Back to results
US 4,727,325 AGranted
NMR imaging method
AssigneeHitachi, Ltd.
InventorsShigeru Matsui, Kensuke Sekihara, Hideki Kohno
Life of this patent
Estimating the term…
Abstract
An NMR imaging method using a rotating field gradient is disclosed in which transverse magnetization is prepared in a portion of an object to be inspected, by the 90.degree.-180.degree. RF pulse excitation, a rotating field gradient is generated to perform a sampling operation for an output signal in a state that the position of signal in a phase space is revolved, the intensity or rotational speed of the rotating field gradient is varied stepwise or continuously to obtain data arranged on concentric circles or a spiral in the phase space, and the data thus obtained undergoes Fourier transformation in each of a plurality of radial directions or two-dimensional Fourier transformation, to form an image of spin distribution.
Claims16
A nuclear magnetic resonance imaging method comprising:
- a first step of preparing transverse magnetization in a desired portion of an object to be inspected, said to-be-inspected object being disposed in a uniform, static magnetic field;
- a second step of generating a field gradient in a predetermined direction to translate the position of signal in a phase space, from the origin thereof;
- and
- a third step of generating a rotating field gradient to perform a measuring operation while rotating the position of signal in the phase space.
1 more element
A nuclear magnetic resonance imaging method comprising:
- a first step of preparing transverse magnetization in a desired portion of an object to be inspected, said to-be-inspected object being disposed in a uniform, static magnetic field;
- a second step of generating a field gradient in a predetermined direction, to translate the position of signal in a phase space, from the origin thereof;
- a third step of generating a rotating field gradient to rotate the position of signal in the phase space, and performing a sampling operation for a signal successively, while varying at least one of the intensity and the rotational speed of the rotating field gradient at each rotation, to obtain signals arranged on a plurality of concentric circles which are formed in said phase space;
- a fourth step of Fourier-transforming said signals obtained in said third step in radial directions of said phase space, to obtain a plurality of projections;
- and
- a fifth step of reconstructing two-dimensional data, from said projections obtained in said fourth step.
3 more elements
A nuclear magnetic resonance imaging method comprising:
- a first step of preparing transverse magnetization in a desired portion of an object to be inspected, said to-be-inspected object being disposed in a uniform, static magnetic field;
- a second step of generating a field gradient in a predetermined direction, to translate the position of signal in a phase space, from the origin thereof;
- a third step of generating a rotating field gradient to rotate the position of signal in the phase space, and performing a sampling operation for a signal successively, while varying at least one of the intensity and the rotational speed of the rotating field gradient at each rotation, to obtain signals arranged on a plurality of concentric circles which are formed in the phase space;
- a fourth step of obtaining data trains which are arranged on rectangular coordinate points in the phase space, from the signals obtained in said third step, by interpolation;
- and
- a fifth step of causing said data trains obtained in said fourth step, to undergo a Fourier transformation.
3 more elements
A nuclear magnetic resonance imaging method comprising:
- a first step of preparing transverse magnetization in a desired portion of an object to be inspected, said to-be-inspected object being disposed in a substantially-uniform, static magnetic field;
- a second step of sampling a signal resulting from the transverse magnetization, in a state that a gradient field is superposed on said uniform, static magnetic field, said gradient field having an oscillating waveform formed of the combination of sine and cosine functions;
- and
- a third step of reconstructing a spin distribution image from said sample signal;
- wherein the period of said sine and cosine functions making up said oscillating waveform is an integral multiple of a sampling interval, at which a sampling operation is performed for the signal sampled in said second step.
2 more elements
A nuclear magnetic resonance imaging method comprising:
- a first step of preparing transverse magnetization in a desired portion of an object to be inspected, said to-be-inspected object being disposed in a substantially-uniform, static magnetic field;
- a second step of measuring a signal resulting from the transverse magnetization, in a state that a gradient field is superposed on said uniform, static magnetic field, said gradient field having an oscillating waveform formed of the combination of sine and cosine functions, and signal appearing at an interval, equal to a value which is obtained by dividing the period of said sine and cosine functions making up said oscillating waveform by an integer, are calculated, by interpolation, from signals which are obtained by a sampling operation for the measured signal;
- and
- a third step of reconstructing a spin distribution image from said interpolated signals.
1 more element
A nuclear magnetic resonance imaging method comprising:
- a first step of preparing transverse magnetization in a desired portion of an object to be inspected, said to-be-inspected object being disposed in a substantially-uniform, static magnetic field;
- a second step of measuring a signal resulting from the transverse magnetization while rotating said to-be-inspected object, in a state that a gradient field is superposed on said static magnetic field, said gradient field being formed of a first gradient field component and a second gradient field component perpendicular thereto, the intensity of said first gradient field component being kept constant, the intensity of said second gradient field component being increased linearly with time;
- and
- a third step of reconstructing a spin distribution image from said measured signal.
1 more element
Dependencies are inferred from the claim text.