APPARATUS AND METHOD FOR GUIDING AN INSTRUMENT BY A LUMINOUS POINTER

Abstract

An instrument, a magnetic resonance imaging scanner and a method for operating the magnetic resonance imaging scanner with the instrument in which the instrument is aligned with a patient. The medical instrument comprises a first projector for projecting a luminous pointer in a predetermined alignment relative to the medical instrument. The magnetic resonance imaging scanner comprises a positioning aid configured to mark a predetermined position on an inner wall of a patient tunnel in a manner that is visible to a user. In the method, a predetermined alignment of the first projector relative to the medical instrument or position of the positioning aid on the wall of the patient tunnel is ascertained in which the luminous pointer of the first projector coincides with the positioning aid when the medical instrument is aligned parallel to a trajectory through an entry point on the patient and a target point in the patient and the medical instrument is aligned such that the luminous pointer and the positioning aid coincide.

Claims

1. A medical instrument for use on or in a patient, the medical instrument comprising: a first projector configured for projecting a luminous pointer in a predetermined alignment relative to the medical instrument; wherein when the medical instrument is positioned on the patient appropriately for an application, the predetermined alignment is directed away from the patient.

2. The medical instrument of claim 1, wherein the medical instrument includes an axis of symmetry and the predetermined alignment is aligned parallel to the axis of symmetry.

3. The medical instrument of claim 1, wherein the medical instrument further comprises: a control input and is configured to set the predetermined alignment of the first projector in a predetermined manner in dependence on an instruction via the control input.

4. The medical instrument of claim 3, wherein the medical instrument further comprises: a sensor configured to detect an alignment of the medical instrument relative to a magnetic resonance imaging scanner.

5. A magnetic resonance imaging scanner, comprising: a positioning aid configured to mark a predetermined position on an inner wall of a patient tunnel in a manner that is visible to a user.

6. The magnetic resonance imaging scanner of claim 5, wherein the positioning aid comprises a marking attached in a visible manner to an inside of the patient tunnel.

7. The magnetic resonance imaging scanner of claim 5, wherein the magnetic resonance imaging scanner further comprises: a projector, wherein the projector is configured to mark a predetermined position on the inner wall of the patient tunnel in a visible manner by a light projection.

8. A method for positioning a medical instrument on a patient with a magnetic resonance imaging scanner that includes a positioning aid configured to mark a predetermined position on an inner wall of a patient tunnel in a manner that is visible to a user, the medical instrument comprising a first projector configured for projecting a luminous pointer in a predetermined alignment relative to the medical instrument, the method comprising: positioning the patient in the magnetic resonance imaging scanner such that a predetermined entry point for the medical instrument on a surface of the patient and a predetermined target point of an intervention in the patient are located in a detection area of the magnetic resonance imaging scanner; ascertaining a predetermined alignment of the first projector relative to the medical instrument or a position of the positioning aid on the wall of the patient tunnel in which the luminous pointer of the first projector coincides with the positioning aid when the medical instrument is aligned parallel to a trajectory through the entry point and the target point; aligning the first projector or outputting the positioning aid; and projecting the luminous pointer.

9. The method of claim 8, wherein the method further comprises: aligning the medical instrument such that the luminous pointer coincides with the positioning aid.

10. The method of claim 8, wherein the method further comprises: providing a map of a patient on an operator interface of a planning controller; and defining an entry point on the surface of the patient and a target point in the patient.

11. The method of claim 8, wherein the alignment of the first projector with the medical instrument is fixed and parallel to an axis of symmetry of the medical instrument, wherein a point of intersection of the luminous pointer is determined and the point of intersection is output.

12. The method of claim 11, wherein the outputting of the point of intersection comprises the outputting of a coordinate for a coordinate system on an inside of the patient tunnel to a user of the medical instrument.

13. The method of claim 8, wherein the alignment of the first projector with the medical instrument is set by the magnetic resonance imaging scanner, and for ascertaining the alignment, an alignment of the first projector relative to the medical instrument is determined under that, on alignment of the medical instrument parallel to a trajectory through the entry point and the target point, a light pointer is aligned with the positioning aid and the first projector is aligned according to the alignment determined.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0047] FIG. 1 depicts a schematic representation of a magnetic resonance imaging scanner with an instrument according to an embodiment.

[0048] FIG. 2 depicts a schematic representation of an embodiment of a magnetic resonance imaging scanner with an instrument.

[0049] FIG. 3 depicts a schematic representation of an embodiment of an instrument.

[0050] FIG. 4 depicts a schematic representation of an embodiment of a magnetic resonance imaging scanner with an instrument.

[0051] FIG. 5 depicts a schematic representation of an embodiment of an instrument.

[0052] FIG. 6 depicts a schematic representation of an embodiment of a magnetic resonance imaging scanner.

[0053] FIG. 7 depicts a schematic representation of an embodiment of an instrument.

[0054] FIG. 8 depicts a schematic flow diagram of a method according to an embodiment.

DETAILED DESCRIPTION

[0055] FIG. 1 depicts a schematic representation of an embodiment of a magnetic resonance imaging scanner 1 for executing the method.

[0056] The magnet unit 10 includes a field magnet 11 that creates a static magnetic field B0 for aligning nuclear spins of samples or the patient 100 in a recording area. The recording area is characterized by an extremely homogeneous static magnetic field B0. The homogeneity relates to the magnetic field strength or the magnitude.

[0057] The recording area is almost spherical and arranged in a patient tunnel 16 that extends in a longitudinal direction 2 through the magnet unit 10. A patient couch 30 may be moved in the patient tunnel 16 by the drive unit 36. The field magnet 11 may be a superconducting magnet able to provide magnetic fields with a magnetic flux density of up to 3 T, or even more in the case of the latest devices. However, for lower magnetic field strengths it is also possible to use permanent magnets or electromagnets with normally conducting coils.

[0058] The magnet unit 10 furthermore includes gradient coils 12 configured to superimpose temporally and spatially variable magnetic fields in three spatial directions on the magnetic field B0 for spatial differentiation of the acquired mapping regions in the examination volume. The gradient coils 12 may be coils made of normally conducting wires that may create mutually orthogonal fields in the examination volume.

[0059] The magnet unit 10 likewise includes a body coil 14 configured to radiate a radio-frequency signal supplied via a signal line into the examination volume and to receive resonance signals emitted by the patient 100 and output them via a signal line.

[0060] A control unit 20 supplies the magnet unit 10 with the various signals for the gradient coils 12 and the body coil 14 and evaluates the received signals.

[0061] Thus, the control unit 20 includes a gradient actuator 21 configured to supply the gradient coils 12 with variable currents via supply lines which provide the desired gradient fields in the examination volume in a time-coordinated manner.

[0062] The control unit 20 includes a radio-frequency unit 22 configured to create a radio-frequency pulse with a prespecified temporal course, amplitude and spectral power distribution for exciting a magnetic resonance of the nuclear spins in the patient 100. Herein, pulse powers in the kilowatt range may be achieved. The excitation signals may be radiated into the patient 100 via the body coil 14 or also via a local transmitting antenna.

[0063] A controller 23 communicates with the gradient controller 21 and the radio-frequency unit 22 via a signal bus 25.

[0064] A medical instrument 60, for example a biopsy needle, is arranged on a patient 100 in a patient tunnel 16.

[0065] FIG. 2 shows a detail of an embodiment in FIG. 1.

[0066] There is a predetermined target point 103 in the patient, for example a node, that was identified with its coordinates in a map of the patient 100. A medical instrument 60, for example a biopsy needle, with which a sample is to be taken from the target object at the target point 103 is placed on an entry point on the surface of the patient which is indicated by a marking 102. The marking may also be visible in a magnetic resonance image. However, a marking 102 formed solely by the impression made by the instrument 60 in the patient may also be visible in the magnetic resonance image. A trajectory 101, a straight line, connects the entry point and the target point 103. The trajectory may be selected such that it does not hit any important organ, blood vessel, nerve, or other tissue to be protected.

[0067] The predetermined trajectory 101 includes a point of intersection with the patient tunnel 16 or the inner wall thereof on a side facing away from the patient 100. If the relative position of the patient 100 to the magnetic resonance imaging scanner 1 is known, this point of intersection may be calculated using the methods of linear algebra. One possibility for determining the trajectory 101 and point of intersection is provided by a magnetic resonance recording of the patient 100 in which the target object 103 and the planned entry point is visible. The point of intersection calculated by the controller 23, for example, may be output to a user in the form of coordinates for a coordinate system 71 attached to the inner wall in a visible manner. This provides the user to identify the predetermined position 80 on the inner wall of the patient tunnel 16 where the trajectory 101 intersects the inner wall. The user may align the instrument 60 in FIG. 2 parallel to the trajectory 101 and thus to the target object 103 if, as shown in more detail in FIG. 3, this projects a light spot or a luminous pointer 70 and the user causes this luminous pointer 70 to coincide with the predetermined position 80. The coordinate system 71 may be projected onto the inner wall of the patient tunnel 16 by a second projector 90.

[0068] FIG. 3 is a schematic representation of an embodiment of the medical instrument. The medical instrument 60 includes an axis of symmetry, defined here by the biopsy needle 61. The symmetry to the axis of symmetry reflects a symmetry of the medical instrument 60 or the application to be performed therewith. In the case of the biopsy needle, this may be rotated about an axis through the longitudinal extent of the hollow needle 61 during the application without further consequences. Accordingly, the axis of symmetry of the medical instrument 60 in FIG. 2 is an axis of rotation through the longitudinal extent of the hollow needle 61. If this is caused to coincide with the predetermined trajectory 101, the alignment of the medical instrument 60 is aligned correctly with the target object 103.

[0069] For this purpose, the medical instrument 60 in FIG. 3 includes a first projector 72. The first projector 72 includes a power source, for example a battery 73. However, the power source may also be a power supply line. The power source supplies a light source, for example, a semiconductor laser 74. However, other light sources, such as lamps or an OLED matrix may be used. The light created is focused by an optical system 75 into a light beam that is emitted parallel to the axis of symmetry of the medical instrument 60 in a direction opposite to the patient 100. When the light beam strikes a surface, for example the inner wall of the patient tunnel 16, it creates a light pointer 70 there in the form of a dot or spot or a more complex pattern, as detailed below.

[0070] If the medical instrument 60 is arranged with the tip or the hollow needle 61 at the entry point and the user aligns the luminous pointer 70 with the predetermined position 80, these two fixed points define a straight line, which corresponds to the predetermined trajectory 101 and ensures alignment of the medical instrument 60 in accordance with the invention.

[0071] FIG. 4 is a representation of an embodiment of the medical instrument 60 and the magnetic resonance imaging scanner 1. The same reference numbers denote the same objects, for example the trajectory 101 is still defined as the straight line through the entry point and target object 103. The embodiment represented in FIG. 4 essentially differs in that the trajectory 101 no longer matches the direction of projection of the luminous pointer 70. This makes it possible to no longer select constantly changing coordinates on the inside of the patient tunnel 16 as the predetermined position 80, but only to mark one or a few predetermined positions 80, which are then, for example, marked by a fixed marking, such as an elevation or depression or reflex point. However, the alignment of the first projector 72 relative to the medical device 60 has to be changed in each case, as represented in detail in FIG. 5.

[0072] In FIG. 5, the first projector 72 is no longer aligned parallel to the axis of symmetry of the medical instrument 60, but may be changed by a first actuator 77 and an optional second actuator 78 relative to the axis of symmetry. For example, a projector controller 76 in the medical instrument may receive setting instructions, for example wirelessly, from the controller 23 of the magnetic resonance imaging scanner 1. The control instructions may specify an angular alignment with respect to the axis of symmetry by the first actuator 77 and/or an angular alignment with respect to a rotation about the axis of symmetry by the second actuator 78. The first actuator and the second actuator may, for example, be motors, for example piezoelectric actuators, that execute a linear movement or a rotation without requiring a disruptive magnetic field.

[0073] Herein, the angles to be set depend upon a rotation of the instrument 60 about the axis of symmetry relative to the magnetic resonance imaging scanner or also the direction of gravity. This rotation may be detected by the projector controller 76 by a sensor 79 and transmitted to the controller 23 for ascertaining the angles for the first actuator 77 and the second actuator 78. The sensor 79 may, for example, be a MEMS-based gravity sensor or a multi-dimensional Hall sensor.

[0074] The first projector 72 may be configured as freely rotatable about the axis of rotation and the weight distribution may be set such that the first projector 72 has a preferred direction under the effect of gravity, for example directed upward against the force of gravity.

[0075] FIG. 6 is a representation of two possibilities for marking the predetermined position 80 in a magnetic resonance imaging scanner 1.

[0076] A second projector 90 is attached in or on the patient tunnel 16 and projects into the interior thereof. The second projector 90 may, for example, project an image with a variable position and/or alignment as a predetermined position 80 for the luminous pointer 70. The image may, for example, be created with an OLED, LCD or DLP matrix. The second projector 90 may be variably aligned using actuators, as was explained in FIG. 5 with respect to the first projector 72.

[0077] However, a variable marking of the predetermined position 80 may also be created, for example by a switchable matrix of light spots 91 on the inner wall of the patient tunnel 16, which are, for example, created by LEDs and optionally transmitted by light guides to the inner wall of the patient tunnel 16.

[0078] FIG. 7 is a schematic representation of an embodiment of a medical instrument 60. The embodiment represented represents an alternative to the variant represented in FIG. 5. Instead of aligning the first projector 72 differently by a first actuator 77 and/or second actuator 78, the projected image is changed. The first projector 72 includes a projection angle that is, for example, greater than 20 degrees, 40 degrees or 60 degrees. This may cause the luminous pointer 70 to coincide with the predetermined position 80 in many different alignments of the trajectory 101. The luminous pointer 70 marks a position and a direction, for example by the point of origin and the alignment of the arrow in FIG. 7. Causing this luminous pointer 70 to coincide with a predetermined position 80, likewise marked by a location marking and a direction marking, may also achieve a defined position of the medical instrument 60 for rotation about the axis of symmetry.

[0079] FIG. 8 depicts a schematic flow diagram of a method.

[0080] In a step S30, the patient 100 is positioned in the magnetic resonance imaging scanner 1, for example with the patient table 30. The patient 100 is to undergo a minimally invasive examination or an intervention by a medical instrument 60 on an organ or tissue, that is referred to below as the target object 103. The way in which this entry point may be determined is explained below. Herein, the positioning takes place such that the entry point and the target object 103 are located in a detection area of the magnetic resonance imaging scanner 1, that is also referred to as the field of view (FoV). The correct position may, for example, be verified using markings 102 on the patient 100 and magnetic resonance imaging scanner 1 or fast image acquisition using the magnetic resonance imaging scanner 1. At the end of the positioning, the patient 100 is in a known relative position and alignment relative to the magnetic resonance imaging scanner 1.

[0081] In another step S40 of the method a predetermined alignment of the first projector 72 relative to the medical instrument 60 and/or position of the positioning aid on the wall of the patient tunnel 16 is ascertained in which the luminous pointer 70 of the first projector 72 coincides with the positioning aid when the medical instrument is aligned parallel to a trajectory 101 through the entry point and the target point.

[0082] Step S40 differs for cases in which the first projector 72 is aligned parallel to the axis of symmetry of the medical instrument, as in FIG. 3, or may itself be aligned with the axis of symmetry, as in FIG. 5 or FIG. 7.

[0083] For the embodiment in FIG. 3 with an axis of symmetry parallel to the trajectory 101, a point of intersection of the trajectory through the predetermined entry point and target object 103 with the inner wall of the patient tunnel 16 on a side of the instrument 60 facing away from the patient 100 is determined in a step S41. This may, for example, take place by solving a system of equations in which the straight-line equation of the trajectory 101 is equated with an envelope of the inner wall.

[0084] In the embodiments in FIGS. 5 and 7, an alignment of the first projector 72 may be set at an angle relative to the axis of symmetry of the medical instrument 60 and an angle of rotation about the axis of symmetry. The predetermined position 80 may be arranged in an invariable manner on the inner wall of the patient tunnel 16 and marked graphically or by a structure. In this case, the alignment of the first projector 72 is determined in a step S42 such that the luminous pointer 70 of the first projector falls onto the predetermined position 80 when the medical instrument 60 is aligned parallel to the trajectory 101 in a manner appropriate for the application. This may be done by solving a system of equations in which the trajectory 101 is multiplied by a rotation matrix containing as variables the two angles of alignment of the first projector 72 and that is equated with the predetermined position 80. The solution according to the two angles provides the alignment of the first projector 72 to be determined, for example by the controller 23 of the magnetic resonance imaging scanner 1. during the ascertaining, the projector controller 76 may ascertain, by a sensor 79, a position of the medical instrument 60 relative to the magnetic resonance imaging scanner 1 and the alignment is ascertained in dependence on this position. For example, this position may be included as an offset in the angle of rotation.

[0085] In a step S50, the result of the ascertaining in step S40 is output.

[0086] For an embodiment of the medical instrument 60 with fixed parallel alignment of the first projector 72 and the luminous pointer 70 created thereby with the axis of symmetry, the coordinate for the predetermined position 80 may be output in a step S51 on an output of the magnetic resonance imaging scanner 1. A second projector 90 may indicate the predetermined position 90 in that the second projector 90 is aligned by actuators with the predetermined position 80 by the controller 23. The second projector 90 may be aligned in a fixed manner, but outputs a variable image with a settable position of a projected marking for the predetermined position 80 which is, for example, set by the controller 23.

[0087] For an embodiment in which the first projector 72, or at least the luminous pointer 80 projected thereby, is variable in alignment relative to the medical instrument 60, the outputting takes place in a step S52, for example in that the first actuator 77 and second actuator 78 are aligned accordingly by a setting instruction from the controller 23 to the projector controller 76.

[0088] In an embodiment with a fixed first projector 72 that projects an image, the projector controller 76 sets the image such that the luminous pointer 70 is projected in the ascertained alignment relative to the medical instrument 60.

[0089] The luminous pointer 70 is then projected by the first projector 72.

[0090] In another step S60, the medical instrument 60 is positioned at the predetermined entry point. This may be done by a user and may also be done earlier in the method.

[0091] Finally, in a step S60, the medical instrument is aligned such that the luminous pointer 70 is caused to coincide with the positioning aid. This may be done by the user by tilting, swiveling and/or rotating the medical instrument 60 until the light pointer 70 coincides with the predetermined position 80. The tip of the medical instrument 60 remains at the entry point. In an embodiment in which the light pointer 70 and the marking for the predetermined position 80 includes a direction marking for displaying directional information, the alignment of the medical instrument 60 may also include rotating the medical instrument 60 about the axis of symmetry until the direction markings coincide.

[0092] In an embodiment, the method furthermore includes the step S10 of outputting a map of the patient 100 on the operator interface of the planning controller. The planning controller may be identical to the controller 23 of the magnetic resonance imaging scanner 1. The map contains at least the target object 103 and an area around a possible entry point. The map may bey a magnetic resonance scan with the magnetic resonance imaging scanner 1. The map may be acquired with another modality and may be provided on a data carrier or via a data network connection.

[0093] In a further step S20, an entry point is defined on the surface of the patient and a target point is defined in the target area 103 in the patient 100. The target point may be defined by an organ or tissue identifiable in the map, for example a node or an entire organ. The entry point may already be marked in the map by a marker detected by the modality. The entry point may only be defined based on the map, for example with the requirement that no sensitive tissue is damaged on the way from the entry point to the target area.

[0094] It is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent, and that such new combinations are to be understood as forming a part of the present specification.

[0095] While the present invention has been described above by reference to various embodiments, it may be understood that many changes and modifications may be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.