CN217561704U

CN217561704U - Local coil and system comprising a local coil and a grid

Info

Publication number: CN217561704U
Application number: CN202122723633.3U
Authority: CN
Inventors: A.亨格勒; R.克里格
Original assignee: Siemens Healthineers AG
Current assignee: Siemens Healthineers AG
Priority date: 2020-11-11
Filing date: 2021-11-08
Publication date: 2022-10-11
Anticipated expiration: 2031-11-08
Also published as: DE102020214197A1

Abstract

The present invention relates to a local coil, wherein the local coil has an antenna loop, which antenna loop encloses a surface along the outside, wherein the local coil is designed to accommodate a measuring device in a predetermined relative position, wherein the measuring device is passed over the surface is extended from one side of the local coil to the opposite side. The utility model discloses still relate to a system that comprises local coil and net.

Description

Local coil and system comprising a local coil and a grid

Technical Field

The invention relates to a device for positioning an instrument by means of a magnetic resonance tomography apparatus and a local coil with a measuring device.

Background

A magnetic resonance tomography apparatus is an imaging apparatus which aligns nuclear spins of an examination subject with an external strong magnetic field in order to image the examination subject, and excites the nuclear spins of the examination subject by an alternating magnetic field to precess around the alignment. Precession or return of spins from this excited state to a lower energy state in response in turn produces an alternating magnetic field, which is received by the antenna.

By means of the gradient magnetic fields, a position coding is applied to the signals, which position coding then enables a correlation of the received signals with the volume elements. The received signals are then analyzed and a three-dimensional imaging representation of the examination object is provided. For receiving the signals, local receiving antennas, so-called local coils, are preferably used, which are arranged directly on the examination subject in order to achieve a better signal-to-noise ratio. The receiving antenna may also be mounted in the patient bed.

Due to the good imaging of organs, magnetic resonance tomography apparatuses are particularly well suited for identifying target regions for biopsy or other surgery. However, most instruments made of metal or plastic are not displayed or only show artifacts, which makes monitoring and control by magnetic resonance techniques difficult.

SUMMERY OF THE UTILITY MODEL

Therefore, the technical problem to be solved by the present invention is to simplify the planning and preparation of the operation.

The object is achieved according to the invention by a local coil, wherein the local coil has an antenna loop which, along the outer circumference, defines a surface, wherein the local coil is designed to accommodate a measuring device in a predetermined relative position, wherein the measuring device extends over the surface from one side of the local coil to the opposite side. The object is also achieved according to the invention by a system of a local coil and a grid, the local coil being of the type mentioned above, wherein the grid is positioned in the holding device in a predetermined position relative to the local coil.

According to the utility model discloses a local coil has the antenna loop, the antenna loop goes out a face along the periphery. The antenna loop may here be shaped as a circle, an ellipse, a polygon or an irregularity. Also conceivable are antenna coils such as saddle coils, which are designed to be uneven, so that the enclosed surface is not flat. Butterfly coils with conductor intersections can also be considered, the intersections being designed such that there is a free surface for the measuring device without conductors.

The local coil is also designed to accommodate the measuring device in a predetermined relative position. In this case, the measuring device can be permanently fixed to the partial coil. It is also conceivable for the local coil to have a holding device for the measuring means, which holds the measuring means in a predetermined relative position with respect to the local coil.

The measuring device can be designed in one dimension similar to a ruler. Two-dimensional measuring devices, such as grids, are also conceivable. The measuring device is designed such that a relative position is defined along an extension of the measuring device in at least one dimension in a predetermined grid, for example at least 2mm, 5mm or 10 mm. The measuring means extend across the surface from one side of the local coil to the opposite side of the surface. In this case, not only straight lines but also generally borders are referred to as sides, wherein the surface is located at least partially between the border of the side and the opposite border.

The local coil according to the invention advantageously enables the instrument to be arranged in a defined position relative to the local coil at least along the measuring means by the measuring means in a predetermined relative position.

The system according to the invention has a local coil with the already mentioned holding device. Furthermore, the system has a grid which is positioned in the holding device in a predetermined relative position with respect to the local coil.

According to the invention, the system has the advantage according to the invention of a local coil, wherein the grid also allows determining the relative position not only in one dimension but also in a second dimension of the face enclosed by the local coil.

According to the utility model discloses a device can be used for in the magnetic resonance tomography equipment with the help of according to the utility model discloses a local coil marks the entry point in the patient. The magnetic resonance tomography apparatus has a patient table which can be moved along a longitudinal z-axis, preferably along the field direction of the B0 field magnet. Furthermore, the magnetic resonance tomography apparatus has a marker indicator which is arranged in a predetermined position on the magnetic resonance tomography apparatus such that a light beam emitted by the marker indicator defines the predetermined position of the local coil on the patient bed at least in one dimension. The marker indicator is preferably arranged at the opening of the patient passageway such that the light beam is oriented perpendicular to the z-axis of the direction of movement of the patient bed. If the local coil is located directly on or on the patient bed and the patient is in turn located on the patient bed, the relative position of the local coil with respect to the magnetic resonance tomography apparatus along the z-axis can be defined by the marker indicator, in particular in combination with a zero marker on the local coil, and changed in combination with a movement of the patient bed by a predetermined distance along the z-axis and with respect to the coordinate system of the magnetic resonance tomography image.

The method comprises the steps of positioning the local coil on the patient bed or the patient and positioning the patient bed by moving the patient bed such that the local coil assumes a predetermined position by marking the indicator marks. This achieves that the local coil occupies a defined position along the z-axis. Furthermore, the position in a second coordinate is defined by the light beam, the second coordinate being perpendicular to the z-axis and the propagation of the light beam. If the marker indicator is arranged, for example, to be aligned vertically from above with respect to the patient bed, the position of the local coil in the plane in which the bed surface of the patient bed extends, i.e. in the horizontal plane with respect to the magnetic resonance tomography apparatus, is defined.

In one step of the method, the local coil is oriented in such a way that the measuring device extends perpendicular to the direction of movement of the patient bed and preferably also perpendicular to the beam direction.

In a further step, a magnetic resonance tomography apparatus acquires a magnetic resonance image of the patient. Based on the known position and orientation of the local coil in the preceding steps relative to the magnetic resonance tomography apparatus, a magnetic resonance image is acquired having a defined relative position of the imaged organ relative to the local coil.

In a subsequent step, the coordinates of the entry point along the extension of the measuring device are determined from the image. For example, for an image of an x-y slice, the entry point may be determined by subtracting the x-position of the zero point of the measurement device determined with the marker pointer from the x-position of the organ (in the horizontal direction).

In a further step, an entry point is marked at the determined coordinates of the measuring device.

The method according to the invention advantageously simplifies the conversion of the coordinates determined by magnetic resonance imaging into the patient.

According to an embodiment of the method, a system is provided for positioning an instrument, which system comprises its magnetic resonance tomography device, a local coil according to the invention and a grid in a holding device for the local coil, wherein the grid has a plurality of markers that can be read by magnetic resonance.

In one step, the local coil is positioned on the patient in such a way that it remains in a constant relative position to the patient, at least for carrying out the method. This can be achieved, for example, by a plaster-like adhesive tape or retaining tape.

In a further step, an image of the patient is acquired by means of the local coil and the magnetic resonance tomography apparatus. The magnetic resonance readable markers are preferably acquired and imaged together with the same image.

In a further step, the image is segmented into organs by a magnetic resonance tomography apparatus. In particular, the organ to be examined or treated, the structure or organ to be protected in particular, and also obstacle structures such as bones are identified during the segmentation.

It is also conceivable to segment the organ to be examined by trained personnel, since here unique features need to be taken into account.

In a further step, possible trajectories between the grid points and the predetermined target region are determined from the segmented image by the magnetic resonance tomography apparatus. The possible trajectories are preferably straight lines through the respective grid points and target region, which do not extend through the organ or obstacle structure to be protected. The position of the grid points can be determined from the position of the detected markers that can be read by magnetic resonance. It is conceivable that each grid point has a marker, or that the grid has at least three markers, so that the position of the grid in space can be determined in magnetic resonance imaging. The position of the grid points in the image can then be determined by a predetermined relative position with respect to the markers. The possible trajectories are preferably output together with the image of the segmented organ in a representation on an output device. It is also possible to display all tracks and in this case to mark the possible tracks in a different way, for example by coloring.

In a subsequent step, one of these trajectories is selected based on the segmented image. This may be done, for example, by trained personnel. However, it is also conceivable for this selection to be made by the magnetic resonance tomography apparatus. The primary selection criterion is that the trajectory does not encounter any organs or obstacles to be protected. As a further rotation criterion, for example, the minimum length of the possible trajectory or the minimum distance from the organ and/or obstacle structure to be protected can also be taken into account.

Grid points through which the trajectory extends are then selected for the selected trajectory. In the simplest case, the trajectory has been defined by grid points through which a straight line extends to the target region. To orient the instrument along the selected trajectory at a grid point, the entry angle or the angle pair allowing this orientation is then determined at the grid point for the selected trajectory. It is contemplated to provide two angles, which the trajectory encloses with the x-coordinate and the y-coordinate of the grid, respectively. The angle of the trajectory with the normal through the grid point and the angle of rotation around this normal with respect to the marked-out direction in the grid plane, e.g. the x-axis, may also be considered.

The grid points of the selected trajectory and the entry angle of the trajectory at the selected grid points are then output. For example, it is conceivable to number grid points and output the numbers. Coordinates in an x-y coordinate grid, for example, may also be output. The entry angle can be output by the two angle values described.

The device according to the invention advantageously makes it possible to determine the trajectory and the entry angle using a single image and a grid and to transfer them to the patient.

In a possible embodiment of the local coil according to the invention, the local coil has a zero marking for marking the indicator. The marking indicator may for example be a laser emitting a light beam which is limited to a narrow width in the direction of the patient bed. Any mark that allows a predetermined relative position to be established between the light beam of the marking indicator and the measuring device is referred to herein as a zero mark. The predetermined relative position has a tolerance of less than 10mm, 5mm, 2mm or 1 mm. The predetermined relative position may for example be such that the beam is aligned on a zero point of the measurement scale or at a predetermined offset with respect to the zero point. The zero point marks may for example have crossing lines, concentric circles, dots or other features visible in the light beam which allow alignment in one or preferably two coordinates.

In an advantageous manner, the zero point marking enables a simpler and more precise alignment of the measuring device with respect to the magnetic resonance tomography apparatus.

In a conceivable embodiment of the local coil according to the invention, the local coil has a holding device for positioning the grid in a predetermined relative position with respect to the local coil. The retaining device is designed to releasably fix the grid to the partial coil so that the grid can be easily replaced. For example, frames with spring tongues which engage in adapted recesses of the grid can be considered. Clamping, screwing or other releasable holding means are also possible.

In an advantageous manner, the releasable holding device enables a quick change of the grid of disposable articles. Thus, the required hygiene requirements can be simply complied with, since there is a possibility of contamination by body fluids.

In a possible embodiment of the system according to the invention, the grid has a plurality of markers readable by magnetic resonance. Such a marker is considered to be readable via magnetic resonance, the position of which marker can be determined by the magnetic resonance tomography apparatus in the image acquisition, preferably simultaneously with the image acquisition of the patient. The marker may for example be constituted by an ampoule with a test liquid, iron oxide or a resonant circuit with resonance at larmor frequency. At least three or four markers are preferably provided in order to be able to unambiguously identify a position in space. By knowing the geometry of the grid, the position of the grid points can then be determined and displayed by the magnetic resonance tomography apparatus. However, it is also possible to assign a marker to each grid point, so that the position of the grid point is directly visible in the image.

In an advantageous manner, the markers enable a simpler and more accurate detection of the position of the grid in the magnetic resonance image.

In a conceivable embodiment of the system according to the invention, the grid has a guide device which is designed to guide the instrument along the longitudinal extension at a grid point of the grid with an adjustable entry angle. For example, the guiding means may be a tube or hole in the body through which the needle is biopsied. The entry angle can preferably be changed, for example if the bore extends through a ball which is rotatably supported in the partial ball shell. The angle can be estimated by a mark on the ball in conjunction with a portion of the spherical shell. Slidable angle gauges, which mark the angle relative to the grid, are also contemplated.

The guiding device advantageously allows a more precise and reproducible guidance and orientation at a predetermined angle.

In a conceivable embodiment of the system according to the present invention, the instrument has a marking designed to make the instrument visible in the magnetic resonance image. The foregoing description regarding the markings on the grid applies in the same manner to the markings on the instrument.

The markers on the instrument make it possible in an advantageous manner to monitor not only the alignment on the trajectory but also the movement along the trajectory.

In one possible embodiment, the guide device is rotatably arranged at the determined grid points and the entry angle can be adjusted on the guide device. The output value for the entry angle together with the guide can be adjusted, for example, by means of an angle scale arranged on the grid or on the guide. It is also conceivable to specify the output angle for the guide by preparing different angle gauges for the output angle, by holding the guide on the grid or by detachably connecting it to the grid. For example, it is conceivable to clip the angle gauge to the grid point if correspondingly adapted holding elements are provided on the grid and the angle gauge.

The trajectory is advantageously defined in a simple and easy to understand manner by adjusting the entry angle at defined grid points.

In a conceivable embodiment, the instrument has a marking which is designed to make the instrument visible in the magnetic resonance image. See the previous description of the marking on the grid and the corresponding device for how to design the marking. In one step, the selected trajectory and the instrument are displayed in a common image on an output device. Here, the instrument may be represented by the marker or by a plurality of markers distributed along the extension of the instrument. It is also conceivable that the instrument is inserted in the illustration, for example, between a plurality of markers or between a marker and a grid point, through which the selected trajectory extends and on which the instrument is positioned.

The markers advantageously enable a real-time display of the instrument in the magnetic resonance image and thus enable monitoring of the alignment and tracking of the position perpendicular to the grid.

Drawings

The above features, characteristics and advantages of the present invention and implementations thereof will be more clearly and easily understood in conjunction with the following description of embodiments, which is set forth in detail in conjunction with the accompanying drawings.

In the drawings:

fig. 1 shows a schematic view of a magnetic resonance tomography apparatus using a system according to the invention;

figure 2 shows a partially cut-away schematic view of an embodiment of a local coil according to the present invention;

fig. 3 shows a schematic view of an embodiment of a system according to the present invention;

fig. 4 shows a schematic view of a part of a grid of a system according to the invention;

figure 5 shows an exemplary flow diagram of an embodiment of a method using a system according to the present invention;

fig. 6 shows an exemplary flow diagram of an embodiment of a method using a system according to the present invention.

Detailed Description

Fig. 1 shows a schematic view of an embodiment of a magnetic resonance tomography apparatus 1 using a system according to the invention.

The magnet unit 10 has a field magnet 11 which generates a static magnetic field B0 for aligning the nuclear spins of the sample or patient 100 in the acquisition region. The recording region is characterized by an extremely homogeneous static magnetic field B0, the homogeneity being dependent in particular on the magnetic field strength or the value. The recording region is virtually spherical and is arranged in a patient tunnel 16, which extends through the magnet unit 10 in the longitudinal direction 2.

The patient bed 30 is movable in the patient tunnel 16 by a traveling unit 36. The marking indicator 17 is arranged at the opening of the patient tunnel 16 in such a way that it can emit a light beam or a laser beam in the direction of the patient bed below.

The field magnet 11 is typically a superconducting magnet, which can provide a magnetic field with a magnetic flux density of up to 3T, and even higher with the latest equipment. For smaller field strengths, however, permanent magnets or electromagnets with normally conductive coils can also be used.

Furthermore, the magnet unit 10 has a gradient coil 12 which is designed to superimpose a magnetic field B0 with a variable magnetic field in three spatial directions for the spatial differentiation of the acquired imaging region in the examination volume. The gradient coils 12 are typically coils of normally conductive wire, which can generate mutually orthogonal fields in the examination volume.

The magnet unit 10 likewise has a body coil 14 which is designed to radiate high-frequency signals fed via a signal line into the examination volume and to receive resonance signals emitted by the patient 100 and to output them via the signal line. In the following, the term transmitting antenna denotes an antenna through which a high frequency signal exciting the nuclear spins is transmitted. This may be the body coil 14 or a local coil 50 with transmit capability.

The control unit 20 provides the magnet unit 10 with different signals for the gradient coil 12 and the body coil 14 and analyses the received signals.

The control unit 20 therefore has a gradient controller 21 which is designed to supply the gradient coils 12 with variable currents via feed lines, which provide the desired gradient fields in the examination volume in a temporally coordinated manner.

Furthermore, the control unit 20 has a radio-frequency unit 22 which is designed to generate radio-frequency pulses having a predetermined temporal profile, amplitude and spectral power distribution for exciting magnetic resonances of the nuclear spins in the patient 100. Pulse powers in the kilowatt range can be achieved here. The excitation signal can be transmitted into the patient 100 via the body coil 14 or else via a local transmitting antenna.

The controller 23 communicates with the gradient controller 21 and the high frequency unit 22 via a signal bus 25.

The local coil 50 is arranged on the patient 100 and is connected to the radio-frequency unit 22 and its receiver by way of a connecting line 33. It is also conceivable, however, for the body coil 14 to be a receiving antenna in the sense of the present invention.

Fig. 2 shows a partially cut-away schematic view of an embodiment of a partial coil according to the invention.

The local coil 50 has an antenna loop 51 which is designed to receive magnetic resonance signals from excited nuclear spins of the patient 100 and/or to excite them by means of excitation pulses. The local coil has an opening with an open face, which is surrounded along the outer circumference by the antenna loop 51 and the housing of the local coil, so that the patient 100 behind or below the local coil 50 can be accessed via this open face. The local coil 50 may be secured to the patient 100 in a fixed relative position, for example using a strap 55 or tape.

A ruler 54 extends over the opening as a measuring device, which enables the position along the ruler to be determined. In order to establish a positional reference relative to the magnetic resonance tomography apparatus 1, the local coil 50 also has a zero point marking 52 which, together with the marking indicator 17 on the magnetic resonance tomography apparatus 1, determines the position along the beam relative to the magnetic resonance tomography apparatus 1 by aligning the zero point marking 52 with the laser beam or the light beam of the marking indicator 17.

For clarity, electrical details of the local coil 50, such as detuning circuitry, preamplifiers, and matching circuitry, are not shown.

Fig. 3 shows an embodiment of a system according to the invention comprising a local coil 50 and a grid 60. In the embodiment of fig. 3, a grid 60 is arranged as a measuring device above the openings of the local coil 50. The grid 60 is preferably arranged detachably in the holding device 53. As shown in fig. 3, the holding device 53 can be formed, for example, from four angular parallel guides, into which prismatic grids 60, for example in the form of cuboids, can be inserted. The grid can be clamped in the guides by snap hooks, but other fixing means, such as clamping, are also conceivable.

The grid 60 has a two-dimensional matrix of a plurality of cannulae into which instruments such as biopsy needles 70 may be inserted at predetermined locations. As explained below with respect to fig. 4, it is also conceivable to arrange or be able to arrange a guide 61 on the sleeves in order to be able to adjust the angle relative to the grid 60. As shown, the grid 60 may have a face made of a carrier material with a matrix of sleeves. However, it is also conceivable that the carrier material is reduced to a carrier structure for a cannula having a through-opening in order to save material or also to improve the visual monitoring of the treatment. It may for example be a narrow grid, in which case the sleeves are arranged at nodes or grid points of the structure.

The grid 60 has at least three markers, which can be detected with the magnetic resonance tomography apparatus 1 in an image with the patient 100, for example, liquid-filled capsules or iron oxide particles in cavities of the grid 60. These markers may be arranged, for example, in the four corners of the grid or at each grid point. Preferably, not all of the markers lie in a straight line, but rather define a space or plane to enable detection of the orientation of the grid 60 in space.

Fig. 4 shows a schematic view of a part of a grid 60 of a system according to the invention. This is a detail of the corner of the grid 60 in fig. 3 with the individual guides 61. The grid 60 continues downwards and to the right with a plurality of guides 61 arranged in a matrix.

The guide 61 has a ball here. The spheres are arranged in the spherical hollows of the grid 60. The grid 60 can be designed as a solid body, for example as a cuboid, made of a material, for example plastic. The spherical recess is designed here as a ball which can just receive the guide 61. It is conceivable that the material of the ball and/or of the grid 60 is embodied as elastic and the hollow forms a cavity which encloses just a little more than a hemisphere. In this case, the ball of the guide 61 can be pressed into the cavity with slight force and snapped into place, so that the ball is then pivotably supported in the cavity of the grid 60.

It is also conceivable that the lattice 60 is not designed as a solid but as a system of lattices 60 with through-openings between which the lattice 60 is designed as a strut. In this case, hollow spheres are arranged at the grid points or intersections of the struts, the spheres of the guide 61 being pivotably supported in the hollow spaces of the hollow spheres as described above. The mesh 60 may be manufactured, for example, by injection molding.

The guide device 61 also has an elongate cavity in which instruments, such as a biopsy needle 70, can be guided. A hole through the ball of the guide 70 may be considered. In the illustration of fig. 4, the hole is elongated by a tube in order to improve the accuracy of the orientation.

In the embodiment of fig. 4, markings in the form of warp and weft threads are arranged on the ball, for example by means of colour markings, laser markings or depressions in the ball. In this way, the predetermined value of the alignment by the tilt angle and the roll angle is achieved together with the zero point mark on the grid 60.

In a simpler embodiment, however, it is also conceivable for the guide means 61 to be designed merely as holes in the grid 60 or in the intersections of the grid 60, through which holes the instrument is guided. It is also conceivable here to fasten the guide 61 to the instrument or to the grid 60, for example by clamping. The guide 61 can be prefabricated for different predetermined angles or have an adjustment mechanism for a defined angle. By orienting the instrument parallel to the guide 61, the desired orientation can be produced.

In a preferred embodiment, the instrument, here exemplified by a biopsy needle 70, also has a marker 71 which can be detected during the magnetic resonance task. The instrument can thus also be tracked in an advantageous manner and the position on the trajectory can be checked by the magnetic resonance tomography apparatus 1.

An exemplary flow diagram of a method of using a system according to the invention is shown in fig. 5.

The method is carried out by a local coil 50 and a magnetic resonance tomography apparatus 1 according to the invention as shown in fig. 2, wherein the magnetic resonance tomography apparatus 1 has a patient bed 30 and a marking indicator 17. The marker indicator 17 is arranged in a predetermined position on the magnetic resonance tomography apparatus 1 such that the light beam emitted by the marker indicator 17 defines a predetermined position of the local coil on the patient bed 30 in at least one dimension. The marking indicator 17 is arranged generally vertically at the opening of the patient passage 16 above the patient bed 30 and radiates vertically downwards.

In step S10, the local coil 50 and the patient table 30 are positioned by the operator by moving and advancing such that the light beam of the marking indicator 17 strikes the zero point marking 62. In this manner, the position of the zero point marker 62 in the x-z plane in which the patient bed 30 is located is defined.

In step S15, the operator orients the local coil 50 such that the measuring means, for example the ruler 54, extends in a direction perpendicular to the direction of movement of the patient bed 30.

In a further step S20, an image of the patient 100 is acquired with the magnetic resonance tomography apparatus 1. Here, a local coil 50 with a measuring device is located in the acquired image region. By moving the patient bed 30 a known distance, predetermined by the control unit 20, the z-position of the local coil 50 and the zero point marker 52 is known. The position of the patient's organ is acquired by means of the image. The y position is given by the arrangement of the local coil 50 on the shown surface of the patient. It is also conceivable, however, for the local coil 50 to have one or more markers which can be detected by magnetic resonance imaging and allow the y position of the local coil to be determined in the image. However, it is also possible that the y position is not initially determined, but is only determined in a subsequent step by the operator or radiologist if the marking is performed directly on the basis of the physiological characteristics of the patient 100.

In step S30, coordinates along the extension of the measuring device are determined from the image. For example, if the image scale and zero point marker are known to pass the position of the marker indicator 17 along the x-axis of the image, the operator or radiologist may acquire the x-coordinate of the organ or region to be examined or treated from the image. It is also conceivable that the operator marks the target point with only an input device, such as a mouse pointer, and that the control unit 20 determines the distance and thus the x-coordinate. It is also possible to consider automatic segmentation and thus determination of the target point by the control unit 20.

In a further step S40, the operator or radiologist marks the determined entry point, marking the determined entry point on the coordinates of the measurement instrument. The x coordinate determined in step S30 can be read here directly on the ruler 54. Perpendicularly thereto, the y-coordinate read out from the image may be provided by the operator.

An exemplary schematic flow diagram of another method of using a system according to the present invention is shown in fig. 6. For example, the method may be implemented with the system of fig. 4.

In step S10, the local coil 50 with the grid 60 is positioned on the patient 100. Unlike the previously described method, alignment by the marking indicator 17 is not required here. Rather, the grid 60 has three or more markers that can be detected in the magnetic resonance image, which markers are arranged such that their positions unambiguously define the position of the grid 60 in space.

In step S20, an image of the patient 100 with the local coil 50 is acquired with the magnetic resonance tomography apparatus 1. The position of the grid 60 is likewise unambiguously determined here by means of the markers likewise detected in the image.

In a further step S50, the acquired image is separated into a plurality of organs by the magnetic resonance tomography apparatus 1.

Subsequently in step S60, a trajectory between the grid point and a predetermined target region is determined from the segmented image. The image is taken into account when determining the trajectory. The trajectory is preferably a connecting line between the grid point and the target area. The target region is here the organ to be examined or a sub-region thereof, the position of which has been acquired together with the image. The target region may be specified by the segmentation of the organ by the control unit 20, but it may also be considered that the target region is determined by a human expert due to unique characteristics.

In a further step S70, a trajectory is selected based on the segmented image. Here, for example, the position of sensitive organs or obstacles such as bones that are not allowed to be damaged is also taken into account. Preferably excluding touching or piercing their trajectory. It is also advantageous to have a trajectory in the patient that is as short a path as possible. Other selection criteria may be free space available for applying instruments distal to the mesh. This selection can be performed by the operator or by the control unit 20 of the magnetic resonance tomography apparatus 1.

Subsequently, in step S80, the operator is determined the adjustment parameters that enable the selected trajectory. Grid points through which the trajectory extends are preferably determined. The entry angle may for example be represented by a pair of angles, which the trajectory encloses with two coordinate axes in the grid plane, for example the x-axis and the y-axis. The angle enclosed with the normal to the grid plane or between the trajectory and the grid plane and the angle representing the rotation around the face normal of the grid plane with a zero point at the positive x coordinate or marker on the grid can also be considered.

Finally in step S90, the magnetic resonance tomography apparatus 1 outputs the grid point and the entry angle through an output device, for example, a display. In this manner, the radiologist can position the instrument on the grid 60 according to these outputs.

While the details of the present invention have been shown and described in detail in the preferred embodiments, the invention is not limited to the disclosed embodiments, and other variations can be derived therefrom by the skilled person without departing from the scope of the invention.

Claims

1. Local coil, characterized in that the local coil (50) has an antenna loop (51) which peripherally defines a surface, and in that the local coil (50) is designed to accommodate a measuring means in a predetermined relative position, which measuring means extends over the surface from one side of the local coil (50) to the opposite side.

2. Local coil according to claim 1, characterized in that the local coil (50) has a zero marking (52) for marking an indicator (17).

3. Local coil according to claim 1 or 2, characterized in that the local coil (50) has a holding device (53) for positioning the grid (60) in a predetermined relative position with respect to the local coil (50).

4. A system of local coils according to claim 3 and a grid (60), characterized in that the grid (60) is positioned in a holding means (53) in a predetermined position with respect to the local coil (50).

5. The system according to claim 4, characterized in that the grid (60) has a plurality of markers that are readable by magnetic resonance, so that in a magnetic resonance image generated by means of the magnetic resonance tomography apparatus (1) the relative position and relative orientation of the grid (60) with respect to the magnetic resonance tomography apparatus (1) can be determined.

6. The system according to claim 4 or 5, characterized in that the grid (60) has a guide device (61) which is designed to guide the instrument along the longitudinal extension at grid points of the grid (60) with an adjustable entry angle.

7. The system according to claim 6, characterized in that the instrument has a marking (71) designed to make the instrument visible in a magnetic resonance image.