Device and method for supporting the shimming of a magnetic resonance apparatus

Abstract

The invention relates to a magnetic resonance apparatus comprising at least one sensor, wherein the magnetic resonance apparatus can be positioned in an examination room and wherein the at least one sensor constitutes a means for determining a spatial position of the magnetic resonance apparatus in the examination room. The invention further relates to a method for supporting an adjustment of shim parameters of a magnetic resonance apparatus, the method having the steps of determining a current spatial position of the magnetic resonance apparatus in the examination room by means of the at least one sensor and adjusting a shim parameter of at least one shim element of the magnetic resonance apparatus depending on the current spatial position of the magnetic resonance apparatus in the examination room and information of a magnetic field database, wherein the magnetic field database comprises information about spatial positions of the magnetic resonance apparatus and magnetic field data associated with the spatial positions.

Description

Technical Field

[0001] This invention relates to a magnetic resonance imaging (MRI) device, the MRI device including at least one sensor, wherein the MRI device can be positioned in an examination chamber, and wherein the at least one sensor constitutes a means for determining the spatial position of the MRI device in the examination chamber. The invention also relates to a method for supporting the adjustment of shimming parameters of the MRI device. Background Technology

[0002] The existence of a uniform magnetic field is a fundamental prerequisite for multiple magnetic resonance imaging (MRI) devices. Magnetic field inhomogeneity can originate from the magnets of the MRI device, but it can also be caused by external influences, such as (electro)magnetic fields and / or electromagnetic dispersions in the environment. The structural materials of the building housing the MRI device can also be an external influence negatively affecting the uniformity of the MRI device's magnetic field. To ensure high-quality imaging, the magnetic field in an MRI device typically needs to be adjusted. Different methods, also known as "shimming," are used here. These methods employ shimming elements, such as thin iron sheets and / or electronic shimming coils, to obtain a master magnetic field that is as uniform as possible.

[0003] For example, the main magnetic field of a magnetic resonance imaging (MRI) device can be linearly compensated in three spatial directions by adjusting the current through the gradient coils of the MRI machine. However, it is equally feasible to use separate shimming coils to compensate for higher-order inhomogeneities. Instead, iron plates are typically mounted at predetermined locations on the MRI machine. In principle, the magnetic field can be set very precisely by selecting the number, location, and / or orientation of the iron plates. Setting the magnetic field by mounting iron plates is a known service method typically performed during the initial installation of an MRI system.

[0004] Known shimming methods are based on the premise that the magnet of the MRI scanner is located at a fixed point within the examination room. Even in the case of MRI scanners with variable positions, such as those that can be moved by means of a ceiling suspension device, a uniform magnetic field is only obtained at the location where the shimming method is performed. This is a significant drawback for MRI scanners where the magnet position can be set according to the patient's body region and / or the imaging examination being performed within the examination room. Summary of the Invention

[0005] Therefore, the object of the present invention is to support the adjustment of the shimming parameters of the shimming element in a magnetic resonance device with variable position.

[0006] According to the present invention, the objective is achieved through the subject matter of embodiments of the invention. Advantageous implementations and improvements that achieve the objective are the subject matter described below.

[0007] The magnetic resonance device according to the present invention includes at least one sensor.

[0008] The magnetic field of a magnetic resonance device can in particular be the static main magnetic field (B0 field) of the magnetic resonance device, which is provided by the main magnet of the magnetic resonance device.

[0009] Magnetic resonance imaging (MRI) devices can be positioned within an examination room. Positioning the MRI device can particularly include changing the spatial location of the MRI device relative to the examination room. The spatial location of the MRI device is preferably characterized by its position within the examination room, for example, by multiple coordinates and / or orientation in a coordinate system formed by the examination room. It is also conceivable that the location of the MRI device is determined by the position of the center of gravity of the MRI device or its magnets. Furthermore, the location can also be determined by the external profile of the MRI device, the patient accommodation area, and / or isocenter. Additionally, the spatial location preferably includes information regarding the orientation of the MRI device and / or its magnets. The orientation of the MRI device and / or the magnets can be characterized, for example, by the direction of the magnetic field and / or by the orientation of the patient accommodation area relative to a flat reference plane of the examination room. The examination room can be any space in which the MRI device is housed and / or in which imaging examinations of the patient can be performed using the MRI device.

[0010] At least one sensor in a magnetic resonance imaging (MRI) device constitutes a means for determining the spatial position of the MRI device within the examination chamber. The at least one sensor can have any measurement principle constituting the determination of the position and / or orientation of the MRI device. Examples of suitable sensors are optical sensors, such as 3D cameras, infrared cameras, 2D cameras, and laser spacing sensors, but also non-optical sensors, such as incremental encoders, absolute encoders, angle sensors, ultrasonic spacing sensors, Hall effect sensors, inductive spacing sensors, capacitive spacing sensors, etc. In a preferred embodiment, the MRI device has multiple sensors constituting a means for determining the spatial position of the MRI device within the examination chamber. The at least one sensor can also be understood as a control device for a motor that can trigger a predetermined movement of the motor. For example, the MRI device may have a stepper motor with multiple switches, which are switched sequentially by the control device to generate rotation of the stepper motor. The number and / or speed of the switching processes of the multiple switches can be considered here to determine the rotational speed or feed of the stepper motor. However, it is also conceivable that the control device is a measuring device for the current absorbed by the motor. The movement generated by the motor can, for example, be associated with the current absorption per time step. In this case, the motion generated by the motor can be determined based on the current absorption per time step.

[0011] External influences, such as the structural materials of the examination room building and the location and / or characteristics of equipment and / or machinery near the MRI device, can undesirably affect the uniformity of the magnetic field of the MRI device. By providing an MRI device with at least one sensor according to the invention, the spatial location of the MRI device can be determined. By means of the spatial location of the MRI device and the correlation of the magnetic field associated with said spatial location, the external influences on the magnetic field can be advantageously quantified in a position-related manner. Thus, the determination of the adjustment of the shimming parameters of the shimming elements of the MRI device can be advantageously supported. Furthermore, the spatial location of the MRI device that has undesirable and / or increased interactions between the magnetic field and external components can be determined and avoided during imaging examinations.

[0012] In one embodiment, the magnetic resonance device according to the invention has a positioning device configured to change the spatial position of the magnetic resonance device.

[0013] The positioning device is preferably designed to position and / or orient the magnetic resonance imaging (MRI) device and / or the magnets of the MRI device according to the patient's position, posture, and / or body region. For example, the positioning device may be configured to set the height and / or tilt angle of the magnets of the MRI device in the examination room, so as to position the MRI device from an examination of the knee region of a first patient to an examination of the head region of a second patient. It is conceivable that the positioning device has a track system, a telescopic system, and / or a hinge.

[0014] Changing the spatial position of an MRI scanner can include movement of the scanner by means of at least one, two, three, or four degrees of freedom. The positioning device may, for example, have a track system configured to position the MRI scanner along a first axis. The track system may also be configured to position the MRI scanner along a second axis. Here, the first and second axes may be arranged perpendicularly to each other in a plane oriented substantially orthogonal to the direction of gravity. The MRI scanner can also be positioned along any trajectory curve within the plane of the first and second axes. It is also conceivable that the positioning device has a telescopic element or another track element configured to position the MRI scanner along a third axis. The third axis may here be oriented perpendicular to the first and second axes and / or substantially parallel to the direction of gravity. Therefore, the MRI scanner can be positioned in a three-dimensional manner within the examination chamber along the first, second, and third axes.

[0015] The positioning device may also have joints and / or hinges that constitute the orientation of the magnetic resonance device. Orientation setting may in particular include rolling, pitching, and / or yaw of the magnetic resonance device, i.e., rotation of the magnetic resonance device and / or magnet units about a first axis, a second axis, and / or a third axis. Changing the spatial position of the magnetic resonance device preferably includes movement of the magnetic resonance device in four, five, or six degrees of freedom by means of the positioning device.

[0016] By providing positioning equipment, the spatial location of the MRI machine can be matched to any area of ​​the patient's body. This allows imaging examinations to be performed on patients in a seated or standing position who are experiencing anxiety or claustrophobia, thereby enabling improved patient cooperation during the imaging examination.

[0017] In another embodiment of the magnetic resonance device according to the invention, at least one sensor is an optical sensor, wherein the optical sensor is configured to detect optical data, the optical data including an indication of the spatial position of the magnetic resonance device in the examination chamber.

[0018] Optical sensors can be configured to determine the spatial position of the magnetic resonance imaging (MRI) device within the examination room using the photoelectric effect. For example, optical sensors can be designed as 3D, 2D, and / or infrared cameras configured to detect image data of the MRI device within the examination room. Similarly, it is conceivable that the optical sensor is a laser spacing sensor. A laser spacing sensor can be configured, for example, to determine the distance from the outline of the MRI device or the wall of the examination room. The MRI device preferably has multiple optical sensors, which can be mounted at predetermined locations on the MRI device and / or in the examination room. It is also conceivable that multiple optical sensors are positioned at different locations on the MRI device and / or in the examination room to determine the spatial position of the MRI device according to different measurement directions. The MRI device may have a computing unit configured to process signals from the multiple optical sensors. In a preferred embodiment, the optical sensors or multiple optical sensors are also used for patient positioning, patient motion recognition, and / or local coil positioning.

[0019] Optical sensors can be advantageously used to identify patients and / or local coils, thereby expanding the functionality of MRI equipment without requiring additional components. Furthermore, the use of optical sensors allows for precise and reproducible determination of the spatial position of the MRI equipment within the examination room.

[0020] In another embodiment of the magnetic resonance device according to the invention, at least one sensor is designed as a position encoder, wherein the position encoder is configured to detect position data, the position data including indications of position changes and / or angle changes of the magnetic resonance device.

[0021] A position encoder can be configured to output a signal proportional to the position of the encoder along a measurement path. For example, a position encoder can be positioned at a servo drive and / or motor. In particular, a position encoder can be configured to determine positional and / or angular changes transmitted to a magnetic resonance device and / or magnet, such as horizontal movement, vertical movement, tilting, and / or rotation. Similarly, it is conceivable that a position encoder is positioned along the motion path of the magnetic resonance device and configured to determine the segments traversed by the magnetic resonance device and / or magnet. The position encoder can here be configured as an incremental encoder or an absolute encoder. For example, a position encoder can have a sliding contact, optical scanning, photoelectric scanning, magnetic scanning, interferometric scanning, inductive scanning, capacitive scanning, gear encoder, etc. In a preferred embodiment, the magnetic resonance device has multiple position encoders, for example, positioned at different servo drives and / or different motion paths of the magnetic resonance device and / or magnet. However, the starting or ending position of a segment of the path of the motor or magnetic resonance device, detected by the motor of the magnetic resonance device, can also be understood as a position encoder.

[0022] Position encoders offer a cost-effective solution for determining the spatial position of magnetic resonance imaging (MRI) devices. Furthermore, costly image processing methods, such as those associated with optical sensors, can be avoided in position encoders.

[0023] In another embodiment, the magnetic resonance device according to the invention includes at least one shimming element, said at least one shimming element constituting a magnetic field for adjusting the magnetic resonance device (10) according to shimming parameters, wherein the shimming element is designed as follows:

[0024] • Shim coil,

[0025] • A uniform thin sheet with ferromagnetic material, and / or

[0026] Ferrofluids.

[0027] At least one shimming element can be configured to interact with the magnetic field of a magnetic resonance device to alter the characteristics of the magnetic field, particularly its strength and / or direction. In particular, the at least one shimming element can be made of a material that manipulates or modifies the magnetic field. Examples of such materials are primarily ferromagnetic materials, such as solids having a fraction of iron or ferrofluid. For example, the shimming parameters of a ferromagnetic shimming element can be its spatial position and / or orientation.

[0028] Furthermore, the shimming element can constitute a magnetic field superimposed on the magnetic field of the magnetic resonance device. Such a shimming element can, in particular, be a shimming coil, such as a superconducting coil or a resistance coil. The shimming coil is typically circulated by a current to generate a magnetic field. The shimming parameter of the shimming coil can be, for example, the current flowing through the shimming coil. In a preferred embodiment, the magnetic resonance device has multiple shimming elements. The multiple shimming elements can include at least 5, at least 10, at least 20, at least 40, or at least 80 shimming elements. It is also conceivable that the magnetic resonance device has different shimming elements, such as iron-based shimming sheets, shimming coils, and / or shimming elements with ferromagnetic fluids.

[0029] The shim can have any shape, such as a rod, cuboid, oval, or homeomorphic shape. Preferably, the shim is made of a ferromagnetic material, such as iron, cobalt, nickel, and certain lanthanide elements, gadolinium, etc. However, it is also conceivable that the shim may be an alloy composed of a ferromagnetic material and additional non-ferromagnetic filler material.

[0030] The ferrofluid preferably contains ferromagnetic nanoparticles, which are present as a liquid, particularly a solution, suspension, or emulsion. The magnetic resonance device preferably includes a delivery device configured to move and / or change the volume of the ferrofluid within the magnetic resonance device to adjust the magnetic field of the device. The shimming parameters of the ferrofluid may, in particular, include the level of the ferrofluid in a reservoir and / or the operating time of the delivery device. In a preferred embodiment, the magnetic resonance device has multiple shimming plates and multiple shimming coils.

[0031] In a preferred embodiment, the magnetic resonance apparatus is configured to compensate for changes in external influences on the magnetic field of the magnetic resonance apparatus when its spatial position changes, by means of adjusting the shimming parameters of at least one shimming element. For this purpose, the computational and / or control units of the magnetic resonance apparatus may be configured to adjust the shimming parameters of at least one shimming element according to a magnetic field database, as described below.

[0032] By adjusting the shimming parameters of the shimming elements, the inherent inhomogeneities of the magnetic field and / or undesirable effects on the magnetic field of the magnetic resonance imaging (MRI) device can be advantageously compensated. In particular, by providing multiple shimming elements, higher-order magnetic field inhomogeneities can be compensated. Thus, the quality of the MRI images obtained in the MRI examination can be advantageously improved. Specifically, by dynamically adjusting the shimming parameters of the shimming elements, the following inhomogeneities in the magnetic field of the MRI device, which arise due to external influences when the spatial position of the MRI device changes, can also be compensated.

[0033] The method for adjusting the shimming parameters for supporting a magnetic resonance imaging device according to the present invention comprises the following steps:

[0034] • The current spatial position of the MRI machine in the examination room is determined using at least one sensor, and

[0035] • Adjust the shimming parameters of at least one shimming element of the magnetic resonance imaging (MRI) device based on the current spatial position of the MRI device in the examination chamber and information from a magnetic field database, wherein the magnetic field database includes information about the spatial position of the MRI device and magnetic field data associated with the spatial position.

[0036] A magnetic field database can include any data structure that enables the organization, linking, association, and / or storage of data and / or values. The data structure is particularly suitable for applying mathematical operations to data and / or values. Examples of suitable data structures are tuples, arrays, vectors, matrices, tables, sets, etc. The magnetic field database includes at least information about the spatial location of the magnetic resonance imaging (MRI) device and information about the magnetic field of the MRI device. Here, the information about the spatial location of the MRI device can be linked to and / or associated with the information about the magnetic field.

[0037] It is conceivable that the magnetic resonance imaging (MRI) device and / or the magnets of the MRI device are matched to the patient's body region for imaging examination. The spatial position of the MRI device matched to the patient can correspond to the current spatial position of the MRI device. However, it is also conceivable that the current spatial position of the MRI device may change independently of the imaging examination, for example, during maintenance, calibration, start-up, etc. Determining the current position of the MRI device in the examination room is preferably based on the signal from at least one sensor. The at least one sensor is preferably configured according to the embodiment of the MRI device according to the invention described above.

[0038] The current spatial position of the magnetic resonance imaging (MRI) device, determined by at least one sensor, is particularly used to adjust the shimming parameters of at least one shimming element. For example, the current spatial position of the MRI device may substantially correspond to a spatial position in a magnetic field database for which magnetic field data has been determined according to the embodiments described above. In this case, the shimming parameters of at least one shimming element can be adjusted based on the magnetic field data already detected for the spatial position. However, it is also conceivable that the current spatial position of the MRI device may not correspond to a spatial position in the magnetic field database. In this case, methods for estimation, calculation, averaging, interpolation, etc., can be applied to determine the magnetic field at the current spatial position of the MRI device based on previously detected magnetic field data from other spatial positions. The shimming parameters and / or at least one shimming element can, for example, be designed according to the embodiments of the MRI device according to the invention described above.

[0039] By adjusting the shimming parameters based on a magnetic field database and the current position of the magnetic resonance imaging (MRI) device, the costly process of determining the uniformity of the magnetic field at the current spatial position of the MRI device prior to imaging can be advantageously avoided. Furthermore, the method according to the invention allows for the time-efficient setting of the shimming parameters of at least one shimming element. Therefore, it is conceivable that the adjustment of the shimming parameters can be performed dynamically, i.e., either during preparation for imaging and / or during the imaging procedure.

[0040] According to one embodiment, the method according to the present invention further comprises the following steps:

[0041] Orienting the MRI equipment within the examination room's spatial location.

[0042] • Detect magnetic field data of the magnetic resonance imaging (MRI) device at the designated spatial location.

[0043] • Information about the spatial orientation of the magnetic resonance imaging device is stored together with the detected magnetic field data in a magnetic field database.

[0044] Orientation of the MRI device in the examination room can be achieved, in particular, by means of a positioning device according to an embodiment of the MRI device described above according to the invention. The positioning device can be configured to move the MRI device along at least one first axis. The MRI device can preferably be positioned along multiple axes, such as two or three perpendicular axes, by means of the positioning device. The perpendicular axes can be movable relative to each other, enabling three-dimensional movement of the MRI device in the examination room. It is also conceivable that the MRI device is supported in a tiltable and / or rotatable manner about at least one axis so that the orientation of the MRI device matches the patient and / or the imaging examination. Orientation of the MRI device in space can here be performed manually by the user, semi-automatically or fully automatically by means of remote control. Orientation of the MRI device in space can particularly include setting the position and / or orientation of the MRI device and / or the magnets of the MRI device.

[0045] Magnetic field data for detecting the magnetic field of a magnetic resonance imaging (MRI) device at a oriented spatial location can be obtained, for example, by means of a magnetometer. Specifically, the magnetometer can be introduced into the image recording area of ​​the MRI device to detect magnetic field data from within that area. Alternatively, the magnetic field data can be detected by the receiving unit of the MRI device. For this purpose, a volume of reference material, such as water or oil, can be introduced into the image recording area of ​​the MRI device and excited by means of a predetermined excitation pulse. The received magnetic resonance signal from the reference material can then be analyzed by means of the receiving unit to obtain information about the magnetic field strength and / or direction. Analyzing the received magnetic resonance signal from the reference material can particularly include comparing the desired magnetic resonance signal from the reference material with the received magnetic resonance signal.

[0046] Information regarding the spatial orientation of the magnetic resonance imaging (MRI) device, along with the detected magnetic field data, is stored in a magnetic field database, preferably on the storage unit of the MRI device using a computing unit. However, the magnetic field database can also be stored using a cloud computer and / or on a storage unit in the cloud. Preferably, the spatial position and magnetic field data of the MRI device are stored in the form of a data structure according to the embodiments described above in the method according to the invention. Information regarding the spatial position may in particular include position data. This position data preferably includes coordinates, angles, and / or dimensions describing the position and / or orientation of the MRI device.

[0047] By providing a magnetic field database, inhomogeneities of the magnets in an MRI scanner can be advantageously detected or mapped at multiple spatial locations, as can external influences on the magnetic field. Furthermore, the database can be used to inform the user of the MRI scanner of the presence of external influences on the magnetic field. This allows for the advantageous avoidance of spatial locations of the MRI scanner with particularly high external influences on the magnetic field during imaging examinations.

[0048] In another embodiment of the method according to the invention, the orientation and magnetic field data of the magnetic resonance device are repeatedly detected at multiple spatial locations in the examination room.

[0049] Here, magnetic field data is preferably recorded for one spatial location out of a plurality of spatial locations of the magnetic resonance imaging (MRI) device. When storing the magnetic field database, each spatial location of the MRI device is associated with the associated magnetic field data. It is conceivable that magnetic field data detection is performed for at least two, three, four, or five spatial locations of the MRI device. However, it is also conceivable that the number of spatial locations for which magnetic field data is detected is greater than five or greater than ten.

[0050] By measuring magnetic field data at multiple spatial locations of a magnetic resonance imaging (MRI) device, the external influences on the MRI's magnetic field can be characterized using the desired spatial resolution. This allows for the advantageous prior determination of magnetic field inhomogeneities at predetermined measurement locations within the MRI device, and their consideration when adjusting the shimming parameters.

[0051] According to another embodiment of the method according to the invention, the orientation of the magnetic resonance device is determined according to a predetermined grid, wherein the predetermined grid has a plurality of points defining the permissible spatial location of the magnetic resonance device in the examination chamber.

[0052] The predetermined grid is preferably matched to the examination chamber. This can mean that the predetermined grid discretizes the volume of the examination chamber in an equidistant or non-equidistant manner. For example, the predetermined grid has multiple volumes uniformly distributed across the examination chamber, which can be occupied by the MRI device. Similarly, it is conceivable that the predetermined grid has multiple points distributed within the examination chamber, at which the isocenter of the MRI device can be located by means of a positioning device. In a preferred embodiment, the predetermined grid takes into account the geometry of the examination chamber and / or the already occupied volume of the examination chamber. This can mean that the predetermined grid only considers the spatial location of the MRI device that allows for its positioning without collision with the examination chamber and / or objects within it. This spatial location can also be considered as the permissible spatial location of the MRI device.

[0053] By using a predetermined grid, the ratio of the examination chamber's coverage to the number of spatial locations of the MRI scanner can be maximized in an advantageous manner. Consequently, the external influence of the MRI scanner's magnetic field on all permissible spatial locations within the examination chamber can be characterized in a particularly efficient manner.

[0054] In another embodiment, the method according to the invention further includes the following steps:

[0055] • Determine (S7) at least one additional spatial location of the magnetic resonance device in relation to the analysis of the magnetic field uniformity at at least one spatial location based on the magnetic field database, and perform steps S1, S2 and S3 for said at least one additional spatial location.

[0056] Uniformity analysis can be performed using a computational unit based on algorithms or functions. The analysis of magnetic field uniformity is preferably performed by comparing multiple measurements of the magnetic field strength and / or multiple measurements of the magnetic field direction, said multiple measurements being detected together with magnetic field data for at least one spatial location of the magnetic resonance imaging (MRI) device. The multiple measurements of magnetic field strength may include at least one first measurement of magnetic field strength and at least one second measurement of magnetic field strength. Correspondingly, the multiple measurements of magnetic field direction may include at least one first measurement of magnetic field direction and at least one second measurement of magnetic field direction. The first and second measurements of magnetic field strength and / or magnetic field direction are preferably detected at different locations within the image recording area of ​​the MRI device. It is also conceivable that the first and second measurements are detected substantially simultaneously within a single measurement range and / or at a constant spatial location of the MRI device. Magnetic field uniformity can be characterized, in particular, by the spatial distribution of multiple measurements of magnetic field direction, for example, by the spatial distribution of the first measurement of magnetic field direction, the second measurement of magnetic field direction, but also possibly other measurements of magnetic field direction. Therefore, magnetic field uniformity can be understood as the spatial distribution of the magnetic field direction of the magnetic field. Uniformity here may include the spatial distribution of the magnetic field direction of the magnetic field at at least one spatial location. However, it is also conceivable that uniformity also takes into account the spatial distribution of magnetic field directions at one or more adjacent spatial locations.

[0057] It is conceivable that when analyzing the homogeneity of a magnetic field, regions with irregularities are identified, where the distribution density of magnetic field data detected by the MRI device at multiple spatial locations increases within these irregular regions. Irregularities can specifically represent regions where a first and second measurement of magnetic field strength and / or a first and second measurement of magnetic field direction deviate from each other by a predetermined degree. Furthermore, irregularities can be characterized by deviations and / or sign changes between the first and second measurements of magnetic field direction. For example, irregularities can be local curvature and / or local gradients of the magnetic field direction. It is also conceivable that analyzing the homogeneity of a magnetic field includes determining the causes of the irregularities. For example, the homogeneity of a magnetic field can be characterized by repeatedly detecting magnetic field data at multiple spatial locations within the examination chamber using the MRI device. Here, external influences on the homogeneity of the magnetic field of the MRI device can differ from the inherent inhomogeneity of the magnet. The inhomogeneity of the magnet can be substantially independent of the spatial location of the MRI device and thus can be distinct from external influences. By determining at least one additional spatial location of the magnetic resonance device and orienting the magnetic resonance device in at least one additional spatial location, detecting magnetic field data of the magnetic field of the magnetic resonance device in at least one additional spatial location, and storing information about the oriented spatial location of the magnetic resonance device together with the detected magnetic field data in a magnetic field database, for example, the magnetic resonance device can be extended and / or further resolved at spatial locations where irregularities are analyzed, such as the predetermined grid or multiple points of the predetermined grid.

[0058] By increasing the distribution density of the detected magnetic field data in an environment with irregularities, it is possible to characterize, in particular, the local and / or location-dependent interactions of the magnetic field with external influences. Consequently, the desired magnetic field can be advantageously determined with high precision for such regions as well.

[0059] In another embodiment of the method according to the invention, determining the current spatial position of the magnetic resonance imaging device in the examination room by means of at least one sensor includes:

[0060] • Detect optical data, which includes an indication of the current spatial position of the magnetic resonance imaging (MRI) device in the examination chamber, and / or

[0061] • Detect position data, which includes indications of changes in the position and / or angle of the magnetic resonance device.

[0062] At least one sensor may be designed, in particular, as an optical sensor and / or position encoder according to an embodiment of the magnetic resonance apparatus according to the invention described above. Preferably, the optical data and / or position data of at least one sensor are transmitted to the computing unit of the magnetic resonance apparatus. The computing unit may be configured to process the optical data and / or position data to determine the current spatial position of the magnetic resonance apparatus. In one example, at least one sensor is a 3D camera that detects image data of the magnetic resonance apparatus in the examination chamber and transmits it to the computing unit. The computing unit may, in particular, have an image processing unit that processes the image data from the 3D camera and determines the current position of the magnetic resonance apparatus in the examination chamber based on the image data. However, it is also conceivable that at least one sensor may have a 2D camera, an infrared camera, multiple 2D cameras, multiple 3D cameras, and / or multiple position encoders.

[0063] Position encoders and / or optical sensors can also be used to identify the position of the magnetic resonance imaging (MRI) device, the patient, and / or local coils and other medical devices at the patient's location. By using at least one sensor multiple times for different functions of the MRI device, the number of components can be minimized and / or the cost of technically implementing the method according to the invention can be reduced in an advantageous manner.

[0064] In another embodiment, the method according to the invention further comprises the following steps:

[0065] • The desired magnetic field is determined using a function based on the current spatial location of the magnetic resonance imaging (MRI) device and information from the magnetic field database.

[0066] The shimming parameters of at least one shimming element are adjusted in relation to the desired magnetic field.

[0067] In the described embodiment, the current spatial location of the magnetic resonance device may differ from the spatial location in the magnetic field database. Here, the function can have any algorithm to determine the desired magnetic field at the current spatial location based on the magnetic field of at least one nearest spatial location in the magnetic field database. It is also conceivable that the function determines the desired magnetic field based on two, three, or more spatial locations having corresponding magnetic field data in the magnetic field database. For this purpose, averaging methods, interpolation methods, extrapolation methods, adjustment methods, etc., can be used, for example. The desired magnetic field can, in particular, be an approximation of the magnetic field actually present at the current spatial location. The information in the magnetic field database is preferably characterized at least by measurements of the magnetic field at the spatial location.

[0068] By using the function and the magnetic field database according to the invention, the desired magnetic field at any current location of the magnetic resonance imaging (MRI) device can be advantageously approximated. This advantageously reduces or minimizes the cost of obtaining magnetic field data for detecting multiple spatial locations of the MRI device within the examination chamber.

[0069] In another embodiment of the method according to the invention, determining the desired magnetic field by means of a function includes applying at least one of the following methods:

[0070] Interpolation method,

[0071] • Extrapolation method

[0072] Adjustment calculations

[0073] Simulation methods

[0074] • Create experience models.

[0075] As described above, the function can have an algorithm that calculates the desired magnetic field at the current spatial location based on the magnetic field at at least one nearest spatial location and / or multiple magnetic fields at multiple spatial locations. In the case of interpolation and extrapolation methods, magnetic field data from at least two known spatial locations in a magnetic field database can be used to determine the desired magnetic field. The at least two known spatial locations are preferably the two nearest or adjacent spatial locations in virtual space adjacent to the current spatial location. Adjustment calculations can particularly include regression methods, fitting methods, and / or optimization methods. It is conceivable that adjustment calculations can be used to adjust the model and / or the model function describing the inhomogeneity of the magnetic field of the magnetic resonance device based on multiple spatial locations of the magnetic resonance device. In particular, least squares methods can be applied to minimize the sum of squared differences between the magnetic field data from the magnetic field database and the results of the model and / or model function. Furthermore, empirical models and / or simulation methods can be used to determine the desired magnetic field based on the current spatial location of the magnetic resonance device and information from the magnetic field database. In one example, the inhomogeneity of the magnetic field can be characterized and / or quantified based on magnetic field data from different spatial locations in the magnetic field database. Based on the inhomogeneity of the magnetic field at different spatial locations, empirical and / or simulation models describing external influences can be created. These models can then be used to determine the desired magnetic field. Furthermore, other methods are conceivable, such as analyzing, calculating, and / or numerically simulating the interaction between the magnetic field of the MRI apparatus and external influences, such as structural materials and / or the electromagnetic interactions of the equipment near the examination chamber.

[0076] By using one or more of the methods described above for determining the desired magnetic field by means of a function, the desired magnetic field can be obtained in a robust and reproducible manner. Furthermore, the desired magnetic field at any current spatial location of the magnetic resonance apparatus can be advantageously obtained based on a finite number of magnetic field data detected by measurement techniques and the associated spatial location.

[0077] In another embodiment of the method according to the invention, adjusting the shimming parameters of at least one shimming element includes:

[0078] • Adjust the spatial position of the shim plate.

[0079] • Adjust the operating parameters of the shimming coil, and / or

[0080] • Displace the ferrofluid and / or change the volume of the ferrofluid in the magnetic resonance device.

[0081] Adjusting the spatial position of the shim can particularly include positioning and / or orienting the shim relative to the magnetic resonance device. Preferably, the shim primarily compensates for inhomogeneities in the magnets of the magnetic resonance device. This can mean that the shim is mechanically connected to the magnetic resonance device once in a predetermined position and / or orientation. However, it is also conceivable that the position and / or orientation of the shim can be changed by means of a servo actuator relative to the spatial position of the magnetic resonance device.

[0082] The operating parameters of the shimming coil can be adjusted as described above. Adjusting the operating parameters preferably includes at least adjusting the current through the shimming coil. The shimming coil can be designed as part of the gradient system of the magnetic resonance apparatus, particularly as a gradient coil. Adjusting the operating parameters may, for example, include adjusting the current through the gradient coil to compensate for deviations from the desired uniformity of the magnetic field caused by external influences on the magnetic field at the current spatial location of the magnetic resonance apparatus. However, it is also conceivable that the shimming coil exists separately from the gradient system. Such a shimming coil can be particularly used to compensate for nonlinear inhomogeneities and / or higher-order inhomogeneities.

[0083] Transferring ferrofluids in a magnetic resonance imaging (MRI) device can specifically include moving a predetermined volume of ferrofluid from a first reservoir to a second reservoir of the MRI device. However, it is also conceivable that the first or second reservoir may be located outside the MRI device. Therefore, when transferring the ferrofluid between the first and second reservoirs, the volume of the ferrofluid can be increased or decreased within the MRI device as needed. Transferring the ferrofluid can be performed, for example, using conveying equipment and / or hydraulic devices, such as pumps, valves, check valves, motor regulating valves, etc. Operating parameters here can specifically refer to the liquid levels in the first and / or second reservoirs, but can also be the rotational speed or volumetric flow rate of the conveying equipment.

[0084] By adjusting the operating parameters of the shimming element mentioned above, not only can the inhomogeneity of the magnet be compensated, but also the inhomogeneity caused by external influences on the magnetic field. Furthermore, by using multiple different shimming elements, the operating parameters of the shimming element, which can achieve particularly efficient adjustment of the magnetic field, can be advantageously and specifically adjusted.

[0085] The computer program product according to the invention can be loaded into the storage unit of the computing unit of the magnetic resonance device according to the embodiments described above, the computer program product having a program code structure so that when the computer program product is executed in the computing unit of the magnetic resonance device, the method according to the invention according to the embodiments described above is executed.

[0086] The computer program product according to the invention allows for the rapid, repeatable, and robust execution of the method according to the invention. The computer program product is configured such that it can execute the method steps according to the invention via a computing unit. Here, the computing unit must have prerequisites, such as a corresponding working memory, a corresponding graphics card, or a corresponding logic unit, to enable efficient execution of the corresponding method steps. The computer program product is stored, for example, on a computer-readable medium or stored on a network, server, or cloud, from which it can be loaded into the processor of a local computing unit. Here, the computing unit can be configured as a standalone system component or as part of a magnetic resonance imaging (MRI) device. Furthermore, control information of the computer program product can be stored on an electronically readable data carrier. The control information on the electronically readable data carrier can be designed such that, when the data carrier is used in the computing unit of the MRI device, the control information executes the method according to the invention. Examples of electronically readable data carriers are DVDs, magnetic tapes, USB flash drives, or any other data storage devices on which electronically readable control information, particularly software, is stored. If the control information is read from the data carrier and transmitted to the control unit and / or computing unit of the MRI device, all embodiments of the method according to the invention described herein can be executed. Attached Figure Description

[0087] Other advantages and details of the invention will become apparent from the embodiments described below and from the accompanying drawings. These are shown herein:

[0088] Figure 1 An embodiment of the magnetic resonance apparatus according to the present invention is shown.

[0089] Figure 2 An embodiment of the magnetic resonance apparatus according to the present invention is shown.

[0090] Figure 3 A schematic representation of a predetermined grid within the examination room.

[0091] Figure 4 A schematic flowchart illustrating the method according to the present invention is shown. Detailed Implementation

[0092] Figure 1 A schematic diagram of a magnetic resonance imaging (MRI) device 10 according to the present invention is shown, which is suitable for imaging examinations of the head region of a patient 15. However, the MRI device 10 according to the present invention can also be configured to perform other imaging examinations, such as:

[0093] • Cardiac imaging

[0094] • Mammography

[0095] Neurological imaging,

[0096] • Urological imaging

[0097] Plastic surgery imaging,

[0098] • Ophthalmic imaging

[0099] • Prostate imaging

[0100] And / or any imaging examination of other body areas of the patient 15. For the purposes stated, the magnetic resonance imaging device 10 and / or the magnet unit 13 of the magnetic resonance imaging device 10 can be positioned relative to the examination room 12 and / or the diagnostically critical body areas of the patient 15 by means of the positioning device 11.

[0101] The magnetic resonance imaging (MRI) device 10 includes a magnet unit 13 and an image recording area 14 configured for recording the examination subject 15, such as the head of a patient 15. In this example, the image recording area 14 is cylindrically configured and surrounded circumferentially by the magnet unit 13. The patient 15 can be positioned on a patient support device 16 for imaging examination. It is conceivable that the magnet unit 13 can be positioned by means of a positioning device 11 along spatial directions Z, X, and / or Y to align the image recording area 14 with diagnostically critical body regions of the patient 15. The positioning device 11 may in particular have a track system, a telescopic system, and / or a hinge configured to set the position and / or orientation of the MRI device 10 and / or the magnet unit 13 relative to the examination chamber 12 and / or the diagnostically critical body regions of the patient 15. For example, the hinge of the positioning device 11 may be configured to rotate the magnet unit 13 along rotational directions Wx, Wy, and / or Wz. Other embodiments of the positioning device 11 are of course conceivable (see, for example, see...) Figure 2 and Figure 3 ).

[0102] The magnet unit 13 has at least one magnet (not shown) configured to generate a magnetic field in the image recording region 14. The magnet may be, for example, a permanent magnet and / or an electromagnet based on a resistive coil, a superconductor, and / or a high-temperature superconductor. The magnet unit 13 may particularly have a gradient coil (not shown) for generating a magnetic gradient field used for position encoding during imaging. The gradient coil is controlled by a gradient control unit 21 of the magnetic resonance device 10. Furthermore, the magnet unit 13 may have a radio frequency antenna (not shown) configured to transmit radio frequency excitation pulses to the image recording region 14. The radio frequency antenna is preferably designed to excite nuclear spins located in the image recording region 14. For this purpose, the radio frequency antenna is controlled by a high-frequency unit 22 of the magnetic resonance device 10. The radio frequency antenna may also be configured to receive magnetic resonance signals from the image recording region 14.

[0103] To control the magnet unit 13, which has a gradient control unit 21 and a radio frequency antenna, the magnetic resonance device 10 has a control unit 20. For this purpose, the control unit 20 can be electrically connected to the gradient control unit 21 and the radio frequency unit 22 via a signal connection. Preferably, the control unit 20 is configured for controlling sequences, such as an imaging GRE (gradient echo) sequence, a TSE (turbo spin echo) sequence, or a UTE (ultra-short echo time) sequence. Furthermore, the control unit 20 may include a computing unit 24 configured to coordinate the detection and / or evaluation of magnetic resonance signals detected from the image recording region 14. Additionally, the computing unit 24 of the magnetic resonance device 10 can be configured to use reconstruction methods to reconstruct a magnetic resonance image based on the magnetic resonance data. The computing unit 24 can also be configured to determine the spatial position of the magnetic resonance device 10 and / or the magnet unit 13 based on signals from the sensor 23. In particular, it is conceivable that the computing unit 24 is configured to process data from a magnetic field database, which includes at least information about the magnetic field and the spatial location of the magnetic resonance device 10.

[0104] Furthermore, the magnetic resonance imaging (MRI) device 10 includes a user interface 23, which has a signal connection to the control unit 20. Control information, such as imaging parameters, and reconstructed MRI images, can be displayed to the user of the MRI device 10 on the output unit 25 of the user interface 23, for example, on at least one monitor. Additionally, the user interface 23 has an input unit 26 by which the user can input parameters for the MRI examination.

[0105] The magnetic resonance imaging (MRI) device 10 may also have a local receiving antenna (not shown) positioned at a location appropriate for the application at a diagnostically critical body region of the patient 15. The local receiving antenna may be configured to detect MRI signals from the patient 15's body region and transmit them to a computing unit 24 of the control unit 20. The local receiving antenna preferably has electrical connections providing signal connectivity with the radio frequency (RF) unit 21 and the control unit 20. Similar to the RF antenna, the local receiving antenna may also be configured to excite nuclear spins and receive MRI signals. For this purpose, the local receiving antenna may be controlled by the RF unit 21. In one example, the local receiving antenna is implemented as a head coil that at least partially surrounds the patient 15's head.

[0106] In this example, the magnetic resonance device 10 also includes position encoders 23a, 23b, and 23c (23a-c), which are configured to determine the movement of the magnetic resonance device 10 and / or the magnet unit 13 along a motion path. For this purpose, the position encoders 23a-c can be connected to a servo drive of the positioning device 11. The motion path can be, for example, a predetermined transport direction of the servo drive and / or movement along a guide portion of a track system and / or telescopic system. In one exemplary embodiment, the position encoder 23 is implemented as a gear encoder configured to determine the deflection caused by the movement of the gear transmission of the positioning device 11. However, the position encoder 23 can also be configured as an inductive position encoder or a Hall sensor, which determines the distance from the magnetic spacing element along the motion path of the magnetic resonance device 10.

[0107] The position encoders 23a-c are preferably configured to transmit signals containing indications of position and / or angle changes of the magnetic resonance device 10 to the computing unit 24 via a wireless or wired signal connection. The computing unit 24 may be configured to determine the current spatial position of the magnetic resonance device 10 and / or the magnet unit 13 based on the signals from the position encoders 23a-c.

[0108] exist Figure 4In the example shown, the shimming element can be designed, for example, as a shimming coil positioned at and / or at least partially surrounding the magnet unit 13 (not shown). Similarly, it is conceivable that the magnetic resonance device 10 has an insert or retaining element on which the shimming sheet can be mounted and / or adjusted. Such an insert or retaining element can be positioned, in particular, inside the cylindrical magnet unit 13 (not shown). The magnet unit 13 may also include one or more reservoirs for ferrofluid. Such reservoirs can be connected to a fluid piping system and suitable delivery equipment to move the ferrofluid within the magnet unit 13 and / or between the magnet unit 13 and a reservoir in the environment. By setting the shimming parameters of the shimming element, the inhomogeneity of the magnetic field generated by the magnet unit 13 or inhomogeneity caused by external influences can be adjusted.

[0109] The illustrated magnetic resonance imaging (MRI) device 10 may, of course, include other components typically found in MRI devices. It is also conceivable that the MRI device 10 may have a C-shaped, triangular (e.g., angled), or asymmetrical configuration of the magnet unit 13, rather than a cylindrical configuration. The MRI device 10 may be specifically configured to perform MRI examinations on patients 15 in a standing or sitting position.

[0110] Figure 2 Another embodiment of the magnetic resonance device 10 according to the present invention is shown. In this example, the magnetic resonance device 10 has a magnet unit 13 with an angled setting. The image recording area 14 is preferably positioned at an angle to the magnet unit 13 and spaced apart from the outer profile of the magnetic resonance device 10. The angled opening can here be an entrance to the image recording area 14 of the magnetic resonance device 10. The positioning device 11 is currently designed as a track system configured to move the magnet unit 13 along the spatial direction Y. It is also conceivable that the positioning device 11 has at least one hinge that can realize the orientation change of the magnet unit 13 along the rotational direction Wy. In the example shown, the positioning device 11 also has a handle 11a configured to manually change the spatial position of the magnet unit 13. However, the positioning device 11 can of course also have an actuator configured to position the magnet unit 13 fully automatically or remotely along at least one spatial direction.

[0111] The magnetic resonance imaging (MRI) device 10 also includes a position encoder 23f and two 2D cameras 23d and 23e, which are configured to detect optical data of the MRI device 10 in the examination chamber 12. The optical data may in particular include image data containing an indication of the current spatial position of the MRI device 10 in the examination chamber 12. The optical data is preferably transmitted wirelessly or via a wired connection to a computing unit 24. The computing unit 24 may in particular include an image processing unit configured to determine the current position of the MRI device 10 based on the optical data. The computing unit 24 may also be configured to correlate the position data of the position encoder 23f with the optical data of the 2D cameras 23d and 23e to determine the current position of the MRI device 10 and / or the magnet unit 13. Of course, the computing unit 24 is not limited to this. Figure 2 The use of sensors is shown in the diagram. The magnetic resonance device 10 can also include sensors with arbitrary measurement principles. Figure 1 and Figure 2 Different numbers of sensors.

[0112] Figure 3 An examination chamber 12 with a magnetic resonance imaging (MRI) device 10 according to the invention is shown. In this example, according to the invention, the examination chamber 12 is divided into a predetermined grid with a plurality of points 31, which discretize the examination chamber 12 in an equidistant manner. It is conceivable that the plurality of points 31 include permissible positions 31a and impermissible positions 31b of the MRI device 10 within the examination chamber 12. The plurality of points 31 may have already taken into account the radius of motion of the MRI device 10 and / or the magnet unit 13, which is substantially achieved by means of a positioning device 11, particularly a hinge of the positioning device 11, to adjust the orientation of the MRI device 10 and / or the magnet unit 13. This radius of motion may, for example, be taken into account by means of a square or cubic segment 33 of the examination chamber 12. In the example shown, the device 32 is located in the examination chamber 12, and when the MRI device 10 is positioned at the impermissible position 31b, the device 32 may collide with the MRI device 10.

[0113] Besides the example shown, the examination chamber 12 can of course be discretized in a non-uniform or random manner. It is also conceivable that the magnetic resonance device 10 and / or the magnet unit 13 have only a finite number of motion paths, such as one, two, or three motion paths, along which corresponding discretization is performed. The magnetic resonance device 10 in... Figure 3 The position and / or orientation shown can be a feasible spatial location for the magnetic resonance imaging device 10 in the examination room.

[0114] Figure 4 A feasible flowchart is shown for a method according to the present invention for adjusting the shimming parameters of a magnetic resonance device 10.

[0115] In optional step S1, the magnetic resonance imaging device 10 is oriented in its spatial position within the examination chamber 12. This is as follows: Figure 1 and Figure 2 As shown, the MRI device 10 can be moved relative to the patient 15 and / or the examination room 12 by means of the positioning device 11. The orientation of the MRI device 10 can be performed manually by means of the handle 11a or remotely or automatically by means of the positioning device 11.

[0116] In one embodiment, the orientation and magnetic field data of the magnetic resonance imaging (MRI) device 10 are repeatedly detected at multiple spatial locations of the MRI device 10 within the examination chamber 12. Preferably, exactly one set of magnetic field data is recorded for each spatial location of the MRI device 10. This set of magnetic field data may here have multiple measurements of magnetic field strength and / or multiple measurements of magnetic field direction. The multiple spatial locations of the MRI device 10 may here be distributed in any manner within the examination chamber 12.

[0117] In one embodiment, the orientation of the magnetic resonance imaging (MRI) device 10 is based on a predetermined grid, wherein the predetermined grid has a plurality of points 31 defining the permissible spatial location of the MRI device 10 within the examination chamber 12. (See also...) Figure 3 As shown, multiple points 31 can be distributed equidistantly within the examination chamber 12. Preferably, the points 31 of the predetermined grid are selected such that the radius of motion of the magnetic resonance device 10 is taken into account. For this purpose, the examination chamber 12 can also be divided into localities 33 that take into account the radius of motion of the magnetic resonance device 10. In one feasible embodiment, point 31 is the midpoint of the isocenter of the magnetic resonance device 10. In another example, the multiple points 31 can also be unevenly distributed within the examination chamber 12 and / or located only along a predetermined path of motion of the magnetic resonance device 10.

[0118] In optional step S2, magnetic field data of the magnetic field of the magnetic resonance device 10 at the oriented spatial location is detected.

[0119] Magnetic field data for detecting the magnetic field of the magnetic resonance imaging (MRI) device 10 at a oriented spatial location can be obtained, for example, by means of a magnetometer. In this case, a magnetometer is introduced into the image recording area 14 of the MRI device 10 to detect magnetic field data in the region of the image recording area 14. Here, it is preferable to orient the magnetometer at multiple locations in the image recording area 14 to detect spatially resolved values ​​of magnetic field strength and / or magnetic field direction. It is also conceivable that the magnetic field data can be detected by the receiving unit of the MRI device 10, such as a radio frequency antenna and / or a local receiving antenna. For this purpose, a volume of reference material, such as water or oil, can be introduced into the image recording area 14 of the MRI device 10 and excited by means of a predetermined excitation pulse. In particular, it is conceivable that a phantom having multiple volumes of reference material is positioned in the image recording area 14. The volumes of reference material and / or the phantom can be positioned such that spatially resolved magnetic field data of the imaging volume of the MRI device 10, especially isocentric magnetic field, can be detected. The magnetic resonance signal received by the receiving unit of the reference material can then be analyzed to obtain information about the magnetic field strength and / or magnetic field direction.

[0120] According to the optional step S3, information about the oriented spatial location of the magnetic resonance device 10, along with the detected magnetic field data, is stored in a magnetic field database. The storage of the spatial location along with the associated magnetic field data preferably includes storage as tuples, arrays, vectors, matrices, tables, sets, etc. This simplifies the organization, linking, association, and / or application of mathematical operations on the data and / or values ​​in the magnetic field database.

[0121] In step S4, the current spatial position of the magnetic resonance imaging (MRI) device 10 in the examination chamber 12 is determined by means of at least one sensor 23. Determining the current spatial position of the MRI device 10 preferably involves detecting the signal of at least one sensor 23 via the interface of the MRI device 10. The signal of at least one sensor 23 can be transmitted, in particular, to a computing unit 24, which determines the spatial position of the MRI device 10 in the examination chamber 12 based on the signal.

[0122] In one embodiment, determining the current spatial position of the magnetic resonance imaging device 10 in the examination chamber 12 by means of at least one sensor 23 includes:

[0123] • Detect optical data, which includes an indication of the current spatial position of the magnetic resonance imaging device 10 in the examination chamber 12, and / or

[0124] • Detect position data, which includes indications of positional and / or angular changes of the magnetic resonance device 10.

[0125] At least one sensor 23 may be configured herein as a position encoder and / or a camera. The computing unit 24 processes the detected optical and / or position data of at least one sensor 23 to determine the spatial position of the magnetic resonance device 10 in the examination chamber 12.

[0126] In optional step S5, the desired magnetic field is determined by means of a function based on the current spatial position of the magnetic resonance imaging device 10 and information in the magnetic field database. In one example, the current spatial position substantially coincides with the spatial position of the magnetic resonance imaging device 10 in the magnetic field database. Therefore, the magnetic field associated with the spatial position in the magnetic field database can be assumed to be the magnetic field of the current spatial position. In particular, it is conceivable that the magnetic field database includes multiple spatial positions of the magnetic resonance imaging device 10 in the examination chamber 12, which are often set as the current spatial position for different imaging examinations. In the example described, the function obtains the magnetic field of the spatial position in the magnetic field database that coincides with the current spatial position of the magnetic resonance imaging device 10. The obtained magnetic field can then be assumed and / or set as the desired magnetic field.

[0127] In one implementation, determining the desired magnetic field by means of a function includes applying at least one of the following methods:

[0128] Interpolation method,

[0129] • Extrapolation method

[0130] Adjustment calculations

[0131] Simulation methods

[0132] • Create experience models.

[0133] In the described embodiment, there is preferably no consistency between the current spatial location of the magnetic resonance device 10 and the spatial location in the magnetic field database. In a simple example, the desired magnetic field at the current spatial location is determined by interpolation or extrapolation using a function based on magnetic field data from at least two of the most recent spatial locations in the magnetic field database. However, it is also conceivable that the function may include applying adjustment calculations, simulation methods, and / or model-based methods to determine the desired magnetic field at the current spatial location of the magnetic resonance device 10.

[0134] According to another step S6, the shimming parameters of at least one shimming element of the magnetic resonance imaging (MRI) device 10 are adjusted based on the current spatial position of the MRI device 10 in the examination chamber 12 and information from the magnetic field database. Adjusting the shimming parameters may include, for example, adjusting the current through the shimming coil, adjusting the position and / or orientation of the shimming sheet, and / or placing a ferrofluid within the MRI device 10. The information in the magnetic field database may include, for example, measurements of magnetic field strength and / or magnetic field direction, associated with the spatial position in which the magnetic field is measured. In a simple example, the current spatial position of the MRI device 10 coincides with a spatial position in the magnetic field database. Therefore, the magnetic field associated with said spatial position can be used for the current spatial position. Preferably, the shimming parameters of at least one shimming element are adjusted based on the magnetic field of the corresponding spatial position to compensate for magnetic field inhomogeneities in the current spatial position.

[0135] In one embodiment, the shimming parameters of at least one shimming element are adjusted according to the desired magnetic field. The desired magnetic field can be obtained as described in step S5.

[0136] In optional step S7, at least one additional spatial location of the magnetic resonance device 10 is determined in relation to the analysis of the magnetic field homogeneity at at least one spatial location based on the magnetic field database, and steps S1, S2, and S3 are performed for the at least one additional spatial location. Preferably, regions with irregularities are identified when analyzing the magnetic field homogeneity, and the distribution density of multiple spatial locations of the magnetic resonance device 10 in which magnetic field data is detected is increased in the environment of the identified regions with irregularities. It is conceivable that irregularities with respect to the magnetic field homogeneity are determined when analyzing the magnetic field at spatial locations in the magnetic field database. Such irregularities may be, for example, gradients in the measured magnetic field strength and / or magnetic field direction. Steps S1 to S3 of the method according to the invention can then be repeated in the environment of spatial locations with irregular magnetic fields, particularly adjacent to said spatial locations. By repeating steps S1 to S3, the irregularities and / or external influences causing the irregularities can be characterized spatially with resolution. It is conceivable that the more frequently steps S1 to S3 are performed in regions with irregularities, the more accurate the interpolation and / or extrapolation methods for determining the desired magnetic field in the regions with irregularities will be.

[0137] Of course, the embodiments of the method and magnetic resonance apparatus according to the invention described herein should be understood as exemplary. Therefore, various embodiments can be extended with features of other embodiments. The order of the method steps according to the invention should in particular be understood as exemplary. The steps may also be performed in a different order or partially or completely overlap in time.

Claims

1. A magnetic resonance device (10), the magnetic resonance device (10) comprising at least one sensor (23) and at least one shimming element, wherein the at least one shimming element is configured to adjust the magnetic field of the magnetic resonance device (10) according to shimming parameters. Its features are, The magnetic resonance imaging device is capable of being positioned within the examination chamber, and the at least one sensor (23) constitutes a means for determining the current spatial position of the magnetic resonance imaging device (10) within the examination chamber (12). The shimming parameters of the at least one shimming element are adjusted based on the current spatial position of the magnetic resonance device (10) in the examination chamber (12) and information from a magnetic field database, wherein the magnetic field database includes information about the spatial position of the magnetic resonance device (10) and magnetic field data associated with the spatial position.

2. The magnetic resonance device (10) according to claim 1, wherein the magnetic resonance device (10) further comprises a positioning device (11), wherein the positioning device (11) is configured to change the spatial position of the magnetic resonance device (10). Changing the spatial position of the magnetic resonance device (10) includes moving the magnetic resonance device (10) along at least one degree of freedom, at least two degrees of freedom, at least three degrees of freedom, or along at least four degrees of freedom.

3. The magnetic resonance device (10) according to claim 1 or 2. The at least one sensor (23) is an optical sensor, and the optical sensor is configured to detect optical data, including an indication of the spatial position of the magnetic resonance device (10) in the examination chamber (12).

4. The magnetic resonance device (10) according to claim 1 or 2. The at least one sensor (23) is designed as a position encoder, and the position encoder is configured to detect position data, which includes indications of position changes and / or angle changes of the magnetic resonance device (10).

5. The magnetic resonance apparatus (10) according to claim 1 or 2, wherein the at least one shimming element is designed as follows: Homogenizing coils Uniform thin sheets of ferromagnetic material, and / or Ferrofluid.

6. A method for supporting the adjustment of shimming parameters of a magnetic resonance apparatus (10) according to any one of claims 1 to 5, the method comprising the following steps: S4 uses at least one sensor (23) to determine the current spatial position of the magnetic resonance device (10) in the examination chamber (12), and S6 adjusts the shimming parameters of at least one shimming element of the magnetic resonance device (10) based on the current spatial position of the magnetic resonance device (10) in the examination chamber (12) and information from the magnetic field database, wherein the magnetic field database includes information about the spatial position of the magnetic resonance device (10) and magnetic field data associated with the spatial position.

7. The method according to claim 6, further comprising the following steps: S1 orients the magnetic resonance device (10) in its spatial position within the examination chamber (12). S2 detects magnetic field data of the magnetic field of the magnetic resonance device (10) at the oriented spatial location. S3 stores information about the oriented spatial location of the magnetic resonance device (10) together with the detected magnetic field data in the magnetic field database.

8. The method according to claim 7, The orientation of the magnetic resonance device (10) and the detection of the magnetic field data are repeated at multiple spatial locations in the examination chamber (12).

9. The method according to claim 8, The orientation of the magnetic resonance device (10) is based on a predetermined grid, and the predetermined grid has a plurality of points (31) that define the permissible spatial location of the magnetic resonance device (10) within the examination chamber (12).

10. The method according to claim 8 or 9, further comprising the following steps: S7 determines at least one additional spatial location of the magnetic resonance device in relation to the analysis of the magnetic field uniformity at at least one spatial location based on the magnetic field database, and performs steps S1, S2 and S3 for the at least one additional spatial location.

11. The method according to any one of claims 6 to 9, The determination of the current spatial position of the magnetic resonance device (10) in the examination room (12) by means of at least one sensor (23) includes: Detect optical data, the optical data including an indication of the current spatial position of the magnetic resonance device (10) in the examination chamber (12), and / or The detection position data includes indications of positional and / or angular changes of the magnetic resonance device (10).

12. The method according to any one of claims 6 to 9, further comprising the following steps: S5 determines the desired magnetic field using a function based on the current spatial position of the magnetic resonance device (10) and information in the magnetic field database. The shimming parameters of the at least one shimming element are adjusted according to the desired magnetic field.

13. The method of claim 12, wherein determining the desired magnetic field by means of the function comprises applying at least one of the following methods: Interpolation method, Extrapolation method, Adjustment calculation, Simulation method, Create an experience model.

14. The method according to any one of claims 6 to 9, Adjusting the shimming parameters of the at least one shimming element includes: Adjust the spatial position of the shim plate. Adjust the operating parameters of the shimming coil, and / or The ferrofluid of the magnetic resonance device (10) is moved and / or the volume of the ferrofluid of the magnetic resonance device (10) is changed.

15. A computer program product capable of being loaded into a storage unit of a computing unit (24) of a magnetic resonance device (10) according to any one of claims 1 to 5, the computer program product having a program code structure for performing the method according to any one of claims 6 to 14 when the computer program product is run in the computing unit (24) of the magnetic resonance device (10).

Images