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US RE37,325 E1Granted
Slice orientation selection arrangement
OwnerHanan Keren, David Freundlichinventors
Life of this patent
Estimating the term…
Abstract
A slice orientation selection arrangement for magnetic resonance imaging in planes oblique to the normal cartesian coordinates. The coordinates are rotated to applying gradient signals using Euler computations.
Claims12
A method of imaging a subject using MRI systems wherein the selected imaging plane is at any desired angle to the usual X, Y and Z coordinate axes of said MRI system, the method comprises the steps of:
- (a) subjecting the subject to a strong static magnetic field along the Z axis in order to align magnetic spins in the Z direction in said subject being imaged;
- (b) applying magnetic gradient vector pulses to vary said static field;
- (c) generating FID signals by applying RF magnetic pulses rotating at Larmor frequencies to nutate said spins;
- (d) selecting desired non-orthogonal imaging planes by selectively rotating the direction of the magnetic gradient vectors by determined angular amounts about coordinate axes prior to applying the magnetic gradient vector pulses;
- (e) determining the angular amount to rotate the magnetic gradient vectors about the coordinate axis using visual indicators;
- and
- (f) projecting said visual indicators onto the image of said subject being imaged.
4 more elements
A method of imaging a subject using MRI systems wherein the selected imaging plane is at any desired angle to the usual X, Y and Z coordinate axes of said MRI system, the method comprising the steps of:
- (a) subjecting the subject to a strong static magnetic field along the Z axis in order to align the magnetic spins in the Z direction in said subject being imaged;
- (b) applying magnetic gradient vector pulses to vary said static field;
- (c) generating FID signals by applying RF magnetic pulses rotating at Larmor frequencies to nutate said spins;
- (d) selecting desired non-orthogonal planes by selectively rotating the direction of the magnetic gradient vectors by determined angular amounts about the coordinate axes prior to applying the magnetic gradient vector pulses;
- (e) imaging in a first plane using the usual coordinate axes;
- (f) imaging in a second plane using the usual coordinate axes;
- (g) placing a visible line on the first plane in an area of interest;
- (h) placing at least a visible dot in the second plane in an area of interest;
- and
- (i) using said line and said dot to define a new plane, said new plane being the selected non-orthogonal imaging plane, wherein said newly defined plane indicates the angular amounts to rotate the direction of the magnetic gradient vector pulses.
7 more elements
A method of imaging a subject using MRI systems wherein the selected imaging plane is at any desired angle to the usual X, Y and Z coordinate axes of said MRI system, the method comprises the steps of:
- (a) subjecting the subject to a strong static magnetic field along the Z axis in order to align magnetic spins in the Z direction in the said subject being imaged;
- (b) applying magnetic gradient vector pulses to vary said static field;
- (c) generating FID signals by applying RF magnetic pulses rotating at a Larmor frequency to nutate said spins;
- (d) selecting desired non-orthogonal imaging planes by selectively rotating the direction of the magnetic gradient vectors by determined angular amounts about the coordinate axes prior to applying the magnetic gradient vector pulses;
- (e) rotating the Z gradient direction through θ degrees to Z′, the X gradient direction through θ φ degrees to X′, the Y gradient direction through ψ degrees to Y′, where θ, φ and ψ are determined angular amounts;
- and
- (f) said last named step including multiplying the X, Y and Z gradients by a matrix A defined as follows:
- [ A = ( cos θcos ψ – sin θ sin φ sin ψ sin θ cos φ cos θsin ψ + sin θ sin φ cos ψ - sin θcos ψ – cos θ sin φ sin ψ cos θ cos φ - sin θsin ψ + cos θ sin φ cos ψ - sin ψ cos φ - sin φ cos φ cos ψ ) ] A = ( cos θcos ψ – sin θ sin φ sin ψ sin θ cos φ cos θsin ψ + sin θ sin φ cos ψ - sin θcos ψ – cos θ sin φ sin ψ cos θ cos φ - sin θsin ψ + cos θ sin φ cos ψ - sin ψ cos φ - sin φ cos φ cos ψ ) .
5 more elements
A method of imaging a subject using MRI systems wherein the selected imaging plane is at any desired angle to the usual X, Y and Z coordinate axes of said MRI system, the method comprises the steps of:
- (a) subjecting the subject to a strong static magnetic field along the Z axis in order to align magnetic spins in the Z direction in the said subject being imaged;
- (b) applying magnetic gradient vector pulses to vary said static field;
- (c) generating FID signals by applying RF magnetic pulses rotating at Larmor frequencies to nutate said spins;
- (d) selecting desired non-orthogonal imaging planes by selectively rotating the direction of the magnetic gradient vectors by determined angular amounts about the coordinate axes prior to applying the magnetic gradient vector pulses;
- and
- (e) rotating the Z, X and Y gradient direction θ degrees to Z, X, and Y respectively, wherein θ is a determined angular amount for the Z gradient, said method of rotating including multiplying the X, Y and Z gradients by a matrix B, said matrix B is defined as:
- B = ( cos θ sin θ 0 - sin θ cos θ 0 0 0 1 ) .
4 more elements
A method of imaging a subject using MRI systems wherein the selected imaging plane is at any desired angle to the usual X, Y and Z coordinate axes of said MRI system, the method comprises the steps of:
- (a) subjecting the subject to a strong static magnetic field along the Z axis in order to align magnetic spins in the Z direction in said subject being imaged;
- (b) applying magnetic gradient vector pulses to vary said static field;
- (c) generating free induction delay (FID) signals by applying RF magnetic pulses rotating at Larmor frequencies to nutate said spins;
- (d) selecting desired non-orthogonal imaging planes by selectively rotating the direction of the magnetic gradient vectors by determined angular amounts about the coordinate axes prior to applying the magnetic gradient vector signals;
- and
- (e) rotating the Z, X and Y gradients φ degrees to Z′, X′ and Y′ where φ is a determined angular amount for the X gradient by multiplying the Z, X and Y gradients by a matrix C, where C is defined as:
- C = ( 1 0 0 0 cos φ sin φ 0 - sin φ cos φ ) .
4 more elements
A method of imaging a subject using MRI systems wherein the selected imaging plane is at any desired angle to the usual X, Y and Z coordinate axes of said MRI system, the method comprises the steps of:
- (a) subjecting the subject to a strong static magnetic field along the Z axis in order to align magnetic spins in the Z direction in said subject being imaged;
- (b) applying magnetic gradient vector pulses to vary said static fields;
- (c) generating FID signals by applying RF magnetic pulses rotating at Larmor frequencies to nutate said spins;
- (d) selecting desired non-orthogonal imaging planes by selectively rotating the direction of the magnetic gradient vectors by determined angular amounts about the coordinate axes prior to applying the magnetic gradient vector pulses;
- (e) rotating the Z, X and Y gradient direction by ψ degrees to Z′, X′ and Y′ respectively where ψ is a determined angular amount for the Y gradient by multiplying the Z X, Y and Z gradients by a matrix D, where D is defined as:
- [ D = ( cos φ 0 sin ψ 0 1 0 - sin ψ 0 cos ψ ) ] D = ( cos ψ 0 sin ψ 0 1 0 - sin ψ 0 cos ψ ) .
3 more elements
A system of imaging subjects using MRI systems wherein the selected imaging plane is at any desired angle to the usual X, Y and Z coordinate axes of said MRI systems, said system comprising:
- (a) means for subjecting the subject to a strong static magnetic field along the Z axis in order to align magnetic spins in the Z direction in said subject being imaged;
- (b) means for applying magnetic gradient vector pulses to vary said static field;
- (c) means for generating FID signals by applying RF magnetic pulses rotated at Larmor frequencies to nutate said spins;
- (d) means for selecting desired non-orthogonal imaging planes by rotating the direction of the magnetic gradient vectors by determined amounts about the coordinate axes prior to applying the magnetic gradient vector pulses;
- and
- (e) means for determining the angular amount to rotate the magnetic gradient vectors about the coordinate axes including means for projecting visual indicators onto images of said subject being imaged.
3 more elements
A system of imaging a subject using MRI systems wherein the selected imaging plane is at any desired angle to the usual X, Y and Z coordinate axes of said MRI systems, said system comprising:
- (a) means for subjecting the subject to a strong static magnetic field along the Z axis in order to align magnetic spins extending in the Z direction in said subject being imaged;
- (b) means for applying magnetic gradient vector pulses to vary said static fields;
- (c) means for generating free induction decay (FID) signals by applying RF magnetic pulses rotating at Larmor frequencies to nutate said spins;
- (d) means for selecting desired non-orthogonal imaging planes by rotating the direction of the magnetic gradient vectors by determined angular amounts about the coordinate axis prior to applying gradient vector signals;
- (e) means for rotating the Z gradient direction through θ degrees to Z′, the X gradient direction through φ degrees to X′, the Y gradient direction ψ degrees to Y′ where θ, φ and ψ are determined angular amounts;
- (f) said last named means including means for multiplying the X, Y and Z gradients by a matrix A defined as follows:
- [ A = ( cos θ sin φ - sin θ sin φ sin ψ sin θ cos φ cos θsin ψ + sin θ sin φ sin ψ - sin θcos φ - cos θ sin φ sin ψ cos θ cos φ - sin θsin ψ + cos θ sin φ cos ψ - cos φ sin θ sin φ cos φ + cos φ ) ] A = ( cos θcos ψ - sin θ sin φ sin ψ sin θ cos φ cos θsin ψ + sin θ sin φ cos ψ - sin θcos ψ - cos θ sin φ sin ψ cos θ cos φ - sin θsin ψ + cos θ sin φ cos ψ - sin ψ cos φ - sin φ cos φ cos ψ ) .
4 more elements
Dependencies are inferred from the claim text.