Method for performing single and multiple slice magnetic resonance spectroscopic imaging
First Claim
1. A method of selectively imaging a two dimensional slice through an object with suppression of short T1 species water components comprising the steps of:
- (a) placing said object in a magnetic field (B0) along one axis (z) thereby aligning nuclear spins in the slice along said axis;
(b) applying an 180°
RF inversion pulse to invert nuclear spins in said slice by 180°
;
(c) applying a 90°
RF pulse to nuclear spins in said slice after a time period after step (b) which is correlated to the spin-lattice relaxation time (T1) of said short T1 species such that the nuclear spins of said short T1 species have relaxed to a magnetic null;
(d) applying a 180°
RF pulse to nuclear spins in said slice which is spectrally and spatially selective of selected nuclear spins in said slice and suppresses nuclear spins of water in said slice;
(e) detecting spin echo signals from said selected nuclear spins; and
(f) generating a two dimensional image using the detected spin echo signals.
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Abstract
A new pulse sequence which uses inversion recovery for lipid suppression and a spectral-spatial refocusing pulse for water suppression in spectroscopic imaging of the brain. In contrast to methods which eliminate fat by restricting the excited volume to lie completely within the brain, inversion recovery techniques allow imaging of an entire slice without such restrictions. A spectral-spatial pulse provides water suppression insensitive to a reasonable range of B0 and B1 inhomogeneities. Metabolite maps covering large volumes of the human brain can be produced with images from single and multiple slices obtained.
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Citations
11 Claims
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1. A method of selectively imaging a two dimensional slice through an object with suppression of short T1 species water components comprising the steps of:
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(a) placing said object in a magnetic field (B0) along one axis (z) thereby aligning nuclear spins in the slice along said axis; (b) applying an 180°
RF inversion pulse to invert nuclear spins in said slice by 180°
;(c) applying a 90°
RF pulse to nuclear spins in said slice after a time period after step (b) which is correlated to the spin-lattice relaxation time (T1) of said short T1 species such that the nuclear spins of said short T1 species have relaxed to a magnetic null;(d) applying a 180°
RF pulse to nuclear spins in said slice which is spectrally and spatially selective of selected nuclear spins in said slice and suppresses nuclear spins of water in said slice;(e) detecting spin echo signals from said selected nuclear spins; and (f) generating a two dimensional image using the detected spin echo signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for the selective imaging of a two dimensional slice through an object and suppressing water components and short T1 species comprising:
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means for generating a magnetic field (B0) along one axis (z) through said object thereby aligning nuclear spins in said slice along said axis; means for applying a 180°
RF inversion pulse to invert nuclear spins in said slice;means for applying a 90°
RF pulse to nuclear spins in said slice at a time period after application of said 180°
RF inversion pulse which is correlated to the spin-lattice relaxation time (T1) of said short T1 species such that the nuclear spins of said short T1 species have relaxed to a magnetic null;means for applying a 180°
RF pulse to nuclear spins in said slice which is spectrally and spatially selective of selected nuclear spins in said slice and suppresses nuclear spins of water; andmeans for detecting spin echoes from the spectrally and spatially selective nuclear spins. - View Dependent Claims (10, 11)
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Specification