Establishing B

1. A method for establishing B 1 -maps for establishing an actuation sequence for a magnetic resonance imaging system comprising a number of transmission channels used for generating a radiofrequency field for magnetic resonance excitation of an examination object, the method comprising:

emitting a first radiofrequency field using a first transmission channel;

acquiring first radiofrequency field measurement values for the emitted first radiofrequency field;

creating a first relative B 1 -map based on the first radiofrequency field measurement values from the first transmission channel;

emitting a further radiofrequency field using a further transmission channel;

acquiring further radiofrequency field measurement values for the emitted further radiofrequency field of the further transmission channel;

creating an additional relative B 1 -map based on the further radiofrequency field measurement values from the further transmission channel;

repeating, for a number of transmission channels, the emitting of a further radiofrequency field, the acquiring of further radiofrequency field measurement values, and the creating an additional relative B 1 -map; and

storing the generated relative B 1 -maps for multiple use.

2. The method as claimed in claim 1 , further comprising:

establishing a quantitative B 1 -map;

establishing normalized B 1 -maps based on the relative B 1 -maps and the quantitative B 1 -map; and

establishing an actuation sequence for acquiring magnetic resonance measurement data using the normalized B 1 -maps.

3. The method as claimed in claim 2 , wherein a number of generated relative B 1 -maps corresponds at least to a number of transmission channels for generating a radiofrequency field in a measurement space of the magnetic resonance imaging system used for acquiring raw magnetic resonance data.

4. The method as claimed in claim 2 , further comprising:

establishing a further quantitative B 1 -map;

establishing further normalized B 1 -maps based on the stored relative B 1 -maps and the further quantitative B 1 -map; and

establishing a further actuation sequence for acquiring further magnetic resonance measurement data using the further normalized B 1 -maps.

5. The method as claimed in claim 4 , wherein a number of generated relative B 1 -maps corresponds at least to a number of transmission channels for generating a radiofrequency field in a measurement space of the magnetic resonance imaging system used for acquiring raw magnetic resonance data.

6. The method as claimed in claim 4 , wherein the quantitative B 1 -map, the further quantitative B 1 -map, or the quantitative B 1 -map and the further quantitative B 1 -map are generated using a combination of a plurality of transmission channels of the magnetic resonance imaging system.

7. The method as claimed in claim 2 , wherein at least one relative B 1 -map is generated using a combination of a plurality of transmission channels of the magnetic resonance imaging system.

8. The method as claimed in claim 7 , wherein the quantitative B 1 -map, the further quantitative B 1 -map, or the quantitative B 1 -map and the further quantitative B 1 -map are generated using a combination of the plurality of transmission channels of the magnetic resonance imaging system.

9. The method as claimed claim 8 , wherein at least two transmission channels of a combination of transmission channels used for generating the quantitative B 1 -map are contained in a combination of transmission channels used for generating at least one of the relative B 1 -maps.

10. The method as claimed in claim 7 , wherein each relative B 1 -map of the number of relative B 1 -maps is generated using a combination of the plurality of transmission channels of the magnetic resonance imaging system.

11. The method as claimed in claim 10 , wherein the quantitative B 1 -map, the further quantitative B 1 -map, or the quantitative B 1 -map and the further quantitative B 1 -map are generated using a combination of the plurality of transmission channels of the magnetic resonance imaging system.

12. The method as claimed claim 11 , wherein at least two transmission channels of a combination of transmission channels used for generating the quantitative B 1 -map are contained in a combination of transmission channels used for generating at least one of the relative B 1 -maps.

13. The method as claimed in claim 2 , wherein the quantitative B 1 -map is determined taking into account a predetermined quality criterion, wherein the predetermined quality criterion is a spatial resolution, a measurement error when determining the qualitative B1-map, or the spatial resolution and the measurement error when determining the quantitative B 1 -map.

14. The method as claimed in claim 2 , wherein there is a comparison between a quality criterion for relative B 1 -maps and a quality criterion for quantitative B 1 -maps, wherein the number of relative B 1 -maps is established based on the comparison.

15. A method for operating a magnetic resonance system, the method comprising:

establishing an actuation sequence for a magnetic resonance imaging system comprising:

(1) establishing a number of relative B 1 -maps comprising:

emitting a first radiofrequency field using a first transmission channel;

acquiring first radiofrequency field measurement values for the emitted first radiofrequency field;

creating a first relative B 1 -map based on the first radiofrequency field measurement values from the first transmission channel;

emitting a further radiofrequency field using a further transmission channel;

acquiring further radiofrequency field measurement values for the emitted further radiofrequency field of the further transmission channel;

creating an additional relative B 1 -map based on the further radiofrequency field measurement values from the further transmission channel;

repeating, for a number of transmission channels, the emitting of a further radiofrequency field, the acquiring of further radiofrequency field measurement values, and the creating an additional relative B 1 -map; and

storing the generated relative B 1 -maps for multiple use;

(2) establishing a quantitative B 1 -map;

(3) establishing normalized B 1 -maps based on the relative B 1 -maps and the quantitative B 1 -map; and

(4) establishing an actuation sequence for acquiring magnetic resonance measurement data using the normalized B 1 -maps; and

operating the magnetic resonance system using the actuation sequence.

16. A B 1 -map establishment system comprising:

an input interface configured to acquire first radiofrequency field measurement values;

a B 1 -map establishment module configured to establish a first quantitative B 1 -map based on the first radiofrequency field measurement values;

a memory module configured to repeatedly recall relative B 1 -maps from a memory module; and

a B 1 -map normalization module configured to establish a number of normalized first B 1 -maps using the relative first B 1 -maps recalled from the memory module and the first quantitative B 1 -map.

17. The B 1 -map establishment system as claimed in claim 16 , further comprising:

a quality criterion interface configured to predetermine a quality criterion.

18. An actuation sequence establishment system comprising:

a B 1 -map establishment system comprising:

an input interface configured to acquire first radiofrequency field measurement values;

a B 1 -map establishment module configured to establish a first quantitative B 1 -map based on the first radiofrequency field measurement values;

a memory module configured to repeatedly recall relative B 1 -maps from a memory module; and

a B 1 -map normalization module configured to establish a number of normalized first B 1 -maps using the relative first B 1 -maps recalled from the memory module and the first quantitative B 1 -map; and

a sequence establishment unit configured to establish an actuation sequence for acquiring magnetic resonance measurement data using the normalized first B 1 -maps, normalized second B 1 -maps, or the normalized first B 1 -maps and the normalized second B 1 -maps,

wherein the normalized second B 1 -maps are established from the B 1 -map normalization module using the relative first B 1 -maps recalled from the memory module and a second quantitative B 1 -map.

19. The system as claimed in claim 18 , further comprising:

a quality criterion interface configured to predetermine a quality criterion.

20. An apparatus comprising:

at least one processor; and

at least one memory including computer program code for one or more programs; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to at least perform:

emit a first radiofrequency field using a first transmission channel;

acquire first radiofrequency field measurement values for the emitted first radiofrequency field;

create a first relative B 1 -map based on the first radiofrequency field measurement values from the first transmission channel;

emit a further radiofrequency field using a further transmission channel;

acquire further radiofrequency field measurement values for the emitted further radiofrequency field of the further transmission channel;

create an additional relative B 1 -map based on the further radiofrequency field measurement values from the further transmission channel;

repeat, for a number of transmission channels, the emitting of a further radiofrequency field, the acquiring of further radiofrequency field measurement values, and the creating an additional relative B 1 -map; and

store the generated relative B 1 -maps for multiple use.