Magnetic resonance method and apparatus for obtaining a set of measured data relating to a breathing object of interest

1. A method for acquiring a magnetic resonance measurement data set of a breathing subject, comprising:

operating a magnetic resonance apparatus, in which a breathing subject is located, to acquire a plurality of magnetic resonance data subsets;

entering the plurality of magnetic resonance data subsets into an electronic memory representing k-space, wherein k-space is comprised of a plurality of segments, and entering the respective magnetic resonance data subsets individually into respective k-space segments;

also operating said magnetic resonance apparatus to make at least two navigator data acquisitions, before each respective acquisition of said magnetic resonance data acquisitions subset acquisitions, and using said navigator data to determine a respiratory position of the subject, and a respiratory phase of the subject and assigning said respiratory position and phase to the magnetic resonance data subset acquired in the respective acquisition; and

providing the respiratory position and the respiratory phase to a processor and, in said processor, using the respiratory position and the respiratory phase, assigned to each of the magnetic resonance data subsets, to decide automatically whether a respective magnetic resonance data subset is included or not included in a final magnetic resonance data set from which a magnetic resonance image is to be reconstructed, and making said final magnetic resonance data set available in electronic form at an output of said processor.

2. A method as claimed in claim 1 comprising determining said respiratory phase using navigator data acquired with at least two of said navigator data acquisitions being acquired with a temporal spacing that is substantially smaller than a duration of a respiratory cycle of the breathing subject.

3. A method as claimed in claim 1 comprising, in said processor, using said respiratory phase for each magnetic resonance data subset to assign a designation of “inhaling” or “exhaling” to the respective magnetic resonance data subset.

4. A method as claimed in claim 3 comprising assigning the respective magnetic resonance data subset a designation of “unknown” if neither of said designations “inhaling” or “exhaling” can be assigned to the respective magnetic resonance data subset.

5. A method as claimed in claim 4 comprising, in said processor, not including any magnetic resonance data subsets, in said final magnetic resonance data set that have an “unknown” designation.

6. A method as claimed in claim 1 comprising, in said processor, including a respective magnetic resonance data subset in said final magnetic resonance data set only if a respiratory position thereof is within a predetermined acceptance window and the respiratory phase thereof has a predetermined value.

7. A method as claimed in claim 1 comprising:

in said processor, subdividing the respiratory position and the respiratory phase of the subject into a plurality of predetermined clusters, each cluster encompassing a predetermined respiratory range of said respiratory positions and said respiratory phases of the subject;

operating said magnetic resonance apparatus to acquire said magnetic resonance data subsets as a plurality of shots, with the magnetic resonance data of each shot filling a predetermined number of lines in k-space that is less than an entirety of all lines in k-space, and each shot exhibiting a three-dimensional k-space trajectory in k-space, with respectively different shots filling respectively different lines in k-space such that each shot fills a predetermined k-space region;

in said processor, assigning a respective shot index to each of said shots that designates a sensitivity of the respective shot to movement by the subject, and assigning said shot indices to the respective shots with adjacent shot indices being assigned to respective shots, among said plurality of shots, that exhibit an incrementally different sensitivity to said movement, with a shot having a highest sensitivity to motion receiving a shot index in the middle of the total index range;

in said processor, assigning a range of adjacent shot indices to each of said clusters, that causes shots to be assigned to specific clusters where said range of shot indices is initially empty;

in said processor assigning a start index to each of said clusters;

operating said magnetic resonance apparatus to acquire the respective shots by (A) acquiring said navigator data, (B) in said processor, selecting a specific cluster in the respective respiratory range in which said navigator data indicate the respiratory position and the respiratory phase occur, (C) from said processor, selecting a shot to be acquired that has a shot index that borders the shot index range of said specific cluster, or if the shot index range is empty, selecting the shot that has the start index of said specific cluster and (D) acquiring said shot to be acquired and assigning said shot to the specific cluster;

repeating (A), (B), (C) and (D) until at least two bordering clusters, that encompass adjacent respiratory regions of the subject, collectively encompass the shot indices of all said shots in said measurement data set; and

reconstructing an MR image from magnetic resonance data of said shots assigned to said two bordering clusters.

8. A method as claimed in claim 7 comprising, in said processor, selecting said shot to be acquired that causes the respective k-space region, to be filled with magnetic resonance data of the shot to be acquired, to be filled as uniformly as possible along a filling criterion selected from the group consisting of respective axis of said three-dimensional k-space trajectory, and different sides of the respective k-space region.

9. A method as claimed in claim 7 wherein said lines in k-space are oriented along a readout axis of a readout gradient field generated in said magnetic resonance data acquisition unit, and wherein the respective k-space is filled such that different lines acquired by a particular shot are disposed substantially radially in a plane that is perpendicular to said readout axis.

10. A method as claimed in claim 9 comprising, in said processor, dividing each k-space region into sectors that are defined with respect to a distance thereof from a center of k-space, with a k-space line located in each sector for each of said shots.

11. A method as claimed in claim 10 comprising, in said processor, selecting the respective k-space trajectories so that each k-space trajectory enters data into a k-space line, that is different for each of said shots, in a series corresponding to a neighborhood of the respective sectors in which the respective k-space lines are located, within a respective k-space region.

12. A magnetic resonance apparatus comprising:

a magnetic resonance imaging device;

a control computer configured to operate said magnetic resonance imaging device, in which a breathing subject is located, to acquire a plurality of magnetic resonance data subsets;

an electronic memory representing k-space;

said control computer being configured to enter the plurality of magnetic resonance data subsets into said electronic memory representing k-space, wherein k-space is comprised of a plurality of segments, by entering the respective magnetic resonance data subsets individually into respective k-space segments;

said control computer being configured to operate said magnetic resonance imaging device to make at least two navigator data acquisitions, before each respective acquisition of said magnetic resonance data subset acquisitions, and to use said navigator data acquisitions to determine a respiratory position of the subject and a respiratory phase of the subject and to assign said respiratory position and phase to the magnetic resonance data subset acquired in the respective acquisition; and

said control computer being configured to use the respiratory position and the respiratory phase, assigned to each of the magnetic resonance data subsets, to decide automatically whether a respective magnetic resonance data subset is included or not included in a final magnetic resonance data set from which a magnetic resonance image is to be reconstructed, and to make said final magnetic resonance data set available in electronic form at an output of said control computer.

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

operate the magnetic resonance apparatus, in which a breathing subject is located, to acquire a plurality of magnetic resonance data subsets;

enter the plurality of magnetic resonance data subsets into an electronic memory representing k-space, wherein k-space is comprised of a plurality of segments, entering the respective magnetic resonance data subsets individually into respective k-space segments;

also operate the magnetic resonance apparatus to make at least two navigator data acquisitions, before each respective acquisition of said magnetic resonance data subset acquisitions, and use said navigator data acquisitions to determine a respiratory position of the subject and a respiratory phase of the subject and assign said respiratory position and phase to the magnetic resonance data subset acquired in the respective acquisition; and

use the respiratory position and the respiratory phase, assigned to each of the magnetic resonance data subsets, to decide whether a respective magnetic resonance data subset is included or not included in a final magnetic resonance data set from which a magnetic resonance image is to be reconstructed, and make said final magnetic resonance data set available in electronic form at an output of said control and processing system.