Time-saving generation of a B0 map based on a dual echo sequence with stimulated echoes
AssigneeSiemens Healthcare GmbH
InventorMichael Köhler
Life of this patent
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Abstract
The disclosure relates to a method for generating a B0 map for a magnetic resonance examination of an examination subject, a magnetic resonance device, and a computer program product for executing the method. The method provides for the application of at least two preparatory RF pulses during a preparatory stage and at least one readout RF pulse during an acquisition stage. At least one stimulated echo signal is acquired after the readout RF pulse. A B0 map that shows the actual spatial distribution of the magnetic field strength of the main magnetic field is derived from the at least one acquired FID echo signal and the at least one acquired stimulated echo signal.
Claims16
A method for generation of a B0 map for a magnetic resonance examination of an examination subject, the method comprising:
- generating a main magnetic field;
- applying to an examination space in which the examination subject is located of an imaging sequence having a preparatory stage and a subsequent acquisition stage, wherein the imaging sequence comprises:
- applying at least two preparatory radio-frequency (RF) pulses during the preparatory stage, wherein a first preparatory RF pulse of the at least two preparatory RF pulses is applied at a time t1, wherein a second preparatory RF pulse of the at least two preparatory RF pulses is applied at a time t2, wherein the times t1 and t2 are separated by a period TS;
- applying at least one readout RF pulse at a time t3 during the acquisition stage;
- acquiring at least one free induction decay (FID) echo signal after the readout RF pulse at a time t4, wherein the times t3 and t4 are separated by a period TEFID;
- and
- acquiring at least one stimulated echo signal after the at least one readout RF pulse at a time t5, wherein the times t3 and t5 are separated by a period TESTE;
- and
- deriving a B0 map that shows an actual spatial distribution of a magnetic field strength of the main magnetic field from the at least one FID echo signal and the at least one stimulated echo signal,
- wherein the period TS is chosen as a function of the periods TEFID and TESTE so that, between the times t4 and t5, a signal component of the echo signals from protons bound in water has a same phase difference as a signal component of the echo signals from protons bound in fat.
A magnetic resonance device comprising:
- a main magnet configured to generate a main magnetic field;
- and
- an examination space in which an examination subject is configured to be positioned,
- wherein the magnetic resonance device is configured to generate an imaging sequence comprising:
- applying at least two preparatory radio-frequency (RF) pulses during a preparatory stage, wherein a first preparatory RF pulse of the at least two preparatory RF pulses is applied at a time t1, wherein a second preparatory RF pulse of the at least two preparatory RF pulses is applied at a time t2, wherein the times t1 and t2 are separated by a period TS;
- applying at least one readout RF pulse at a time t3 during an acquisition stage;
- acquiring at least one free induction decay (FID) echo signal after the readout RF pulse at a time t4, wherein the times t3 and t4 are separated by a period TEFID;
- and
- acquiring at least one stimulated echo signal after the at least one readout RF pulse at a time t5, wherein the times t3 and t5 are separated by a period TESTE,
- wherein the magnetic resonance device is further configured to derive a B0 map that shows an actual spatial distribution of a magnetic field strength of the main magnetic field from the at least one FID echo signal and the at least one stimulated echo signal, and
- wherein the period TS is chosen as a function of the periods TEFID and TESTE so that, between the times t4 and t5, a signal component of the echo signals from protons bound in water has a same phase difference as a signal component of the echo signals from protons bound in fat.
A non-transitory computer program product comprising a program configured to be loaded directly into a memory of a programmable system control unit of a magnetic resonance device, wherein the program, when executed in the programmable system control unit of the magnetic resonance device, causes the magnetic resonance device to:
- generate a main magnetic field;
- apply to an examination space in which an examination subject is located of an imaging sequence having a preparatory stage and a subsequent acquisition stage, wherein the imaging sequence comprises:
- applying at least two preparatory radio-frequency (RF) pulses during the preparatory stage, wherein a first preparatory RF pulse of the at least two preparatory RF pulses is applied at a time t1, wherein a second preparatory RF pulse of the at least two preparatory RF pulses is applied at a time t2, wherein the times t1 and t2 are separated by a period TS;
- applying at least one readout RF pulse at a time t3 during the acquisition stage;
- acquiring at least one free induction decay (FID) echo signal after the readout RF pulse at a time t4, wherein the times t3 and t4 are separated by a period TEFID;
- and
- acquiring at least one stimulated echo signal after the at least one readout RF pulse at a time t5, wherein the times t3 and t5 are separated by a period TESTE;
- and
- derive a B0 map that shows an actual spatial distribution of a magnetic field strength of the main magnetic field from the at least one FID echo signal and the at least one stimulated echo signal,
- wherein the period TS is chosen as a function of the periods TEFID and TESTE so that, between the times t4 and t5, a signal component of the echo signals from protons bound in water has a same phase difference as a signal component of the echo signals from protons bound in fat.
Dependencies are inferred from the claim text.