Device, medical instrument and method for obtaining a spatial image of a medical instrument using a magnetic resonance imaging device

Abstract

Device (1) for obtaining a spatial instrument image (60) of a medical instrument (50) and an anatomical image (62) using a magnetic resonance imaging (MRI) device (10), wherein the device (1) comprises a medical instrument (50), a MRI device (10), and a computing and control unit (70), wherein the medical instrument (50) comprises at least one marker material in at least one region (52, 52', 52'') that exhibits a nuclear magnetic resonance outside the proton resonance range, and wherein the computing and control unit (70) for controlling the MRI device (10) is configured such that, by means of the MRI device (10), a nuclear magnetic resonance imaging scan using proton resonance is performed to obtain a spatial anatomical image (62), and a nuclear magnetic resonance imaging scan using the nuclear magnetic resonance of the at least one marker material is performed. Acquisition of a spatial instrument image (60) is carried out,wherein the computing and control means (70) is designed to receive the anatomy image (62) and the instrument image (60) and to superimpose the anatomy image (62) and the instrument image (60) in the correct position and orientation, characterized in that the computing and control means (70) comprises an image model (56) of the medical instrument (50) and is designed to determine the position and orientation of the medical instrument (50) by means of the instrument image (60) and to superimpose the image model (56) of the medical instrument (50) onto the anatomy image (62) in the correct position and orientation.

Description

[0001] The present invention relates to a device for obtaining a three-dimensional image of a medical instrument using a magnetic resonance imaging (MRI) scanner. Furthermore, the present invention relates to a corresponding medical instrument and a corresponding method for obtaining a three-dimensional image of a medical instrument using a magnetic resonance imaging (MRI) scanner.

[0002] Magnetic resonance imaging, or MRI, is a well-known imaging technique used primarily in medical diagnostics to visualize the structures and functions of soft tissues and organs in a subject, such as a human or animal patient. While it offers many advantages over other imaging techniques like computed tomography, X-ray imaging, or ultrasound, MRI has the disadvantage that objects with low water or fat content are, by their very nature, only faintly depicted in an MRI image and are therefore difficult to identify. In particular, the position and orientation of a medical instrument or device in relation to other components, such as soft tissue, are often difficult to discern in an MRI image.

[0003] One application where information regarding the position of a medical instrument in relation to other objects, such as organs, is of great importance is brachytherapy. Brachytherapy is a minimally invasive procedure used to irradiate a tumor, such as prostate, cervical, breast, or laryngeal cancer, using internal radiation therapy or radiation treatment in its immediate target region. For this purpose, one or more radiation sources are placed in close proximity to the area to be irradiated. A significant advantage over teletherapy with a linear accelerator is that...External Beam Radiotherapy (EBRT) is characterized by the fact that, if radioisotopes with a correspondingly short range are chosen, as is the case with beta emitters, the radiation exposure for the surrounding tissue is minimal, whereas in teletherapy the beam of the linear accelerator must also penetrate healthy tissue to reach the target.

[0004] To introduce the radiation sources, so-called applicators or guides—catheter-like devices or hollow needles—are often inserted or implanted into the body, near the tumor or directly into the tumor tissue. In so-called temporary brachytherapy, the radiation sources can remain in the body temporarily, for example, for a few minutes or hours, or in permanent brachytherapy for a longer period or indefinitely. Permanent brachytherapy is also known as low-dose-rate brachytherapy (LDR), while temporary brachytherapy, because a more powerful radiation source is used to irradiate the tumor, is known as high-dose-rate brachytherapy (HDR).

[0005] To determine the precise target position of the radiation sources, a computed tomography (CT) or magnetic resonance imaging (MRI) scan of the region to be irradiated can be performed before therapy. Using this data set, a treatment planning system calculates the exact dose distribution in the target region. Based on the ideal dose distribution at or within the tumor, the number and positions of the applicators and radiation sources to be inserted are determined. Dose planning ensures that the radiation is applied in high doses only where the tumor is located. Dose distribution can also be recalculated after the implantation of the applicators and, if necessary, again during the insertion of the radiation sources for quality control purposes. This prevents unnecessary irradiation of the surrounding, and in some cases highly radiosensitive, tissue and minimizes potential damage.Furthermore, unlike external irradiation, the skin is not damaged, as the irradiation is from within.

[0006] Following a preliminary examination, dose planning, and procurement of the necessary materials, the actual brachytherapy procedure takes place. For this, the patient is sedated or anesthetized in a sterile operating room, and the applicators are implanted. This can be done under 2D fluoroscopy. After successful verification of the applicator position, internal irradiation is performed using radioactive sources, so-called seeds, for example, in the form of capsules approximately one to five millimeters long made of cesium-137. In the so-called afterloading procedure, the seeds are manually or automatically inserted into their target area by the applicators, possibly in stages. The radiation dose in the target area is calculated based on the expected radiation intensity of the individual seeds and their dwell time in the applicator and / or the target area.Once the predicted implant duration is reached, the seeds and applicators are removed, possibly in stages, in the case of temporary brachytherapy. The implant duration and the calculated administered dose can be documented.

[0007] It is evident that precise knowledge of the position of the applicators or seeds relative to other structures is necessary for dose calculation. However, an accurate representation of the tumor and surrounding organs at risk (OAR) is also crucial for calculating a dose distribution for both the tumor volume and the organs at risk. Generally, various imaging techniques can be used for this purpose; however, computed tomography (CT) is most commonly used in current clinical practice because it provides spatially accurate 3D datasets in which the applicators are clearly visible. A disadvantage of CT is that the target organs are not sufficiently delineated, for example, in the pelvis. Magnetic resonance imaging (MRI) would be more suitable, but with the aforementioned drawback that the applicators are then difficult to identify. These must be painstakingly located by a user, e.g.,The tumors must be identified and segmented by a physician to be included in a planning system. This disadvantage is so significant that magnetic resonance imaging (MRI) is rarely used for this application. Other weaknesses of MRI that play a major role in dosimetry for EBRT procedures, such as distortion, determining tissue attenuation values, and the skin boundary being outside the imaging range of the device, are hardly relevant in brachytherapy because the target volume is close to the isocenter of the MRI scanner, only the immediate vicinity of the tumor needs to be considered, and deviations in radiation absorption are negligible due to the minimal range. Therefore, MRI would be very well suited for dose calculations for brachytherapy if the problem of applicator visibility were solved.

[0008] The object of the present invention is to provide a device for obtaining a three-dimensional image of a medical instrument using a magnetic resonance imaging (MRI) scanner. Furthermore, it is an object of the invention to describe a corresponding medical instrument and a corresponding method for obtaining a three-dimensional image of a medical instrument using a MRI scanner.

[0009] The invention solves this problem with a device for obtaining a three-dimensional image of a medical instrument using a magnetic resonance imaging (MRI) device, comprising the features of the first independent claim, a medical instrument for obtaining a three-dimensional image of a medical instrument using a MRI device, comprising the features of the second independent claim, and a method for obtaining a three-dimensional image of a medical instrument using a MRI device, comprising the features of the third independent claim. Advantageous embodiments are described in the dependent claims.

[0010] A fundamental concept of the invention is a device for obtaining a spatial image of a medical instrument using a magnetic resonance imaging (MRI) device, wherein the device comprises a medical instrument, a MRI device, and a computing and control means, wherein the medical instrument comprises at least one marker material in at least one region that exhibits a nuclear magnetic resonance outside the proton resonance range, and wherein the computing and control means for controlling the MRI device is configured such that, by means of the MRI device, a nuclear magnetic resonance imaging scan can be performed using the nuclear magnetic resonance of the at least one marker material to obtain a spatial image of the instrument, and wherein the computing and control means is configured for receiving the instrument image.

[0011] This basic concept of the invention describes a device with which a three-dimensional image of a medical instrument, e.g., a catheter, or at least a part of the medical instrument, can be obtained using a magnetic resonance imaging (MRI) scanner. The device comprises the medical instrument from which the three-dimensional image can be obtained, an MRI scanner, and a computing and control unit. According to the invention, the medical instrument comprises, in at least one region, at least one marking material that exhibits a nuclear magnetic resonance outside the proton band.The computing and control unit is designed to control the magnetic resonance imaging (MRI) scanner. Both the computing and control unit and the MRI scanner are configured such that the MRI scanner can be used to acquire a three-dimensional instrument image by means of the magnetic resonance of at least one marker material. The computing and control unit is designed to receive the instrument image. The medical instrument thus incorporates a material, referred to here as the marker material, that exhibits a magnetic resonance at a frequency that does not correspond to proton resonance. Consequently, areas containing the marker material are not visible, or only barely visible, in a magnetic resonance image acquired with a conventional MRI scanner.To visualize the marker material in a magnetic resonance imaging (MRI) image, also known as an instrumental image, the computer and control unit controls the MRI scanner in such a way that magnetic resonance imaging is enabled using the nuclear magnetic resonance of the marker material. For this purpose, for example, high-frequency pulses are emitted in the MRI scanner by a high-frequency antenna unit using suitable antenna elements, and the emitted magnetic resonance signals are then received and processed by suitable high-frequency antennas.

[0012] Preferably, the at least one marking material comprises a fluorine compound, a sodium compound and / or a phosphorus compound.

[0013] Fluorine compounds, 19F, such as perfluorocarbons, are preferred as markers because they occur in the body only in very small amounts. However, other isotopes such as sodium, 21Na, or phosphorus, 31P, and their compounds are also conceivable as markers.

[0014] In an advantageous further development, the medical instrument comprises, in addition to the at least one marking material, a transparency material that exhibits a nuclear magnetic resonance outside the proton resonance and outside the nuclear magnetic resonance of the at least one marking material.

[0015] By using a transparency material whose nuclear magnetic resonance (NMR) does not correspond to either the proton resonance or the NMR of the at least one labeling material, the transparency material is virtually transparent in an image obtained with standard parameters of a magnetic resonance imaging (MRI) scanner and in an image obtained using MRI with the NMR of the at least one labeling material. In particular, the medical instrument contains little or no material that causes artifacts in MRI, especially no metals or other electrically conductive materials. Preferably, the transparency material is a plastic.

[0016] In a further advantageous embodiment, the medical instrument comprises at least one marking material as a coating, as a compound, as an encapsulated inclusion, or at least one marking material is dissolved in a material of the medical instrument.

[0017] The marking material can be dissolved in a material of the medical instrument, e.g., in the material of the outer casing of the medical instrument, or it can be included as a compound. Particularly if the material is a transparent material, such as plastic, the marking material can be mixed with it through simple manufacturing processes. By applying a marking material as a coating to at least part of the outer shape of the medical instrument, the outer profile can be made visible in the instrument image in the area of ​​the marking material. A preferred embodiment involves applying a coating of fluorinated plastics, e.g., PTFE (trade name "Teflon"), to a medical instrument, e.g., an applicator.This has the advantage that the coating directly improves the properties of the medical instrument; for example, bacteria or other deposits adhere less readily to the instrument. If the medical instrument is a seed, it can be encased in a plastic containing the marking material or substance. Alternatively, the marking material could be in liquid form within suitable chambers inside the instrument.

[0018] With particular advantage, the computing and control device for controlling the magnetic resonance imaging device is designed in such a way that nuclear magnetic resonance imaging with proton resonance can be carried out to obtain a spatial anatomical image using the magnetic resonance imaging device, and the computing and control device is designed to receive the anatomical image and to superimpose the anatomical image and the instrument image in the correct position and orientation.

[0019] Magnetic resonance imaging (MRI) using proton resonance is the standard imaging technique used with a magnetic resonance imaging (MRI) scanner. This feature allows for the acquisition of an instrument image, depicting the medical instrument itself, and an anatomical image, depicting the anatomical structures surrounding the instrument. This can be done sequentially or, through appropriate sequences, simultaneously or near-simultaneously. The images can then be superimposed, fused, or registered. Image registration of two images refers to a digital image processing technique used to align two images of at least a similar scene as closely as possible.Particularly when both images are acquired simultaneously or within a short time of each other, the spatial relationship between the medical instrument and the anatomical structures is established, because both images are taken at the same position of the subject.

[0020] This makes registering the two images easy.

[0021] Preferably, the computing and control means is designed for segmenting the medical instrument in the instrument image.

[0022] Segmentation is a common technique in medical image processing. In this context, it can be understood as isolating the medical instrument from other objects or image components not belonging to the medical instrument. A simple segmentation method is, for example, a threshold method. For segmenting the medical instrument, segmentation algorithms that appear appropriate to a specialist, such as a region-growing algorithm, can be used. Segmentation is easily possible because the normal anatomical structures are not depicted in the instrument image, as these contain the marker substance either not at all or only in minute quantities and therefore do not emit a signal.

[0023] It is proposed that, depending on the geometry and / or deformability of the medical instrument, the medical instrument may predeterminably include several areas of at least one marking material.

[0024] The markings on the medical instrument can be positioned so that the instrument's position and path can be clearly determined from the instrument image. For example, a rigid, needle-shaped applicator requires at least two markings in different positions, with one marking preferably located at the distal end of the applicator. For a flexible medical instrument, several markings are preferably distributed across its shape to allow its position and path to be determined from the instrument image. Alternatively, the entire medical instrument can be marked, for example, by manufacturing it entirely from a plastic that exhibits the desired resonance behavior, or by applying the marking material as a strip along the instrument.For seeds, one marking is sufficient.

[0025] Another advantageous embodiment provides that the at least one area with the at least one marking material has a predefinable geometry.

[0026] This allows certain structures to be specially marked, which are particularly relevant for correct positioning, for example the ring on applicators for cervical cancer.

[0027] In an alternative embodiment of the invention, the medical instrument comprises several areas with different marking materials.

[0028] One marker can be labelled with a material such as fluorine (19F), and another with a different material such as sodium (21Na). While this requires capturing as many images as there are labelling materials used, it also increases the information content, as different ends of the medical instrument can be marked with different materials.

[0029] It is conceivable that the computational and control means is designed to correct geometric distortions of the instrument image and / or the anatomical image from a known position and / or geometry of the at least one area with the at least one marking material.

[0030] One advantage of using multiple markers is that, if the distance between the markers is known, geometric distortion artifacts can be easily identified and at least partially compensated, since an absolute scale is available.

[0031] It has proven advantageous if information is encoded by a geometric arrangement and / or by the type of marking material and / or by the number and / or by the density of marking material in the at least one area with at least one marking material.

[0032] The markings can also be arranged, for example, in a barcode-like manner, so that the arrangement, material, or quantity is specific to a particular type of medical instrument, such as an applicator, thus enabling easy identification of the medical instrument and preventing mix-ups. This can be achieved, for example, by using different marking spacings or different marking materials. Furthermore, the amount or density of the material can vary, allowing differentiation based on the measured signal intensity.

[0033] Furthermore, it is advantageous if the calculation and control tool is designed to determine the position and location of the medical instrument using the instrument image and to make this information available to a planning tool.

[0034] In many cases, the spatial relationship of a medical instrument to anatomical structures is of great importance, for example, in neurosurgical procedures. Using the instrument image, the position and orientation of the medical instrument can be determined and made available to a planning tool, which can then use this information to, for example, determine the distance of a biopsy needle to a blood vessel.

[0035] Ideally, the computing and control system includes an image model of the medical instrument, and the computing and control system is designed to determine the position and orientation of the medical instrument using the instrument image and to overlay the image model of the medical instrument onto the anatomical image in the correct position and orientation.

[0036] As an alternative to overlaying an anatomical image with image data of the instrument, the position and orientation of the medical instrument in the image space can be determined using known digital image processing methods, and an image model—that is, a simplified representation of the medical instrument—is superimposed on the anatomical image. The image model of the medical instrument can be defined with a predefined level of detail. For example, the medical instrument can be modeled realistically or abstractly using known ray tracing methods, e.g., only with an arrow indicating the orientation and a distal end. In one embodiment, the position and orientation of an applicator can be shown to a customer schematically, e.g., as a dot with an attached line, in real time superimposed on the anatomical representation.The type of applicator can also be determined from a previously described marking and represented in a model.

[0037] The medical instrument is suitable as an applicator for performing brachytherapy or as a radiation agent for use in brachytherapy.

[0038] As can be seen from the preceding explanations, the described devices according to the invention are particularly suitable for obtaining a spatial image with a magnetic resonance imaging device of an applicator or a radiation agent for use in brachytherapy.

[0039] Another basic idea of ​​the invention is a medical instrument for obtaining a spatial image of a medical instrument with a magnetic resonance imaging device, wherein the medical instrument for obtaining a spatial image of a medical instrument with a magnetic resonance imaging device can be used if it is designed like one of the previously described medical instruments and is operated with one of the previously described devices.

[0040] For example, such a medical instrument for obtaining a three-dimensional image of a medical instrument using a magnetic resonance imaging (MRI) device comprises at least one marker material in at least one region that exhibits a nuclear magnetic resonance outside the proton band. Together with a device comprising an MRI device and a computing and control unit, wherein the computing and control unit is configured to control the MRI device such that MRI imaging using the nuclear magnetic resonance of the at least one marker material can be performed, a three-dimensional image of the medical instrument can be obtained and received by the computing and control unit.

[0041] Another basic idea of ​​the invention is a method for obtaining a spatial image of a medical instrument using a magnetic resonance imaging device, wherein the method uses one of the previously described devices according to the invention for obtaining a spatial image of a medical instrument using a magnetic resonance imaging device.

[0042] A method according to the invention comprises process steps for which components of the device according to the invention are preferably designed. In the case of a marking material that exhibits a nuclear magnetic resonance outside the proton resonance range and a computing and control means that is designed to control a magnetic resonance imaging (MRI) device such that an MRI scan using the MRI device can be performed with the nuclear magnetic resonance of the at least one marking material to obtain a three-dimensional instrument image, a process step of a method according to the invention can be: Control of the MRI device by the computing and control means such that an MRI scan using the MRI device is performed with the nuclear magnetic resonance of the at least one marking material and obtaining a three-dimensional instrument image.

[0043] The following describes an example of a method according to the invention in brachytherapy. In brachytherapy, after the applicators are inserted, at least one image is taken using proton resonance (the anatomy image), and at least one image is taken using the at least one resonance frequency of the marker substance (the instrument image). This can be done sequentially or simultaneously. The applicators are then automatically segmented in the instrument image. This is not very complex, since the normal anatomical structures are not depicted in this image because they do not contain the marker substance or only in minute quantities and therefore do not emit a signal. However, the spatial relationship to the anatomical structures is still ensured because both images are taken in the same position without repositioning the patient. The positions determined in this way, or rather,The course of the applicators is subsequently taken into account when planning brachytherapy. For this purpose, they are superimposed on the anatomical image and, for example, highlighted in color.

[0044] The exemplary embodiments described in more detail below represent preferred embodiments of the present invention.

[0045] Further beneficial training opportunities arise from the following figures and descriptions. They show: Fig. 1. A description of brachytherapy according to the state of the art; Fig. 2. Schematic and exemplary representation of a medical instrument for obtaining a spatial image of a medical instrument using a magnetic resonance imaging device; Fig. 3. Schematic and exemplary illustrations of an instrument image, an anatomy image, and a superimposition of the two images; Fig. 4. Schematic and exemplary representation of a device for obtaining a spatial image of a medical instrument using a magnetic resonance imaging device;

[0046] Fig. Figure 1 shows a diagram describing a state-of-the-art brachytherapy procedure. In a patient 30, here a human patient, brachytherapy is performed to treat a target 32, here a tumor. For this purpose, an applicator 35, here in the form of a catheter, is inserted into a target area 31. The target area 31 includes at least the target 32; that is, the target area is generally a volume within the patient 30, within which at least the target 32 ​​lies. Using the applicator 35, a radiation agent 33, here a so-called seed made of a radionuclide, for example cesium-137, cobalt-60, iridium-192, iodine-125, palladium-103, or ruthenium-106, or even a miniaturized low-energy X-ray source, can be brought into the immediate vicinity of the target 32. The radiation medium 33 emits high-energy radiation, in which Fig. 1 indicated by lines 34, which penetrate the target object 32. A major advantage of brachytherapy is that the radiation effect is very limited to a specific area around the radiation source. Nevertheless, tissues and organs in the vicinity of the radiation medium 33 are also irradiated, so the injection site, the type of radiation medium 33, and the duration of treatment must be carefully considered to minimize the health risks to the subject 30.

[0047] In Fig. Figure 2 schematically and exemplarily shows a medical instrument 50, here a catheter, for obtaining a three-dimensional image of a medical instrument 50 using a magnetic resonance imaging (MRI) scanner. The medical instrument 50 has a material, here called marker material, in several areas 52, 52', 52", 54, which exhibits nuclear magnetic resonance at a frequency that does not correspond to proton resonance. Consequently, the areas 52, 52', 52", 54, which contain the marker material, are not visible or barely visible in an MRI image obtained with a conventional MRI scanner. To visualize the marker material in an MRI image, the so-called instrument image, a computer and control unit controls the MRI scanner in such a way that MRI imaging with the nuclear magnetic resonance of the marker material is enabled. The Fig. The medical instrument 50 shown in Figure 2 has a cuff-like area 52, a ring-shaped area 52', a strip-shaped area 52'', and an area 54 containing a marker material. Area 54 is characterized by the fact that its special geometric shape encodes information, for example, the type of medical instrument 50. Furthermore, the medical instrument 50 has areas 56 that comprise a so-called transparency material. By using a transparency material whose nuclear magnetic resonance (NMR) does not correspond to either the proton resonance or the NMR of the at least one marker material, the transparency material is quasi-transparent in an image obtained with standard parameters of a magnetic resonance imaging (MRI) scanner and in an image obtained using MRI with the NMR of the at least one marker material.

[0048] Fig. Figure 3 schematically and exemplarily shows an instrument image 60, an anatomical image 62, and a superposition of the two images 64. One of the devices described above is designed to obtain a three-dimensional instrument image 60 of a medical instrument using a magnetic resonance imaging (MRI) device. For this purpose, the device comprises the medical instrument, the MRI device, and a computing and control unit 70. The medical instrument includes a marker material in regions 52 and 52' that exhibits a nuclear magnetic resonance outside the proton resonance range. The computing and control unit 70 is designed to control the MRI device such that MRI imaging using the nuclear magnetic resonance of the at least one marker material can be performed to obtain the three-dimensional instrument image 60. Regions 52 and 52', respectively, are...The markings on the medical instrument are positioned so that the position and course of the medical instrument can be clearly determined from the instrument image 60. In this embodiment, a rigid catheter, the two areas are located in different positions: area 52' at the distal end of the applicator and the other area 52 on the catheter shaft. In this embodiment, the computing and control unit 70 is also configured to control the magnetic resonance imaging (MRI) device, enabling proton resonance imaging to generate a spatial anatomical image 62 of an anatomical structure 66, in this case, a vessel. The computing and control unit 70 receives the instrument image 60 and the anatomical image 62 from the MRI device.The computing and control unit 70 uses known digital image processing methods to determine the position and location of the medical instrument from the instrument image 60 and overlays an image model 56 of the medical instrument onto the anatomical image 62, correctly aligning it and creating a superimposed image 64. This superimposed image 64 can be displayed, for example, on a display device such as a computer monitor. The position and location of the medical instrument can also be provided to a medical planning or documentation system so that it can use this information further.

[0049] In Fig.Figure 4 schematically and exemplarily illustrates a device 1 for obtaining a three-dimensional image of a medical instrument 50 using a magnetic resonance imaging (MRI) scanner 10. The MRI scanner 10 comprises a magnet unit 11 with a superconducting main magnet 12 for generating a strong and, in particular, constant main magnetic field 13. The MRI scanner also has a patient acquisition chamber 14 for receiving an examination object 30, in this case, a human patient. In the present embodiment, the patient acquisition chamber 14 is cylindrical and is surrounded in a cylindrical shape by the magnet unit 11 in one circumferential direction. However, a different configuration of the patient acquisition chamber 14 is conceivable. The examination object 30 can be moved into the patient acquisition chamber 14 using a patient positioning device 25 of the MRI scanner 10.The patient positioning device 25 includes a reclining table 26 that is movable within the patient acquisition room 14. The magnet unit 11 also includes a gradient coil unit 16 for generating magnetic field gradients, which are used for spatial coding during imaging. The gradient coil unit 16 is controlled by a gradient control unit 17 of the magnetic resonance imaging (MRI) scanner 10. The magnet unit 11 further comprises a high-frequency antenna unit 18 for exciting a polarization that is established in the main magnetic field 13 generated by the main magnet 12. The high-frequency antenna unit 18 is controlled by a high-frequency antenna control unit 19 of the MRI scanner 10 and transmits high-frequency magnetic resonance sequences into an examination room, which is essentially formed by the patient acquisition room 14 of the MRI scanner 10.The magnetic resonance imaging (MRI) device includes a control unit 20 for controlling the main magnet 12, the gradient control unit 17, and the high-frequency antenna control unit 19. The control unit 20 centrally controls the MRI device, for example, by performing a predetermined imaging gradient echo sequence. The control unit 20 also includes an evaluation unit (not shown) for evaluating image data. Control information, such as imaging parameters, as well as reconstructed MRI images, can be displayed to an operator on a display unit 21, for example, on at least one monitor, of the MRI device 10. The MRI device 10 also includes an input unit 22, by means of which an operator can enter information and / or parameters during a measurement procedure.The depicted magnetic resonance imaging (MRI) device 10 can, of course, include other components that are commonly found in MRI devices. Furthermore, the general operating principle of an MRI device is known to those skilled in the art, so a detailed description of the other components is omitted. The device 1 for obtaining a three-dimensional image of a medical instrument 50 using an MRI device 10 comprises the medical instrument 50, here an applicator for performing brachytherapy, the MRI device 10, and a computing and control device 70, for example, a computer. The medical instrument 50 includes, in at least one region, at least one marker material that exhibits a nuclear magnetic resonance outside the proton resonance range.The computing and control device 70 is designed to control the magnetic resonance imaging (MRI) device 10, and the computing and control device 70 and the MRI device 10 are configured such that the MRI device 10 can also be used to perform magnetic resonance imaging (MRI) using the nuclear magnetic resonance of at least one marker material to obtain a three-dimensional image of the instrument. The computing and control device 70 is designed to receive the instrument image and has a connection, in this case an electrical conductor, to the control unit 20 of the MRI device 10. The medical instrument 50 thus has a marker material that exhibits nuclear magnetic resonance at a frequency that does not correspond to proton resonance.Consequently, areas containing the marker material are not visible or barely visible in a magnetic resonance imaging (MRI) image acquired with a conventional MRI scanner 10. To visualize the marker material in an MRI image, the computer and control unit 70 controls the MRI scanner 10 in such a way that magnetic resonance imaging using the nuclear magnetic resonance of the marker material is enabled. For this purpose, for example, high-frequency radiofrequency pulses are emitted by the radiofrequency antenna unit 18 in the MRI scanner 10 using suitable antenna devices, and the emitted magnetic resonance signals are subsequently received and processed by suitable radiofrequency antennas.

[0050] The computing and control device 70 can also be integrated into the magnetic resonance imaging device 10, e.g., in the control unit 20. Furthermore, the computing and control device 70 can be designed to determine the position and orientation of the medical instrument 50 using the instrument image and to transmit this information to a planning device 80, in this case, a planning system for brachytherapy. The medical instrument 50 can carry information through its geometric arrangement, the type of marking material, the number of markings applied, or the density of marking material with which at least one area of ​​the medical instrument 50 is coated. This information can be decoded by the computing and control device 70 and displayed, for example, on the display unit 21.

[0051] In summary, further embodiments and advantages of the invention are described. The invention proposes, among other things, a device that enables the automatic identification of brachytherapy applicators in magnetic resonance imaging (MRI). This is achieved using markers with a suitable substance and MRI at a different frequency than proton imaging.

[0052] The advantage lies in the simple and error-free identification of the applicator positions relative to the anatomy. Even with poor image quality, the applicators can be easily identified if an isotope, such as fluorine, is used that occurs in the body only in very small amounts.

Claims

[1] Device (1) for obtaining a spatial instrument image (60) of a medical instrument (50) and an anatomical image (62) using a magnetic resonance imaging device (10), wherein the device (1) comprises a medical instrument (50), a magnetic resonance imaging device (10), and a computing and control means (70), wherein the medical instrument (50) comprises at least one marking material in at least one region (52, 52', 52'') having a nuclear magnetic resonance outside of proton resonance, and wherein the computing and control means (70) for controlling the magnetic resonance imaging device (10) is configured such that, by means of the magnetic resonance imaging device (10), a nuclear magnetic resonance imaging with proton resonance is performed to obtain a spatial anatomical image (62), and a nuclear magnetic resonance imaging with the nuclear magnetic resonance of the at least one Marking material to obtain a spatial instrument image (60) are used,wherein the computing and control means (70) is designed to receive the anatomy image (62) and the instrument image (60) and to superimpose the anatomy image (62) and the instrument image (60) in the correct position and orientation, characterized by , that the computational and control means (70) includes an image model (56) of the medical instrument (50) and is designed to determine the position and location of the medical instrument (50) by means of the instrument image (60) and to superimpose the image model (56) of the medical instrument (50) onto the anatomy image (62) in the correct position and location. [2] Device (1) according to claim 1, wherein the at least one marking material comprises a fluorine compound, a sodium compound and / or a phosphorus compound. [3] Device (1) according to claim 1 or claim 2, wherein the medical instrument (50) comprises, in addition to the at least one marking material, a transparency material which has a nuclear magnetic resonance outside the proton resonance and outside the nuclear magnetic resonance of the at least one marking material. [4] Device (1) according to one of the preceding claims, wherein the medical instrument (50) comprises the at least one marking material as a coating, as a compound or as an encapsulated inclusion or wherein the at least one marking material is dissolved in a material of the medical instrument (50). [5] Device (1) according to one of the preceding claims, wherein the calculating and control means (70) is designed for segmenting the medical instrument (50) in the instrument image (60). [6] Device (1) according to one of the preceding claims, wherein, depending on the geometry and / or deformability of the medical instrument (50), the medical instrument (50) may predetermine several areas (52, 52') of at least one marking material. [7] Device (1) according to one of the preceding claims, wherein the at least one area with the at least one marking material has a predefinable geometry (52'). [8] Device (1) according to one of the preceding claims, wherein the medical instrument (50) comprises several areas (52, 52', 52'') with different marking materials. [9] Device (1) according to one of the preceding claims, wherein the calculating and control means (70) is designed to correct geometric distortions of the instrument image (60) and / or the anatomy image (62) from a known position and / or geometry of the at least one area (52, 52', 52'') with the at least one marking material. [10] Device (1) according to one of the preceding claims, wherein information is encoded by a geometric arrangement and / or by the type of marking material and / or by the number and / or by the density of marking material of the at least one area (54) with at least one marking material. [11] Device (1) according to one of the preceding claims, wherein the calculating and control means (70) is designed to determine the position and location of the medical instrument (50) by means of the instrument image (60) and to make it available to a planning means (80). [12] Device (1) according to any of the preceding claims, wherein the medical instrument (50) is an applicator for performing brachytherapy or a radiation medium (33) for use in brachytherapy. [13] Medical instrument (50) for obtaining a spatial instrument image (60) of a medical instrument (50) with a magnetic resonance imaging device (10), wherein the medical instrument (50) for obtaining a spatial instrument image (60) of a medical instrument (50) with a magnetic resonance imaging device (10) is usable if it is designed according to one of claims 1 to 12 and is operated with a device (1) according to one of claims 1 to 12. [14] Method for obtaining a spatial instrument image (60) of a medical instrument (50) using a magnetic resonance imaging device (10), wherein the method utilizes a device (1) for obtaining a spatial instrument image (60) of a medical instrument (50) using a magnetic resonance imaging device (10) according to any one of claims 1 to 12.

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