Echo-specific k-space sampling with multi-echo sequences

Patent metadata

Field	Value
Publication number	US-11762048-B2
Application number	US-202117488719-A
Country	US
Kind code	B2
Filing date	Sep 29, 2021
Priority date	Sep 29, 2020
Publication date	Sep 19, 2023
Grant date	Sep 19, 2023

Abstract

In a method, an imaging sequence is irradiated into an examination region in which an examination object is located. The imaging sequence includes an acquisition section. The acquisition section includes acquiring a plurality of echo signals, each of which samples a k-space region of a k-space. The plurality of echo signals comprises a plurality of first echo signals and a plurality of second echo signals. The plurality of first echo signals and the plurality of second echo signals are generated from different magnetization configurations. The k-space regions sampled by the plurality of first echo signals sample the k-space in a different order to the k-space regions sampled by the plurality of second echo signals.

First claim

The invention claimed is:

1. A method for the acquisition of echo signals during a magnetic resonance examination of an examination object, the method comprising:
irradiating an imaging sequence into an examination region in which the examination object is located, wherein the imaging sequence comprises an acquisition section,
wherein the acquisition section comprises acquiring a plurality of echo signals, each echo signal of the plurality of echo signals sampling a k-space region of a k-space,
wherein the plurality of echo signals comprises a plurality of first echo signals and a plurality of second echo signals,
wherein the plurality of first echo signals and the plurality of second echo signals are generated from different magnetization configurations,
wherein the k-space regions sampled by the plurality of first echo signals sample the k-space in a different order to the k-space regions sampled by the plurality of second echo signals,
wherein the plurality of first echo signals are FID echo signals, and the plurality of second echo signals are stimulated echo signals,
wherein the FID echo signals are acquired before the stimulated echo signals, or the stimulated echo signals are acquired before the FID echo signals, and
wherein the order of the k-space regions sampled by the plurality of first echo signals is characterized in that spacing from a k-space center decreases during the course of acquisition of the plurality of first echo signals.

2. The method of claim 1 , wherein the acquisition section further comprises irradiating a plurality of gradient pulses in a phase encoding direction, which is capable of setting the k-space regions to be sampled by the echo signals.

3. The method of claim 1 , wherein each of the k-space regions is a k-space line.

4. The method of claim 1 , wherein the order of the k-space regions sampled by the plurality of second echo signals is characterized in that spacing from a k-space center increases during the course of acquisition of the plurality of second echo signals.

5. The method of claim 1 , wherein the acquisition section further comprises:
irradiating a plurality of readout RF pulses,
wherein each readout RF pulse of the plurality of readout RF pulses is operable to trigger at least one first echo signal of the plurality of first echo signals, at least one second echo signal of the plurality of second echo signals, or the at least one first echo signal and the at least one second echo signal.

6. The method of claim 1 , wherein the imaging sequence further comprises a preparation section preceding the acquisition section, and
wherein a phasing of the plurality of second echo signals is prepared by the preparation section.

7. The method of claim 5 , further comprising:
generating a main magnetic field during the imaging sequence; and
deriving a B 0 map that specifies an actual spatial distribution of a magnetic field strength of the main magnetic field, the B 0 map comprising the at least one first echo signal and the at least one second echo signal.

8. The method of claim 7 , wherein the imaging sequence further comprises a preparation section preceding the acquisition section,
wherein the imaging sequence comprises:
irradiating at least two preparation RF pulses during the preparation section, wherein there is a time span between irradiating one of the at least two preparation RF pulses and irradiating another one of the at least two preparation RF pulses;
irradiating a plurality of readout RF pulses during the acquisition section;
acquiring one first echo signal of the plurality of first echo signals in each case after one readout RF pulse of the plurality of readout RF pulses, wherein there is a time span between irradiating the respective one readout RF pulse of the plurality of readout RF pulses and acquiring the respective one first echo signal;
acquiring one second echo signal of the plurality of second echo signals in each case after one readout RF pulse of the plurality of readout RF pulses, wherein there is a time span between irradiating the respective one readout RF pulse of the plurality of readout RF pulses and acquiring the respective one second echo signal,

wherein the time span between irradiating the one preparation RF pulse and irradiating the another one preparation RF pulse is chosen such that between an instant at which the at least one first echo signal is acquired, and an instant at which the at least one second echo signal is acquired, a signal component of echo signals of the plurality of echo signals from protons bound in water has a same phase difference to a signal component of echo signals of the plurality of echo signals from protons bound in fat.

9. The method of claim 8 , wherein

TS
=

N
*

1

δ
WF

*

(

γ
⁢

/

⁢
2
⁢
π

)

*

B

0
,
desired

+

TE
STE

-

TE
FID

wherein TS is the time span between irradiating the one of the at least two preparation RF pulses and irradiating the another one of the at least two preparation RF pulses, TE STE is the time span between irradiating the respective one readout RF pulse of the plurality of readout RF pulses and acquiring the respective one second echo signal, TE FID is the time span between irradiating the respective one readout RF pulse of the plurality of readout RF pulses and acquiring the respective one first echo signal, N is a whole number>0, δ WF specifies a chemical shift of water and fat, and γ specifies a gyromagnetic ratio of protons bound in water.

10. The method of claim 7 , wherein the main magnetic field has a desired magnetic field strength of less than 2 T.

11. A magnetic resonance device operable to acquire echo signals during a magnetic resonance examination of an examination object, the magnetic resonance device comprising:
a coil operable to irradiate an imaging sequence into an examination region in which the examination object is located, wherein the imaging sequence comprises an acquisition section,
wherein the acquisition section comprises acquisition of a plurality of echo signals, each echo signal of the plurality of echo signals sampling a k-space region of a k-space,
wherein the plurality of echo signals comprises a plurality of first echo signals and a plurality of second echo signals,
wherein the plurality of first echo signals and the plurality of second echo signals are generated from different magnetization configurations, and
wherein the k-space regions sampled by the

Assignees

• Siemens Healthcare Gmbh

Inventors

• Köhler Michael

Classifications

• G01R33/4818 Primary

  MR characterised by data acquisition along a specific k-space trajectory or by the temporal order of k-space coverage, e.g. centric or segmented coverage of k-space · CPC title

• G01R33/4822

  in three dimensions · CPC title

• G01R33/243

  Spatial mapping of the polarizing magnetic field · CPC title

• G01R33/5616

  using gradient refocusing, e.g. EPI · CPC title

• G01R33/5602

  by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse · CPC title