Computer-implemented method for operating a magnetic resonance device, magnetic resonance device, computer program and electronically readable data carrier

Abstract

A computer-implemented method for operating a magnetic resonance device (47), comprising a main magnet unit (26) with a particularly cylindrical patient receptacle (25), wherein a field of view (29) of the magnetic resonance device (47) is located within the patient receptacle (25), which field of view is defined by the homogeneity of a main magnetic field generated by a main magnet (48) of the main magnet unit (26), and a patient bed (2) for positioning the patient (19) in the patient receptacle (25) is movable along a longitudinal direction (3) of the patient bed (2), wherein at least one local coil arrangement (1) with at least one coil element (4) for measuring magnetic resonance data is freely positionable on the patient bed (2) and / or a patient (19) to be measured, at least with respect to the longitudinal direction (3), the method comprising the following steps: - with the patient bed (2) located at least partially outside the patient support (25) and after positioning the local coil arrangement (1), determining position information that describes the position of the local coil arrangement (1) on the patient bed (2) at least in the longitudinal direction (3) with a measuring means (7), wherein a magnetic field sensor, in particular a Hall sensor (8), installed in the local coil arrangement (1) is used as the measuring means (7), wherein the complete three-dimensional position and the complete three-dimensional orientation of the local coil arrangement (1) are determined as position information by the measuring means (7), and wherein a six-dimensional pose of the local coil arrangement (1) is used to select coil elements (4) to be used in the measurement,wherein coil elements (4) lying in the field of view (29) and / or not overlapping in the physical gradient axes and / or logical gradient axes of the magnetic resonance device (47) are selected for measurement, - determining recording information that describes a positioning of the local coil arrangement (1) relative to the field of view (29), and - automatic positioning of the patient couch (2) in the longitudinal direction (3) at an approach position determined from the position information and the recording information.

Description

[0001] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0002] The invention relates to a computer-implemented method for operating a magnetic resonance device, comprising a main magnet unit with a, in particular cylindrical, patient receptacle, wherein a field of view of the magnetic resonance device, which is defined by the homogeneity of a main magnetic field generated by a main magnet of the main magnet unit, lies within the patient receptacle, and a patient bed for positioning the patient in the patient receptacle is movable along a longitudinal direction of the patient bed, which corresponds in particular to the longitudinal direction of the patient receptacle, wherein at least one local coil arrangement with at least one coil element for measuring magnetic resonance data is freely positionable on the patient bed and / or a patient to be measured, at least with respect to the longitudinal direction. In addition, the invention relates to a magnetic resonance device, a computer program, and an electronically readable data carrier.

[0003] Due to its diverse application possibilities, excellent image quality, and wide range of possible applications, magnetic resonance imaging is a frequently used modality in medical technology. However, this diversity of applications also brings with it a high degree of complexity in the configuration and selection of acquisition protocols and magnetic resonance sequences used to measure magnetic resonance data. Therefore, efforts are already underway in the state of the art to reduce the operating effort of magnetic resonance systems while still delivering sufficiently good image quality for the magnetic resonance data.

[0004] A frequently used tool in magnetic resonance imaging to achieve high image quality is so-called local coils. Local coils have the advantage that they can be placed extremely close to the examination area in the patient, in contrast to, for example, body coils that span a cylindrical patient receptacle. A distinction can be made between fixed local coil arrangements, which then comprise at least one local coil, and freely positionable local coil arrangements. The former group of local coil arrangements includes, for example, head coils, which have a fixed installation position on a patient couch with which the patient is moved into the patient receptacle of the magnetic resonance imaging system, or which are even permanently installed.Another example is spinal coils, which can be integrated into the patient bed, for example, in the spinal support area. Examples of freely positionable local coil arrangements include coil blankets covering multiple anatomical areas or other local coil arrangements that can be placed on the patient or the patient bed.

[0005] When using local coils, it is important to position them skillfully relative to the field of view of the magnetic resonance scanner. The field of view of the magnetic resonance scanner is typically defined by the homogeneity of the main magnetic field (B0 field) and can, for example, be formed by the so-called homogeneity volume. To achieve high-quality magnetic resonance data during measurement, at least the coil elements of the local coil array used for measurement, especially reception, should ideally be placed within the field of view (FOV), particularly in the center of the field of view (often referred to as the isocenter in magnetic resonance scanners).

[0006] To simplify the operation of stationary local coil arrangements, such as head coils, integrated spinal coils, and the like, operator support methods have been proposed that utilize the fact that the longitudinal position (position in the longitudinal direction) of the stationary local coil arrangements on the patient bed is known, so that the patient bed can be specifically positioned so that the corresponding local coil is in the field of view. In other words, for example, a local coil arrangement or a sub-coil of the local coil arrangement that has a fixed position on the patient bed can be selected, and the patient is positioned fully automatically by means of the patient bed in the field of view of the magnetic resonance imaging system such that the local coil arrangement or sub-coil, and thus the desired examination region, are positioned in the field of view.

[0007] However, this is more problematic with non-stationary local coil arrays that can be freely positioned, at least longitudinally, along the patient bed. In this case, the current approach requires either a manual, laborious positioning of the patient bed by a user such that the local coil array is positioned within the field of view, or the use of a patient model to determine the examination area and thus the appropriate positioning of the patient bed.

[0008] Virtual patient models, which can be used to estimate the position of anatomical features and / or anatomical regions based on the patient's positioning on the patient couch, can, for example, be statistically determined for a large number of patients and adapted to the patient's height and / or weight, for example. Nevertheless, the use of a virtual patient model can lead to deviations. On the one hand, the patient's positioning on the patient couch may be inaccurate, and on the other hand, the individual, current patient may deviate from the assumed norm of the patient model.Positioning the patient feet first usually presents greater problems than positioning the patient head first, since in the latter orientation, the patient's head must be positioned in the head coil and / or on the patient couch's head pillow for safety reasons. The use of a heel cushion is not necessarily required for the foot area; however, knee cushions positioned under the knees are often used, which can modify the patient's effective length.

[0009] Aids for manual positioning have also been proposed. For example, it is known to provide a laser marking device at the entrance to the patient admission area, whereby the local coil arrangement, in particular its center or the coil elements to be used / the local coil to be used, can then be positioned below the marking. This means that a position on the patient couch is known and can be used to achieve the most precise positioning of the local coil arrangement or the coil elements in the field of view by moving the patient couch. To do this, the point to be marked must first be correctly positioned below the laser marking device, the input must be confirmed, and only then can an automatic target movement of the patient couch be triggered.This is somewhat time-consuming due to the manual input, and the examination area is not necessarily visible, especially when focusing on specific organs, which can lead to inaccuracies. This can also apply to coil elements or the sub-coils of the local coil array formed by them. Alternatively, the target position can also be entered manually as numerical values. The following publications represent the state of the art: DE 10 2016 203 255 A1, US 10 799 119 B2, and DE 102 2008 040 003 A1.

[0010] The invention is therefore based on the object of providing an improved possibility, in particular through automation, of assisting a user in positioning the patient couch in a patient recording when using a freely positionable local coil arrangement.

[0011] This object is achieved according to the invention by a method having the features of claim 1, a magnetic resonance device having the features of claim 10, a computer program having the features of claim 11 and an electronically readable data carrier having the features of claim 12. Advantageous embodiments emerge from the subclaims.

[0012] In a computer-implemented method of the type mentioned above, the invention provides that the method comprises the following steps: - when the patient bed is at least partially outside the patient receiving area and after positioning the local coil arrangement, determining position information which describes the position of the local coil arrangement on the patient bed at least in the longitudinal direction, using a measuring device, - Determination of recording information that describes a positioning of the local coil arrangement in relation to the field of view, and - automatic positioning of the patient bed in the longitudinal direction at a starting position determined from the position information and the recording information.

[0013] In this case, automatic positioning is carried out in particular such that the local coil arrangement is arranged in the approach position, which can also be referred to as the target position, of the patient bed in a position relative to the field of view that is optimized for the measurement to be performed and / or a localizer acquisition prior to the measurement. As is generally known, the field of view can be defined by the homogeneity volume of the magnetic resonance imaging system, for example, as an area in which the homogeneity of the main magnetic field meets a specific limit value. In many cases, the field of view of the magnetic resonance imaging system corresponds to the center of the patient image, particularly in the case of a cylindrical patient image. It can be provided that the center of the field of view corresponds to the center of the patient image. The center of the field of view can also be referred to as the isocenter.

[0014] The local coil arrangement can provide a single local coil through its at least one coil element. However, it is also conceivable for the local coil arrangement to comprise multiple partial coils, each formed by at least one coil element, as individually usable local coils. For example, the local coil arrangement can be a type of "coil blanket" that extends from the patient's knees to the abdomen or chest of the patient. Such an extended local coil arrangement can then contain, for example, partial coils for the knees, the hip area, the abdominal area, and the like. So-called phased array coils, for example, are known in the prior art. These coil elements comprise a plurality of coil elements arranged in the manner of an array or matrix, which can in particular also be combined or interconnected differently to form specific partial coils as local coils.

[0015] In a specific embodiment, it can be provided that an approach context linking the position information and the acquisition information with the approach position, in particular comprising a look-up table, is used to determine the approach position. For example, dependencies for supported workflows, such as acquisition protocols and / or magnetic resonance sequences, and / or local coil arrangements, can be managed in a special approach context, particularly preferably a look-up table, which is stored in a permanent storage medium of a control device of the magnetic resonance device, which can also implement the method according to the invention. In addition to the position information and the acquisition information, further information can preferably also be included in the determination of the approach position.For example, the starting context can additionally use at least one piece of coil information, such as a type of local coil arrangement and / or the division of the local coil arrangement into sub-coils, as input information. Coil information can be retrieved from connected local coil arrangements, for example, directly via the plug connection at a coil slot and / or by means of identification information that can be determined, for example, via the plug connection. PIN coding and the like can be used for this purpose, as is generally known.Further expedient, optional input data for the approach context can represent workflow information, for example, at least one acquisition protocol to be used and / or at least one magnetic resonance sequence to be used and / or an examination region of the patient to be examined and / or a medical question and / or an acquisition target. Furthermore, patient information, in particular patient arrangement information, can optionally also be included in the determination of the approach position, for example, age, height, gender, positioning type, and the like. Such information can, in particular, be recorded at least partially during patient registration.

[0016] According to the invention, it is therefore proposed to use a measuring device to automatically determine the position of the local coil arrangement on the patient bed, in particular at least the longitudinal position. This enables further automation, which can, in particular, at least partially supplement the procedure for stationary local coil arrangements. Among these, a procedure known as "Select & Go" is known, for example, in which a stationary local coil arrangement is selected directly or indirectly, and from this, a starting position for the patient bed is directly derived. This position, if necessary after confirmation, can then be automatically approached by appropriately controlling the actuators of the patient bed using the control device.After the missing information, namely the arrangement of the local coil array on the patient bed, is added by the position information—which can be automatically acquired with the measuring device—the acquisition information, which is determined at least partially based on user input, can be additionally used to provide an analogous procedure, i.e., a "Select & Go," for freely positionable, non-stationary local coil arrays, with a corresponding increase in comfort. In particular, the aforementioned approach context can provide additional information relevant to the case of non-stationary local coils.

[0017] A key advantage of the present invention is the time savings in measurement preparation. In particular, it is no longer necessary to manually move a patient bed under a laser marking device and to target the local coil array / anatomy, as the magnetic resonance imaging system can independently determine the required approach position using the position information of the local coil array provided by the measuring device. Fewer work steps are required, which also reduces sources of error in the workflow, for example, in handling the laser marking device or, in the opposite case, inaccuracies in the body model, and allows for significantly faster patient positioning.

[0018] The position information, which, due to the longitudinal position of the patient bed, is generally known in the control device of the magnetic resonance system, also describes the relative positioning of the local coil arrangement to the patient bed, is expediently determined outside the patient receptacle, thereby providing sufficiently good access for at least one measuring device and enabling a measurement without having to deal with the interaction with the fields used for magnetic resonance imaging. After placing the local coil arrangement on the patient or directly on the patient bed, the position information can be determined immediately, and the approach position can then be derived from it as soon as the receptacle information is known.

[0019] A particularly advantageous embodiment of the present invention provides that a magnetic field strength sensor, in particular a Hall sensor, is used as the measuring means, which is installed in the local coil arrangement. In particular, several, preferably three-dimensional, Hall sensors can also be installed in the local coil arrangement. From the sensor data of the at least one three-dimensional Hall sensor, at least the coordinate in the longitudinal direction of the patient bed, which usually also corresponds to the longitudinal direction of the patient support, is determined as position information. Other magnetic field strength sensors are also conceivable in principle.

[0020] It should be noted at this point that in magnetic resonance systems with cylindrical patient supports, certain principal directions are typically used, which may also correspond to the physical gradient axes of the gradient coils in the gradient coil arrangement of the magnetic resonance system. The Z-direction is typically used as the aforementioned, corresponding longitudinal direction of the patient bed and the patient support. The Y-direction is the vertical direction perpendicular to this, and the X-direction is the horizontal direction perpendicular to this. This means that for this commonly used coordinate system of the magnetic resonance system, the longitudinal direction discussed here corresponds to the Z-direction.

[0021] The determination of position information for a local coil arrangement using a three-dimensional Hall sensor has already been proposed in the prior art, independent of the application discussed here. For example, DE 10 2016 203 255 A1 discloses a method and a device for determining positions in a magnetic resonance imaging scanner, using a magnetic field strength sensor arranged in a fixed position relative to the local coil arrangement there. After the main magnetic field of the magnetic resonance scanner is ultimately measured, it is possible to infer the position of the local coil arrangement from the sensor data of the Hall sensor using a corresponding main magnetic field map (B0 field map).The aforementioned DE 10 2016 203 255 A1 also describes an optimal measuring point, a so-called "sweet spot," at which the magnetic field strength of the main magnetic field is as dependent as possible on coordinates perpendicular to the longitudinal direction (Z direction) (X direction and Y direction). Such a "sweet spot" can also be advantageously utilized within the scope of the present invention, which will be discussed in more detail below.

[0022] It should be noted at this point that, since an at least essentially homogeneous main magnetic field exists inside the patient bed and especially in the field of view, this variant of position determination is not applicable there. However, by measuring with the magnetic field strength sensor outside the patient bed, where a spatially highly variable main magnetic field exists, a point whose position relative to the position of the local coil arrangement is known, in particular the local coil arrangement itself, can be specifically brought into the field of view of the magnetic resonance imaging system due to the known longitudinal position and controllable mobility of the patient bed.

[0023] In addition to the at least one magnetic field strength sensor, in particular a Hall sensor, an inclination sensor can preferably also be installed in the local coil arrangement as a measuring device. Such an inclination sensor can be used, in particular, to determine the orientation of the local coil arrangement, for example, with respect to the Earth's gravity, so that, despite symmetries of the main magnetic field, the pose, i.e., the position encompassing the orientation, can be determined in all six degrees of freedom, i.e., in the three spatial degrees of freedom (in particular X, Y, Z) as well as in the three orientation degrees of freedom (in particular, yaw, pitch, and roll angles). It is then possible to determine a six-dimensional pose as position information.

[0024] It should be noted at this point that, particularly in the case of local coil arrangements exhibiting asymmetry, for example with regard to the coil elements, a yaw angle of the local coil arrangement can also be expediently determined, in particular directly from the sensor data of the Hall sensor. This angle describes the horizontal orientation of the local coil arrangement, so that, for example, it can be determined whether an elongated local coil arrangement extends in the Z direction (longitudinal direction) or in the transverse direction (X direction), although intermediate orientations are also conceivable. In this way, the individual coil elements of the local coil arrangement can be particularly advantageously localized, which can also influence the selection of the approach position and thus the implementation of the recording information.However, both for the determination of a six-dimensional pose and for the yaw angle itself, knowing them can be of highly relevant benefit in the further process, especially with regard to measurement, as will be explained in more detail below.

[0025] To determine the position information, a position of the magnetic field strength sensor, in particular a Hall sensor, which was determined from its sensor data, can be corrected by a displacement of the magnetic field strength sensor from a coordinate origin of a local coil coordinate system of the local coil arrangement, in particular using orientation information determined by means of the at least one measuring means, for example by means of the magnetic field strength sensor and / or the inclination sensor, which describes the orientation of the local coil arrangement at least in the horizontal plane. Of course, in this context, the orientation, if it forms part of the position information, can also be corrected based on the known orientation of the magnetic field strength sensor relative to the local coil arrangement, in particular its local coil coordinate system.Thus, the position information then specifically describes the position of the coordinate origin of the local coil coordinate system.

[0026] For many local coil arrangements, such a local coil coordinate system, whose coordinates are often denoted by (U, V) in the plane in which the coil elements extend, is generally known. It is therefore advisable to use its coordinate origin as the location to which the position information refers. In particular, the coordinate origin of the local coil coordinate system can generally be chosen at the center of the local coil arrangement.

[0027] Since the magnetic field strength sensor, in particular the Hall sensor, is generally not located in the center of the local coil arrangement due to its design, its position, or thus the position of the coordinate origin, can be calculated using the known displacement between the coordinate origin and the magnetic field strength sensor. The control device implementing the method can be aware of the relevant information, for example, based on the coil information already mentioned. Identification of a local coil arrangement can occur, for example, by plugging it into a slot on the patient bed, so that corresponding coil information allowing identification of the coil is provided. A coil file containing further essential information about the local coil arrangement can be assigned to the coil information or identification information in a storage means of the control device.Alternatively, such a coil file can also be retrieved by the control device, for example, from a server. The coil file can store, for example, the location of the at least one magnetic field strength sensor and / or the at least one coil element in the coordinates of the local coil coordinate system (U, V).

[0028] Alternatively or in addition to the preferred embodiment with a magnetic field strength sensor installed in the local coil arrangement, other measuring devices can also be used within the scope of the present invention. For example, a 3D camera can be used as the measuring device. Such 3D cameras, for example terahertz cameras, have already been proposed in the prior art for measuring outside of the patient admission area and partially within the patient admission area and can also be used within the scope of the present invention, although in such a case, more complex data processing may be required.

[0029] A fundamental concept of the present invention is that the targeted placement of the local coil array and the corresponding skill of the user performing the placement provide clear indications of where to take the measurement. If the position information of the placed local coil array is measured, this information is also available in the control unit of the magnetic resonance imaging system and can thus be used to derive a positioning position for the patient bed and automatically move to it. In other words, it is even conceivable to automatically infer the acquisition information or suggestions for this from existing information or even to specify them.

[0030] In general, it can be said that the acquisition information describes the positioning of the local coil arrangement relative to the field of view directly or indirectly, in particular by mediating the patient's position on the patient couch and / or patient arrangement information describing the local coil arrangement. A number of possibilities exist in this regard.

[0031] In a particularly preferred embodiment of the present invention, it can be provided that the recording information is determined at least partially describing the positioning of the local coil arrangement center and / or the coordinate origin of the local coil coordinate system and / or of one of the at least one coil element, for example a partial coil, relative to the field of view, in particular in the field of view center. As already mentioned, the local coil arrangement center can correspond to the coordinate origin of the local coil coordinate system. However, the recording information can also refer to one of the partial coils of the local coil arrangement, if present, or even to a specific, individual coil element.This preferred specification of recording information is based on the assumption that an experienced user will optimally position a local coil arrangement for the intended measurement, in particular in such a way that the desired examination area of ​​the patient can be recorded in the field of view with the local coil arrangement in the field of view. In other words, it can be assumed that the local coil center of the local coil to be used is positioned so that it coincides with the intended field of view center (center point of the field of view). If the local coil arrangement is to be used as a whole, the local coil center refers to the center of the local coil arrangement, in particular the coordinate origin of the local coil coordinate system of the local coil arrangement. In the case of partial coils, the local coil center then refers to the corresponding partial coil as the local coil. This can therefore lead to corresponding shifts orOffsets with respect to the longitudinal position of the local coil arrangement contained in the position information occur with regard to their usefulness in determining the approach position.

[0032] While in a simple case the center of the local coil arrangement or local coil center can be assumed to be moved to the center of the field of view to determine the approach position, which represents an intuitive, easy-to-implement case, certain workflows or measurements or general recording situations may require other shifts to be taken into account, for example, if a local coil arrangement cannot be positioned precisely so that its center coincides with the center of the field of view for the measurement to be performed. In this case, corresponding longitudinal shifts can preferably be determined automatically using the approach context. In other words, to determine the approach position it can generally be assumed that the center of the local coil arrangement is to be placed in the center of the field of view, which results in a basic value for a displacement distance of the patient bed.The starting context now determines an applicable longitudinal displacement to this basic value, which in the simplest case is zero.

[0033] More generally, the approach position can be defined using a base value that describes the longitudinal distance of the local coil arrangement from the center of the field of view based on the position information and that is modified by a longitudinal shift. The longitudinal shift can be zero.

[0034] In a specific embodiment, it can be provided that when using multiple local coil arrangements arranged adjacently on the patient in a non-overlapping manner, when one of the local coil arrangements is intended to be used, a longitudinal displacement to be applied for the approach position is determined by means of a displacement relationship, in particular forming part of the approach relationship, depending on the provided coil information describing the local coil arrangements. This displacement relationship forms part of the approach relationship, by which one local coil arrangement is shifted in the longitudinal direction from an ideal position for the measurement due to the additional arrangement of the further local coil arrangement. In a specific example, for example, two local coil arrangements can be used: an abdominal local coil arrangement and a chest local coil arrangement. The abdominal local coil arrangement is placed above the abdomen, and the chest local coil arrangement is placed on the patient's chest.If the position information for both local coil arrays is known from the measuring device, and a measurement is now to be performed on the heart first, it can be determined that the chest local coil array, intended for cardiac measurements, could not be placed directly over the heart, as otherwise it would have to be placed overlapping with the abdominal local coil array. In such a case, the displacement relationship can, for example, specify a longitudinal displacement of +5 cm. However, numerous other specific examples are also conceivable in which such a displacement might make sense.

[0035] In this context, it is particularly useful if the displacement context is already integrated into the approach context. In this example, the additional information that the heart should be scanned first can be transferred as workflow information, from which the corresponding conclusions can be drawn automatically if two local coil arrangements of the corresponding type are present. For example, such cases can also be covered as an approach context in a look-up table.

[0036] Even independent of an integrated design with the starting context, it is also particularly useful for such shift contexts to provide them as a trained artificial intelligence shift function, thus determining them through machine learning. This can, of course, also be advantageously applied to a starting context in which at least one shift context is integrated, so that, for example, it can also contain a trained artificial intelligence start function instead of or in addition to a look-up table.

[0037] In addition to a direct reference to the local coil arrangement or a partial coil / coil element, as already mentioned, the recording information can also indirectly establish the reference to the local coil arrangement. For example, it can be provided that the recording information is at least partially descriptively determined as the recording information, a positioning of an anatomical feature and / or an anatomical region, in particular of its center, in the center of the field of view, derived in particular from an already known portion of the recording information. In other words, it can also be provided to place the center of a body region, for example the abdomen, or the center of an anatomical feature, for example an organ such as the heart, kidney, or lung, in the center of the field of view.The positioning of the local coil array can then be derived from patient arrangement information regarding the patient bed (and its known longitudinal position), since the relative position between the anatomical feature and / or the anatomical region and the local coil array can be derived. The aforementioned patient arrangement information can in some cases also be determined using a measuring device, for example, in the case of a 3D camera. However, it is preferable, for example, in the case of the magnetic field strength sensor as the measuring device, to derive or estimate the patient arrangement information in the simplest possible manner.

[0038] For example, to determine patient positioning information, it can be provided that patient information from a registration is evaluated. Patient information recorded during registration can, for example, include name and age, as well as height, weight and position, for example "head first prone". This takes advantage of the fact that patient couches often already provide aids for correct patient positioning, such as target positions for the head and / or feet / heels. For example, positioning of the head on a pillow or in a head coil can be specified. Corresponding reference positions can be specified on the foot side for "feet first" positions. Together with the patient's height and weight, this results in a good estimate of where and how the patient is positioned on the patient couch.The position of certain anatomical features and / or anatomical regions can therefore also be estimated with good quality.

[0039] Determining the patient arrangement information with respect to the patient bed is also expedient in other respects within the scope of the present invention, for example when the recording information is to be determined at least partially on the basis of a user input.

[0040] Thus, an advantageous development of the invention provides that patient arrangement information relating to the patient bed is determined or provided, wherein a, in particular schematic, representation of the relative positioning of the patient and the local coil arrangement and / or at least one coil element, in particular of the partial coils, of the local coil arrangement is generated from the patient arrangement information and the position information and output to an output means, wherein the recording information is determined at least partially from a user input related to the representation. In particular, a representation can thus be generated with the patient and the local coil arrangement, in particular against the background of the patient bed, which can particularly advantageously allow the recording information to be completely determined via a single operating action or, in the case of a confirmation, two operating actions.The user input also relates generally to the representation and can, for example, relate to the selection of the local coil arrangement center, the center of at least one coil element, in particular a partial coil, the center of an anatomical region and / or the center of an anatomical feature. The point selected accordingly in the user input can then be the point that is to be placed in the center of the field of view according to the acquisition information. The selection therefore allows a longitudinal displacement starting from the longitudinal position of the local coil arrangement to be determined according to the position information and to be taken into account accordingly when determining the approach position. If, for example, the local coil arrangement center is selected by the user input, the longitudinal displacement is zero, since the local coil arrangement center, which is expediently specified via the longitudinal position anyway, is to be moved to the center of the field of view.For partial coils, for example, the longitudinal displacement relative to the local coil arrangement center results directly from the coil information discussed above. Regarding the selection of the center of an anatomical region and / or an anatomical feature, a back calculation is generally conceivable if the respective longitudinal positions on the patient bed are known. In this case, a good estimate would be required with regard to the patient arrangement information, particularly as described above.

[0041] However, it is particularly advantageous to initially assume that the local coil arrangement has been correctly positioned for user input relating to an anatomical region and / or an anatomical feature, for example, an organ such as the heart, kidney, or lung. A longitudinal displacement can be derived from empirical values ​​or the like, as already discussed above generally regarding acquisition information and the displacement context, for example. An example, cardiac acquisition using two adjacent local coil arrangements, was already discussed above. It should be noted again that the dependencies of the longitudinal displacement for all supported workflows and local coil arrangements can also be managed integrated in a starting context, for example, using a special look-up table.

[0042] In principle, various variants are conceivable for the representation, for example comprising a selectable image of the local coil arrangement and / or its partial coils in relation to the patient, in particular taking into account a size of the patient, or as a selectable body region in relation to the patient, selected on the basis of the position information and in particular also coil information of the local coil arrangement.

[0043] Generally speaking, it can be provided that the display includes at least one current suggestion for the recording information and the user input relates to a confirmation or rejection of at least one of the at least one suggestion. In accordance with the above explanations, it can preferably be provided that at least one of the at least one suggestion is determined descriptively, the positioning of the local coil arrangement center and / or the coordinate origin of the local coil coordinate system and / or at least one of the at least one coil element in the field of view, in particular the field of view center. For example, in the case of several partial coils, the local coil center of each of these partial coils can be displayed as a suggestion. In the case of several local coil arrangements, these can also be displayed accordingly as a suggestion and can be confirmed.In this context, it is also conceivable that at least one of the at least one suggestion is determined by describing the positioning of an anatomical feature and / or an anatomical region, in particular its center, in the center of the field of view, derived in particular from an already known portion of the acquisition information. After confirmation of a suggestion, it can become acquisition information.

[0044] An input device can be used for user input. In a particularly advantageous embodiment of the present invention, the input device can be integrated with the output device. In particular, it can be provided that a touchscreen, particularly provided on a front side of the main magnet unit, is used as the output device, wherein the user input is determined comprehensively by a user interaction with the display on the touchscreen.For example, a schematic representation of the at least one local coil arrangement or its partial coils can then be generated as a representation, in particular superimposed as accurately as possible on a patient image based on the patient arrangement information. In this case, for example, by tapping the local coil arrangement as a whole, the user input can describe an arrangement of the local coil arrangement center or the coordinate origin of the local coil coordinate system in the center of the field of view, and accordingly for the partial coils. Interaction with anatomical regions and / or anatomical features is also conceivable in principle, as described above. In this way, the recording information can be defined particularly intuitively and easily, which then describes what is to be arranged in the center of the field of view and thus also the relative position of the center of the field of view to the local coil arrangement.Here, too, as already explained, a reference to the local coil arrangement or its coil elements / coil sections is particularly preferred, assuming that the local coil arrangement is positioned in such a way that the desired measurement can also be carried out.

[0045] In this way, a type of "Select & Go" is ultimately implemented, since, in a single operating step, which may be accompanied by a confirmation, the item to be placed in the center of the field of view can be selected—preferably the entire local coil array and / or one of several sub-coils provided by it. Since the position information provides the longitudinal position of the local coil array, a corresponding approach position can be easily determined, if the longitudinal displacement relative to the local coil array can be determined, and used to automatically position the patient bed.

[0046] In a particularly preferred development of the method according to the invention, it can be provided that, when using a Hall sensor as a measuring means for more precise positioning at the approach position by means of the Hall sensor, a previously known optimal measuring point in the longitudinal direction, at which the sensor data of the Hall sensor are least dependent on the position of the Hall sensor perpendicular to the longitudinal direction, is localized by means of the Hall sensor during the retraction of the patient bed into the patient receptacle, and the localization result is used to correct the position information and / or approach position. Such an optimal measuring point, as also discussed in DE 10 2016 203 255 A1, can also be referred to as a "sweet spot."If X, Y, and Z are used as the main directions, with the longitudinal direction corresponding to the Z direction, it can be said that the optimal measuring point is the Z position at which the smallest deviation from the main magnetic field measured as sensor data occurs for different X and Y positions. This also means, however, that the highest accuracy for determining the Z coordinates exists at this optimal measuring point, i.e. the "sweet spot." This accuracy can be higher than that determined for the Z coordinate of the position information. If this can be related to a corresponding longitudinal position of the patient bed, a corresponding correction of the longitudinal position of the local coil arrangement or the approach position derived from it is clearly possible.In other words, in this embodiment, the more precise determination of the position of the local coil array in the longitudinal direction (Z-direction) is based on the fact that when the patient bed with the local coil array is moved into the patient receptacle, the optimal measuring point, i.e., the "sweet spot," is passed, where the determination of the coordinate in the longitudinal direction is possible with a high degree of accuracy, for example, less than 3 mm. In a previous position outside the patient receptacle, this accuracy can be significantly lower, for example, in the range of 3 cm.

[0047] If a high-speed data connection, for example by means of a fiber optic cable, exists in the magnetic resonance device between the Hall sensor and the control device carrying out the method, and if the position of the patient bed in the longitudinal direction is also available at least essentially in real time, a direct comparison is possible: The longitudinal position of the patient bed at the time of passing through the optimal measuring point is immediately known, so that with the known longitudinal position of the optimal measuring point, the knowledge of the longitudinal position of the patient bed also at the time of recording the position information and the position of the patient bed at the time of passing through the optimal measuring point, comparable positions of the local coil arrangement or the Hall sensor on the patient bed are obtained, of which the higher reliability of the newer ones is known.so that the error can be identified and corrected accordingly.

[0048] However, in many known magnetic resonance systems, to which the method according to the invention is intended to be applicable, a slower communication connection, for example an I2C bus, exists between the local coil arrangement and thus the Hall sensor and the control device. In such an embodiment, it is proposed to establish synchronization between the longitudinal position of the patient bed and the passage through the optimal measurement point (measured longitudinal position of the local coil arrangement) over time.

[0049] In this case, an expedient embodiment of the present invention provides that, in order to localize the measuring point, when the patient bed starts moving, the Hall sensor is switched to a localization mode in which the main magnetic field is measured for each of a plurality of time steps and compared with a predetermined threshold value for the main magnetic field at the optimal measuring point, wherein the threshold value time, in particular as the time step number since activation at which the threshold value is exceeded, is stored, wherein at the end of the movement of the patient bed, the localization mode is ended and the total time of the localization mode, in particular as the number of time steps, is stored, wherein the localization result is determined from the threshold value time and the total time. In this case, it is assumed in the present considerations that, as is usual, the patient bed is moved at a constant speed.At the beginning of the patient bed's movement, the three-dimensional Hall sensor is switched to localization mode, which can also be referred to as "sweet-spot search mode." When the patient bed stops, this localization mode is deactivated. In localization mode, the three-dimensional Hall sensor does not transmit any data, but instead measures the main magnetic field and compares it with a threshold value that corresponds to the measured value of the main magnetic field strength at the optimal measurement point. This threshold value depends on the specific design of the magnetic resonance imaging system, in particular the field strength of the main magnetic field, and can be determined, for example, through simulations or measurements.Once the threshold has been found with sufficient accuracy, the corresponding time and, in particular, the corresponding sensor data are stored in the three-dimensional Hall sensor, in particular in a memory device of a microcontroller of the Hall sensor, along with the number of elapsed time steps, which can then be, for example, microcontroller ticks. After the start time and end time of the localization mode, i.e., the total time of the localization mode by difference, have also been stored, it is now possible, in particular, to calculate a ratio as the time steps to the optimal measurement point (i.e., threshold time minus start time) divided by the total time (also in time steps). This ratio can be transmitted to the control device upon completion of the localization mode.This in turn makes it possible to determine on the control device which lying position was present at a corresponding ratio times the total time measured there.

[0050] In this case, it can be specifically provided that a control device of the magnetic resonance device, which controls the Hall sensor and the patient bed, also measures a total time of the movement of the patient bed as well as the start position and the end position of the patient bed, wherein after completion of the movement, a threshold position of the patient bed assigned to the threshold time is determined from the total time on the Hall sensor side, the threshold time, the total time on the control device side and the start and end positions and, together with a threshold position of the Hall sensor, in particular measured by the Hall sensor and / or assumed as the longitudinal position of the measuring point, is used to correct the position of the local coil arrangement on the patient bed and the position information and / or the approach position therefrom.In one variant, however, it is also possible for the position of the patient couch to be logged regularly, for example, 30 times per second, as it is moved into the patient receptacle. This creates a longitudinal position profile of the patient couch in the control unit. From this profile, the threshold position of the patient couch associated with the threshold time can easily be determined, even if the ratio or threshold time and the corresponding total times are known. In all of these cases, even if real-time calibration is not possible, a position of the local coil arrangement or the Hall sensor on the couch can be determined, once at a position with higher measurement accuracy and once at a longitudinal position with lower measurement accuracy. This allows the value at the measurement position with higher measurement accuracy to be used for correction or, in general, to more accurately approach the approach position.For example, the difference between these relative positions of the local coil array to the patient bed can be understood as a correction value to be applied to the approach position (and, if applicable, also to the position information). However, the approach position can also be directly updated using the current position information of the "sweet spot." For example, if the approach context determines a longitudinal shift relative to the base value (displacement distance of the local coil array center to the field of view center), this can simply be applied to the current, precisely determined displacement distance.

[0051] To further increase accuracy, it can also be provided that a threshold position of the Hall sensor assigned to the threshold time is determined, in particular by interpolation with a discretely known main magnetic field profile and / or between time steps. In a rougher approximation, the (previously known) longitudinal position of the optimal measuring point can also be assigned to the threshold time as the threshold position of the Hall sensor, or the threshold time can be corrected by interpolation between at least one main magnetic field strength measurement before the threshold is exceeded and at least one main magnetic field strength measurement after the threshold is exceeded to more accurately describe the optimal measuring point.However, the preferred variant is that the actual distance of the measured optimal measuring point to the center of the field of view, which is usually used as a reference, is determined from the magnitude of the flux density at the optimal measuring point.

[0052] Regardless of whether such a suggested correction is performed using an optimal measurement point, the patient bed stops at the corresponding approach position and the measurement of the magnetic resonance data can begin. In an advantageous development of the method according to the invention, the position information can also be advantageously used for other purposes while performing the measurement or during the measurement.

[0053] As already mentioned, it can be provided that the measuring device determines the complete three-dimensional position and / or the complete three-dimensional orientation of the local coil arrangement, in particular the complete six-dimensional pose of the local coil arrangement, as position information, especially when a Hall sensor and an inclination sensor are installed in the local coil arrangement. At least parts of the position information, in particular the entire position information, are measured, as already mentioned, before entering the patient admission area, for example, in the case of the Hall sensor, since this would no longer be able to detect sufficient differences in the homogeneity volume.Nevertheless, based on the position information measured outside of the patient scan, a current longitudinal position of the local coil array can always be derived by using the change in the longitudinal position of the patient bed for updating. Corresponding position feedback from the patient bed is usually already available in the control unit of the magnetic resonance imaging system. Thus, even at the approach position, the current location of the local coil array, in particular the coordinate origin of the local coil coordinate system, and / or the orientation of the local coil array is known.

[0054] Such a more detailed determination of the position information can, in particular, initially allow workflow information that more precisely describes the magnetic resonance data measurement to be performed to be automatically determined. For example, it can be provided that the position information is evaluated to automatically determine at least one piece of workflow information, in particular an examination region to be acquired and / or a laterality. User input is then no longer required for this workflow information, which further simplifies and accelerates operation. In this case, it can again be assumed that the operator positions the local coil arrangement appropriately for the acquisition. For example, with conventional procedures, a laterality must often be specified for organs or anatomical features that are present on both sides of the patient, i.e. whether the image should be acquired from the left or right, or even both.For example, when imaging the hip, it is possible to choose whether the left hip, the right hip, or both hips should be imaged. However, the determination of position information now also allows the laterality to be determined automatically, so that, for example, only user confirmation is required. For example, if the local coil arrangement (or a partial coil to be used) is positioned more toward one side of the patient, it can be concluded that the measurement should be taken there. A similar approach can be used for other workflow information.

[0055] Based on a complete position determination and, if applicable, orientation determination, it can be expediently provided that, for recording a localizer at the beginning of the measurement, the center of the localizer is placed on the current local coil arrangement center or, depending on off-center information relating to the subsequent measurement of the magnetic resonance data, which describes a displacement of an examination region of interest of the patient from the center of view, an offset for the center of the localizer from the local coil arrangement center is determined in at least one spatial direction using an offset relationship. A localizer, usually recorded at the beginning of a measurement on a patient, can, for example, comprise three orthogonal slices, wherein the center of the localizer is then given in particular by their intersection point.As already mentioned, the center of the local coil array corresponds in particular to the coordinate origin of the local coil coordinate system and / or to the determined three-dimensional spatial position of the local coil array. For examinations in the center of the field of view, the center of the localizer is intended to be located in this field of view. However, there are also so-called off-center measurements, for example, in examinations of shoulders or knees, for which it may be desirable to position the center of the localizer differently. Previously, a user had to manually intervene in the localizer settings, which was time-consuming.

[0056] In this case, however, it can be exploited that information about additional, in particular all six, degrees of freedom of the local coil pose (in particular the X coordinate, Y coordinate, Z coordinate, yaw angle, roll angle, and pitch angle) is available. The position of the localizer can then be automatically changed so that manual correction is unnecessary and the measurement is accelerated. In the simplest case, the current three-dimensional position of the local coil arrangement, when placed in the center of the field of view, can be assigned to the center of the localizer. If the approach position was determined such that the current position of the local coil arrangement lies outside the center of the field of view, the corresponding longitudinal displacements are known, so that the center of the localizer can also easily be placed in the center of the field of view.

[0057] However, more complex cases are also conceivable, where only a portion of the coordinates are adopted, or even offsets are provided for all three spatial coordinates. For example, when examining shoulders and / or knees, it is useful to provide a corresponding offset for the corresponding shoulder or knee in the horizontal direction perpendicular to the longitudinal direction, i.e., for example, the X-direction. Generally speaking, depending on the workflow, especially depending on an acquisition protocol, offsets can be estimated that automatically shift the center of the localizer from the center of the field of view.Such special features of a current workflow, in particular a recording protocol, describe the offset information from which, in this exemplary embodiment, an offset for the center of the localizer in at least one spatial direction can be determined using an offset relationship, in particular relative to the local coil arrangement center, but optionally relative to the field of view center, whose relative position to the local coil arrangement center in the approach position is known. The offset relationship can be based, for example, on empirical values, whereby the offset relationship can also be stored integrally as part of the approach relationship. In particular, the offset relationship can comprise a trained artificial intelligence offset function that was trained using machine learning. In summary, in this embodiment, optimal positioning of the localizer can be carried out automatically.

[0058] In another advantageous use of further position information, here in particular the six-dimensional pose, it can be provided that the six-dimensional pose of the local coil arrangement is used to select coil elements to be used in the measurement, wherein coil elements located in the field of view and / or that do not overlap in the physical gradient axes and / or logical gradient axes of the magnetic resonance device are selected for measurement. In other words, the position information about the three spatial coordinates and the orientation, in particular the pitch angle, yaw angle, and roll angle, is used in this embodiment to automatically select the coil elements of the local coil arrangement to be used for the measurement, in particular the coil elements to be used to receive magnetic resonance signals.In this regard, it has already been proposed in the prior art to select those coil elements for reception whose longitudinal coordinates lie within the field of view, if the position of the local coil arrangement in the longitudinal direction is known (see, for example, US 2008 / 0211502 A1). Using the information in the other two spatial directions and for orientation, reception elements can also be selected and / or deselected (deactivated) depending on their further spatial coordinates, for example, the X-coordinate and / or the Y-coordinate. Deselected elements are particularly useful when coil elements of the local coil arrangement overlap, for example, in the horizontal transverse direction (X-direction), which would lead to poorer image quality due to coupling.Due to the six-dimensional pose in the position information, especially together with the coil information already mentioned, this problem can be solved automatically by deselecting and deactivating problematic coil elements, thus achieving improved image quality.

[0059] In this context, it should also be noted that the embodiments just mentioned for using position information related to at least three orthogonal spatial axes, in particular together with orientation information, in the localizer positioning and the selection of coil elements, in particular for reception, can also be used advantageously independently of the main subject matter of this disclosure described by claim 1, namely determination and automatic approach to the approach position.

[0060] In addition to the method, the invention also relates to a magnetic resonance device, comprising a control device and a main magnet unit with a particularly cylindrical patient receptacle, wherein a field of view of the magnetic resonance device, which is defined by the homogeneity of a main magnetic field generated by a main magnet of the main magnet unit, lies within the patient receptacle, and wherein a patient bed is movable along a longitudinal direction of the patient bed for positioning the patient in the patient receptacle, wherein the magnetic resonance device further comprises at least one local coil arrangement with at least one coil element for measuring magnetic resonance data, which is freely positionable on the patient bed and / or a patient to be measured at least with respect to the longitudinal direction, and a measuring means for detecting the position of the local coil arrangement positioned for the measurement at least in the longitudinal direction,wherein the control device comprises: - a measuring unit for determining position information of the local coil arrangement with the measuring means when the patient bed is at least partially outside the patient receiving area, - a determination unit for determining recording information that describes a positioning of the local coil arrangement relative to the field of view, and - a positioning unit for automatically positioning the patient bed in the longitudinal direction at a starting position determined from the position information and the recording information.

[0061] All statements regarding the method according to the invention can be applied analogously to the magnetic resonance device according to the invention, with which the aforementioned advantages can also be achieved. It is particularly preferred if the measuring means comprises a magnetic field strength sensor installed in the local coil arrangement and / or an inclination sensor installed in the local coil arrangement, in particular provided in addition to the magnetic field strength sensor.

[0062] The control device is configured to carry out the method according to the invention and can, in particular, comprise at least one processor and at least one memory means. Functional units are implemented in the control device by hardware and / or software, which may include further functional units in addition to the measuring unit, the determination unit, and the positioning unit. For example, a generally known sequence unit can be provided for carrying out the measurement, in particular also the localizer acquisition, of the magnetic resonance data. A display unit can generate and output a display, as described, for which purpose the magnetic resonance device can comprise an output means. The magnetic resonance device can furthermore also comprise an input means for receiving user input. The output means and the input means can particularly advantageously be combined as a touchscreen.Further conceivable functional units of the control device comprise a correction unit, in particular for correction using the optimal measuring point, wherein a corresponding design of the sequence unit can be carried out with regard to the described localizer positioning and / or coil element selection.

[0063] A computer program according to the invention can be loaded directly into a storage means of a control device of a magnetic resonance device and has program means for carrying out the steps of a method according to the invention when the computer program is executed on the control device of the magnetic resonance device. The computer program can be stored on an electronically readable data carrier according to the present invention, which thus comprises control information comprising at least one computer program according to the invention and is designed such that, when the data carrier is used in a control device of a magnetic resonance device, the device is designed to carry out the method according to the invention.

[0064] Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawings. These show: Fig. 1 a flow chart of an embodiment of the method according to the invention, Fig. 2 a schematic diagram of a local coil arrangement with a Hall sensor installed therein, Fig. 3 a possible display on a touchscreen, Fig. 4 a schematic sketch of a patient bed moving into a patient reception area, Fig. 5 a diagram explaining the time synchronization for locating an optimal measuring point, Fig. 6 a sketch of the interpolation regarding the optimal measuring point, Fig. 7 a magnetic resonance device according to the invention, and Fig. 8 the functional structure of a control device of the magnetic resonance device.

[0065] Fig. 1 shows a flowchart of an exemplary embodiment of the method according to the invention. This assumes a situation at a magnetic resonance system with a cylindrical patient receptacle, in which a patient is positioned on the patient bed while the patient couch is still at least partially outside the patient bed, just as at least one local coil arrangement to be used for a measurement on the patient has already been positioned in the correct position on the patient bed and / or the patient. This means that the at least one local coil arrangement is freely positionable at least in the longitudinal direction of the patient bed, which also corresponds to the longitudinal direction of the patient bed and thus to the Z direction of the magnetic resonance system. The horizontal direction perpendicular to the longitudinal direction is the X direction, and the vertical direction perpendicular to the Z direction is the Y direction.In this situation, a positioning position for the patient bed must be selected that is as optimal as possible for measuring magnetic resonance data from a corresponding examination area of ​​the patient. The requirements for a user of the magnetic resonance system, for example, a medical assistant operating the magnetic resonance system, should be kept as low as possible, and it is assumed that at least one local coil arrangement on the patient and / or the patient bed is positioned sensibly and relatively precisely, so that it ultimately already provides a clear indication of where the measurement should be taken.

[0066] In the exemplary embodiment illustrated here, in a step S1, position information of the local coil arrangement is first determined using at least one measuring device. In this case, the position information comprises all three spatial coordinates and three orientation angles—in this case, a pitch angle, a roll angle, and a yaw angle—which relate to the coordinate system of the magnetic resonance device. This coordinate system of the magnetic resonance device relates to the Z-axis in the longitudinal direction, the X-axis in the X-direction, and the Y-axis in the Y-direction. In this exemplary embodiment, its coordinate origin is in the center, i.e., the midpoint, of the field of view—in this case, the homogeneity volume of the main magnetic field of the magnetic resonance device.In this case, the position information refers to the coordinate origin of the local coil coordinate system of the local coil array, which in this case coincides with the center of the local coil array. The coordinates of the local coil coordinate system are denoted by (U, V).

[0067] The measuring devices used here are at least one Hall sensor, which measures the main magnetic field strength, and an inclination sensor, which are installed in the local coil arrangement. This is achieved by Fig. This is explained in more detail in Figure 2, which shows a schematic diagram of a local coil arrangement 1 already positioned on a patient bed 2 extending in the longitudinal direction 3 (Z-direction). The local coil arrangement 1 comprises several coil elements 4 arranged in a matrix, which form one or more local coils (sub-coils). Using a coil cable 5, the local coil arrangement 1 can be connected to a socket 6 of the patient bed 2.

[0068] A Hall sensor 8 and an inclination sensor 9 are installed in the local coil arrangement 1 as measuring devices 7. The three-dimensional Hall sensor 8 is designed to determine position coordinates and orientation information based on the known profile of the main magnetic field strength, whereby any remaining uncertainties can be clarified using the inclination sensor 9, for example, with regard to symmetries of the main magnetic field. For the basic principle of the Hall sensor 8 and the associated inclination sensor 9, reference is made to the aforementioned DE 10 2016 203 255 A1. It is evident that the Hall sensor 8 is not installed in the center 10 of the local coil arrangement, which also serves as the coordinate origin of the local coil coordinate system 11, but is arranged offset.In order to provide position information related to the local coil arrangement center 10, the offset 12 is taken into account accordingly, which can be done by the Hall sensor 8 itself or by a control device of the magnetic resonance device carrying out the method.

[0069] In this context, it should be noted that identification of the local coil arrangement 1, as is generally known in the prior art, can occur by inserting the plug 13 into the slot 6. For example, a coil file containing further coil information can be present, assigned to the local coil arrangement 1, in a storage medium of the control device or retrievable by the control device. The coil information can, for example, describe the position of the coil elements 4 in the local coil coordinate system 11 as well as the position of the Hall sensor 8 in the local coil coordinate system 11 and thus the offset 12. Furthermore, the coil information can also contain a type of local coil arrangement 1 (e.g., abdominal coil, phased array coil from knee to chest, or the like) as well as the position of sub-coils to be used as separate local coils.

[0070] In other embodiments, a 3D camera or similar can alternatively or additionally be used as measuring means 7.

[0071] While it is fundamentally conceivable to specify recording information, for example, the content that the local coil arrangement center 10 should be located in the center of the field of view for the measurement, or to determine it automatically, for example, from already available workflow information for the measurement, it has proven expedient to consider user input, which can be queried on a reliable basis using the position information. Therefore, in a next step S2 (see Fig. 1) a representation to be output on an output means is determined, which shows the local coil arrangement 1 and, if applicable, its partial coils formed by coil elements 4 in relation to the patient and the patient bed 2, for which purpose patient arrangement information and the coil information already discussed (with regard to the partial coils and their corresponding local coil center) are also used.

[0072] The patient arrangement information ultimately describes the position of the patient on the patient couch 2 and can already be deduced with sufficient accuracy from the patient information obtained during registration. This takes advantage of the fact that the patient couch can have predefined desired or even mandatory positions for certain patient parts, in particular the head and heels. For example, it is common practice to request that the patient's head be placed on a special head cushion and / or within a permanently mounted head coil for "head first" positioning. Corresponding positions, for example recesses, can also be used for the foot area for "feet first" positioning, for example a heel cushion and / or a suitable recess for placing the heels.Assuming correct positioning here, information on the location of certain anatomical features and / or regions can be obtained from the patient's height, weight, and possibly also their gender and / or age, within an acceptable estimate. Since acceptable patient arrangement information, which describes the relative position of the patient to the patient bed 2, as well as the position information, which describes a relative position of the local coil arrangement 1 to the patient bed 2 via the current longitudinal position of the patient bed 2, which is present in the control device or can be retrieved, are thus known, a representation 14, for example, can be generated as shown in FIG. Fig. 2 is shown.

[0073] A touchscreen 17 is used as the output means 15 and the combined input means 16. This touchscreen is provided on the front side of the magnetic resonance system from which the patient bed 2 is moved into the main magnet unit, more precisely the patient receptacle. The representation 14 clearly contains, in addition to a schematic representation 18 of the main magnet unit, also schematically the patient bed 2, the local coil arrangement 1, and the patient 19 according to the patient arrangement information. From the coil information, a button 20 indicated with a precise location for the local coil arrangement center 10 as well as buttons 21 arranged with a precise location relative to the respective local coil center for selecting partial coils were added. The buttons 21 can, of course, also be omitted if the local coil arrangement 1 provides only a single local coil.

[0074] By interacting with buttons 20, 21, a user can now select whether the entire local coil array 1 or one of its subcoils formed by coil elements 4 should be used to measure the magnetic resonance data and should be positioned accordingly in the center of the field of view. After a confirmation, if required, corresponding acquisition information is generated (local coil center of a subcoil or local coil array center 10 should be placed in the center of the field of view). Buttons 20, 21 and the associated positioning instructions can be understood as suggestions.

[0075] This approach to determining the recording information, which relates to the local coil arrangement 1 and, if applicable, its partial coils, is preferred because the position information, if applicable together with the coil information, which describes the local coil center of a partial coil relative to the local coil arrangement center 10, can be at least substantially sufficient to easily define the approach position for the patient couch 2. In simple cases in which no longitudinal displacements, which will be discussed in more detail below, need to be taken into account, the approach position results from the offset of the local coil arrangement center 10 or the local coil center of a selected partial coil in the longitudinal direction 3 relative to the field of view center.If, as is usual, the longitudinal position or, more specifically, the longitudinal coordinate in the magnetic resonance device coordinate system is already related to the coordinate origin in the center of the field of view, when selecting the local coil arrangement center 10 in such simple cases, the required displacement distance and thus the approach position can ultimately simply be read from the position information as the longitudinal position of the local coil arrangement 1, following the instruction of the acquisition information.

[0076] However, embodiments are also conceivable in which a reference to the anatomy of the patient 19 can be derived through interaction with the representation 14. For example, it can be selected via the representation 14 that the center of an anatomical region, for example the abdomen, and / or an anatomical feature, for example an organ such as the heart, kidney, lung, and the like, is to be placed in the center of the field of view in the longitudinal direction, in which case a corresponding longitudinal displacement can then also be expediently derived.

[0077] Furthermore, it should be pointed out again at this point that it is not absolutely necessary to work with a representation 14, but this is preferred in order to provide flexibility for the user. In particular, for example when using a single local coil arrangement 1 with only a single local coil, it can also be automatically assumed that this is positioned relative to the desired examination region of the patient 19 such that, for optimal measurement conditions of the magnetic resonance data, the center of the local coil arrangement 10 is to be placed in the center of the field of view. Furthermore, additional available workflow information can already provide an indication, when a selection option is available between local coil arrangements 1 or partial coils, as to which should be placed in the center of the field of view for the subsequent measurement step. This can also be offered as a suggestion to be confirmed in the representation 14.An actual selection can then, for example, be limited to cases in which it is actually unclear which local coil or local coil arrangement 1 is to be used.

[0078] Furthermore, it should be noted that other operating elements, information and the like can of course also be displayed on the touchscreen 17 with the display 14.

[0079] For example, it is conceivable, particularly when determining the six-dimensional pose of the local coil arrangement 1, to also automatically determine workflow information and output it for confirmation in the display 14. Thus, the desired laterality can be deduced from the arrangement of the local coil arrangement with respect to the X-direction (horizontal transverse direction) (e.g., left lung, right lung, or both in the case of central positioning).

[0080] The recording information and the position information, optionally with additional use of the coil information and / or workflow information and / or patient information, are used in a start-up context to determine the start-up position for the patient couch 2 in a step S3 (cf. Fig. 1). The starting context may, for example, comprise a look-up table stored in a memory means of the control device, but may also be implemented at least partially in another way, for example using a trained starting function of artificial intelligence and / or other mathematical (formula) relationships.

[0081] In this case, to determine the approach position, it is generally assumed that the local coil array center 10 is to be placed in the center of the field of view. In other words, when selecting the coordinate systems as described above, the longitudinal position of the local coil array 1 could easily define the required displacement distance. The approach context then determines an applicable longitudinal displacement for this base value, which in the simplest case is zero. If a specific subcoil has been selected, the corresponding longitudinal displacement (of the associated local coil center relative to the local coil array center 10) is simply derived from the coil information.These variants are based on the assumption that an experienced user optimally positions the local coil array 1 for the intended workflow, for example, an acquisition protocol, so that the local coil center or local coil array center 10 is positioned in alignment with the intended field of view center. This scenario is intuitive and therefore easy to implement for all users.

[0082] However, workflows are also conceivable in which other reasons for longitudinal shifts from the base value may exist, which can be taken into account accordingly via the approach context, communicated in particular as workflow information. An example case for such a necessary additional longitudinal shift always arises when positioning the local coil arrangement center 10 or the local coil center of the partial coil exactly over the intended examination region of the patient 19 is not possible, but this intended examination region must be placed in the center of the field of view. This can occur when multiple local coil arrangements 1 are used, for example in the case of two local coil arrangements 1 being placed on the patient 19 in the torso region, one being placed over the abdomen and the second on the chest. The second local coil arrangement 1 can be intended for a cardiac measurement.The position information and the coil information are known for both local coil arrangements 1. If the anatomical feature of the heart or the second local coil arrangement 1 is selected to determine the acquisition information, it may be that the second local coil arrangement 1 is not positioned exactly over the heart (in the longitudinal direction 3) because the local coil arrangements 1 cannot be placed overlapping. Empirical values ​​show that a longitudinal shift of 5 cm relative to the heart results. The approach context then provides this longitudinal shift for determining the approach position. The use of machine learning to determine at least part of the approach context can be useful, especially for mapping such empirical values ​​in certain situations.

[0083] The now in Fig. 1, is optional and relates to increasing the accuracy of determining the longitudinal position of the local coil arrangement 1 by means of the measuring device 7 comprising the Hall sensor 8. This takes advantage of the fact that an optimal measuring point ("sweet spot") exists in the main magnetic field of the magnetic resonance device, at which the measured value of the main magnetic field strength, which can be stored in the control device as a threshold value, in particular along with its longitudinal position relative to the center of the field of view, varies only very slightly with the X and Y positions, in particular varies minimally. This allows for extremely precise determination of the longitudinal position, i.e., the Z coordinate. For example, an accuracy of less than 3 mm can be achieved.Therefore, it is proposed for step S4 that when the patient couch 2 is moved into the patient receptacle, with the local coil arrangement 1 being moved through the optimal measuring point, this measuring point be located and the now more accurate measurement be used to determine the approach position more precisely, thus correcting it compared to the previous determination.

[0084] This situation explains the illustration in Fig. 4 in more detail, which schematically shows the moment at which the Hall sensor 8 is located at the optimal measuring point 23, which is indicated in a magnitude curve 24 of the main magnetic field strength, during a movement of the patient couch 2 from a starting position 22 to an end position. Typically, this optimal measuring point 23 is located shortly before entering the patient receptacle 25 of the main magnet unit 26. The end position 27 shown here, by way of example, is the center 28 of the field of view 29 of the magnetic resonance device, wherein the longitudinal position of the patient couch 2 in the longitudinal direction 3 present or retrievable in the control device refers to the front edge 30 of the patient couch 2.If it is now known where the Hall sensor 8 is located when passing through the optimal measuring point 23 to the center of the field of view 28 (distance S) and, at the same time, the longitudinal position of the front edge of the patient bed 2 to the center of the field of view 28 at this time (distance O) is also known, the longitudinal distance ZH between the Hall sensor 8 and the front edge 30 of the patient bed 2 (and, with the known arrangement of the Hall sensor 8 in the local coil arrangement 1, also the relative longitudinal position of the local coil arrangement 1 to the front edge 30 of the patient bed 2) is simply given by ZH = S - O. Since the longitudinal position of the patient bed 2 was already known when determining the position information in step S1, the corresponding relative longitudinal positions can, for example, be compared in order to derive a correction; on the other hand, a correction is also possible by directly applying the newly, more precisely measured longitudinal position of the local coil arrangement 1.

[0085] Thanks to the clever choice of end position 27 as the field of view means 28, the highly accurately determined relative longitudinal position of the local coil arrangement 1 on the patient table 2 can then be used as a base value for the final approach to the more precisely determined approach position, with the longitudinal displacement, if different from zero, possibly also being added. Clearly, various concrete options for implementing an increase in accuracy when approaching the approach position are possible and can be used in the method presented here.

[0086] Given a high-speed data connection, for example, a fiber optic and / or an infrared connection, between the control device and the Hall sensor 8, it is fundamentally conceivable to locate the longitudinal position of the patient bed 2 associated with the passage of the optimal measuring point 23 in real time. However, in the present case, a slower data connection is assumed, for example, an I2C bus from the control device to the local coil arrangement 1 and thus to the Hall sensor 8. It is then proposed to carry out the longitudinal synchronization between the patient bed 2 and the Hall sensor 8 over time. For this purpose, it is proposed to switch the Hall sensor to a localization mode at the beginning of the movement of the patient bed 2 from the start position 22 to the end position 27, which is then deactivated again when the patient bed 2 stops at the end point 27.In localization mode, the Hall sensor 8 does not send any data, but merely measures the main magnetic field and compares it with the threshold value for the corresponding magnetic resonance device, i.e. the main magnetic field measurable at the optimal measuring point (see also magnitude curve 24). The measurements of the main magnetic field are carried out in time steps, for example at 30 measurements per second. The time step can correspond to the internal ticks of a microcontroller of the Hall sensor 8. If the threshold value is exceeded for the first time during a measurement in a time step, the time step as well as the measured value of the main magnetic field for this time step are stored in a memory of the microcontroller as the threshold time. The start and end times of the localization mode are also stored in microcontroller ticks. This and the synchronization over time are achieved by . Fig. 5 is explained in more detail.

[0087] The left side 31 relates to the control device, the right side 32 to the Hall sensor 8. The arrows 33 running from top to bottom each symbolize the passage of time, for example, in absolute seconds for the control device, and in microcontroller ticks for the Hall sensor. Arrow 34 symbolizes a control signal for starting the localization mode from the control device to the Hall sensor 8. This confirms the start of the localization mode according to arrow 35. Arrow 36 symbolizes the control signal for stopping the localization mode. During the active localization mode, measurements are taken at time steps 37 symbolized by dots until the threshold value is exceeded in a time step 38, meaning the optimal measuring point 23 is passed.The task now is to find the corresponding time and the associated longitudinal position of patient bed 2 as the threshold position of the patient bed, indicated here as an example by a point 39.

[0088] A total time in ticks of the microcontroller can now be determined for the Hall sensor 8 from the start time and the end time. A value proportional to the threshold time of time step 38 can be determined as the ratio of the time up to time step 38 in ticks to the total duration in ticks. Since the ticks are found in the numerator and denominator, the ratio is dimensionless and always lies in the interval [0...1]. This ratio parameter is sent as a response from the Hall sensor 8 to the control unit of the magnetic resonance imaging system, as indicated by arrow 40.

[0089] The ratio, applied to the total time measured by the control device, now makes it possible to determine time 39 on the control device. If the longitudinal position of the patient table was recorded there, for example, with 30 queries per second, the longitudinal position of the patient table 2 assigned to time step 38 can be directly determined from this range of motion of the patient table 2 as the longitudinal position of the patient couch 2 assigned to time 39 corresponding to the threshold time as the threshold position in the movement sequence.

[0090] However, it may also be sufficient to know only the starting position 22 and the end position 27, since then, with the known, constant longitudinal speed of the patient couch 2, the corresponding longitudinal position of the patient couch can of course also be determined via the ratio.

[0091] In this context, it should be noted that for the greatest possible accuracy, since the threshold value and thus the optimal measuring point 23 at time step 38 are usually not exactly reached, the longitudinal position is determined precisely in the usual manner provided in the Hall sensor 8. It is also possible to interpolate more precisely when the optimal measuring point 23 was passed, see. Fig. 6, where the magnitude curve 24 with the measuring grid for the time step 38 and the preceding time step 37 are shown, namely the determined longitudinal position 41 and the magnitude 42 of the main magnetic field at the time step 38 as well as the determined longitudinal position 43 and the measured magnitude 44 of the main magnetic field at the time step 37 immediately preceding the time step 38. The position of the threshold value 45 is also shown. By interpolation, its longitudinal position 46 can then be interpolated with high precision and compared with the stored value for the optimal measuring point 23 or, when determining the ratio, a corresponding fraction between the time step 38 and the immediately preceding time step 37 can be used as the threshold time.

[0092] In a step S5, the optionally more precisely determined approach position is then approached.

[0093] However, the position information can optionally also be used during the measurement of the magnetic resonance data or to set measurement parameters for the measurement of the magnetic resonance data.

[0094] In step S5, at the beginning of the magnetic resonance data acquisition, a localizer is first measured. This localizer comprises three mutually perpendicular slices and allows for the planning of additional measurement slices or, in general, measurement volumes. Typically, the three orthogonal slices intersect at the center of the field of view 28. However, a different position of the localizer may be appropriate for some workflows, particularly acquisition programs, especially for off-center measurements (e.g., of the shoulders or knees). For example, offsets for the center of the localizer may then be required.Since the position information relates to all six degrees of freedom of the local coil arrangement position—namely, the X coordinate, Y coordinate, Z coordinate, yaw angle, roll angle, and pitch angle—by means of the measuring means 7, in particular the use of the inclination sensor 9, it can also be used to automatically change the position of the localizer's center point so that the user does not have to correct it manually and the magnetic resonance data can be measured more quickly. In principle, the local coil arrangement center 10, optionally modified by the longitudinal displacement, can also be used for the localizer's center point.However, if off-center information is available indicating that the measurement is off-center, workflow-dependent offsets for the center of the localizer from the local coil arrangement center 10 can be determined in at least one spatial direction using an offset relationship, for example, for the X direction, the Y direction, and the Z direction (longitudinal direction 3). Of course, this assumes the current local coil arrangement center 10 at the approach position.

[0095] In a step S7, the position information can also be used to select the coil elements of the local coil array to be used to receive magnetic resonance signals. In this case, the coil elements that are located in the field of view 29 and do not overlap with another coil element in one of the main directions are preferably selected. For example, overlaps in the X, Y, and Z directions can be checked. In this way, the position information can also be used to optimize image quality.

[0096] Fig. Figure 7 shows a schematic diagram of a magnetic resonance system 47 according to the invention. This system comprises, as is generally known, the main magnet unit 26, in which a particularly superconducting main magnet 48 is installed to generate the main magnetic field. The main magnet unit defines the cylindrical patient support 25 and, due to the homogeneity of the main magnetic field, the field of view 29 with the field of view center 28, which in this case coincides with the center of the patient support 25. A radio-frequency coil arrangement 49 (body coil) and a gradient coil arrangement 50 with gradient coils for the X, Y, and Z directions can also be provided surrounding the patient support 25. The magnetic resonance system 47 further comprises the patient bed 2 and the at least one local coil arrangement 1. The operation of the magnetic resonance system 47 is controlled by the aforementioned control device 51.This also communicates with the output means 15 and the input means 16, in particular implemented as the touchscreen 17. The magnetic resonance device 47 can of course also comprise further components not shown in detail here, for example a cooling device, gradient amplifiers and the like.

[0097] The control device 51 is designed to carry out the method according to the invention. Fig. 8 shows the functional structure of the control device 51 in more detail. This first comprises a storage means 52, in which, for example, the starting relationship with the integrated displacement relationship, as well as optionally the offset relationship, can be stored. For example, the aforementioned relationships can be provided as a common, large look-up table; however, they can also include trained functions and the like.

[0098] As is generally known, the control device 51 further comprises a sequence unit 53, which controls the recording operation, thus the measurement operation for magnetic resonance data, of the magnetic resonance device 47. In the present case, the sequence unit 53 is also particularly suitable for carrying out steps S6 and S7 according to Fig.1. To implement the method according to the invention, the control device 51 further comprises a measuring unit 54 for controlling the measuring means 7, in particular the Hall sensor 8, so that the position information (step S1) can also be determined by the measuring unit 54. In a determination unit 55, the recording information can be determined according to step S2 and step S3. An optional correction unit 56 is designed to carry out step S4, thus increasing the accuracy of the approach position based on the optimal measuring point 23. A positioning unit 57 is designed to automatically determine the approach position from the position information and the recording position using the approach context and then transfers this approach position to a bed control unit 58, which takes over the general control of the patient bed 2.In other words, the positioning unit 57 and the bed control unit 58 are jointly designed to carry out step S5.

[0099] To handle the output of the representation 14 as well as user inputs, a display unit 59 is also provided with which the representation 14 can be generated and which can also generally serve as an input-output control unit.

[0100] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

[1] A computer-implemented method for operating a magnetic resonance device (47), comprising a main magnet unit (26) with a particularly cylindrical patient receptacle (25), wherein a field of view (29) of the magnetic resonance device (47), which is defined by the homogeneity of a main magnetic field generated by a main magnet (48) of the main magnet unit (26), is located within the patient receptacle (25), and a patient bed (2) for positioning the patient (19) in the patient receptacle (25) is movable along a longitudinal direction (3) of the patient bed (2), wherein at least one local coil arrangement (1) with at least one coil element (4) for measuring magnetic resonance data is freely positionable on the patient bed (2) and / or a patient (19) to be measured, at least with respect to the longitudinal direction (3), the method comprising the following steps: - with the patient bed (2) located at least partially outside the patient support (25) and after positioning the local coil arrangement (1), determining position information that describes the position of the local coil arrangement (1) on the patient bed (2) at least in the longitudinal direction (3) with a measuring means (7), wherein a magnetic field sensor, in particular a Hall sensor (8), installed in the local coil arrangement (1) is used as the measuring means (7), wherein the complete three-dimensional position and the complete three-dimensional orientation of the local coil arrangement (1) are determined as position information by the measuring means (7), and wherein a six-dimensional pose of the local coil arrangement (1) is used to select coil elements (4) to be used in the measurement,wherein coil elements (4) lying in the field of view (29) and / or not overlapping in the physical gradient axes and / or logical gradient axes of the magnetic resonance device (47) are selected for measurement, - determining recording information that describes a positioning of the local coil arrangement (1) relative to the field of view (29), and - automatic positioning of the patient couch (2) in the longitudinal direction (3) at an approach position determined from the position information and the recording information. [2] Method according to claim 1, characterized by that the recording information is determined at least partially describing the positioning of the local coil arrangement center (10) and / or the coordinate origin of the local coil coordinate system (11) and / or at least one of the at least one coil element (4) relative to the field of view (29), in particular in the field of view center (28). [3] Method according to claim 2, characterized by that when using several local coil arrangements (1) which are to be arranged adjacently on the patient (19) in a non-overlapping manner, when one of the local coil arrangements (1) is intended to be used, a longitudinal displacement to be used for the approach position, by which the one local coil arrangement (1) is displaced in the longitudinal direction (3) from an ideal position for the measurement due to the additional arrangement of the further local coil arrangement (1), is determined by means of a displacement relationship as a function of the provided coil information describing the local coil arrangements (1). [4] Method according to one of the preceding claims, characterized bythat patient arrangement information relating to the patient bed (2) is determined or provided, wherein a representation (14) of the relative positioning of the patient (19) and the local coil arrangement (1) and / or at least one coil element (4), in particular the partial coils, of the local coil arrangement (1) is generated from the patient arrangement information and the position information and is output to an output means (15), wherein the recording information is determined at least partially from a user input related to the representation (14). [5] Method according to claim 4, characterized by that the display (14) comprises at least one current suggestion for the recording information and the user input concerns a confirmation or rejection of at least one of the at least one suggestion. [6] Method according to claim 4 or 5, characterized bythat a touchscreen (17) is used as output means (15), wherein the user input is determined by comprehensively determining an interaction of the user with the display (14) on the touchscreen (17). [7] Method according to one of the preceding claims, characterized by that when using a Hall sensor (8) as a measuring means (7) for more precise positioning at the approach position by means of the Hall sensor (8) during the retraction of the patient couch (2) into the patient receptacle (25) by means of the Hall sensor (8), a previously known optimal measuring point (23) in the longitudinal direction (3) in which the sensor data of the Hall sensor (8) are least dependent on the position of the Hall sensor (8) perpendicular to the longitudinal direction (3) is localized and the localization result is used to correct the position information and / or approach position. [8] Method according to claim 7, characterized byin that, in order to localize the measuring point (23), when the patient bed (2) starts moving, the Hall sensor (8) is switched into a localization mode in which the main magnetic field is measured for each of a plurality of time steps (37, 38) and compared with a predetermined threshold value (45) for the main magnetic field at the optimal measuring point (23), wherein the threshold value time, in particular as a time step number since activation at which the threshold value (45) is exceeded, is stored, wherein at the end of the movement of the patient bed (2) the localization mode is ended and the total time of the localization mode, in particular as a number of time steps (37, 38), is stored, wherein the localization result is determined from the threshold value time and the total time. [9] Method according to one of the preceding claims, characterized byin that, in order to record a localizer at the beginning of the measurement, the center point of the localizer is placed on the current local coil arrangement center (10) or, depending on off-center information relating to the following measurement of the magnetic resonance data, which describes a displacement of an examination region of interest of the patient (19) from the field of view center (28), an offset for the center point of the localizer from the local coil arrangement center (10) in at least one spatial direction is determined by means of an offset relationship. [10] Magnetic resonance device (47), comprising a control device (51) and a main magnet unit (26) with a particularly cylindrical patient receptacle (25), wherein a field of view (29) of the magnetic resonance device (47), which is defined by the homogeneity of a main magnetic field generated by a main magnet (48) of the main magnet unit (26), is located within the patient receptacle (25), and a patient bed (2) for positioning the patient (19) in the patient receptacle (25) is movable along a longitudinal direction (3) of the patient bed (2), wherein the magnetic resonance device (47) further comprises at least one local coil arrangement (1) with at least one coil element (4) for measuring magnetic resonance data, which is freely positionable on the patient bed (2) and / or a patient (19) to be measured at least with respect to the longitudinal direction (3),and a measuring means (7) for detecting the position of the local coil arrangement (1) positioned for the measurement at least in the longitudinal direction (3), wherein a magnetic field sensor, in particular a Hall sensor (8), installed in the local coil arrangement (1) is used as the measuring means (7), and wherein the measuring means (7) determines the complete three-dimensional position and the complete three-dimensional orientation of the local coil arrangement (1) as position information, and wherein a six-dimensional pose of the local coil arrangement (1) is used to select coil elements (4) to be used in the measurement, wherein coil elements (4) lying in the field of view (29) and / or non-overlapping in the physical gradient axes and / or logical gradient axes of the magnetic resonance device (47) are selected for measurement, wherein the control device (51) comprises: - a measuring unit (54) for determining position information of the local coil arrangement (1) with the measuring means (7) when the patient bed (2) is at least partially located outside the patient receiving area (25), - a determination unit (55) for determining recording information which describes a positioning of the local coil arrangement (1) relative to the field of view (29), and - a positioning unit (57) for automatically positioning the patient bed (2) in the longitudinal direction (3) at a starting position determined from the position information and the recording information. [11] Computer program which carries out the steps of a method according to one of claims 1 to 9 when it is executed on a control device (51) of a magnetic resonance device (47). [12] An electronically readable data carrier on which a computer program according to claim 11 is stored.

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