excitation RF pulses emitted at predetermined points of time following said first inversion RF pulse to excite a plurality of slices in a predetermined order;
(b) emitting slice-selecting gradient field pulses based on emission timing of said RF pulses in said first group of RF pulses;
(c) emitting phase-encoding gradient field pulses for phase-encoding echo signals generated by said first excitation RF pulses, respectively;
(d) applying reading gradient field pulses to echo signals generated by said first group of RF pulses to read and collect a first group of echo signals successively;
(e) emitting a second group of RF pulses including a second inversion RF pulse having substantially the same frequency band as said first inversion RF pulse, and second excitation RF pulses emitted at predetermined points of time following said second inversion RF pulse to excite said plurality of slices in an order reverse to said predetermined order;
(f) emitting slice-selecting gradient field pulses based on emission timing of said RF pulses in said second group of RF pulses;
(g) emitting phase-encoding gradient field pulses for phase-encoding echo signals generated by said second excitation RF pulses, respectively;
(h) applying reading gradient field pulses to echo signals generated by said second group of RF pulses to read and collect a second group of echo signals successively;
(i) repeating a pulse sequence from step (a) to step (h), predetermined times, while varying said phase-encoding gradient field pulses emitted at steps (c) and (g);
(j) adding two data corresponding to each slice, which data are included, respectively, in a first group of data acquired from said first group of echo signals and in a second group of data acquired from said second group of echo signals, thereby forming a new group of data; and
(k) reconstructing a plurality of slice images from said new group of data.
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Abstract
An MR imaging method using NMR phenomenon and including the following steps: emitting a first group of RF pulses including a first inversion RF pulse, and excitation RF pulses emitted to excite a plurality of slices in a predetermined order; emitting slice-selecting gradient field pulses; emitting phase-encoding gradient field pulses; collecting a first group of echo signals; emitting a second group of RF pulses including a second inversion RF pulse having substantially the same frequency band as the first inversion RF pulse, and second excitation RF pulses emitted to excite the plurality of slices in a reverse order; emitting slice-selecting gradient field pulses; emitting phase-encoding gradient field pulses; collecting a second group of echo signals; repeating this pulse sequence while varying the phase-encoding gradient field pulses; adding two data corresponding to each slice, which data are included, respectively, in a first group of data and in a second group of data, thereby forming a new group of data; and reconstructing slice images.
21 Citations
10 Claims
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1. An MR imaging method using NMR phenomenon, comprising the steps of:
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(a) emitting a first group of RF pulses including a first inversion RF pulse having a frequency band for inverting proton spins included in a plurality of slices, and first excitation RF pulses emitted at predetermined points of time following said first inversion RF pulse to excite a plurality of slices in a predetermined order; (b) emitting slice-selecting gradient field pulses based on emission timing of said RF pulses in said first group of RF pulses; (c) emitting phase-encoding gradient field pulses for phase-encoding echo signals generated by said first excitation RF pulses, respectively; (d) applying reading gradient field pulses to echo signals generated by said first group of RF pulses to read and collect a first group of echo signals successively; (e) emitting a second group of RF pulses including a second inversion RF pulse having substantially the same frequency band as said first inversion RF pulse, and second excitation RF pulses emitted at predetermined points of time following said second inversion RF pulse to excite said plurality of slices in an order reverse to said predetermined order; (f) emitting slice-selecting gradient field pulses based on emission timing of said RF pulses in said second group of RF pulses; (g) emitting phase-encoding gradient field pulses for phase-encoding echo signals generated by said second excitation RF pulses, respectively; (h) applying reading gradient field pulses to echo signals generated by said second group of RF pulses to read and collect a second group of echo signals successively; (i) repeating a pulse sequence from step (a) to step (h), predetermined times, while varying said phase-encoding gradient field pulses emitted at steps (c) and (g); (j) adding two data corresponding to each slice, which data are included, respectively, in a first group of data acquired from said first group of echo signals and in a second group of data acquired from said second group of echo signals, thereby forming a new group of data; and (k) reconstructing a plurality of slice images from said new group of data. - View Dependent Claims (2, 3)
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4. An MR imaging apparatus using NMR phenomenon, comprising:
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(a) a main magnet for generating a uniform static magnetic field in an imaging space; (b) a first, a second and a third gradient field coils attached to said main magnet for generating three types of gradient field pulses, i.e. slice-selecting gradient field pulses, reading gradient field pulses and phase-encoding gradient field pulses, with magnetic strengths varying in three orthogonal directions in said imaging space; (c) a RF coil for emitting RF pulses to an examinee placed in said imaging space, and detecting echo signals generated from said examinee; (d) RF emitting means for successively emitting, through said RF coil, a first group of RF pulses including a first inversion RF pulse having a frequency band for inverting proton spins included in a plurality of slices, and first excitation RF pulses emitted at predetermined points of time following said first inversion RF pulse to excite a plurality of slices in a predetermined order, and a second group of RF pulses including a second inversion RF pulse having substantially the same frequency band as said first inversion RF pulse, and second excitation RF pulses emitted at predetermined points of time following said second inversion RF pulse to excite said plurality of slices in an order reverse to said predetermined order; (e) gradient field control means connected to said first, second and third gradient field coils and operable, based on emission timing of said RF pulses in said first group of RF pulses and said second group of RF pulses from said RF coils, for applying slice-selecting gradient field pulses through said first gradient field coil, applying phase-encoding gradient field pulses through said second gradient field coil, and applying reading gradient field pulses through said third gradient field coil to echo signals generated by said RF pulses, thereby forming a pulse sequence, said pulse sequence being repeated predetermined times while varying said phase-encoding gradient field pulses; (f) adding means for successively reading, through said RF coil, a first group of echo signals and a second group of echo signals generated by said first group of RF pulses and said second group of RF pulses, respectively, and adding two data corresponding to each slice, which data are included, respectively, in a first group of data acquired from said first group of echo signals and in a second group of data acquired from said second group of echo signals, thereby forming a new group of data; and (g) data processing means for reconstructing a plurality of slice images from said new group of data. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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Specification