Method for performing an MR pre-measurement, MR device and computer program product

Abstract

Procedure for performing an MRI pre-measurement, the procedure includes: - Providing at least one principal measurement parameter according to which a principal MR measurement is to be performed, - Performing the MR pre-measurement prior to the main MR measurement according to at least one pre-measurement parameter using an MR device, where at least one preliminary measurement parameter is determined depending on at least one main measurement parameter, wherein at least one main measurement parameter includes a first layer layer, a first field of view and / or a first layer coverage, wherein a second layer layer is determined as at least one pre-measurement parameter depending on the first layer layer and / or a second field of view depending on the first field of view and / or a second layer coverage depending on the first layer coverage according to a respective predetermined relation.

Description

[0001] The invention relates to a method for performing an MR pre-measurement, an MR device and a computer program product.

[0002] In medical technology, imaging using magnetic resonance (MR), also known as magnetic resonance imaging (MRI), is characterized by high soft tissue contrast. Typically, a human or animal patient is positioned in the imaging volume of an MR device. During an MR examination, high-frequency excitation pulses, i.e., alternating electromagnetic fields, are radiated into the patient using a radio-frequency antenna unit of the MR device according to an MR sequence. This is to be distinguished from a magnetic field generated by a magnet coil unit of the MR device, which typically comprises a static main magnetic field and one or more superimposed gradient magnetic fields. The excitation pulses generate MR signals in the patient, which can be received by the MR device. MR images can be reconstructed from the MR signals.

[0003] An MRI examination is often divided into an MRI pre-measurement and a main MRI measurement. Based on the results of the MRI pre-measurements, adjustments, particularly adjustments, can be made for the subsequent main MRI measurement. These adjustments can include coil sensitivities to compensate for signal inhomogeneities, a center frequency, an optimal shim state, and much more. These MRI pre-measurements can generally last in the range of seconds to minutes, thus noticeably extending the overall MRI examination.

[0004] JP 2014-230 610 A discloses a measuring method comprising a preliminary measurement. DE 10 2014 201 475 A1 discloses a transmit coil arrangement for transmitting a high-frequency signal with at least two transmission channels. US 2007 / 0 276 221 A1 discloses a measuring method comprising multiple preliminary measurements.

[0005] The object of the present invention can be considered to optimize the MR pre-measurement, in particular to reduce its duration to a necessary minimum.

[0006] The problem is solved by the features of the independent claims. Advantageous embodiments are described in the dependent claims.

[0007] Accordingly, a method for performing an MR pre-measurement is proposed. At least one main measurement parameter is provided, according to which an MR main measurement is to be performed. Depending on the at least one main measurement parameter, at least one pre-measurement parameter is determined. The MR pre-measurement is performed according to the at least one pre-measurement parameter using an MR device prior to the MR main measurement.

[0008] A measurement parameter, for example a pre-measurement parameter and / or a main measurement parameter, can in particular be a parameter that establishes and / or determines the operation of the MR device when performing an MR measurement. The at least one main measurement parameter can in particular comprise various parameters that establish and / or determine the operation of the MR device when performing a planned MR main measurement. The at least one pre-measurement parameter can in particular comprise various parameters that establish and / or determine the operation of the MR device when performing the pre-MR measurement.

[0009] A measurement parameter can, for example, be a parameter of an MR sequence that is applied, in particular played back, during the MR measurement. A measurement parameter can, for example, specify a time, a shape, a duration, and / or a strength of a module of an MR sequence, e.g., a radiofrequency pulse or gradient pulse.

[0010] Preferably, the main MR measurement should be performed according to the at least one main measurement parameter. The pre-MR measurement preferably takes place before the main MR measurement. Performing the pre-MR measurement preferably includes acquiring pre-measurement MR signals that are not suitable for generating diagnostically useful MR images.

[0011] Providing at least one main measurement parameter preferably comprises inputting and / or selecting the at least one main measurement parameter by an operator of the MR device. The MR device preferably comprises a user interface for this purpose. For example, the operator selects a preset MR sequence or an MR protocol comprising an MR sequence. Providing the at least one main measurement parameter can, in particular, comprise providing and / or setting a slice position, a field of view (FOV), and / or slice coverage.

[0012] The layer position can in particular comprise a position and / or a tilt of a layer to be measured.

[0013] The field of view is preferably the image area to be measured. The image area can be square, for example. The smaller the field of view, the higher the spatial resolution is typically, as the voxels become smaller for the same matrix size (pixel size = FOV / matrix).

[0014] Adjusting the field of view can, in particular, involve positioning the field of view in image space, for example, the field of view for measuring the right knee. For this purpose, a position can be defined with respect to an isocenter, for example, to what extent the field of view is spatially shifted, for example, in the xyz direction. Additionally, the field of view can be tilted.

[0015] Preferably, the at least one preliminary measurement parameter is determined automatically depending on the at least one main measurement parameter. Advantageously, the operating personnel do not have to intervene directly when determining the at least one preliminary measurement parameter depending on the at least one main measurement parameter. The MR device preferably comprises a computing unit for this purpose. The computing unit can, in particular, have one or more processors and / or one or more memory modules.

[0016] Advantageously, by determining the at least one pre-measurement parameter as a function of the at least one main measurement parameter, the MR pre-measurement can be optimized, in particular in terms of time and / or quality.

[0017] Conventional pre-measurement parameters are not adapted to the main MR measurement, but are generalized measurement parameters or protocols ("one-size-fits-all"). Such conventional protocols cover the broadest possible application horizon. For example, they have a very large FOV that always covers the required area, regardless of whether the subsequent measurement protocol of the main MR measurement even requires such a large area. Advantageously, the long measurement times of the MR pre-measurements resulting from this can be reduced with the proposed method. Furthermore, the MR pre-measurement can also be performed at a higher resolution, which can improve the quality of any subsequent calculations.

[0018] According to a further embodiment, the method comprises performing the main MR measurement using the MR device, wherein performing the pre-measurement MR measurement comprises acquiring pre-measurement MR signals. The main MR measurement is performed taking the pre-measurement MR signals into account.

[0019] For example, the (originally provided) at least one main measurement parameter is adjusted taking into account the pre-measurement MR signals, so that the main MR measurement is performed using the MR device according to the adjusted at least one main measurement parameter. For example, at least one module of an (originally provided) MR sequence is adjusted taking into account the pre-measurement MR signals. For example, at least one magnetic field map, e.g., a B0 map and / or a B1 map, is generated based on the pre-measurement MR signals, and at least one radio-frequency pulse and / or gradient pulse of the (originally provided) MR sequence is changed depending on the at least one magnetic field map.

[0020] Preferably, at least one dynamic pulse, in particular a pTx pulse, is determined based on the at least one magnetic field map, wherein the at least one dynamic pulse is generated by the MR device when the main MR measurement is carried out.

[0021] A dynamic pulse can be considered, in particular, a radio-frequency pulse whose phase and / or amplitude changes over time while a gradient trajectory, in particular a predetermined one, is scanned by the gradient coil unit. In particular, the gradient trajectory is scanned temporally with the variation in phase and / or amplitude of the radio-frequency pulse.

[0022] It is also conceivable to consider the entirety of the radio-frequency pulse and the gradient trajectory as a dynamic pulse. In this case, the radio-frequency pulse would be part of the dynamic pulse.

[0023] "pTx" stands for "parallel transmission." A pTx pulse can comprise multiple partial pulses that are transmitted in parallel, in particular simultaneously, by a transmission coil of the radio-frequency antenna unit of the MR device. Each transmission coil can in turn be assigned a transmission channel. The partial pulses can differ, in particular, in their shape and / or amplitude and / or phase. Furthermore, the partial pulses can have a delay relative to one another. For example, an emittable radio-frequency pulse is composed of multiple partial pulses that differ from one another and can each be transmitted by a transmission coil of a multi-channel transmission coil arrangement of the radio-frequency antenna unit. Preferably, at least some of the multiple partial pulses, in particular all of the partial pulses, are dynamic pulses.

[0024] A dynamic pulse and / or a pTx pulse can advantageously control the generated B1 field more precisely. Such control can be particularly advantageous in applications with a reduced field of view, shaped saturation bands, or to reduce the specific absorption rate (SAR). In particular, a pTx pulse can be used to compensate for magnetic field inhomogeneities (for example, in the context of "RF shimming"), which can be particularly advantageous at higher field strengths of the main magnetic field, starting at 7 Tesla.

[0025] According to a further embodiment, the method comprises performing the main MR measurement using the MR device and reconstructing at least one MR image based on the main measurement MR signals. Performing the preliminary MR measurement comprises acquiring preliminary measurement MR signals, and performing the main MR measurement comprises acquiring primary measurement MR signals. The primary MR measurement and / or the reconstruction of the at least one MR image are then performed taking the preliminary measurement MR signals into account.

[0026] For example, at least one magnetic field map, e.g., a B0 map and / or a B1 map, is generated based on the pre-measurement MR signals. Depending on the at least one magnetic field map, at least one MR image is reconstructed based on the main measurement MR signals. For example, any inhomogeneities in the magnetic field are corrected.

[0027] The at least one main measurement parameter comprises a first slice position, a first field of view, and / or a first slice coverage, wherein a second slice position is determined as a function of the first slice position and / or a second slice field is determined as a function of the first field of view and / or a second slice coverage is determined as a function of the first slice coverage according to a respective predetermined relationship. Slice coverage is preferably understood to mean spatial coverage by a measurement slice.

[0028] For example, the second field of view is 10%, 20%, or 50% larger than the first field of view. In particular, the second field of view covers a volume that is 10%, 20%, or 50% larger than the first field of view. For example, the second layer coverage is 10%, 20%, or 50% larger than the first layer coverage. In particular, the second layer coverage covers a volume that is 10%, 20%, or 50% larger than the first layer coverage. Advantageously, edge effects can be avoided by a larger volume. Furthermore, a larger volume of the second field of view or the second layer coverage can enable greater flexibility in the event of a possible change to the first field of view or the first layer coverage, without the need for another preliminary measurement. By a targeted, comparatively small enlargement of the second field of view or the second layer coverage relative to the first field of view orfor the first layer coverage, the field of view or the layer coverage can be advantageously reduced compared to conventional preliminary measurements, so that the necessary measurement time can also be reduced.

[0029] Preferably, the at least one main measurement parameter comprises a first phase encoding direction, wherein a second phase encoding direction is determined as at least one preliminary measurement parameter depending on the first phase encoding direction. In particular, a second phase encoding direction is determined as at least one preliminary measurement parameter identical to the first phase encoding direction. Advantageously, the phase encoding direction of the main MR measurement is adopted, since this is often selected to reduce or prevent folding or other possible influences due to flow or pulsation.

[0030] The phase encoding direction is preferably the direction in which a magnetic field gradient is applied for phase encoding. Phase encoding typically involves briefly applying a magnetic field gradient between an RF excitation pulse and a readout of the MR signal, which imposes a phase shift on the spins from k-space line to k-space line. Depending on the measurement matrix (e.g., 256 or 512), phase encoding steps are required to completely measure a slice. A subsequent Fourier transformation can assign the different phase positions to the corresponding lines.

[0031] Preferably, the at least one main measurement parameter comprises a first selection of active coil elements, wherein a second selection of active coil elements is determined as at least one pre-measurement parameter identical to the first selection of active coil elements, ie the active coil elements selected for the MR main measurement can be adopted for the MR pre-measurement.

[0032] The MR device may comprise one or more coil elements. The coil elements are preferably configured to transmit radiofrequency pulses and / or receive MR signals. The coil elements may be components of one or more coils of the MR device, such as one or more local coils and / or a body coil permanently installed in the MR device. Active coil elements are those coil elements that transmit radiofrequency pulses and / or receive MR signals during an MR measurement, in particular during the MR pre-measurement and / or the MR main measurement.

[0033] Preferably, the at least one main measurement parameter comprises at least a first saturation modulus of a first MR sequence, wherein at least one second saturation modulus of a second MR sequence is determined as at least one preliminary measurement parameter depending on the at least one first saturation modulus of the first MR sequence. In particular, at least one second saturation modulus of a second MR sequence is determined as at least one preliminary measurement parameter identical to the at least one first saturation modulus of the first MR sequence.

[0034] Saturation modules are preferably used for cardiac MR measurements. The saturation modules of the main MR measurement are advantageously adopted for the preliminary MR measurement as far as possible, depending on timing and potential influence on the contrast of the preliminary MR measurement.

[0035] Preferably, the at least one main measurement parameter comprises a first gating setting, wherein a second gating setting is determined as at least one pre-measurement parameter depending on the first gating setting. In particular, a second gating setting can be determined as at least one pre-measurement parameter identical to the first gating setting.

[0036] The first or second gating setting can, in particular, be a trigger setting. Triggering can be understood as a form of prospective gating, in which MR data acquisition only begins after the detection of a desired physiological event (e.g., an R wave or a peripheral pulse). Triggering can be used, for example, to obtain static MR images at a specific time in a cardiac cycle.

[0037] In particular, gating can be prospective or retrospective. With retrospective gating, MR signals are acquired continuously. For example, an electrocardiogram (ECG) or a pulse can be recorded simultaneously with the MR signals. The MR signals can then be rearranged, grouped, or correlated with a phase of the cardiac cycle. Retrospective gating is the method typically used for cine cardiac motion studies.

[0038] Advantageously, the gating settings of the main MR measurement are applied to the MR pre-measurement as far as possible. This can advantageously reduce image artifacts, especially in regions with respiratory and / or cardiac motion. For example, a consistent respiratory cycle (inspiration, expiration) can be achieved.

[0039] Furthermore, an MR device is proposed that is configured to carry out a method described above. The MR device preferably comprises a system control unit configured to determine at least one preliminary measurement parameter as a function of at least one main measurement parameter.

[0040] The advantages of the proposed MR device essentially correspond to the advantages of the method for performing a preliminary MR measurement, which are described in detail above. Features, advantages, or alternative embodiments mentioned herein can also be applied to the other claimed subject matter, and vice versa.

[0041] Furthermore, a computer program product is proposed that comprises a program and is directly loadable into a memory of a programmable system control unit of an MR device. It also has program means, e.g., libraries and auxiliary functions, for executing a proposed method when the computer program product is executed in the system control unit of the MR device. The computer program product can comprise software with a source code that still needs to be compiled and linked or that only needs to be interpreted, or an executable software code that only needs to be loaded into the system control unit for execution.

[0042] The computer program product allows the proposed method to be executed quickly, advantageously in an identically repeatable, and robust manner. The system control unit advantageously has the necessary prerequisites, such as a suitable RAM, a suitable graphics card, or a suitable logic unit, so that the respective method steps can be executed efficiently.

[0043] The computer program product is stored, for example, on a computer-readable medium or on a network or server, from where it can be loaded into the processor of a local system control unit, which can be directly connected to the MR device or formed as part of the MR device. Furthermore, control information of the computer program product can be stored on an electronically readable data carrier. The control information of the electronically readable data carrier can be configured such that, when the data carrier is used in a system control unit of an MR device, it carries out a proposed method. Examples of electronically readable data carriers are a DVD, a magnetic tape, or a USB stick on which electronically readable control information, in particular software, is stored.If this control information is read from the data carrier and stored in a system control unit of the MR device, all proposed embodiments of the previously described methods can be carried out.

[0044] Further advantages, features, and details of the invention will become apparent from the exemplary embodiments described below and from the drawings. Corresponding parts are provided with the same reference numerals in all figures.

[0045] They show: Fig. 1 an MR device in a schematic representation, Fig. 2 a sequence of a method for performing an MR pre-measurement, Fig. 3 an illustration of a determination of pre-measurement parameters depending on main measurement parameters.

[0046] In Fig. 1 schematically illustrates an MR device 10. The MR device 10 comprises a magnet unit 11 having a main magnet 12 for generating a strong and, in particular, temporally constant main magnetic field 13. Furthermore, the MR device 10 comprises a patient receiving area 14 for receiving a patient 15. The patient receiving area 14 in the present exemplary embodiment is cylindrical and is surrounded in a circumferential direction by the magnet unit 11. In principle, however, a different design of the patient receiving area 14 is conceivable at any time. The patient 15 can be pushed into the patient receiving area 14 by means of a patient support device 16 of the MR device 10. For this purpose, the patient support device 16 has a patient table 17 designed to be movable within the patient receiving area 14.

[0047] The magnet unit 11 further comprises a gradient coil unit 18 for generating magnetic field gradients used for spatial encoding during imaging. The gradient coil unit 18 is controlled by a gradient control unit 19 of the MR device 10. The magnet unit 11 further comprises a radio-frequency antenna unit 20, which in the present exemplary embodiment is designed as a body coil permanently integrated into the MR device 10. The radio-frequency antenna unit 20 is controlled by a radio-frequency antenna control unit 21 of the MR device 10 and radiates radio-frequency MR sequences into an examination space, which is essentially formed by a patient receiving area 14 of the MR device 10. As a result, the main magnetic field 13 generated by the main magnet 12 excites atomic nuclei. MR signals are generated by relaxation of the excited atomic nuclei.The radio frequency antenna unit 20 is designed to receive the MR signals.

[0048] The MR device 10 has a system control unit 22 for controlling the main magnet 12, the gradient control unit 19, and the radio-frequency antenna control unit 21. The system control unit 22 centrally controls the MR device 10 based on measurement parameters, such as the execution of a predetermined imaging gradient echo sequence.

[0049] In addition, the system control unit 22 includes an evaluation unit (not shown in detail) for evaluating the MR signals acquired during the magnetic resonance examination. Furthermore, the MR device 10 includes a user interface 23 connected to the system control unit 22. Control information such as measurement parameters and reconstructed MR images can be displayed on a display unit 24, for example, on at least one monitor, of the user interface 23 for medical personnel. Furthermore, the user interface 23 has an input unit 25, by means of which, in particular, measurement parameters for an MR measurement can be entered by the medical personnel.

[0050] A magnetic resonance examination can comprise multiple MR measurements, in particular an MR pre-measurement and an MR main measurement. During the pre-measurement, data, in particular MR signals, are advantageously acquired, which are used, for example, for the main MR measurement and / or for an evaluation of the MR signals received in the main MR measurement. The manner in which MR measurements are performed can be determined by measurement parameters, in particular main measurement parameters for the main MR measurement and pre-measurement parameters for the MR pre-measurement. The application of the measurement parameters can be controlled by the system control unit 22.

[0051] In Fig. Figure 2 shows a possible sequence of a method for performing an MR pre-measurement. At least one main measurement parameter is provided in S10, according to which a main MR measurement, in particular a clinical measurement, is to be performed. For example, if the operating personnel wishes to perform a clinical measurement as the main MR measurement, in which the acquisition of MR pre-measurements is planned, for example, to acquire B0 or ​​B1 maps for sequences with dynamic pulses, the user sets the associated main measurement parameters, e.g., selecting slice position, FOV, slice coverage, etc.

[0052] In S20, at least one pre-measurement parameter is determined depending on the at least one main measurement parameter. In S30, an MR pre-measurement, in particular an adjustment measurement, is performed according to at least one pre-measurement parameter using the MR device 10, with pre-measurement MR signals being acquired. After the operating personnel has, for example, instructed the start of the main MR measurement, the MR pre-measurement is performed.

[0053] In S40, the main MR measurement is performed using the MR device 10. Main measurement MR signals are acquired. In S50, at least one MR image is reconstructed based on the main measurement MR signals using the evaluation unit of the MR device 10.

[0054] The main MR measurement in S40 can be performed according to the at least one main measurement parameter provided in S10 or according to at least one modified main measurement parameter. The modification of the main measurement parameters can be performed, in particular, taking into account the pre-measurement MR signals, so that the main MR measurement is also performed taking into account the pre-measurement MR signals.

[0055] Furthermore, a magnetic field map, e.g., a B1 and / or B0 map, can be determined based on the pre-measurement MR signals, which can be used to determine at least one dynamic pulse. The dynamic pulse can then be used in the main MR measurement in S40.

[0056] The reconstruction of the at least one MR image in S50 can be carried out taking into account the pre-measurement MR signals, for example taking into account a magnetic field map determined on the basis of the pre-measurement MR signals.

[0057] Appendix of Fig. 3, the determination of the pre-measurement parameters VMP comprising P1', ... P7' depending on the main measurement parameters HMP comprising P1, ... P7 in S20 is to be described by way of example. For example, if a main measurement parameter is a first slice position P1, then a second slice position P1' is determined as one of the pre-measurement parameters VMP depending on P1. Further possible main measurement parameters are, for example, a first field of view P2, a first slice coverage P3, a first phase encoding direction P4, a first selection of active coil elements P5, a first saturation modulus P6, or a first gating setting P7. Depending on these main measurement parameters HMP, a respective pre-measurement parameter VMP, in particular a second field of view P2', a second slice coverage P3', a second phase encoding direction P4', a second selection of active coil elements P5', a second saturation modulus P6', or a second gating setting P7', can then be determined.

[0058] For example, in the case of MR pre-measurements intended to create maps, in particular magnetic field maps, for further calculation in preparation for the main MR measurement, the measurement protocol of these MR pre-measurements is adapted as far as possible to the main MR measurement, in particular the actual clinical measurement.

[0059] This may include, in particular, the following aspects: a. The second field of view P2' and / or the second slice coverage P3' is adapted to the subsequent clinical measurement, i.e., the first field of view P2 or the first slice coverage P3, respectively, with additional regions being included. It may be advantageous to cover a volume 10%, 20%, or 50% larger to avoid edge effects and / or to eliminate the need for further measurements in subsequent clinical measurements with slightly different volumes. This can sometimes significantly reduce the measurement volume of the MR preliminary measurements compared to the state of the art, and in many cases, the measurement time of the preliminary measurement can be reduced by the same amount. b. In addition, it may be advantageous to adopt the first phase encoding direction P4, since this is often chosen to reduce or prevent folding or other influences due to flow or pulsation. c. The first selection of the active local coils P5 can be adopted. d. Clinical measurements often include saturators, especially P6 saturation modules, e.g., over the cardiac region. These should be adopted as far as possible—depending on timing and potential impact on the contrast of the MR pre-measurement. e. Image artifacts can occur, especially in regions with respiratory or cardiac movement. The trigger and gating settings (P7) of the clinical measurement should also be adopted for the MRI pre-measurement, as far as possible. This can be advantageous, for example, to achieve the same respiratory cycle (inspiration, expiration).

[0060] In conclusion, it can be stated that a method is proposed that automatically integrates the settings selected by the operating personnel for a main MR measurement, in particular a clinical measurement, into the MR pre-measurements required for this measurement. This is intended to ensure that these MR pre-measurements do not take longer than actually necessary and that they advantageously achieve optimal image quality, on the basis of which any post-processing and preparation calculations can then be started. Advantageously, the acquisition time and quality of MR pre-measurements required for a clinical measurement can be reduced or increased. The latter can also lead to a direct improvement in image quality in selected follow-up measurements. Advantageously, the settings of the clinical measurement are adopted in as many aspects as possible.

[0061] Finally, it should be noted once again that the methods described in detail above, as well as the illustrated MR device, are merely exemplary embodiments that can be modified in a variety of ways by those skilled in the art without departing from the scope of the invention. Furthermore, the use of the indefinite articles "a" or "an" does not exclude the possibility that the respective features may be present in multiple instances. Likewise, the term "unit" does not exclude the possibility that the respective components consist of several interacting subcomponents, which may also be spatially distributed.

Claims

[1] Method for performing an MR pre-measurement, the method comprising: - Providing at least one main measurement parameter according to which a main MR measurement is to be carried out, - performing the MR pre-measurement prior to the MR main measurement according to at least one pre-measurement parameter using an MR device, wherein the at least one pre-measurement parameter is determined depending on the at least one main measurement parameter, wherein the at least one main measurement parameter comprises a first layer position, a first field of view and / or a first layer coverage, wherein a second layer position is determined as a function of the first layer position and / or a second field of view is determined as a function of the first field of view and / or a second layer coverage is determined as a function of the first layer coverage according to a respective predetermined relation as at least one pre-measurement parameter. [2] Method according to claim 1, the method further comprising: - performing the main MR measurement using the MR device, wherein performing the pre-MR measurement comprises acquiring pre-measurement MR signals, The main MR measurement is carried out taking into account the pre-measurement MR signals. [3] Method according to claim 1, the method further comprising: - performing the main MR measurement by means of the MR device, wherein performing the main MR measurement comprises acquiring main measurement MR signals, - Reconstructing at least one MR image based on the main measurement MR signals, wherein performing the MR pre-measurement comprises acquiring pre-measurement MR signals, wherein the main MR measurement and / or the reconstruction of the at least one MR image are carried out taking into account the pre-measurement MR signals. [4] Method according to claim 2, wherein at least one magnetic field map is determined based on the pre-measurement MR signals, wherein the main MR measurement is carried out taking into account the at least one magnetic field map. [5] Method according to claim 3, wherein at least one magnetic field map is determined based on the pre-measurement MR signals, wherein the carrying out of the main MR measurement and / or the reconstruction of the at least one MR image takes place taking into account the at least one magnetic field map. [6] Method according to claim 4 or 5, wherein at least one dynamic pulse is determined on the basis of the at least one magnetic field map, wherein the at least one dynamic pulse is generated by the MR device when carrying out the main MR measurement. [7] Method according to claim 6, where the dynamic pulse is a pTx pulse, wherein the pTx pulse can comprise a plurality of partial pulses which are transmitted in parallel, in particular simultaneously, by a respective transmitting coil of a radio-frequency antenna unit of the MR device. [8] Method according to one of the preceding claims, wherein the at least one main measurement parameter comprises a first phase encoding direction, wherein a second phase encoding direction is determined as at least one pre-measurement parameter depending on the first phase encoding direction. [9] Method according to one of the preceding claims, wherein the at least one main measurement parameter comprises a first selection of active coil elements, wherein a second selection of active coil elements is determined as at least one pre-measurement parameter identical to the first selection of active coil elements. [10] Method according to one of the preceding claims, wherein the at least one main measurement parameter comprises at least a first saturation module of a first MR sequence, wherein at least one second saturation modulus of a second MR sequence is determined as at least one pre-measurement parameter depending on the at least one first saturation modulus of the first MR sequence. [11] Method according to one of the preceding claims, wherein the at least one main measurement parameter comprises a first gating setting, wherein a second gating setting is determined as at least one pre-measurement parameter depending on the first gating setting. [12] MR device adapted to carry out a method according to any one of the preceding claims. [13] A computer program product comprising a program and being directly loadable into a memory of a programmable system control unit of an MR device, with program means for executing a method according to any one of claims 1 to 11 when the program is executed in the system control unit of the MR device.

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