Method for Determining a Trajectory Representing an Inserting of a Patient Into an MR Scanner

Abstract

A trajectory is determined for inserting a patient into an MR scanner. An avatar representing specific body dimensions is provided. The avatar includes location information relating to an implant. A spatial magnetic field gradient data set relating to the scanner is provided. An avatar pose at a starting point of the trajectory is defined, and a course for the trajectory is provided. For several points on the trajectory, the corresponding magnetic field value are determined by combining the spatial magnetic field gradient data set with the avatar pose. The trajectory and/or the avatar pose are determined so that the at least one implant only passes regions within the MR scanner that are below a predetermined threshold value concerning the magnetic field gradient.

Claims

1. A method for determining a trajectory for inserting a patient into a magnetic resonance (MR) scanner, comprising: providing an avatar representing body dimensions of a patient, the avatar including location information relating to an implant identified with the patient; providing a spatial magnetic field gradient data set relating to the MR scanner; defining (i) an avatar pose at a starting point of the trajectory, and (ii) a course for the trajectory for inserting the patient into the MR scanner; determining, for several points on the trajectory, a corresponding magnetic field value and/or a corresponding gradient value using the spatial magnetic field gradient data set and the avatar pose; determining the trajectory and/or the avatar pose such that the implant passes through regions within the MR scanner having a magnetic field gradient that is less than a predetermined threshold value; and generating an information signal that indicates whether the determined trajectory leads to the implant entering regions having a magnetic field gradient exceeding the predetermined threshold value.

2. The method according claim 1, wherein the implant is from among a plurality of implants, and wherein the avatar comprises location information of the plurality of implants, and further comprising: determining a set of separate trajectories, each one of the set of separate trajectories corresponding to one of the plurality of implants by applying, for each one of the set of separate trajectories, a separate predetermined threshold value.

3. The method according to claim 2, further comprising: generating a warning signal when none of the set of separate trajectories results in a passage of a corresponding implant through respective regions within the MR scanner having a magnetic field gradient below the corresponding predetermined threshold value.

4. The method according to claim 1, wherein the act of determining the trajectory comprises: applying a coordinate system with respect to the MR scanner, wherein a coordinate of the coordinate system represents an insertion depth of the patient into the MR scanner.

5. The method according to claim 1, wherein the avatar comprises information regarding the pose of the patient, and wherein the act of determining the trajectory comprises determining the trajectory considering a maximum insertion depth of the patient into the MR scanner and the pose of the patient.

6. The method according to claim 1, wherein the act of adapting the trajectory comprises adapting the trajectory by determining the pose of the avatar for a starting point of the trajectory using one or more images of the patient at the starting point.

7. The method according to claim 1, wherein the act of providing the avatar comprises providing the avatar using data acquired via (i) a camera, (ii) a first sensor configured to measure dimensions of the patient, and/or (iii) a second sensor configured to measure a weight of the patient.

8. The method according to claim 1, wherein the act of providing the avatar comprises providing a three-dimensional (3D) avatar using data acquired via (i) a 3D camera, (ii) a magnetic resonance imaging (MRI) scan, (iii) a magnetic resonance tomography (MRT) scan, and/or (iv) a computerized tomography (CT) scan.

9. The method according to claim 8, wherein the act of determining the trajectory comprises: determining a three-dimensional trajectory in which a point corresponding to the implant changes in a vertical direction along the trajectory, wherein the vertical direction is perpendicular to an insertion direction of the patient into the MR scanner.

10. The method according to claim 1, wherein the avatar is fused with data relating to the implant, and wherein the data is provided by (i) an X-ray photograph, (ii) a magnetic resonance imaging (MRI) image, and/or (iii) a computerized tomography (CT) image.

11. The method according to claim 1, wherein the avatar is fused with data relating to the implant, and wherein the avatar is approximated by a rectangular model.

12. The method according to claim 1, further comprising: fusing the spatial magnetic field gradient data set and the trajectory to provide a magnetic path data set.

13. The method according to claim 1, further comprising: approximating the location information of the implant as one or more planar areas or volumes which completely contain the implant.

14. The method according to claim 1, further comprising: determining positioning instructions for adapting the trajectory based upon the act of determining the trajectory and/or determining the avatar pose.

15. The method according to claim 1, wherein the implant is from among a plurality of implants, and further comprising: determining a set of separate trajectories, each one of the set of separate trajectories corresponding to one of the plurality of implants, and each one of the set of separate trajectories relating to a course of a respective implant.

16. The method according to claim 1, wherein the trajectory of the implant is determined based upon patient body dimensions represented via the avatar and gantry dimensions of the MR scanner.

17. A non-transitory computer-readable medium having instructions stored thereon that, when executed via processing circuitry, cause the processing circuitry to determine a trajectory for inserting a patient into a magnetic resonance (MR) scanner by: providing an avatar representing body dimensions of a patient, the avatar including location information relating to an implant identified with the patient; providing a spatial magnetic field gradient data set relating to the MR scanner; defining (i) an avatar pose at a starting point of the trajectory, and (ii) a course for the trajectory for inserting the patient into the MR scanner; determining, for several points on the trajectory, a corresponding magnetic field value and/or a corresponding gradient value using the spatial magnetic field gradient data set and the avatar pose; determining the trajectory and/or the avatar pose such that the implant passes through regions within the MR scanner having a magnetic field gradient that is less than a predetermined threshold value; and generating an information signal that indicates whether the determined trajectory leads to the implant entering regions having a magnetic field gradient exceeding the predetermined threshold value.

18. A data processing apparatus, comprising: a magnetic resonance (MR) scanner comprising an insertion tool configured to insert a patient into the MR scanner; an interface configured to receive data identified with an avatar that represents body dimensions of the patient, the avatar including (i) location information relating to an implant identified with the patient, and (ii) a spatial magnetic field gradient data set relating to the MR scanner; and control circuitry configured to determine a trajectory for inserting the patient into the magnetic resonance (MR) scanner by: defining (i) an avatar pose at a starting point of the trajectory, and (ii) a course for the trajectory for inserting the patient into the MR scanner; determining, for several points on the trajectory, a corresponding magnetic field value and/or a corresponding gradient value using the spatial magnetic field gradient data set and the avatar pose; determining the trajectory and/or the avatar pose such that the implant passes through regions within the MR scanner having a magnetic field gradient that is less than a predetermined threshold value; and generating an information signal that indicates whether the determined trajectory leads to the implant entering regions having a magnetic field gradient exceeding the predetermined threshold value.

19. The data processing apparatus according to claim 18, wherein the MR scanner further comprises a camera, and wherein the control circuitry is further configured to utilize a detected movement inside the MR scanner for determining and/or evaluating the trajectory.

20. The data processing apparatus according to claim 18, wherein the MR scanner further comprises a lifting device configured to lift and/or lower at least a part of the patient's body to provide vertical movement of the implant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The disclosure is further described by the following figures. The figures only exemplarily show how the disclosure can possibly be realized. All mentioned features relating to the figures can be extracted and combined with the embodiments mentioned in this implication. The following figures show:

[0049] FIG. 1 illustrates an example schematic front cover view of an MR scanner in accordance with one or more embodiments of the present disclosure;

[0050] FIG. 2 illustrates an example vertical section through the scanner in a side view in accordance with one or more embodiments of the present disclosure;

[0051] FIG. 3 illustrates an example top view of a horizontal section through the scanner in accordance with one or more embodiments of the present disclosure;

[0052] FIG. 4 illustrates an example field plot indicating magnetic field values inside the MR scanner in accordance with one or more embodiments of the present disclosure;

[0053] FIG. 5 illustrates an example schematic overview of a data processing apparatus in accordance with one or more embodiments of the present disclosure;

[0054] FIG. 6 illustrates an example schematic flow diagram representing an example of conducting a method of this disclosure in accordance with one or more embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0055] FIGS. 1-3 show different exemplary views of an MR scanner 11. In FIG. 1, a front cover view of the MR scanner 11 is shown. A gantry 10 is indicated by a double arrow. The gantry 10 is the opening through which a patient 27 is inserted into the MR scanner 11. Some MR scanners 11 are provided with information concerning critical regions 21. In FIG. 1, the critical region 21 is illustrated by an ellipse on the left side of the gantry 10. In these critical regions 21, a spatial gradient value may be present that may be harmful with respect to an implant 25 (see FIG. 2). The MR scanner 11 may be in connection with (e.g. communicatively coupled with) a control unit 15 (e.g. control circuitry). The control unit 15 may be realized by a computer, a microprocessor, processing circuitry, etc. Nevertheless, the method can be performed without the MR scanner 11 if all necessary data are provided beforehand. This means that determining or calculating a trajectory 23 may be conducted before the patient 27 will be inserted into the gantry 10. Determining the trajectory 23 may be performed remotely on a separate computer. The so-determined trajectory 23 may be transmitted to the MR scanner 11 via an appropriate interface 30. FIG. 5 shows an overview of a possible data processing apparatus 100. The MR scanner 11 is driven by a magnetic field that is regarded as a “field of the gradient system” B1. The field of the gradient system B1 is applied around the gantry 10, and is not the same as the magnetic field gradient B0 that is present inside the MR scanner 11 in the gantry tube. For this disclosure, the field of the gradient system B1 is of minor relevance.

[0056] FIG. 2 shows the magnetic field B0 together with an avatar 22 inside the MR scanner 11. In FIG. 2, a vertical section through the scanner is shown in a side view. In FIG. 2, the avatar 22 is indicated together with the implant 25. The implant 25 can be e.g. a pacemaker. The avatar 22 may be regarded as a model or a data set that represents the body dimensions of the patient 27. In most cases, it is sufficient if the avatar 22 approximates the extremities of the patient 27. The patient's extremities are his torso, head, arms, and legs. In many cases, such an approximation is precise enough to determine the appropriate trajectory 23.

[0057] In FIG. 2, a starting point 23s is indicated. The starting point 23s is outside the MR scanner 11. FIG. 2 shows a camera 14, which allows for the detection of any movement inside the gantry tent. In case a movement of the patient 27 is detected, it can be registered by the control unit 15. If the control unit 15 detects a movement of the patient 27 inside the MR scanner 11, the control unit 15 can dynamically (e.g. instantly, excepting for system latency) recalculate the trajectory 23. If the recalculated trajectory 23 would enter a region inside the MR scanner 11 which exceeds a defined threshold value concerning the magnetic field gradient value B0, an appropriate warning signal may be provided.

[0058] FIG. 3 shows a top view in a horizontal section through the scanner 11. The avatar 22 can be a model or data set relating to the MR scanner 11. Since the patient 27 usually lies on a patient table 13, a determining or calculating of the trajectory 23 can be based on the patient table position. The MR scanner 11 can comprise a lifting device 29. The lifting device 29 allows for an active influence on the trajectory 23 of the implant 25. For example, the lifting device 29 can be a hydraulic platform. A part of the patient's body such as a leg can be lifted and lowered. The lifting device can also be used as a blocking element. Therefore, it can be avoided that the trajectory 23 enters any critical regions 21. This allows for a bypass of the implant 25 with regard to critical regions 21.

[0059] In FIG. 4, an exemplary field plot is presented. This field plot shows areas within the gantry 10 that are related to different magnetic field values B0. Above the gantry 10, the field of the gradient systems B1 is indicated that drives the MR scanner 11. Areas with the same magnetic field values B0 are shown by contour lines 20. The x-axis represents a direction of the patient table 13. The z-axis represents the vertical direction perpendicular to the patient table 13. The z-axis may be a vertical (i.e. upward) direction with respect to the patient table 13. As can be seen from FIG. 4, the magnetic field values B0 vary from 0.1 Tesla per meter up to 6 Tesla per meter. The gray region in the z-direction between 0.4 and 1.1 represents an area with a nearly homogenous magnetic field B0.

[0060] A critical region 21 is indicated in FIG. 4. In this position, the magnetic field value B0 is 6 Tesla per meter. If the implant 25 is not to enter a region where the magnetic field value is larger than 3 Tesla per meter, the trajectory 23 has to be calculated or determined so that the trajectory 23 bypasses such critical areas 21.

[0061] In FIG. 4, two exemplary trajectories 23 are indicated. These two exemplary trajectories 23 have two endpoints 24. The endpoints 24 relate to a maximum insertion depth of the patient 27 into the gantry 10. Any spatial change in the magnetic field B0 and hence a resulting spatial field gradient can cause forces and torques on ferromagnetic materials. Iron for example is a ferromagnetic material.

[0062] Again, although many implants 25 are constructed without ferromagnetic materials, in some cases it is necessary to use such ferromagnetic materials for implants 25. In such situations, it is necessary to determine or calculate the trajectory 23 that does not enter any critical regions 21. Usually implant manufacturers try to avoid ferromagnetic materials by using alternative materials such as titanium. However, in rare cases ferromagnetic or even magnetic materials have to be used within implants 25. In this case, a maximum spatial field gradient is provided together with the implant 25 by the manufacturer. These limits shall guarantee a safe handling and scanning in the environment of an MR scanner 11.

[0063] This situation may lead to a quite complicated workflow for an operator of the MR scanner 11. At first, the operator has to research all magnetic field value B0 limits for the implants 25 inside or at the patient 27. The operator has to make sure that the MR scanner 11 will not exceed these limits during the whole examination of the patient 27. It should be considered that the operator has to consider multiple limits. For example, the operator has to consider a SAR value. The operator further has to consider an additional magnetic field B0 that results during the scanning process while the patient 27 is still resting inside the gantry 10. With regard to the additional magnetic field that is only relevant during the scanning process, only the end position and pose of the patient 27 at the endpoint 24 is of importance. In this case, the control unit 15 may also consider or determine an avatar pose at the endpoint 24. This avatar pose at the endpoint 24 represents the pose of the patient 27 when he has reached his end position in the endpoint 24.

[0064] The trajectories 23 presented in FIG. 4 may not be the final trajectories. It is possible that these trajectories represent intermediate trajectories during an iterative determining of a final trajectory 23. The operator can define another trajectory 23, and the control unit 15 can determine whether such trajectory would guide the implant 25 in such a way that it does not enter any critical regions. Again, a critical region is a region where the magnetic field value or its gradient exceeds a certain threshold value, which is often defined by the manufacturer of the implant 25.

[0065] The magnetic field B0 inside the gantry 10 and around is mostly not constant in all regions inside the scanner 11. The name spatial field gradient already indicates that the magnetic field values B0 may vary inside the scanner 11. In some areas, the magnetic field B0 may vary spatially so much that it could harm the patient 27 with certain implants 25. Usually, the operator has to find out all volumes which may exceed a predetermined limit and then handle the patient 27 in such a way that the implant 25 never enters these volumes. This means that the implant 25 should never enter a volume around the critical regions 21.

[0066] It is important to note that the positioning of the patient 27 on the table 13 may significantly define how the implant 25 proceeds into the bore or gantry 10. This means that the pose of the patient 27 at the starting point 23s significantly influences the trajectory 23 for the implant 25. The pose of the patient 27 can be represented by the pose of the avatar 22. Since the avatar 22 represents the body dimensions of the patient 27, a pose of the avatar 22 can be regarded as a pose of the patient 27. The pose may consider the position and orientation of all extremities of the patient 27. The extremity that contains the implant 25 is of significant relevance.

[0067] For instance, in the case of a pacemaker, the focus for determining the trajectory 23 is on the torso of the patient's body. A certain pose for the avatar 22 is defined for the patient 27, and the patient table 13 moves along the x axis as indicated in FIG. 4. The control unit is able to determine or calculate the corresponding trajectory 23. Conventionally, the operator has to figure out the right or appropriate pose for the patient 27 on his own. In many cases, the critical regions 21 are rings around the bore entry so that the operator has to position the patient 27 with the implant 25 close to the center axis of the magnet.

[0068] In practice, some obstacles may arise concerning the insertion of the patient 27 into the gantry 10. For example, most of the MR scanner operators do not know what the spatial field gradient is. MR-physicists usually have this knowledge, but technical and radiological people often do not have this knowledge. In many cases, the spatial field gradient is associated with the field of the gradient system. These two expressions sound similar, but in fact relate to different aspects. The field of the gradient system relates to a patient 27 without any motion during scanning in the scanner 11. The field of the gradient system is usually not relevant for determining the trajectory 23. The spatial field gradient, on the other hand, is relevant for determining the trajectory 23. If the operator mistakes these two aspects, it may be possible that the process of inserting the patient 27 into the gantry 10 relies on incorrect facts. Spatial field gradients are usually given by the MR scanner manufacturers in the form of field plots, e.g. as shown in FIG. 4. The spatial magnetic field gradient B0 used for imaging is only present during MRI scanning In practice, it is not impossible, but it is very difficult to translate this highly technical information into a positioning guidance. The operator has to figure out by himself how to correctly position the patient 27 on the table and correctly move the patient 27 into the gantry 10. A field plot as shown in FIG. 4 does not contain any positioning information such as “The implant 25 must not come closer than 50 centimeters to the edge of the patient table,” for example. This means that there is a need for supporting the operator to assist her in inserting the patient 27 into the MR scanner 11.

[0069] Therefore, this disclosure provides different embodiments for determining the trajectory 23 for the implant 25 so that the implant 25 does not enter any critical regions 21. In FIG. 5, a schematic overview over the data processing apparatus 100 is shown. FIG. 5 shows a three-dimensional camera 17, and two different trajectories 23 for two different respective implants 25. Furthermore, the patient 27 is approximated by the avatar 22. A first sensor 18 can measure a size of the avatar 22 or patient 27. A second sensor 19 can measure a weight. The second sensor can be integrated in the patient table 13.

[0070] Although in FIG. 5 the avatar 22 is presented two-dimensionally, it is possible to gather a three-dimensional avatar model by the three-dimensional camera 17. The MR scanner 11 can comprise an interface 30 for transmitting necessary data to determine the correct trajectory 23. A three-dimensional camera 17 can provide the avatar 22 of the patient 27 during positioning of the patient 27 on the table 13. The avatar 22 represents the body dimensions of the patient 27, and the data processing apparatus or the control unit 15 can calculate or determine the relative position of the avatar 22 to the patient table 13 and hence to the complete scanner 11. If the position of the implants 25 within the avatar 22 are known, the control unit 15 can determine all positions of the implants 25 during inserting the patient 27 into the MR scanner 11.

[0071] In FIG. 5, two arrows close to the implants 25 indicate a direction of inserting the patient 27 into the scanner 11. Using the interface 30, the control unit 15 is configured to receive all necessary data sets and information for determining the trajectories 23 of the implants 25. Together with the magnetic field gradient data set, the control unit 15 is configured to determine all critical regions 21 where the implants 25 would reach an area where the magnetic field gradient value exceeds a given threshold value. The threshold value is usually given or provided by the manufacturer of the implant 25. Since the control unit 15 is configured to determine an avatar pose from the patient 27 at a starting point 23s, the control unit 15 is also configured to recalculate the trajectories 23 if the pose of the patient 27 is changed. For example, in case of FIG. 5, the operator immediately can see that the implant 25 nearby the hand of the patient 27 will enter a critical region 21. Since the control unit 15 may visualize this trajectory 23, it is easy to see that the patient 27 should move his right arm close to the torso.

[0072] In case of FIG. 5, the data processing apparatus 100 includes the three-dimensional camera 17. This three-dimensional camera 17 can create the avatar 22. The two different implants 25 are at different positions within the avatar 22. In case of FIG. 5, the patient is lying on the patient table 13, and the patient 27 has a pacemaker as one implant 25 and another implant 25 near his right hand. With the help of the received information, the control unit 15 can calculate the trajectories 23 for these two implants. This means that two different trajectories 23 are calculated, and the control unit 15 is configured to combine the trajectories 23 with the magnetic field gradient data set provided by the MR scanner 11. Therefore, the control unit 15 is configured to calculate the critical region 21 for the implant 25 of the patient's hand. For this implant in the patient's hand 25, the control unit 15 of the data processing apparatus 100 is configured to provide a warning signal to the operator.

[0073] Furthermore, the control unit 15 is configured to determine a different pose of the avatar 22 at the starting point 23s that leads to another different trajectory 23 which does not enter any critical regions 21. In case of FIG. 5, the control unit 15 can suggest to move the implant 25 of the patient's hand by a certain distance towards the center of the patient table 13. It is also possible that the control unit 15 is configured to generate an appropriate positioning instruction such as “please move the right hand near to your main body” before the patient table 13 is moved into the gantry 10. All necessary information may be collected and/or provided by the operator for the control unit 15. This information may comprise e.g. the pose of the avatar 22, localization information of the implants 25 inside the avatar 22, the provided magnetic field gradient data set of the MR scanner 11, the moving direction of the patient table 13 and/or an intended vertical movement of the implant 25, etc. The control unit 15 may be configured to provide an information signal that indicates that more information is necessary to determine the correct trajectory 23. From the given information, the control unit 15, a computer, or a microprocessor is configured to calculate the position of the at least one implant 25 relative to the patient table 13. By assuming that the table 13 moves the patient's body to the isocenter of the scanner 11, the control unit 15 is configured to calculate all positions of the implant 25 during the motion of the patient table 13. Furthermore, the control unit 15 is configured to check if any of the calculated positions has a higher spatial field gradient than the threshold value. Therefore, the control unit 15 is configured to compare the spatial field gradient values along the trajectories 23 with the corresponding threshold value.

[0074] The control unit 15 is configured to optically enhance the determined trajectories 23. For example, the control unit 15 is configured to provide three-dimensional field plots, look up tables, a two-dimensional representation as shown in FIG. 5, or even write a mathematical function for easier positioning of the patient on the table 13. Moreover, the control unit 15 may be configured to warn the operator during inserting the patient 27 into the gantry 10 if the implant 25 would enter a critical region 21. For this purpose, the control unit 15 may provide an acoustic instruction e.g. “please move the patient 27 five centimeters to the right!” The operator can provide the control unit 15 with information regarding whether it is from the corresponding patient file. The control unit 15 may be configured to assist the patient 27 to move himself into the right position with visual cues. For this purpose, a live view of the patient's body can be provided by the camera 17 accompanied with red or green light. By means of appropriate arrows, a movement of relevant parts of the body can be indicated. This can assist the patient 27 or the operator in positioning the patient 27 in the right pose that leads to the desired trajectory 23 of the implant 25.

[0075] The control unit 15 may be configured to refine its prediction by knowing how far the avatar 22 is moved into the scanner 11. For example, if the patient 27 is positioned with his feet first and receives an examination of the ankle, any implant 25 in the brain of the patient 27 will stay far away from the isocenter. In this case, it is possible that the implant 25 is exposed to smaller spatial field gradient values B0 than if it had been moved into the isocenter. In this case, the implant 25 of the brain does not even reach any critical region 21 since the end point 24 would stop before reaching the critical region 21. The control unit 15 may utilize images from other imaging techniques to provide a fused data set for determining the desired trajectory 23. Therefore, the control unit 15 can use data from CT-scans, X-ray scans, or previous MR examinations which are typically needed to screen for magnetic resonance imaging anyway.

[0076] By means of the three-dimensional camera 17, a three-dimensional avatar 22 can be created. The control unit 15 may be configured to predict the trajectory 23 that is the path of the implant 25 while moving the patient 27 into the MR scanner 11. This information can be combined with information about the spatial field gradients B0 of the scanner 11. Therefore, the control unit 15 is able to predict whether the implant 25 reaches or touches critical regions 21 where a magnetic field gradient value B0 exceeds the corresponding threshold value. In such situations, the control unit 15 or the data processing apparatus 100 can warn the operator or even derive guidance for enhanced positioning. In the best case, the control unit 15 can assist the operator in avoiding any violation of the limits with regard to the spatial field gradients and in combination with the implants 25. Overall, this disclosure provides different embodiments that can help the operator to position the patient 27 and thus the implant 25 correctly. This is achieved by determining the correct trajectory 23 that does not enter any critical region 21. This correct trajectory 23 is influenced by different poses of the avatar 22 that represent the pose of the patient 27.

[0077] FIG. 6 shows a possible flow diagram concerning a method for determining a trajectory 23 for inserting a patient 27 into the MR scanner 11. In a first step a) the avatar 22 is provided, which in this example consists of several ellipses that represent the head, the arms, the torso and the legs. The avatar 22 represents specific body dimensions of the predetermined patient 27. As indicated in FIG. 6 the avatar 22 preferably includes location information with regard to the at least one implant 25. In the case of FIG. 6, the implant 25 is a pacemaker.

[0078] In a next step b) the spatial magnetic field gradient B0 data set is provided with regards to the MR scanner 11.

[0079] In a next step c) the avatar pose is defined at the starting point 23s of the trajectory 23. Furthermore, the course of the trajectory 23 is also defined for inserting the patient 27 into the MR scanner 11. This means that steps a) to c) are preferably designed to gather all information needed for determining the trajectory 23 to insert the patient 27 into the MR scanner 11. In FIG. 6 it is indicated that the spatial magnetic field gradient data set B0 and the starting point 23s, as well as the trajectory 23, can be input data with respect to the relevant steps.

[0080] In a next step d) several points on the trajectory 23 of the corresponding magnetic field value B0 and/or its gradient value are determined. This means that in step d) may be e.g. based on the input data in steps a) to c) in which any suitable type of calculating, determining, or outputting function is performed. Step d) can be regarded as fusing step, in which the trajectory 23 is fused with the magnetic field values B0. In this case, several trajectory points 23 together with their corresponding magnetic field values B0 are calculated or determined. This may e.g. be achieved by combining the spatial magnetic field gradient B0 data set with the avatar pose.

[0081] In a next step e) another trajectory 23 can be determined and/or the trajectory 23 can be adapted. This is also true concerning the avatar 22 and the pose of the avatar 22.

[0082] In FIG. 6 it is indicated that the avatar 22 in step a) has another pose than in step e). In step a) the head of the avatar is directed to the right, and in step e) the head of the avatar 22 rather faces upwards. This may represent another pose concerning the avatar 22. Of course the trajectory 23, the starting point 23s, of the trajectory 23, and the pose of the avatar 22 can be changed or adapted as mentioned or explained in all embodiments of this disclosure. A new trajectory, starting point 23s, and/or pose of the avatar 22 may be determined and/or adapted in a way so that the at least one implant 25 only passes regions within the MR scanner 11 that are below their predetermined threshold value concerning the magnetic field gradient B0, as discussed herein.

[0083] In a next step f) the information signal can be generated. The information signal may be indicated as an exclamation point or as an “OK” signal. Of course, the information signal can be more complex. For example, the information signal can be an animation with arrows that may show on a monitor how the avatar 22 shall be changed with regard to its pose. If the information signal is not “OK”, the method can be carried out again and/or the method can be turned into a regulation. In this case, it is possible that the method starts again with step a). It is also possible that the method starts at another step, for instance step b), step c) or step d). The method may be performed any suitable number of times as required until in step f) the “OK” signal is outputted.

[0084] FIG. 6 is only one exemplary embodiment that shows one possible way of realizing the disclosure. All explanations with regard to the other figures can be analogously implemented in the procedure with regards to FIG. 6. Overall, this disclosure shows how a patient 27 can be inserted safely into the MR scanner 11. This is especially relevant if the patient 27 contains the implant 25, in this case a pacemaker. In this way, a more convenient examination can be provided for the patient 27.

[0085] The various components described herein may be referred to as “units” or “apparatuses”. Such components may be implemented via any suitable combination of hardware and/or software components as applicable and/or known to achieve the intended respective functionality. This may include mechanical and/or electrical components, processors, processing circuitry, or other suitable hardware components, in addition to or instead of those discussed herein. Such components may be configured to operate independently, or configured to execute instructions or computer programs that are stored on a suitable computer readable medium. Regardless of the particular implementation, such devices, units, and facilities, as applicable and relevant, may alternatively be referred to herein as “circuitry,” “processors,” or “processing circuitry,” or alternatively as noted herein.