WO2009034115A1

WO2009034115A1 - Method for recording a magnetic resonance tomography measurement sequence using a magnetic resonance tomography device and associated magnetic resonance tomography device

Info

Publication number: WO2009034115A1
Application number: PCT/EP2008/062030
Authority: WO
Inventors: Wilfried Schnell; Karsten Wicklow
Original assignee: Siemens Aktiengesellschaft
Priority date: 2007-09-12
Filing date: 2008-09-11
Publication date: 2009-03-19
Also published as: DE102007043445A1

Abstract

Method for recording a magnetic resonance tomography measurement sequence using a magnetic resonance tomography device (1), wherein the magnetic resonance tomography measurement sequence is recorded by means of at least one high-frequency pulse sequence (13), the pulses (12) of which are varied at least partially under consideration of a plurality of optimization techniques (7, 8), particularly at least partially moving in opposite directions, image-related, and/or relating to recording technology.

Description

MRI WITH VARIATING RF PULSES

description

Method for recording a magnetic resonance tomography measurement sequence with a magnetic resonance tomography device and associated magnetic resonance tomography device.

The invention relates to a method for recording a magnetic resonance tomography measuring sequence with a magnetic resonance tomography device and to an associated magnetic resonance tomography device.

In the preparation of magnetic resonance tomography recordings, high-frequency signals are used, for example, to excite the nuclear spins or as part of a refocusing. In order to determine or determine the parameters for a magnetic resonance measurement sequence, different requirements must be taken into account, which are often contradictory specifications. For example, at a constant to be achieved flip angle by short high-frequency pulses with high amplitudes, a high specific absorption rate and correspondingly a high load for the patient due, while on the other hand long pulses with low amplitude the high-frequency amplifier, so components of a magnetic resonance system burden. Ideally, the sequence parameters for a measurement sequence should be chosen so that good layer profiles are achieved with low image artifacts, the images should have a good signal-to-noise ratio, while the high frequency load for the patient and the requirements of the high-frequency power amplifier as low as possible or at least not too high, taking into account the instrumental loads not least a cost-effective design of the instruments should be kept in mind.

Accordingly, the sequence parameters determining the pulses of the radio-frequency pulse sequence are selected for the entire measurement in such a way that, on the one hand, the specific absorption rate, ie the load on the patient, is a certain predetermined measure or limits, while on the other hand, the limitations of the high-frequency amplifier, ie instrumental specifications, are taken into account. In this way, a uniform high-frequency pulse shape is determined, which is then kept constant for the measurement sequence or measurement. However, this is not always an optimal measurement data recording guaranteed or possible.

The invention is therefore based on the object of specifying an improved method for recording a magnetic resonance tomography measuring sequence with a magnetic resonance tomography device and an associated magnetic resonance tomography device.

To achieve this object, a method is provided for recording a magnetic resonance tomography measuring sequence with a magnetic resonance tomography device, in which the magnetic resonance tomography measuring sequence is recorded by means of at least one radio-frequency pulse sequence whose pulses are at least partially taking into account a plurality of, in particular at least partially opposing, image-related and / or acquisition-related optimization specifications be varied.

Thus, fixed sequence parameters, ie fixed or uniform pulses in the individual radio-frequency pulse sequences, are not used as usual, but the pulses are varied within a measuring sequence. Thus, for example, image recordings are made in which in certain image areas a first radio-frequency pulse form z. B. is used for nuclear magnetic excitation, while in other areas, for example in a central image area in contrast to edge areas of the image, a different pulse shape is based. Of course, the pulse shapes within the measurement sequence can also be varied or changed more frequently, so that not only two different pulse shapes are used for the pulses overall, but, for example, five, six or even more different pulses or pulse pulses. are used for excitation within a measurement sequence.

Decisive for the change of the pulses or the different pulses within a single measurement sequence is the consideration of contrary optimization specifications or parameters. These optimization specifications can be image-related or acquisition-related. For example, an optimization preset may affect the image quality to be achieved in a given time unit. In this case, it would be a picture-based optimization preset. In addition, however, it is also possible to take account of recording technology-related optimization requirements. To give an example, here is the burden on the patient due to the specific absorption rate. A further optimization-related optimization specification is given by instrumental specifications. An example of this is the performance of the high frequency amplifier. In addition, data concerning component protection in the area of the magnetic resonance system or the high-frequency instruments can also be taken into account.

Thus, not only is there an optimization specification, for example in that an amplifier should not be overloaded excessively or beyond a certain value, but there exist several, at least two optimization specifications which make it appropriate for optimal performance of the measurement, to vary the pulses of the RF pulse sequence within the sequence. These optimization targets or optimization goals, if only the goal to be achieved such as a high image quality is defined, are at least partially or in certain areas contrary, ie contrary in the broadest sense such that, if necessary, only in part, conflicting goals in the determination of a suitable pulse shape or other pulse parameters arise. For example, the goal of a low high-frequency load for the patient is difficult to reconcile with the goal of the highest possible image quality. Accordingly, the optimization requirements are to be weighed against each other or be taken into account under certain weightings, so that different currently optimal pulses within the same measurement sequence arise, with which an optimal image acquisition can take into account the contrary requirements.

The variation of the pulses or the change of the pulses is preferably determined by a computing device or a control device of the magnetic resonance tomography device for recording the measurement sequence. Thus, the latter preferably has a program means which can access stored or user-entered optimization specifications in order to determine the pulse which is just optimal, ie an optimum pulse for a specific range of the measurement sequence or a specific image acquisition range. If the optimization specifications change during the measurement sequence, for example for a border area of an image acquisition, for which a lower image quality can be accepted in comparison to the center, this leads to the fact that another pulse shape deviating from the first pulse shape is determined, which is suitably used for nuclear spin excitation, refocusing and the like. In this case, not every change in the optimization specifications must lead to the fact that actually a different pulse shape is used, but it can be set for example by the computing device or by an operator limits, from which a change in the pulse shape. In this case, the different pulse shapes can follow specific specifications (for suitable forms) or else completely different pulse shapes can be selected, in particular calculated by a program means of a control device of the magnetic resonance tomography device.

As at least one optimization specification, an image-related optimization specification relating to an image quality to be achieved in a certain image acquisition time and / or an instrument that concerns at least one instrument required for image acquisition and / or a patient's exposure can be selected. Technically-related optimization specification are taken into account. It is thus stipulated that, for example, in a given recording time, a specific image quality of the image to be recorded or of the images to be recorded is to be ensured. In addition, a specification may concern an instrument required for image acquisition, such as the high-frequency amplifier or the like, or the load of a patient (in particular the specific absorption rate and its limit values). These optimization requirements sometimes require counter-measures so that, if they are to be taken into account, they can not all be equally satisfied within the entire measurement sequence. Nevertheless, several optimization specifications of this kind are taken into account, which means that in order to acquire a desired image without too much stress for the instruments or the patient, the optimization specifications with different weights have to be used for data acquisition or these weights are changed within the measurement sequence must be so that ultimately different optimal pulse types are determined.

The pulses of the radio-frequency pulse sequence are therefore, since these several different optimization specifications are taken into account with their conflicting requirements for the pulse shape, changed within a single measurement sequence in order to obtain an optimal recording.

According to the invention, at least one limit value for a specific absorption rate for a patient and / or technical data of at least one high-frequency amplifier, in particular at least one power value and / or at least one duty cycle value and / or technical data of at least one radio frequency amplifier, optionally at specific time constants, can be provided as at least one optimization-related optimization specification At least one input for protecting at least one component of the magnetic resonance tomography device and / or as image-related optimization target at least one slice layer to be recorded, in particular the sharpness and / or image quality and / or position adjacent ter layers, and / or a temporal sequence of excitation of adjacent layers and / or avoiding image artifacts are taken into account.

The limits of the specific absorption rate determine the stress due to the heat input by the radio-frequency pulses for the patient. The peak power of the high-frequency pulses is limited by limits of the corresponding hardware, ie the instruments such as the high-frequency amplifier, as well as component protection specifications. Besides exist

Limits for the heating of tissue, which limit the power that can be introduced on average over long time constants by the high-frequency radiation. Duty cycle limitations can be calculated according to different models that take into account design limits of high frequency components. Furthermore, the layer thickness for magnetic resonance imaging and the desired freedom from artifacts (eg with regard to chemical shift artifacts) should be taken into account as a possible default, as well as a desired layer profile, which is determined by the image quality and position of adjacent layers.

Within one measurement, the high-frequency pulses, in particular the excitation pulses, contribute very differently to the image generation, so that the (currently) optimum choice of the pulse parameters will be different within the measurement sequence, ie for certain sections of the measurement data acquisition or the region to be recorded. The time sequence of the excitation of adjacent layers, if taken into account, can also lead to optimization possibilities if the layer profile is varied within the measurement sequence.

At least one optimization target can be taken into account weighted. By weighting the optimization specifications, especially in the case that very different and a large number of optimization specifications are taken into account, their significance for the variation or change the pulses reproduced within the pulse sequence. For example, there are specifications whose fulfillment (at least in certain reception areas) is less important, while other requirements, for example compliance with the limit values for the patient's exposure to high-frequency heat input, must be strictly adhered to. Accordingly, the pulse shape is only changed by the weighting so that the important parameters or specifications are respected as a priority, while the lower-input specifications are taken into account subordinate. In contrast to the dose entry in the case of X-ray radiation, the instantaneous value is not decisive for the high-frequency-induced heat input, but the temporal averaging value is important, with an average value over a period of six minutes typically being considered.

In particular, the weighting within the pulse sequence, in particular from pulse to pulse, can be changed. In this case, for each individual pulse, a calculation of the optimal pulse shape taking into account or in dependence on the specifications is carried out again, so that the currently actually optimal pulse for the excitation of the nuclear spins or the refocusing can be used. The weighting can, however, also be changed within the pulse sequence only for specific blocks of pulses, for example in the edge region of the recording. In this case, the optimal pulse shape or duration and / or amplitude is not recalculated each time, but the weighting of the optimization specifications remains the same for certain blocks or regions of the sequence, so that, given otherwise identical optimization specifications, an identical pulse shape for this recording area is determined.

At least one optimization specification can, in particular by weighting, depending on the position of at least one

Receiving signal in k-space are taken into account. Expediently, therefore, the optimization specification for different regions in k-space is changed or undergoes various modifications. ne areas in k-space have a different weighting. This is due to the fact that the position of the received signals in k-space affects the sharpness, the contrast and the signal-to-noise ratio of the pictures to be recorded. Since, for example, the duration of an excitation pulse influences the sharpness of the achievable layer profile, on the one hand a sharp layer profile is desirable, on the other hand long radio-frequency pulses lead to a high thermal load of the output stages of the high-frequency amplifier, it is expedient only for the lines in the center of To use k-space long RF excitation pulses and to choose a less good layer profile for the outer lines in favor of a reduced load of the high-frequency amplifier. The corresponding variable weights or a change in the optimization specifications as such may be stored in a memory area of the control device or another computing device of the magnetic resonance device, in particular for accessing a program means for carrying out the method according to the invention.

Furthermore, a pulse envelope can be taken into account, ie an envelope for the pulses of the pulse train. This then indicates, for example, which power is applied in a certain time. Specifications for the envelope or envelope curve can also be included in the weighting of the optimization specifications or be taken into account as and within the scope of an optimization specification. In addition, it is conceivable that the optimization specifications are changed or weighted depending on further conditions for the recording of the measurement sequence. Thus, further optimization potentials not mentioned here can be included in the consideration of the optimization specifications.

According to the invention, the pulses may be at least partially in terms of duration and / or shape and / or amplitude as

Pulse parameters are varied. Certain pulses or certain groups of pulses can therefore only deviate from the other pulses in terms of their duration. On the other hand it lies also in the context of the invention, when the pulses are varied in terms of their shape and / or amplitude and optionally additionally the duration. Of course, some pulses may remain unchanged even with respect to an initial pulse shape or basic shape. In certain areas, all the pulse parameters that determine the pulses of the pulse train, ie both the duration and the shape and amplitude, can be changed. The duration of an excitation pulse influences, for example, the sharpness of the achievable slice profile. A sharp layer profile is desirable for reasons of image quality as an optimization specification, but on the other hand long radio-frequency pulses lead to a high thermal load on the output stages of high-frequency amplifiers. Accordingly, a variation of the pulses according to the invention may look so long that only for the lines in the center of the k-space

High frequency excitation pulses are used, while for the outer lines a less good layer profile is chosen in favor of a reduced load of the high frequency amplifier. The peak power of the radio frequency pulses and their bandwidth can also be varied. Advantageously, a corresponding program means that regulates or controls the change in the pulses, a change in all pulse parameters, so as to obtain optimal pulse shapes, durations and amplitudes.

According to the invention, the pulses may be at least partially varied in duration such that longer pulses are used in a central region of the k-space than in the remaining region and / or excitation pulses are omitted in at least one decentralized region. Thus, in certain decentralized areas it is possible to dispense with long pulses for the excitation of the nuclear spins, while it makes sense for reasons of the required image quality to use longer pulses in the central area of the k-space. Non-sharp layer profiles can certainly be tolerated in outer k-space lines, whereby artefacts in spatially adjacent layers can be avoided by omitting these neighboring layers at the next excitation. One Such omission of excitations is possible in the context of partial Fourier techniques, in particular in the outer lines of k-space.

To accommodate the optimization specifications, a space of compatible pulse parameters can be defined. The peak power of the radio-frequency pulses is determined, for example, by limiting the hardware and the component protection for the components of the magnetic resonance device, the bandwidth of the pulses through the layer thickness and a desired chemical shift artifact freedom. A desired layer profile is determined by the image quality and location of the adjacent layers. The average power over longer time constants is dictated by the limits to tissue warming, whereas duty cycle limitations can be measured by different models and represent design limitations of high frequency components.

Advantageously, the pulses of at least one high-frequency pulse sequence can be varied at least partially taking into account and / or together with at least one associated slice selection gradient. In other words, the so-called "building blocks", that is to say units which are formed from the radio-frequency pulse sequence and the associated gradients, are varied, which means that not only the individual pulse but also, if appropriate, the associated gradient are varied in that the signals of the radio-frequency field and of the gradient field are regarded as a unit which is to be changed as such, so that the result is the desired image taking into account the recording specifications.

According to the method according to the invention, the pulses of at least one radio-frequency pulse sequence for excitation of the core pins or for refocusing can be varied. It is thus possible for the pulses to be varied by excitation pulse trains. Likewise, however, refocusing pulse sequences for the measuring sequence may vary within the scope of the method according to the invention. have derte pulses. The decisive factor is therefore that in a measurement sequence individual pulses of a radio-frequency pulse sequence, which is used for image acquisition, are changed as a function of a plurality of optimization specifications.

Furthermore, the pulses can be varied by means of a control device of the magnetic resonance device, in particular using optimization software. For this purpose, the optimization software can resort to stored data such as optimization specifications or possible pulse shapes and the like. Expediently, databases for this purpose are used in which the different data are stored, for example, as a function of a selected measurement sequence for the recording. The optimization software can be a single program or a package of programs.

Moreover, the invention relates to a magnetic resonance tomography device, which is designed to carry out a method as described above. Thus, this magnetic resonance tomography device has a magnetic resonance scanner with an associated control device or computing device with the aid of which the recording mode is controlled, that is to say, for example, a measuring sequence or suitable protocols are selected, whereupon the data is recorded. In this case, the radio-frequency pulses which are required for the measurement data recording are changed by a program means of the control device or of the computing device of the magnetic resonance tomography device as described above.

For this purpose, databases with optimization specifications and further data for changing the pulses can be used. Contrary optimization parameters can be weighted differently from pulse to pulse or in certain ranges of the pulse sequence, in particular taking into account the positions of the measured received signals in the so-called k-space, which are fed to the control device or from this are determined to then flow into the calculation of the appropriate pulse signals.

This can be obtained with the magnetic resonance imaging device an optimal image in compliance with the specifications for the instruments or the burden on the patient and the like. In this case, further optimization specifications can be taken into account, which were not explicitly mentioned above.

Further advantages, features and details of the invention will become apparent from the following embodiments and from the drawings. Showing:

1 shows a sketch for recording a magnetic resonance tomography measuring sequence with a magnetic resonance tomography device according to the invention,

2 is a schematic diagram of a variation of pulses according to the invention,

3 shows a sketch of a "building block" from a high-frequency pulse and the associated gradients and

FIGS. 4 and 5 are schematic diagrams for mutually changing a radio-frequency pulse and a slice selection gradient within the scope of a method according to the invention.

FIG. 1 shows a sketch for recording a magnetic resonance tomography measuring sequence with a magnetic resonance tomography device 1. The magnetic resonance tomography device 1 according to the invention has a magnetic resonance tomography tube 2 with an associated patient table 3, on which a patient, not shown here, is located to record a measurement sequence. Furthermore it has the magnetic resonance tomography device 1 via a control device 4, which is associated with a screen 5, with the operator inputs and a display of results for an operator are possible.

On the control device 4, a program means or software is stored, with the or the control of the recording operation, in particular also the not shown here in detail devices for the production of Hochfrequenzfel- countries, is possible. For this purpose, in the software, taking into account several optimization specifications which are image-related or recording technology-related, the suitable optimized pulses, in particular as varied pulses, are determined for the radio-frequency pulse sequence for data acquisition. For this purpose, the program means of the control device 4 accesses corresponding data in a memory area such as a database or the like, the optimization specifications and their weighting, especially taking into account the k-space position or envelopes for the pulse sequence concern.

The control device 4 thus accesses, as indicated here by the curved arrow 6, to different image-related optimization specifications 7 or recording technology-related optimization specifications 8, that is, for example, instrumental restrictions and conditions. The fact that the individual areas of the image-related optimization specifications 7 or the recording-technology-related optimization specifications 8 can comprise a plurality or a plurality of individual specifications as groups of optimization specifications is indicated here by the arrows 9 and 10, respectively.

Finally, the image-related or acquisition-related optimization specifications 7, 8 flow into the variation of the pulses of the radio-frequency pulse sequence according to box 11 in order to achieve an optimized image while maintaining the instrumental restrictions or the specifications for a permissible heat input for the patient. This means that the individual pulses 12 of a pulse sequence 13, for example for exciting the nuclear spins, are no longer necessarily constant for the entire measurement sequence in the acquisition of magnetic resonance data by means of the magnetic resonance tomography device 1, but taking into account the image-related or acquisition-related optimization specifications 7 If necessary, these optimization specifications are weighted, taking into account in particular the position of a received signal in k-space. For a more flexible and therefore better image acquisition is possible with respect to the applied pulses.

FIG. 2 shows a schematic representation of a variation of pulses according to the invention, wherein initially on the right side a representation 14 of recorded magnetic resonance data in the positional space is indicated, which shows an examination object 15. By a Fourier transformation, here by a so-called fast Fourier transformation, as indicated by the arrow 16, the transition into a k-space

Presentation achieved. In the present case, different regions 17, 18 and 19 are distinguished in k-space, with region 18 forming the central region of k-space, while regions 17 and 19 designating the outer regions of k-space.

In the photograph according to representation 14, this is a two-dimensional image in which, accordingly, the horizontal region in the image reproduces the x-direction, while the vertical region indicates the y-direction.

In order to determine the shape, duration and amplitude of the pulses of the radio-frequency pulse sequence for the production of the image recording as shown in illustration 14 with the underlying magnetic resonance tomography device, the various optimization specifications are taken into account in a weighted manner such that in the center of the k-space, So in the area 18, the image quality experiences a higher weighting, while in areas 17 and 19, the image quality with a lower weighting in favor of the conservation of the instruments or the reduction of the high-frequency load or the heat input for the patient flows. This results in different (in each case optimal for a range 17, 18, 19) high-frequency pulses 20, 21 and 22, wherein the pulse forms shown here are to be understood merely as examples, as well as the pulse forms of the preceding FIG.

Of course, the variation of the pulses according to the invention within a radio-frequency pulse sequence within the scope of a single measurement sequence recording is likewise possible when producing three-dimensional recordings.

In the illustrated case, the pulse 21 for the central region 18 as well as the respective pulses 20 and 22 in the decentralized regions 17 and 19 are kept constant within these regions 17, 18 and 19, respectively. However, it is also conceivable that, for an improved optimization, additional regions are defined with again changed pulse shapes or additional, additional pulse shapes or changes in the pulse shapes are used or made in the individual regions 17, 18 and 19.

3 shows a unit consisting of a radio-frequency pulse 23 and the associated gradients 24, 25 and 26 which together form a so-called "building block." Of course, other radio-frequency pulses (in particular other forms) may of course be used than the high-frequency pulse shown here 23 and / or other gradients are used as the illustrated gradients 24, 25 and 26. The radio-frequency pulse 23 and the associated gradients 24, 25 and 26 each form a unit which, as will be explained below, is common for optimizing the image acquisition should be varied.

Accordingly, schematic diagrams are shown in FIGS. 4 and 5 for mutually changing a high-frequency pulse 27 and an associated radio-frequency pulse. Rigen Schichtselektionsgradienten 28 shown in the context of a method according to the invention. An initial form for the radio-frequency pulse 27 and the associated slice selection gradient 28 is shown in FIG. 4. The gradient 28 and the high-frequency pulse 27 form a "building block" which, in order to optimize the image to be recorded, is to be varied as a unit or included in the calculation as a function of the present optimization specifications The further gradients are not shown here.

Finally, FIG. 5 shows the varied radio-frequency pulse 29 with the associated likewise varied slice selection gradient 30. The optimization specifications are thus not only used for the variation of the radio-frequency pulse 27 according to FIG. 4 for the pulse shape of the radio-frequency pulse 29, but serve overall for optimizing the unit of FIG Radio-frequency pulse 27 with the associated slice selection gradient 28.

Thus, in the context of the method according to the invention, different optimization specifications can be taken into account, and a corresponding change of the radio-frequency pulses with their associated gradients can be carried out.

Reference sign list

1 magnetic resonance imaging device

2 magnetic resonance imaging tube

3 patient table

4 control device

5 screen

6 arrow

7 image-related optimization target

8 Aufnähmete related optimization target

9 arrow

10 arrow

11 boxes

12 pulse

13 pulse train

14 Presentation

15 examination object

16 arrow

17 area

18 area

19 area

20 high frequency pulse

21 high frequency pulse

22 high frequency pulse

23 high frequency pulse

24 gradient

25 gradient

26 gradient

27 high frequency pulse

28 slice selection gradient

29 high-frequency pulse

30 slice selection gradient

Claims

claims

1. A method for recording a magnetic resonance tomography measuring sequence with a magnetic resonance tomography device (1), characterized in that the magnetic resonance tomography measuring sequence is recorded by means of at least one radio-frequency pulse sequence (13) whose pulses (12, 20, 21, 22, 23, 27, 29) at least may be varied, taking into account a plurality of, in particular at least partially opposing, image-related and / or recording-technology-related optimization specifications (7, 8).

2. The method according to claim 1, characterized in that at least one optimization specification (7, 8) relates to an image quality optimization target (7) to be achieved in a specific image acquisition time and / or at least one instrument required for image acquisition and / or Load-related optimization target (8).

3. The method according to any one of the preceding claims, characterized in that at least one limiting value for a specific absorption rate for a patient and / or technical data of at least one high-frequency amplifier, in particular at least one, possibly related to certain time constants, as at least one receiving technique-related optimization specification (8) Power value and / or at least one Dutycycle- value and / or the load of at least one output stage related value, and / or at least one default for protecting at least one component of the magnetic resonance tomography device (1) and / or as image-related optimization vorgäbe (7) at least one Sheath profile to be recorded, in particular the sharpness and / or image quality and / or position of adjacent layers, and / or a temporal sequence of a Excitation of adjacent layers and / or avoidance of image artifacts are taken into account.

4. The method according to any one of the preceding claims, characterized in that at least one optimization target (7, 8) is taken into account weighted.

5. The method according to claim 4, characterized in that the weight within the high-frequency pulse train (13), in particular of pulse (12, 20, 21, 22, 23, 27, 29) to pulse (12, 20, 21, 22, 23 , 27, 29) is changed.

6. The method according to any one of the preceding claims, characterized in that at least one optimization target (7, 8), in particular by weighting, depending on the position of at least one received signal in k-space and / or at least one of the high-frequency pulse train (13) assignable envelope, in particular a time-related envelope, is taken into account.

7. The method according to any one of the preceding claims, characterized in that the pulses (12, 20, 21, 22, 23, 27, 29) are varied at least partially in terms of duration and / or shape and / or amplitude as pulse parameters.

8. The method according to claim 7, characterized in that the pulses (12, 20, 21, 22, 23, 27, 29) are at least partially varied in duration such that in a central region (18) of the k-space longer Pulse (12, 20, 21, 22, 23, 27, 29) than in the remaining area (17, 19) are used and / or excitation pulses (12, 20, 21, 22, 23,

27, 29) in at least one decentralized area (17, 19) are omitted.

9. The method according to any one of the preceding claims, characterized in that for the consideration of the optimization specifications (7, 8) a space of compatible pulse parameters is defined.

10. The method according to any one of the preceding claims, characterized in that the pulses of at least one radio-frequency pulse sequence (13) at least partially in consideration and / or together with at least one associated Schichtselektionsgradienten (28, 30) are varied.

11. The method according to any one of the preceding claims, characterized in that pulses (12, 20, 21, 22, 23, 27, 29) at least one

High frequency pulse train (13) for exciting the nuclear spins or for refocusing can be varied.

12. The method according to any one of the preceding claims, characterized in that the pulses (12, 20, 21, 22, 23, 27, 29) by means of a control device (4) of the magnetic resonance device (1) are varied, in particular using an optimization software.

13. Magnetic resonance tomography device (1), designed to carry out a method according to one of the preceding claims.