Optimized recording of measurement data by means of magnetic resonance technology

Abstract

In a method for improving the recording of measurement data of an object under inspection, the method includes loading desired imaging parameters and a desired flip angle for recording the measurement data by means of a recording method, wherein the gradient to be switched for position encoding of the measurement data has its full intensity during the incident RF excitation pulse. A quantization value of a desired interference for the recording method is determined based on the desired imaging parameters, and a check on the feasibility of correcting for the interference is performed based on the quantization value and the desired flip angle.

Description

Technical Field

[0001] The present invention relates to an improved recording of measurement data by means of magnetic resonance technology, and in particular by means of a radial recording method with a recording gap. Background Technology

[0002] Magnetic resonance imaging (MR, abbreviated below, stands for magnetic resonance) is a known technique by which images of the interior of an object being examined can be generated. In short, for this purpose, the object is positioned in an MR apparatus in a relatively strong, static, uniform fundamental magnetic field, also known as the B0 field, with a field strength of 0.2 Tesla to 7 Tesla and greater, such that the nuclear spins of the object are oriented along the fundamental magnetic field. To trigger nuclear spin resonance, which can be measured as a signal, a radio frequency excitation pulse (RF pulse) is incident on the object. The triggered nuclear spin resonance, as so-called k-space data, is measured by means of coils designed for receiving, and MR images or spectroscopic data are reconstructed based on the k-space data. The alternating magnetic field generated by the excitation pulse incident by means of at least one transmit coil is also called the B1 field. To positionally encode the measurement data, a rapidly switching magnetic gradient field, simply called a gradient, is superimposed on the fundamental magnetic field. The pattern used to describe the temporal order of the incident RF pulse and the gradient to be switched is called the pulse sequence (schema), or simply sequence. The recorded measurement data is digitized and stored as complex values ​​in a k-space matrix. From the k-space matrix occupied by the values, the corresponding MR image can be reconstructed, for example, by means of a multidimensional Fourier transform.

[0003] Therefore, conventional sequences, such as (T)SE sequences (“(Turbo)Spin Echo”) or GRE sequences (“Gradient Echo”), cannot record substances or tissues with T2* times significantly below 500 microseconds (μs), such as bones, tendons, ligaments, teeth, or even ice, because the corresponding signals of the substances or tissues have decayed at the recording time in the (T)SE or GRE sequences.

[0004] However, MR methods are known that allow very short echo times (TE) (e.g., TE < 500 μs) within the corresponding decay time range. It is feasible, for example, to display bones, teeth, or ice in MR images using these MR methods, even though the object's T2* time is in the range of 30 μs to 80 μs.

[0005] For example, belonging to these MR methods is the UTE sequence (“Ultrashort Echo Time”), as described in particular in Sonia Nielles-Vallespin’s article “3D radial projection technique with ultrashort echo times for sodium MRI: Clinical applications in human brain and skeletal muscle”, Magn. Res. Med. 2007; 57; pp. 74-81. In this sequence type, after a waiting period following non-selective or slice-selective excitation, the gradient rises and begins simultaneously with data acquisition. The k-space trajectory scanned after excitation extends radially outward from the center of k-space. Therefore, the original data must first be converted to a Cartesian k-space grid, for example, by so-called rerasterization, before reconstructing the image data from the original data recorded in k-space using Fourier transform.

[0006] Other MR methods that allow for exceptionally short echo times include zTE ("zero echo time") and PETRA ("pointwise encoding time reduction with radial acquisition"), as well as WASPI ("water-and fat-suppressed proton projection MRI") sequences, and for example, in Weiger et al.'s article "MRI with Zero Echo Time: Hard versus Sweep Pulse Excitation," Magnetic Resonance in Medicine 66: 379–389, 2011, in US8878533B2 (PETRA), and in Wu et al.'s article "Density of Organic Matrix of Native Mineralized Bone Measured by Water-and Fat-Suppressed Proton Projection." The method is described in "MRI (Water and Fat Suppressed Proton Projection MRI for Measurement of Organic Matrix Density of Naturally Mineralized Bone)," Magn. Reson. Med. 50: pp. 59-68, 2003. In both methods, measurements are recorded along radial spokes in k-space, where the gradient switched for position encoding has already fully risen at the moment of spin excitation in the subject under examination, saving valuable encoding time. However, this also creates areas in the center of k-space that cannot be scanned by the radial spokes. Compared to the UTE method, the zTE and PETRA methods are more robust because the switched gradient or eddies in the incident RF pulse or unwanted small time offsets have little or no effect on the measurement.

[0007] exist Figure 1The diagram illustrates an example of a portion of a pulse sequence used to record measurement data along radial spokes, as is used in the zTE, WASPI, and PETRA methods. The top line, “Tx / Rx,” shows the incident RF excitation pulse RF and the readout time window of the ADC during which measurement data is recorded. The middle line, “G,” shows gradients that switch in the encoding direction, each gradient reaching its desired intensity for subsequent measurement data recording at the moment of the incident RF excitation pulse RF1. The bottom line, “k-sp,” shows the k-space points scanned along a pre-defined k-space trajectory for recording measurement data. Here, measured k-space points are shown as black dots, and k-space points not read before the start of the readout time window of the ADC are shown as “empty” points. The failure to read k-space points is due to the fact that, as described, a constant gradient field is applied before the incident RF excitation pulse RF. Therefore, the central k-space point (k=0) is measured simultaneously with the incident RF excitation pulse RF1, which is technically impractical. Measurement data recording can only begin in the readout time window ADC after at least the required switching time Ts, which is hardware-dependent and depends on the RF excitation pulse RF1. This also yields the (shortest) echo time TE. The first k-space point k* read in the readout time window ADC has the minimum distance from the k-space center k0. The last k-space point k* read in the readout time window ADC... max The maximum distance from the k-space center k0 is given at the k-space point being read. The duration of the ADC's readout time window (acquisition duration) is given by the intensity of the applied gradient field G and the required resolution or desired image area (field of view, FOV) or the matrix of the image to be constructed from the measurement data.

[0008] exist Figure 2The scanning mode to which the k-space belongs is shown, where the radial k-space spokes correspond to the k-space trajectory, and measurement data is recorded along the k-space trajectory in the read time window ADC. The measurement data is recorded along the radial spokes in different encoding directions until, for example, the desired density in the k-space of the scan is reached. The radius of the central region B in which the measurement data is not recorded along the described radial spokes depends on the k-space moment accumulated until the measurement data is recorded after the excitation, and thus depends on the echo time TE and the strength of the switched gradient field G, during which the gradient of constant strength is switched. The longer the echo time TE and the stronger the strength of the gradient, and thus the larger the read bandwidth, the more k-space points are not measured on the radial k-space trajectory. Therefore, the zTE method, the WASPI method, and the PETRA method are characterized in that the methods record the echo signal and the methods detect the echo signal along the radial k-space trajectory as measurement data, however, the measurement data has a recording gap depending on the minimum used echo time, and the recording gap may correspond to the described non-radial scanned region B because no measurement data is recorded for k-space points k < k*. If a radial recording method with a recording gap is generally referred to hereinafter, it means a recording method such as the zTE method, the WASPI method, or the PETRA method, in which the gradient used for encoding the measurement data has reached its desired strength at the start of the excitation by the RF excitation pulse, and the strength remains constant during the subsequent read time window ADC.

[0009] The MR data from the non-radial scanned region B can be algebraically reconstructed from the measurement data of the radial spokes in the zTE method. In the WASPI method, a small number of other measurements are performed along a second radial k-space trajectory, where the strength of the gradient is reduced so that measurement data can also be recorded closer to the k-space center.

[0010] In the PETRA method, measurement data from region B of the non-radial scan can be recorded using MR single-point recording methods, particularly on a Cartesian grid. These MR single-point recording methods are, for example, RASP (“rapid single point”), described, for example, in Heid et al., “Rapid Single Point (RASP) imaging”, Proc. Intl. Soc. Mag. Reson. Med., p. 684, 1995, or “Single-Point SPRITE”, described, for example, in Balcom et al., “Single-Point Ramped Imaging with T1 Enhancement (SPRITE)”, J. Magn. Reson. A123(1): pp. 131-134, 1996.

[0011] However, the presence of gradients during excitation also introduces certain drawbacks to zTE, WASPI, and PETRA sequences compared to, for example, UTE sequences, because the feasibility of this type of excitation is limited. While spatially restrictive RF excitation pulses can be used in UTE sequences, for example, for two-dimensional (2D) or three-dimensional (3D) spatially selective excitation, the corresponding excitation in zTE, PETRA, or WASPI sequences must be performed using spatially non-selective rectangular pulses, also known as "hard pulses." As described in Grodzki et al.'s article "Correcting sliceselectivity in hard pulse sequences," Proc. Intl. Soc. Mag. Reson. Med. 20, p. 2479, 2012, despite using such spatially non-selective hard pulses as RF excitation pulses, the slice selectivity can only be corrected to a certain extent precisely because the gradients that have already switched during the incident RF excitation pulse may exhibit undesirable slice selectivity. Correction is feasible if at least one first zero-crossing of the spectral pulse profile of the RF excitation pulse used is located outside the field of view (FOV), which corresponds to a sinusoidal shape in the case of a rectangular RF excitation pulse. It is advantageous to use the shortest possible RF excitation pulse if the excitation bandwidth of the RF pulse, indicating the spectral width of the feasible excitation, is derived by the reciprocal of the RF pulse duration. This results in a high excitation bandwidth and thus a high half-value width for the pulse profile of the used RF excitation pulse, simplifying the matrix inversion-based correction described in the aforementioned article by Grodzki et al. However, the shorter the RF excitation pulse used, the smaller the achievable flip angle.

[0012] Other correlations between typical imaging parameters and the RF excitation pulse used are, for example:

[0013] i) The intensity of the gradient switched during the incident RF excitation pulse is proportional to the selected readout bandwidth and the selected resolution, which is obtained as the quotient of the desired field of view and the desired matrix size of the k-space matrix to be filled with the measurement data [FOV / matrix size = resolution].

[0014] ii) The selected flip angle of the RF excitation pulse used (for the same B1 amplitude) is proportional to the pulse duration of the RF excitation pulse.

[0015] In known radial recording methods with recording gaps to date, particularly for the zTE, WASPI, and PETRA methods, the same hard-coded hard pulse is always used as the RF excitation pulse with fixed pulse parameters, especially a fixed pulse duration, regardless of desired imaging parameters such as the selected readout bandwidth, desired resolution, or even the required flip angle. This pulse duration, along with the maximum pulse amplitude, determines the maximum flip angle. For most users of such radial recording methods with recording gaps, this correlation is too complex to allow for independent optimization of the imaging and pulse parameters used, especially when it is also desirable to correct for interferences caused by undesirable slice selection. Nevertheless, users have so far strived to avoid artifacts by selecting the readout bandwidth or resolution, for their chosen field of view, not too high (and thus not too high the intensity of the gradient switching during the incident RF excitation pulse). This is generally unsuccessful. Furthermore, due to the historically fixed pulse duration of the RF excitation pulse used, the achievable flip angle is always the same, although it is entirely possible, depending on the application, to desire a flip angle larger or significantly smaller than the maximum feasible flip angle. Summary of the Invention

[0016] The purpose of this invention is to enable the determination of optimized parameters for RF excitation pulses, particularly optimized pulse parameters such as pulse duration, and / or the determination of imaging parameters for radial recording methods with recording gaps, thereby simplifying or enabling feasible correction of interference caused by undesirable slice selection, wherein imaging parameters that are coordinated with the desired imaging protocol and application can be considered in particular.

[0017] The objective is achieved by the method according to the invention for improving the recording of measurement data from an object being examined within the measurement volume of a magnetic resonance apparatus, the magnetic resonance apparatus according to the invention, the computer program according to the invention, and the electronically readable data carrier according to the invention.

[0018] The method according to the present invention for improving the recording of measurement data from an object under examination located in the measurement volume of a magnetic resonance facility includes the following steps:

[0019] - For recording the echo signal generated after an RF excitation pulse as measurement data using a recording method, desired imaging parameters are loaded, wherein the gradient to be switched for position encoding of the measurement data has its full intensity during the incident RF excitation pulse, wherein the desired imaging parameters include a desired field of view and at least one imaging parameter from the group consisting of: a desired readout bandwidth, a desired resolution, and a desired matrix size in which the measurement data should be stored.

[0020] -The desired flip angle for the incident RF excitation pulse.

[0021] - Determine the quantization value of the expected interference to the recording method based on the desired imaging parameters.

[0022] - Check the feasibility of performing interference correction based on quantization values.

[0023] If the feasibility of the correction is confirmed, the recording method is performed using the loaded imaging parameters and the loaded flip angle. If the feasibility is denied, the pulse duration of the incident RF excitation pulse within the range of the recording method is adjusted based on the quantization value, and / or the desired flip angle is adjusted to an adjusted flip angle, and / or at least one of the desired imaging parameters is adjusted to an adjusted imaging parameter. The recording method is then performed using the adjusted pulse duration and / or the adjusted flip angle and / or the adjusted imaging parameter.

[0024] - Store and / or further process the measurement data recorded using the recording method performed.

[0025] According to the present invention, the feasibility of correcting for anticipated interferences in the recording method is examined, and parameters important to the recording method are adjusted, particularly automatically, as necessary, to ensure the feasibility of correction. This allows for optimized recording of measurement data, taking into account the user's desired imaging parameters (e.g., for a specific imaging protocol or application), without artifacts resulting from the interference without correction.

[0026] When using radial recording methods with recording gaps, particularly when recording measurement data using the zTE, WASPI, and PETRA methods, as mentioned above, interference arises due to undesirable slice selection. The method of this invention ensures that boundary conditions derived from the simplified (or achievable) correction of the interference are automatically complied with, without the user needing to understand, the complex correlation between the RF excitation pulse used and other imaging parameters. More specifically, the method automatically limits the pulse parameters of the RF excitation pulse to be used from desired parameters that can be set by the user, such as readout bandwidth, field of view (FOV), and matrix size (which together pre-set the intensity of the gradient switched during excitation) or flip angle. This takes into account limitations in the hardware-determined achievable amplitude (B1m) of the RF excitation pulse and limits the parameter space that can be selected by the user, especially the parameter space of imaging parameters such as readout bandwidth, resolution, or feasible flip angle.

[0027] The magnetic resonance apparatus according to the invention includes a magnet unit, a gradient unit, a radio frequency unit, and a control device constituting an execution of the method according to the invention, the control device having an optimization unit.

[0028] When a computer program according to the invention is executed on a control device, the computer program implements the method according to the invention on the control device. The computer program includes, for example, instructions that, when executed by a control device, such as a control device of a magnetic resonance imaging (MRI) facility, cause the control device to perform the method according to the invention. The control device may be designed in the form of a computer.

[0029] The computer program may also exist in the form of a computer program product, which can be directly loaded into the memory of the control device. The computer program product has a program code structure so that when the computer program product is executed in the computing unit of the computing system, the method according to the invention is performed.

[0030] The computer-readable storage medium according to the invention includes instructions that, when executed by a control device, such as a control device of a magnetic resonance facility, cause the control device to perform the method according to the invention.

[0031] Computer-readable storage media can be designed as electronically readable data carriers, the data carriers including electronically readable control information stored thereon, the control information including at least one computer program according to the invention, and designed to execute the method according to the invention when the data carrier is used in the control apparatus of a magnetic resonance facility.

[0032] The advantages and implementation methods described herein are also applicable to magnetic resonance imaging (MRI) facilities, computer program products, and electronically readable data carriers. Attached Figure Description

[0033] Other advantages and details of the invention will become apparent from the embodiments described below and from the accompanying drawings. The examples listed are not intended to limit the invention. The drawings show:

[0034] Figure 1 A schematic illustration of the pulse sequence pattern used to detect measurement data is shown in the portion.

[0035] Figure 2 An exemplary k-space scanning pattern is shown schematically.

[0036] Figure 3 A schematic flowchart of the method according to the present invention is shown.

[0037] Figure 4 The magnetic resonance apparatus according to the present invention is shown schematically. Detailed Implementation

[0038] Figure 3 This is a schematic flowchart of a method according to the present invention for improving the recording of measurement data (MDS) from an object under examination located in the measurement volume of a magnetic resonance facility.

[0039] For recording the echo signal generated after an RF excitation pulse as measurement data using a recording method (where the gradient G to be switched for position encoding of the measurement data has its full intensity during the incident RF excitation pulse), the desired imaging parameters BP and the desired flip angle FA (box 101) are loaded, wherein the desired imaging parameters include the desired field of view and at least one imaging parameter from the group consisting of: the desired readout bandwidth, the desired resolution, and the desired matrix size of the matrix in which the measurement data should be stored. Such recording can be performed, for example, by means of a radial recording method with a recording gap, particularly by means of the zTE method, the WASPI method, or the PETRA method.

[0040] The quantization value SG of the expected interference to the recording method is determined based on the desired imaging parameter BP (box 103). Here, the quantization value SG is selected such that the quantization value is characterizing of the expected interference.

[0041] For radial recording methods with recording gaps, for example, a value indicating the shape of the pulse profile of the RF excitation pulse used is suitable as the quantization value SG, since the expected interference can be described as aliasing in the pulse profile to the magnetization distribution recorded as the echo signal. In particular, the quantization value SG can be a value related to the excitation bandwidth of the incident RF excitation pulse and / or the half-value width of the pulse profile, because—as described above in the article by Grodzki et al.—the feasibility of correcting the interference by the proposed matrix inversion depends on the pulse profile, and especially on the first zero-crossing of the pulse profile.

[0042] The quantization value SG can in particular correspond to the intensity of the gradient G that is switched during the incident RF excitation pulse, which is proportional to the imaging parameters “readout bandwidth and field of view” (and thus also proportional to the imaging parameter “resolution” and inversely proportional to the imaging parameter “matrix size”).

[0043] Based on the determined quantization value SG, an executability check 100 for interference correction is performed. For example, the executability check for interference correction may include comparing the position of the first zero-crossing point of the pulse profile of the incident RF excitation pulse, determined based on the quantization value SG, with the desired field of view, wherein executability is confirmed, for example, if the first zero-crossing point is outside the field of view.

[0044] If the feasibility of the correction is confirmed by check 100 (100, "y"), the recording method is performed with the help of the loaded imaging parameters BP and the loaded flip angle FA, so that the measurement data MD (box 109) is recorded, which can be stored and / or further processed.

[0045] If the executability check is negative (100, "n"), then optimization is performed based on the quantization value SG: a) adjusting the pulse duration of the RF excitation pulse to be incident within the range of the recording method to an adjusted pulse duration PD', and / or b) adjusting the desired flip angle to an adjusted flip angle FA', and / or c) adjusting at least one of the desired imaging parameters to an adjusted imaging parameter BP' (box 107). The recording method is then performed using at least one adjusted parameter from the group consisting of: the adjusted pulse duration PD', the adjusted flip angle FA', and / or at least one adjusted imaging parameter BP', such that measurement data MD is recorded (box 109).

[0046] The pulse duration of the incident RF excitation pulse within the scope of the recording method can be adjusted to an adjusted pulse duration PD' (box 107.2) such that, through the adjusted pulse duration PD', the first zero-crossing point of the pulse profile of the incident RF excitation pulse is located outside the desired field of view. Here, the adjusted pulse duration PD' can be particularly smaller than the previously given unadjusted pulse duration. As mentioned above, by adjusting the pulse duration in the form of reducing the pulse duration, the position of the first zero-crossing point is moved outward.

[0047] The pulse duration of the RF excitation pulse to be incident can be adjusted to an adjusted pulse duration PD' within the range of the recording method, taking into account the inherent maximum amplitude B1m of the RF excitation pulse to be incident on the magnetic resonance apparatus used. Especially when a small desired flip angle of the maximum amplitude B1m of the RF excitation pulse to be incident is not fully utilized within a preset pulse duration, the adjusted pulse duration can be reduced relative to the preset pulse duration while simultaneously increasing the amplitude of the RF excitation pulse to be incident, in order to obtain the desired flip angle. Here, the amplitude can be increased, for example, to the maximum amplitude B1m of the RF excitation pulse to be incident, in order to determine the minimum adjusted pulse duration PD'.

[0048] Based on the determined quantization value SG and the adjusted pulse duration PD', a further check 100' on the feasibility of interference correction can be performed. For example, the further check 100' on the feasibility of interference correction may include comparing the position of a first zero-crossing point of the incident RF excitation pulse, determined based on the quantization value SG, with the desired field of view, wherein feasibility is confirmed, for example, if the first zero-crossing point is outside the field of view.

[0049] If the feasibility of the calibration is further examined (100', "y"), a suitable adjusted pulse duration can be determined, and a recording method can be performed with the aid of the loaded imaging parameter BP and the loaded flip angle FA, as well as with the aid of the adjusted pulse duration PD', so that measurement data MD (box 109) can be recorded, which can be stored and / or further processed.

[0050] When the desired flip angle FA is adjusted to an adjusted flip angle FA', the adjusted flip angle FA' can be smaller than the (original) desired flip angle FA. For a smaller flip angle FA', greater flexibility is derived in adjusting the pulse duration, and more likely, the feasibility of interference correction is feasible.

[0051] If it is not feasible to adjust the pulse duration of the RF excitation pulse to be incident within the scope of the recording method such that, with the adjusted pulse duration PD', the first zero-crossing point of the pulse profile of the incident RF excitation pulse is outside the desired field of view, then the desired flip angle FA can be adjusted to an adjusted flip angle FA'. The flip angle FA (and additionally the pulse duration) can be adjusted such that the first zero-crossing point of the pulse profile of the incident RF excitation pulse is outside the desired field of view. For this purpose, the maximum possible adjusted flip angle FA' can be determined, for example, based on the maximum amplitude B1m and by determining the longest possible altered pulse duration, by which the position of the first zero-crossing point of the pulse profile of the incident RF excitation pulse is exactly outside the desired field of view, wherein the maximum possible flip angle can be determined proportionally to the product of the maximum amplitude B1m and the longest possible pulse duration.

[0052] If, despite adjusting the flip angle FA', it is still not feasible to adjust the pulse duration of the incident RF excitation pulse within the scope of the recording method such that, with the adjusted pulse duration, the first zero-crossing point of the pulse profile of the incident RF excitation pulse is outside the desired field of view, then by adding or alternatively adjusting the flip angle FA to the adjusted flip angle FA', at least one of the desired imaging parameters BP can be adjusted to the adjusted imaging parameter BP'. Because the loaded desired imaging parameter BP is what the user expects, the imaging parameter should only be adjusted if, in other cases, even though the flip angle FA' has been adjusted and the pulse duration PD' has been adjusted, the feasibility of interference correction cannot be confirmed.

[0053] At least one imaging parameter BP can be adjusted such that the feasibility of the correction check, performed based on the adjusted quantization value SG determined according to the adjusted imaging parameter BP', confirms feasibility. In other words, in particular, the imaging parameter based on which the quantization value SG is determined is adjusted such that the adjusted quantization value enables the feasibility of correcting for interference. Taking the intensity of the gradient G switched by the incident RF excitation pulse during excitation as the quantization value SG as an example, a decrease in the intensity of the gradient G causes a widening of the pulse profile of the RF excitation pulse, thereby causing an outward shift of the position of the first zero-crossing point of the pulse profile. Here, the maximum reduction in the intensity of the gradient G can be obtained. To achieve this maximum reduction in the intensity of the gradient G, for example, the desired resolution of the desired imaging parameter BP can be reduced to an adjusted resolution and / or the desired readout bandwidth of the desired imaging parameter BP can be reduced to an adjusted readout bandwidth in order to reduce the intensity of the gradient G.

[0054] Here, it may be suggested to the user to either reduce the desired resolution to an adjusted resolution and / or reduce the desired read bandwidth to an adjusted read bandwidth, or a combination of both measures, so that the user can decide to adjust the imaging parameters, such adjustments being best coordinated with the desired imaging protocol or with the desired application for a given imaging area, and thus perceived as minimal constraints.

[0055] Therefore, adjusting at least one of the desired imaging parameters BP to an adjusted imaging parameter BP' may include reducing the desired resolution to an adjusted resolution and / or reducing the desired readout bandwidth to an adjusted readout bandwidth.

[0056] Because the adjusted imaging parameters BP' are precisely determined such that the imaging parameters allow for the feasibility of correcting for interference, a recording method can be performed using the adjusted imaging parameters BP' to record measurement data MD (box 109).

[0057] Measurement data MD recorded by the recording method can be stored or further processed, such as reconstructed into image data BD (box 111).

[0058] Figure 4 A magnetic resonance apparatus 1 according to the present invention is schematically shown. The magnetic resonance apparatus 1 includes a magnet unit 3 for generating a basic magnetic field, a gradient unit 5 for generating a gradient field, a radio frequency unit 7 for incident and receiving radio frequency signals, and a control device 9 constituting a method according to the present invention.

[0059] exist Figure 4 The sub-units of the magnetic resonance facility 1 are only roughly schematically shown. The radio frequency (RF) unit 7 may consist of multiple sub-units and, for example, include multiple coils. In particular, the RF unit 7 may include a body coil that is fixedly integrated into the magnetic resonance facility 1, and may, for example, include two antenna elements 7.1 and 7.2. Furthermore, the RF unit 7 may include one or more different local coils 7*, which may be designed only for transmitting RF signals, only for receiving triggered RF signals, or both, and may themselves include multiple antenna elements and associated coil channels.

[0060] To examine an object U, such as a patient or a phantom, the object U can be introduced into the magnetic resonance apparatus 1 on the examination table L within the measurement volume of the magnetic resonance apparatus 1. Slice S1 or S2 is an exemplary target volume of the object from which echo signals can be recorded and detected as measurement data.

[0061] The control device 9 is used to control the magnetic resonance facility 1, and in particular, it can control the gradient unit 5 by means of the gradient control device 5' and the radio frequency unit 7 by means of the radio frequency transmit / receive control device 7'. Here, the radio frequency unit 7 may include multiple channels on which signals can be transmitted or received.

[0062] The radio frequency (RF) unit 7, together with its RF transmit / receive control device 7', is responsible for generating and transmitting an incident (transmitted) RF alternating field to manipulate the spins in the region to be manipulated of the object under inspection U (e.g., in the slice S to be measured). Here, the intermediate frequency of the RF alternating field, also known as the B1 field, is typically set as close as possible to the resonant frequency of the spin to be manipulated. The deviation between the intermediate frequency and the resonant frequency is called off-resonance. To generate the B1 field, a current controlled by the RF transmit / receive control device 7' is applied to the HF coil in the RF unit 7.

[0063] Furthermore, the control device 9 includes an optimization unit 15, which is used to adjust the pulse duration of the incident RF excitation pulse within the range of the recording method and / or adjust the desired flip angle to an adjusted flip angle and / or adjust at least one desired imaging parameter to an adjusted imaging parameter. The control device 9 is generally configured to perform the method according to the invention.

[0064] The computing unit 13 included in the control device 9 is configured to perform all computational operations required for necessary measurements and determinations. Intermediate and final results required or obtained herein can be stored in the storage unit S of the control device 9. Here, the units shown are not necessarily understood as physically separate units, but merely as units of meaning; however, they can be implemented, for example, in fewer physical units or even in a single, unique physical unit.

[0065] The input / output device E / A of the magnetic resonance facility 1 can transmit control commands to the magnetic resonance facility by the user and / or display the results of the control device 9, such as image data.

[0066] The methods described herein may also exist in the form of a computer program comprising instructions that implement the described methods on the control device 9. Similarly, a computer-readable storage medium comprising instructions that, when executed by the control device 9 of the magnetic resonance facility 1, causes the control device to perform the described methods.

[0067] Regardless of the grammatical gender of a particular term, persons of either male or female gender are included.

Claims

1. A method for improved recording of measurement data (MD) from an examination object (U) in a measurement volume of a magnetic resonance facility (1), the method comprising the following steps: - Loading desired imaging parameters (BP) for recording echo signals generated after an RF excitation pulse as measurement data (MD) by means of a recording method, wherein a gradient (G) to be switched for position encoding of the measurement data (MD) along a radial spoke in k-space has its full intensity during incidence of the RF excitation pulse, and wherein the desired imaging parameters (BP) include a desired field of view and at least one imaging parameter from the following group: a desired read bandwidth, a desired resolution, and a desired matrix size of a matrix in which the measurement data should be stored; - Loading a desired flip angle (FA) for an incident RF excitation pulse; - Determining a quantification value (SG) of an expected interference for the recording method based on the desired imaging parameters; - Performing a check (100) of the feasibility of correcting the interference based on the quantification value (SG); - If the check (100) confirms the feasibility of the correction, performing the recording method with the loaded imaging parameters (BP) and the loaded flip angle (FA), and if the check negates the feasibility, adjusting the pulse duration of the RF excitation pulse to be incident within the scope of the recording method to an adjusted pulse duration (PD'), and / or adjusting the desired flip angle (FA) to an adjusted flip angle (FA'), and / or adjusting at least one imaging parameter of the desired imaging parameters (BP) to an adjusted imaging parameter (BP'), and performing the recording method with the adjusted pulse duration (PD') and / or with the adjusted flip angle (FA') and / or with the adjusted imaging parameter (BP'); - Storing and / or further processing the measurement data (MD) recorded by means of the performed recording method.

2. The method according to claim 1, wherein the quantification value (SG) is related to a half-width of a pulse profile of the incident RF excitation pulse, in particular wherein wherein the quantification value (SG) corresponds to the intensity of a gradient (G) switched during incidence of an RF excitation pulse.

3. The method according to any one of the preceding claims, wherein the check of the feasibility of correcting the interference includes comparing the position of a first zero crossing of the pulse profile of an incident RF excitation pulse with a desired field of view, and if the first zero crossing lies outside the field of view, confirming the feasibility.

4. The method according to any one of the preceding claims, wherein the pulse duration of the RF excitation pulse to be incident within the scope of the recording method is adjusted to an adjusted pulse duration (PD') such that, by means of the adjusted pulse duration (PD'), the first zero crossing of the pulse profile of the incident RF excitation pulse lies outside the desired field of view.

5. The method according to any one of the preceding claims, Wherein, considering the maximum amplitude (B1m) of the RF excitation pulse to be incident, the pulse duration of the RF excitation pulse to be incident within the scope of the recording method is adjusted to an adjusted pulse duration (PD’).

6. The method according to any one of the above claims, wherein the adjusted flip angle (FA’) is smaller than the desired flip angle (FA).

7. The method according to any one of the above claims, wherein if it is not feasible for the desired flip angle (FA) to be loaded to adjust the pulse duration of the RF excitation pulse to be incident within the scope of the recording method to an adjusted pulse duration (PD’) such that, through the adjusted pulse duration (PD’), the first zero crossing of the pulse profile of the incident RF excitation pulse is located outside the desired field of view, then the desired flip angle (FA) is adjusted to an adjusted flip angle (FA’), and the desired flip angle (FA) and the pulse duration are adjusted such that the first zero crossing of the pulse profile of the incident RF excitation pulse is located outside the desired field of view.

8. The method according to any one of the above claims, wherein if it is not feasible to adjust the pulse duration of the RF excitation pulse to be incident within the scope of the recording method to an adjusted pulse duration (PD’) such that, through the adjusted pulse duration (PD’), the first zero crossing of the pulse profile of the incident RF excitation pulse is located outside the desired field of view, then at least one imaging parameter of the desired imaging parameter (BP) is adjusted to an adjusted imaging parameter (BP’), and the at least one imaging parameter (BP) is adjusted such that the check of the executability based on the quantization value (SG) determined according to the adjusted imaging parameter (BP’) confirms the executability.

9. The method according to any one of the above claims, wherein adjusting at least one imaging parameter of the desired imaging parameter (BP) to an adjusted imaging parameter (BP’) includes reducing the desired resolution to an adjusted resolution and / or reducing the desired read bandwidth to an adjusted read bandwidth.

10. A magnetic resonance facility (1), the magnetic resonance facility (1) comprising a magnet unit (3), a gradient unit (5), a radiofrequency unit (7) and a control device (9), the control device (9) having a radiofrequency transmission / reception control device (7’) and an optimization unit (15), wherein the control device (9) is configured to execute the method according to any one of claims 1 to 9 on the magnetic resonance facility (1).

11. A computer program, the computer program comprising instructions which, when the program is executed by the control device (9) of a magnetic resonance facility (1), cause the control device to execute the method according to any one of claims 1 to 9.

12. A computer-readable storage medium, the computer-readable storage medium comprising instructions which, when executed by a control device (9) of a magnetic resonance facility (1), cause the control device to perform the method according to any one of claims 1 to 9.

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