Method and apparatus for fast imaging by nuclear magnetic resonance
AssigneeGE Medical Systems Global Technology Company, LLC
InventorPatrick Le Roux
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Abstract
In the acquisition of NMR signals in FSE or fast spin echo type sequences the emission phase of the 180° refocusing pulse evolves quadratically. Prevention of problems of oscillation of the output signal, the sequence is subjected to a preparation pulses. A history is provided for the common difference of the quadratic sequence of the phase variation with respect to the first seven refocusing pulses. This history leads to an immediate thermal equilibrium.
Claims29
A method of signal acquisition in an NMR experiment comprising:
- subjecting a body to be examined to a magnetic orientation field;
- subjecting the body thus magnetically oriented to an initial electromagnetic excitation;
- subjecting the body to a succession of refocusing excitations;
- modifying quadratically the phase Φxi of the refocusing excitations numbered i in the succession wherein it is of the Φxi−Φxi−1=δi+δi−1 type with a common difference Δ equal to δi−δi−1;
- and
- applying at the start of the quadratic evolution, a sequence of preparation excitations during which the common difference Δ evolves according to a chronological sequence planned in advance.
An apparatus for signal acquisition in NMR comprising:
- means for subjecting a body to a magnetic orientation field;
- means for subjecting the body to an initial electromagnetic excitation;
- means for subjecting the body to a succession of refocusing excitations;
- wherein the phase Φxi of the refocusing excitations is modified quadratically numbered i in the succession and wherein it is of the Φxi−Φxi−1=δi+δi−1 type with a common difference Δ equal to δi−δi−1;
- and
- means for subjecting the body to sequence of preparation excitations at the start of the quadratic evolution, the sequence of preparation excitations is applied during which the common difference Δ evolves according to a chronological sequence planned in advance.
An article of manufacture having computer readable program code means embodied therein for causing signal acquisition in NMR, the computer readable program code means in the article of manufacture comprising:
- computer readable program code means for means for subjecting a body to a magnetic orientation field;
- computer readable program code means for subjecting the body to an initial electromagnetic excitation;
- computer readable program code means for subjecting the body to a succession of refocusing excitations;
- wherein the phase Φxi of the refocusing excitations is modified quadratically numbered i in the succession and wherein it is of the Φxi−Φxi−1=δi+δi−1 type with a common difference Δ equal to δi−δi−1;
- and
- computer readable code means for subjecting the body to sequence of preparation excitations at the start of the quadratic evolution, the sequence of preparation excitations is applied during which the common difference Δ evolves according to a chronological sequence planned in advance.
A computer program product for use with a NMR apparatus, the computer program product comprising:
- a computer usable medium having computer readable program code means embodied in the medium for causing a signal acquisition in the apparatus, the computer program product having:
- computer readable program code means for means for subjecting a body to a magnetic orientation field;
- computer readable program code means for subjecting the body to an initial electromagnetic excitation;
- computer readable program code means for subjecting the body to a succession of refocusing excitations;
- wherein the phase Φxi of the refocusing excitations is modified quadratically numbered i in the succession and wherein it is of the Φxi−Φxi−1=δi+δi−1 type with a common difference Δ equal to δi−δi−1;
- and
- computer readable code means for subjecting the body to sequence of preparation excitations at the start of the quadratic evolution, the sequence of preparation excitations is applied during which the common difference Δ evolves according to a chronological sequence planned in advance.
A program storage device readable by a machine, tangibly embodying a program of instructions to perform method steps for acquiring an NMR signal, the method steps comprising:
- subjecting a body to be examined to a magnetic orientation field;
- subjecting the body thus magnetically oriented to an initial electromagnetic excitation
- subjecting the body to a succession of refocusing excitations;
- modifying quadratically the phase Φxi of the refocusing excitations numbered i in the succession wherein it is of the Φxi−Φxi−1=δi+δ−1 type with a common difference Δ equal to δi−δi−1;
- and
- applying at the start of the quadratic evolution, a sequence of preparation excitations during which the common difference Δ evolves according to a chronological sequence planned in advance.
Dependencies are inferred from the claim text.