DEFORMATION MODEL FOR A TISSUE

Abstract

The disclosure relates to techniques for generating a deformation model for a tissue of an examination object in dependence on a positioning of the examination object. The technique may include provisioning of long-term MR data recorded in a first time period from a region of interest comprising the tissue of the examination object, an ascertainment of time-resolved first position data describing the tissue based on the long-term MR data, a provisioning of time-resolved second position data recorded in the first time period from at least two surface points of a surface of the examination object, and a determination of the deformation model for the tissue by correlating the first position data with the second position data.

Claims

1. A method for generating a deformation model for a tissue of an examination object dependent upon a positioning of the examination object, comprising: acquiring, via one or more processors, magnetic resonance (MR) data recorded during a first time period from a region of interest comprising the tissue of the examination object; ascertaining, via one or more processors, time-resolved first position data describing the tissue based on the MR data; acquiring, via one or more processors, time-resolved second position data recorded during the first time period from at least two surface points associated with a surface of the examination object; and determining, via one or more processors, the deformation model for the tissue by correlating the first position data with the second position data.

2. The method as claimed in claim 1, further comprising: arranging a sensor on at least one surface point of the at least two surface points of the surface of the examination object during the first time period.

3. The method as claimed in claim 1, wherein the act of acquiring the time-resolved second position data comprises optically acquiring the time-resolved second position data during the first time period.

4. The method as claimed in claim 1, wherein the act of acquiring the time-resolved second position data comprises acquiring the second position data via a camera during the first time period.

5. The method as claimed in claim 1, wherein at least one surface point of the at least two surface points of the surface of the examination object corresponds to one of the following landmarks: a forehead, chin, nose, shoulder, elbow, knee, front of foot, heel, hip, wrist, or skullcap of the examination object.

6. The method as claimed in claim 1, wherein the act of ascertaining the time-resolved first position data comprises determining a fixed tissue point.

7. The method as claimed in claim 1, wherein the act of ascertaining the time-resolved first position data comprises determining tissue-specific landmarks.

8. The method as claimed in claim 7, wherein the act of ascertaining the time-resolved first position data comprises determining a statistical tissue model based on the tissue-specific landmarks.

9. The method as claimed in claim 7, wherein the act of ascertaining the time-resolved first position data comprises determining a deformation field and/or a vector field based on the tissue-specific landmarks.

10. The method as claimed in claim 6, wherein the act of determining the deformation model comprises correlating the first position data with the second position data by relating the fixed tissue point with at least one surface point of the at least two surface points of the surface of the examination object.

11. The method as claimed in claim 1, wherein the examination object adopts at least two positions during the first time period.

12. The method as claimed in claim 1, wherein the first time period comprises at least one sleeping phase associated with the examination object.

13. The method as claimed in claim 1, wherein the act of determining the deformation model comprises correlating the first position data with the second position data by using a trained artificial neural network.

14. The method as claimed in claim 1, further comprising: storing the deformation model as part of a virtual image of the examination object.

15. The method as claimed in claim 1, further comprising: ascertaining third position data from at least one surface point of the surface of the examination object; and determining fourth position data describing the tissue based on the third position data and the deformation model.

16. The method as claimed in claim 15, further comprising: using the fourth position data to perform an interventional examination of the examination object and/or in combination with image data mapping the tissue of the examination object.

17. The method as claimed in claim 1, wherein the first time period has a duration of at least one hour.

18. A non-transitory computer-readable medium having instructions stored thereon that, when executed by one or more processors, cause the one or more processors to generate a deformation model for a tissue of an examination object dependent upon a positioning of the examination object by: acquiring magnetic resonance (MR) data recorded during a first time period from a region of interest comprising the tissue of the examination object; ascertaining time-resolved first position data describing the tissue based on the MR data; acquiring time-resolved second position data recorded during the first time period from at least two surface points associated with a surface of the examination object; and determining the deformation model for the tissue by correlating the first position data with the second position data.

19. A magnetic resonance (MR) device for generating a deformation model for a tissue of an examination object in dependence on a positioning of the examination object, comprising: a first input configured to acquire MR data recorded during a first time period from a region of interest comprising the tissue of the examination object; ascertaining circuitry configured to ascertain time-resolved first position data describing the tissue based on the MR data; a second input configured to acquire time-resolved second position data recorded during the first time period from at least two surface points of the surface of the examination object; and determining circuitry configured to determine the deformation model for the tissue by correlating the first position data with the second position data.

20. The MR device of claim 19, further comprising: detector circuitry configured to acquire the second position data from the at least two surface points of the surface of the examination object.

Description

DETAILED DESCRIPTION

[0077] FIG. 1 shows a system 40 according to an embodiment of the disclosure for carrying out a method according to the disclosure in a schematic depiction. The system 40 comprises a first input 41 configured to acquire long-term MR data recorded in a first time period 91 from a region of interest 12 comprising the tissue of the examination object 15. The system 40 comprises an ascertaining unit 43 configured to ascertain time-resolved first position data describing the at least one tissue based on the long-term MR data. The system 40 comprises a second input 42 configured to acquire time-resolved second position data recorded in the first time period 91 from at least two surface points 51 of the surface of the examination object 15. The system 40 comprises a determining unit 44 configured to determine the deformation model for the tissue by correlating the first position data with the second position data. The first input 41 is e.g. connected to the ascertaining unit 43 and/or integrated therein. The second input 42 is e.g. connected to the determining unit 44 and/or integrated therein. The determining unit 44 and the ascertaining unit 43 can be part of a generating unit 46. The determining unit 44 and the ascertaining unit 43 can be implemented as separate from one another or as a single unit. The system 40 e.g. comprises an output 45 via which the system 40 can output the deformation model generated. The output 45 is typically connected to the determining unit 44.

[0078] For this, the determining unit 44 and/or the ascertaining unit 43, e.g. the generating unit 46, have computer programs and/or software, which can be loaded directly into a memory unit (and which are not depicted in further detail) of the determining unit 44 and/or ascertaining unit 43 and/or generating unit 46, with program means for carrying out a method for generating a deformation model for a tissue of an examination object 15 in dependence on a positioning of the examination object 15 when the computer programs and/or software are executed in the determining unit 44 and/or ascertaining unit 43 and/or generating unit 46. For this, the determining unit 44 and/or ascertaining unit 43 and/or generating unit 46 may have one or more processors, processing circuitry, etc. not depicted in further detail, configured or otherwise designed to execute the computer programs and/or software. Alternatively thereto, the computer programs and/or software can also be stored on an electronically readable data carrier 21 embodied separately from the determining unit 44 and/or ascertaining unit 43 and/or generating unit 46, wherein the determining unit 44 and/or ascertaining unit 43 and/or generating unit 46 can have data access to the electronically readable data carrier 21 via a data network. The system 40 typically comprises a display unit and/or an input unit.

[0079] The depicted system 40 can comprise further components. Hence, the system 40 is configured, together with the determining unit 44 and the ascertaining unit 43, to carry out a method according to the disclosure for generating a deformation model for a tissue of an examination object 15 dependent upon a positioning of the examination object 15.

[0080] A method for generating a deformation model for a tissue of an examination object 15 dependent upon a positioning of the examination object 15 can also be provided in the form of a computer program product that implements the method on the system 40 and/or on the generating unit 46 when it is carried out on the system 40 and/or on the generating unit 46. Similarly, an electronically readable data carrier 21 can be provided with electronically readable control information, which comprises at least one such above-described computer program product and is designed to carry out the described method when the data carrier 21 is used in a determining unit 44 and/or ascertaining unit 43 and/or generating unit 46 of a system 40.

[0081] FIG. 2 shows a magnetic resonance device 11 according to the disclosure for carrying out a method according to the disclosure and embodied to record long-term MR data in a schematic depiction. The magnetic resonance device 11 comprises an ascertaining unit 38 formed by a magnet unit 13 with a main magnet 17 for generating a strong and constant main magnetic field 18. The magnetic resonance device 11 also has a cylindrical patient-receiving region 14 for receiving an examination object 15, wherein the patient-receiving region 14 is enclosed by the magnet unit 13 in a cylindrical shape in a circumferential direction. The examination object 15 can be pushed into the patient-receiving region 14 by means of a patient-support apparatus 16 of the magnetic resonance device 11. For this, the patient-support apparatus 16 has a patient table arranged movably within the magnetic resonance device 11.

[0082] The magnet unit 13 also has a gradient coil unit 19 used for position encoding during imaging. The gradient coil unit 19 is actuated by means of a gradient control unit 28. Furthermore, the magnet unit 13 has a radio-frequency antenna unit 20, which, in the case shown, is implemented as a body coil permanently integrated in the magnetic resonance device 11, and a radio-frequency antenna control unit 29 for exciting polarization that is established in the main magnetic field 18 generated by the main magnet 17. The radio-frequency antenna unit 20 is actuated by the radio-frequency antenna control unit 29 and radiates high-frequency radio-frequency pulses into an examination space, which is substantially formed by the patient-receiving region 14.

[0083] To control the main magnet 17, the gradient control unit 28, and the radio-frequency antenna control unit 29, the magnetic resonance device 11 has a control unit 24. The control unit 24 centrally controls the magnetic resonance device 11, such as, for example, the performance of MR control sequences. The control unit 24 also comprises a reconstruction unit, not depicted in further detail, for reconstructing medical image data acquired during the magnetic resonance examination. The magnetic resonance device 11 has a display unit 25. Control information such as, for example, control parameters and reconstructed image data can be displayed on the display unit 25, for example on at least one monitor, for a user.

[0084] The magnetic resonance device 11 also has an input unit 26 by means of which a user can input information and/or control parameters during a scanning process. The control unit 24 can comprise the gradient control unit 28 and/or radio-frequency antenna control unit 29 and/or the display unit 25 and/or the input unit 26. As a result, the magnetic resonance device 11 is configured to acquire long-term MR data from a region of interest 12 comprising the tissue of the examination object 15. For this, the control unit 24 has computer programs and/or software, which can be loaded directly into a memory unit of the control unit 24, not depicted in further detail, with program means for carrying out a method for recording long-term MR data of the examination object 15 when the computer programs and/or software are executed in the control unit 24. For this, the control unit 24 has a processor, not depicted in further detail, designed to execute the computer programs and/or software.

[0085] The magnetic resonance device 11 comprises a detector unit 39 configured to acquire time-resolved second position data from at least two surface points 51 of a surface of the examination object 15. In each case, a sensor 59 is e.g. arranged on the at least two surface points 51 of the surface of the examination object 15. The magnetic resonance device 11 comprises a system 40 according to the disclosure the individual components of which can be seen in FIG. 1. The system 40 is typically connected to the detector unit 39 and the ascertaining unit 38. The system 40 can be integrated in the control unit 24. The system 40 can be arranged and/or designed as separate from the control unit 24. The system 40 can e.g. be operated by means of the display unit 25 and/or the input unit 26.

[0086] The magnetic resonance device 11 depicted can obviously comprise further components that magnetic resonance devices 11 normally have. In addition, the general mode of operation of a magnetic resonance device 11 is known to the person skilled in the art, so there is no detailed description of the further components. Hence, the magnetic resonance device 11 is configured to carry out a method according to the disclosure.

[0087] The magnetic resonance device 11 according to the disclosure is e.g. also configured to carry out a further method for generating a deformation model for a tissue of an examination object 15 dependent upon a positioning of the examination object 15 in accordance with the following method steps:

[0088] acquiring long-term MR data from a region of interest 12 comprising the tissue of the examination object 15 in a first time period 91 using a magnetic resonance device 11;

[0089] ascertaining time-resolved first position data describing the tissue based on the long-term MR data;

[0090] acquiring time-resolved second position data from at least two surface points 51 of a surface of the examination object 15 in the first time period 91 using a detector unit 39; and

[0091] determining the deformation model for the tissue by correlating the first position data with the second position data.

[0092] The further method for generating a deformation model can also be provided in the form of a computer program product that implements the method on the control unit 24 when it is executed on the control unit 24. Similarly, an electronically readable data carrier 21 can be provided with electronically readable control information stored thereupon, which comprises at least one such above-described computer program product and is designed to carry out the described further method when the data carrier 21 is used in a control unit 24 of a magnetic resonance device 11.

[0093] FIG. 3 shows a flow diagram of a first embodiment of a method according to the disclosure for generating a deformation model for a tissue of an examination object 15 dependent upon a positioning of the examination object 15. At the start of the method, the provisioning of long-term MR data recorded in a first time period 91 from a region of interest 12 comprising the tissue of the examination object 15 takes place in method step 110. When method step 110 has been carried out, the ascertainment of time-resolved first position data describing the tissue based on the long-term MR data takes place in method step 120. The provisioning of time-resolved second position data recorded in the first time period 91 from at least two surface points 51 of a surface of the examination object 15 takes place in accordance with method step 130, e.g. independently of method steps 110 and 120. When method steps 130 and 120 have been carried out, the determination of the deformation model for the tissue by correlating the first position data with the second position data takes place in accordance with method step 140. The deformation model determined can optionally be provided in accordance with method step 150. For instance, the provision in accordance with method step 150 can be stored as part of a digital twin of the examination object 15.

[0094] Method step 130 can optionally be preceded by method step 128 and/or method step 129 during the first time period 91. According to method step 128, the second position data from the at least two surface points 51 of the surface can be optically acquired during the first time period 91. According to method step 129, the second position data from the at least two surface points 51 of the surface can be acquired by means of a camera during the first time period 91. According to method steps 128 and/or 129, the second position data from the at least two surface points 51 of the surface can be acquired by means of the detector unit 39 during the first time period 91. Method step 110 can optionally be proceeded by method step 109 during the first time period 91. In accordance with method step 109, long-term MR data can be acquired from the region of interest 12 comprising the tissue of the examination object 15 by means of a magnetic resonance device 11, in particular by means of an ascertaining unit 38.

[0095] FIG. 4 shows a flow diagram of a second embodiment of a method according to the disclosure. With respect to method steps 110, 120, 130, 140, 150, reference is made to the description of FIG. 3. In addition, the second embodiment of the method according to the disclosure for determining third position data describing a tissue dependent upon a positioning of the examination object 15 and provides the ascertainment of fourth position data from at least one surface point 51 of a surface of the examination object 15 in method step 210. According to method step 220, the determination of third position data describing the tissue takes place based on the fourth position data and the deformation model. Optionally, according to method step 230, the use of the third position data can take place in the context of an interventional examination of the examination object 15 and/or in combination with image data mapping the tissue of the examination object 15.

[0096] FIG. 5 shows an examination object 15 in a schematic depiction. The at least two surface points 51 of the surface of the examination object 15, from which at least two surface points 51 second position data is recorded in the first time period 91, are depicted and each correspond to one of the following landmarks: forehead, chin, nose, shoulder, elbow, knee, front of foot, heel, hip, wrist, skullcap. However, these surface points are provided by way of example and not limitation, and additional or alternate surface points 51 may be used. In an embodiment, in each case a sensor 59 is arranged on the at least two surface points 51. One of the at least two surface points 51, e.g. the surface point 51 corresponding to the skullcap, can define a reference point 52.

[0097] The second position data can e.g. comprise the relative positions of the at least two surface points 51 to the reference point 52. Similarly, the reference point 52 can define a reference coordinate system 53. The reference coordinate system 53 is typically aligned along an anatomical axis of the examination object 15, in particular the skull of the examination object 15.

[0098] FIG. 6 shows a heart in a schematic depiction including first position data at a first time point. The heart is an example of an organ as a tissue of the examination object 15. The first position data at the first time point, which is ascertained in method step 120 based on the long-term MR data, e.g. comprises tissue-specific landmarks 61, 62. These tissue-specific landmarks 61, 62 can, for example, be differentiated as surface landmarks 61, which are, for example, arranged on a surface of the heart, and middle-point landmarks 62, defined as landmarks arranged in the middle between two surface landmarks 61. Similarly, it is possible to use a dedicated tissue-specific landmark 61, 62 as a fixed tissue point 63. During the correlation of the first position data with the second position data in accordance with method step 140, there is e.g. a determination of the relationship between the fixed tissue point 63 and at least one of the at least two surface points 51. The fixed tissue point 63 is typically comprised by the region of interest 12. The one of the at least two surface points 51 can lie outside the region of interest 12.

[0099] The first position data can comprise a statistical tissue model based on the tissue-specific landmarks. FIG. 6 shows such a statistical tissue model at the first time point. The statistical tissue model can, for example, take place by adapting graphics primitives, such as, for example, spheres and/or ellipsoids, based on the middle-point landmarks 62 to the tissue. Herein, it is e.g. possible to use the surface landmarks 61 and/or the surface of the tissue as a restriction for the determination of the size of the graphics primitives.

[0100] The ascertainment of the time-resolved first position data in accordance with method step 120 can comprise a determination of a deformation field and/or a vector field based on the tissue-specific landmarks 61, 62. As an example, the fixed tissue point 63 can also be taken into account when determining the deformation field and/or the vector field. The tissue-specific landmarks 61, 62 and thus also the fixed tissue point 63 typically have positions that are different from one another during at least two first time points that are different from one another within the first time period 91.

[0101] The absolute position of the fixed tissue point 63 at two first time points that are different from one another, in particular two successive first time points, within the first time period 91 can be described as a vector field. Consequently, the vector field describes at least one translation of the fixed tissue point 63 within the first time period 91. Similarly, the fixed tissue point 63 can be used as the origin of a coordinate system relative to which all tissue-specific landmarks 61, 62 for at least two first time points within the first time period 91 are determined in the form of coordinates. Coordinates of the tissue-specific landmarks 61, 62 determined in this way correspond to a deformation field describing a deformation of the tissue.

[0102] FIG. 7 shows the examination object 15 within the first time period 91 in two positions that are different from one another at two time points t1, t2 in a schematic depiction. In the embodiment shown, the fixed tissue point 63 and all the tissue-specific landmarks depicted correspond to middle-point landmarks 62. A comparison of the tissue at both time points has a translation described by a change of the fixed tissue point 63, for example as a vector field, and a deformation described by the position of the tissue-specific landmarks 61, 62 relative to the fixed tissue point 63, for example as a deformation field. In the case depicted, the examination object 15 in each case adopts a lying position such as is, for example, possible during a sleeping phase of the examination object 15 at the time points t1, t2. The two time points t1, t2 may be, for instance, first time points and second time points. Although the disclosure was illustrated and described in further detail by the preferred exemplary embodiments, the disclosure is not restricted by the disclosed examples and other variations can be derived herefrom by the person skilled in the art without departing from the scope of protection of the disclosure.