METHOD TO GENERATE MAGNETIC RESONANCE EXPOSURES

• US 20130033262A1
• Filed: 07/20/2012
• Published: 02/07/2013
• Est. Priority Date: 08/02/2011
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Porter, David Andrew
• Granted Patent: US 9,095,302 B2
• Time in Patent Office: Days
• US Class Current: 324/309
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: G01R 33/5602 by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse
• CPC Class Codes: G01R 33/5616 using gradient refocusing, e.g. EPI
• CPC Class Codes: G01R 33/56341 Diffusion imaging
• CPC Class Codes: G01R 33/5676 Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction

Abstract

In a method described for generating magnetic resonance exposures in which diffusion-coded raw data are acquired with of a diffusion gradient measurement sequence having a number of partial diffusion gradient sequences, at least one diffusion coding gradient pulse is emitted in each partial data set, and raw data of a k-space region are acquired during a first echo after a defined first echo time the k-space regions in total covering a complete k-space. Raw data of an established navigator k-space region are acquired during a second echo after a second echo time the navigator k-space region being identical for different partial diffusion gradient sequences. Reference raw data are acquired by a reference measurement sequence with multiple partial reference sequences.

Claims

1. A method to generate magnetic resonance exposures of an examination subject, comprising:

operating a magnetic resonance data acquisition unit to acquire diffusion-coded raw data from an examination subject in the data acquisition unit, by executing a diffusion gradient measurement sequence comprising a plurality of successive partial diffusion gradient sequences;

in each of said partial diffusion gradient sequences, emitting at least one diffusion coding gradient pulse, acquiring raw data during a first partial diffusion gradient sequence echo after a defined first partial diffusion gradient echo sequence time and entering said raw data into a k-space region of k-space, with the respective k-space regions acquired during respective different partial diffusion gradient sequences in total encompassing said k-space, and acquiring navigator raw data during a second partial diffusion gradient sequence echo after a defined second partial diffusion gradient sequence time and entering said navigator raw data into a predetermined navigator k-space region of k-space, said navigator k-space region being identical for each partial diffusion gradient sequence;

acquiring reference raw data by operating said magnetic resonance data acquisition unit with a reference measurement sequence comprising a plurality of partial reference sequences; and

in each of said partial reference sequences, acquiring first reference raw data during a first reference sequence echo after a first reference sequence echo time and entering said first reference raw data into a k-space region of k-space, the respective k-space regions into which said reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space, and acquiring second reference raw data during a second reference sequence echo at a second reference sequence echo time, and entering said second reference raw data into k-space regions, said k-space regions into which said second reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space.

2. A method as claimed in claim 1 comprising configuring said reference measurement sequence in order to allow image data to be reconstructed with a spatial resolution based on said first reference raw data and to allow image data with the same spatial resolution to be reconstructed based on the second reference raw data.

3. A method as claimed in claim 1 comprising operating said magnetic resonance data acquisition unit to emit a refocusing pulse in each of said partial reference sequences after said first partial reference sequence echo and before said second partial reference sequence echo.

4. A method as claimed in claim 1 comprising:

operating said magnetic resonance data acquisition unit to implement a plurality of diffusion gradient measurement sequences, each corresponding to said diffusion gradient measurement sequence, and executing each of said plurality of diffusion gradient measurement sequences with a respectively different diffusion gradient strength, in order to acquire a plurality of diffusion-coded raw data sets;

in a computer, reconstructing respective sets of image data, that are differently diffusion-weighted, from the respective sets of differently diffusion-coded raw data; and

in said computer, generating parameter maps as a combination of said image data sets.

5. A method as claimed in claim 1 comprising, in a computer, generating synthetic image data from said first reference raw data and said second reference raw data with a defined echo time outside of said first echo time and said second echo time.

6. A method as claimed in claim 5 wherein said defined echo time is between said first echo time and said second echo time.

7. A method to generate magnetic resonance exposures of an examination subject, comprising:

operating a magnetic resonance data acquisition unit to acquire diffusion-coded raw data from an examination subject in the data acquisition unit, by executing a diffusion gradient measurement sequence comprising a plurality of successive partial diffusion gradient sequences;

in each of said partial diffusion gradient sequences, emitting at least one diffusion coding gradient pulse, acquiring raw data during a first partial diffusion gradient sequence echo after a defined first partial diffusion gradient echo sequence time and entering said raw data into a k-space region of k-space, with the respective k-space regions acquired during respective different partial diffusion gradient sequences in total encompassing said k-space, and acquiring navigator raw data during a second partial diffusion gradient sequence echo after a defined second partial diffusion gradient sequence time and entering said navigator raw data into a predetermined navigator k-space region of k-space, said navigator k-space region being identical for each partial diffusion gradient sequence;

acquiring reference raw data by operating said magnetic resonance data acquisition unit with a reference measurement sequence comprising a plurality of partial reference sequences;

in each of said partial reference sequences, acquiring first reference raw data during a first reference sequence echo after a first reference sequence echo time and entering said first reference raw data into a k-space region of k-space, the respective k-space regions into which said reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space, and acquiring second reference raw data during a second reference sequence echo at a second reference sequence echo time, and entering said second reference raw data into k-space regions, said k-space regions into which said second reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space;

in a computer, generating first image data from said first raw data;

in said computer, generating second image data from said second raw data; and

generating synthetic image data with a defined echo time that is outside of said first echo time and said second echo, by geometrically averaging said first image data and said second image data.

8. A method as claimed in claim 7 wherein said defined echo time is between said first echo time and said second echo time.

9. A method as claimed in claim 7 comprising generating said synthetic image data by respectively weighting, with different predetermined weighting factors, said first image data and said second image data in said geometric averaging of said first image data and said second image data.

10. A magnetic resonance system comprising:

a magnetic resonance data acquisition unit;

a control unit configured to operate said magnetic resonance data acquisition unit to acquire diffusion-coded raw data from an examination subject in the data acquisition unit, by executing a diffusion gradient measurement sequence comprising a plurality of successive partial diffusion gradient sequences;

said control unit being configured to operate said magnetic resonance data acquisition unit to emit, in each of said partial diffusion gradient sequences, at least one diffusion coding gradient pulse, and to acquire raw data during a first partial diffusion gradient sequence echo after a defined first partial diffusion gradient echo sequence time and to enter said raw data into a k-space region of k-space, with the respective k-space regions acquired during respective different partial diffusion gradient sequences in total encompassing said k-space, and to acquire navigator raw data during a second partial diffusion gradient sequence echo after a defined second partial diffusion gradient sequence time and to enter said navigator raw data into a predetermined navigator k-space region of k-space, said navigator k-space region being identical for each partial diffusion gradient sequence;

said control unit being configured to operate said magnetic resonance data acquisition unit to acquire reference raw data with a reference measurement sequence comprising a plurality of partial reference sequences; and

said control unit being configured to operate said magnetic resonance data acquisition unit to, in each of said partial reference sequences, acquire first reference raw data during a first reference sequence echo after a first reference sequence echo time and to enter said first reference raw data into a k-space region of k-space, the respective k-space regions into which said reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space, and to acquire second reference raw data during a second reference sequence echo at a second reference sequence echo time, and to enter said second reference raw data into k-space regions, said k-space regions into which said second reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space.

11. A magnetic resonance system comprising:

a magnetic resonance data acquisition unit;

a control unit configured to operate said magnetic resonance data acquisition unit to acquire diffusion-coded raw data from an examination subject in the data acquisition unit, by executing a diffusion gradient measurement sequence comprising a plurality of successive partial diffusion gradient sequences;

said control unit being configured to operate said magnetic resonance data acquisition unit to emit, in each of said partial diffusion gradient sequences, at least one diffusion coding gradient pulse, and to acquire raw data during a first partial diffusion gradient sequence echo after a defined first partial diffusion gradient echo sequence time and to enter said raw data into a k-space region of k-space, with the respective k-space regions acquired during respective different partial diffusion gradient sequences in total encompassing said k-space, and to acquire navigator raw data during a second partial diffusion gradient sequence echo after a defined second partial diffusion gradient sequence time and to enter said navigator raw data into a predetermined navigator k-space region of k-space, said navigator k-space region being identical for each partial diffusion gradient sequence;

said control unit being configured to operate said magnetic resonance data acquisition unit to acquire reference raw data with a reference measurement sequence comprising a plurality of partial reference sequences;

said control unit being configured to operate said magnetic resonance data acquisition unit to, in each of said partial reference sequences, acquire first reference raw data during a first reference sequence echo after a first reference sequence echo time and to enter said first reference raw data into a k-space region of k-space, the respective k-space regions into which said reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space, and to acquire second reference raw data during a second reference sequence echo at a second reference sequence echo time, and to enter said second reference raw data into k-space regions, said k-space regions into which said second reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space;

a computer configured to generate first image data from said first raw data;

said computer being configured to generate second image data from said second raw data; and

said computer being configured to generate synthetic image data with a defined echo time that is outside of said first echo time and said second echo, by geometrically averaging said first image data and said second image data.

12. A non-transitory, computer-readable data storage medium encoded with programming instructions, said data storage medium being loaded into a computerized control and evaluation unit of a magnetic resonance system, said magnetic resonance system comprising a magnetic resonance data acquisition unit, and said programming instructions causing said computerized control and evaluation system to:

operate said magnetic resonance data acquisition unit to acquire diffusion-coded raw data from an examination subject in the data acquisition unit, by executing a diffusion gradient measurement sequence comprising a plurality of successive partial diffusion gradient sequences;

operate said magnetic resonance data acquisition unit to emit, in each of said partial diffusion gradient sequences, at least one diffusion coding gradient pulse, in order to acquire raw data during a first partial diffusion gradient sequence echo after a defined first partial diffusion gradient echo sequence time and enter said raw data into a k-space region of k-space, with the respective k-space regions acquired during respective different partial diffusion gradient sequences in total encompassing said k-space, and in order to acquire navigator raw data during a second partial diffusion gradient sequence echo after a defined second partial diffusion gradient sequence time and enter said navigator raw data into a predetermined navigator k-space region of k-space, said navigator k-space region being identical for each partial diffusion gradient sequence;

acquire reference raw data by operating said magnetic resonance data acquisition unit with a reference measurement sequence comprising a plurality of partial reference sequences; and

operate said magnetic resonance data acquisition unit to acquire, in each of said partial reference sequences, first reference raw data during a first reference sequence echo after a first reference sequence echo time and enter said first reference raw data into a k-space region of k-space, the respective k-space regions into which said reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space, and to acquire second reference raw data during a second reference sequence echo at a second reference sequence echo time, and enter said second reference raw data into k-space regions, said k-space regions into which said second reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space.

13. A non-transitory, computer-readable data storage medium encoded with programming instructions, said data storage medium being loaded into a computerized control and evaluation unit of a magnetic resonance system, said magnetic resonance system comprising a magnetic resonance data acquisition unit, and said programming instructions causing said computerized control and evaluation system to:

operate a magnetic resonance data acquisition unit to acquire diffusion-coded raw data from an examination subject in the data acquisition unit, by executing a diffusion gradient measurement sequence comprising a plurality of successive partial diffusion gradient sequences;

operate said magnetic resonance data acquisition unit to emit, in each of said partial diffusion gradient sequences, at least one diffusion coding gradient pulse, in order to acquire raw data during a first partial diffusion gradient sequence echo after a defined first partial diffusion gradient echo sequence time and enter said raw data into a k-space region of k-space, with the respective k-space regions acquired during respective different partial diffusion gradient sequences in total encompassing said k-space, and in order to acquire navigator raw data during a second partial diffusion gradient sequence echo after a defined second partial diffusion gradient sequence time and enter said navigator raw data into a predetermined navigator k-space region of k-space, said navigator k-space region being identical for each partial diffusion gradient sequence;

acquire reference raw data by operating said magnetic resonance data acquisition unit with a reference measurement sequence comprising a plurality of partial reference sequences;

operate said magnetic resonance data acquisition unit to acquire, in each of said partial reference sequences, first reference raw data during a first reference sequence echo after a first reference sequence echo time and enter said first reference raw data into a k-space region of k-space, the respective k-space regions into which said reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space, and to acquire second reference raw data during a second reference sequence echo at a second reference sequence echo time, and enter said second reference raw data into k-space regions, said k-space regions into which said second reference raw data are entered during respective different partial reference sequences in total encompassing all of said k-space;

generate first image data from said first raw data;

generate second image data from said second raw data; and

generate synthetic image data with a defined echo time that is outside of said first echo time and said second echo, by geometrically averaging said first image data and said second image data.