MR surface coil with heat dissipation element

Abstract

The invention relates to an MR surface coil with a heat dissipation element, a system comprising an MR surface coil, a patient table, and a magnetic resonance device. The MR surface coil comprises at least one RF antenna for transmitting and / or receiving RF signals, at least one electronic component electrically connected to the at least one RF antenna, a housing within which the at least one RF antenna and the at least one electronic component are arranged, and at least one heat dissipation element thermally connected to the at least one electronic component, wherein the at least one heat dissipation element is configured to dissipate heat energy from the at least one electronic component to the outside and / or to distribute it over a surface.

Description

[0001] The invention relates to an MR surface coil with a heat dissipation element, a system comprising an MR surface coil and a patient table and a magnetic resonance apparatus.

[0002] In medical technology, imaging using magnetic resonance (MR), also known as magnetic resonance tomography (MRI), is characterized by high soft tissue contrast. A subject to be examined, for example a human or animal patient, is positioned in the examination zone of a magnetic resonance scanner with a static main magnetic field. During a magnetic resonance measurement, radiofrequency (RF) pulses and gradient pulses are radiated into the examination zone to excite the slices to be measured. This triggers spatially encoded magnetic resonance signals in the subject. The magnetic resonance signals are typically received as measurement data by surface coils and used to reconstruct magnetic resonance images.

[0003] Surface coils are typically mounted directly on the object being examined, which is why they are also called local coils. Due to the proximity of the surface coil to the location where the magnetic resonance signal is generated, the measurement data received by a surface coil advantageously has a high signal-to-noise ratio. Surface coils can also be used to transmit RF signals. Surface coils typically have one or more RF antennas, often called coil elements, for transmitting and / or receiving the RF signals.

[0004] During magnetic resonance imaging (MRI) scanning, surface coils can heat up. Since surface coils are typically in direct contact with the patient, this heating must be limited. The objective of the present invention is to reduce the risk to patients caused by excessive heating of surface coils. In particular, temperature peaks in the areas where such components heat up are to be avoided.

[0005] The problem is solved by the features of the independent claims. Advantageous embodiments are described in the dependent claims. Regardless of the grammatical gender of a particular term, it encompasses persons with male, female, or other gender identities.

[0006] Accordingly, an MR surface coil is proposed, comprising at least one RF antenna for transmitting and / or receiving RF signals and at least one electronic component electrically connected to the at least one RF antenna. The at least one RF antenna and the at least one electronic component are arranged within a casing of the MR surface coil. The casing preferably delimits the MR surface coil to the outside.

[0007] Furthermore, the MR surface coil comprises at least one heat dissipation element that is thermally connected to the at least one electronic component. The at least one heat dissipation element is designed to dissipate thermal energy from the at least one electronic component to the outside and / or to distribute it over a large area.

[0008] By dissipating and / or distributing the thermal energy, the heat acting on the patient can advantageously be reduced. Furthermore, temperature peaks can advantageously be avoided, particularly in areas where the at least one electronic component is located. The thermal energy is preferably thermal energy generated by the at least one electronic component.

[0009] The thermal energy can be generated, in particular, by inducing an RF signal during a measurement. Furthermore, an MR surface coil is typically supplied with current, particularly direct current, even outside of a measurement, which can cause heating of at least one electronic component. It is even conceivable that for components whose electrical resistance increases with temperature, more electrical power must be applied at higher temperatures, which in turn causes an additional temperature increase.

[0010] Advantageously, with the help of at least one heat dissipation element, the locally generated heat is distributed and / or specifically redirected over as large an area as possible on the surface of the MR surface coil, thus avoiding strong local heating. Advantageously, more power can be introduced into the MR surface coil by at least one heat dissipation element. This allows for higher pulses, which advantageously increases the image quality of the magnetic resonance images. Furthermore, the geometry of the electronic components can be reduced, since any spacer materials for limiting heating can be omitted.

[0011] The at least one RF antenna can, for example, comprise an electrical conductor loop. In particular, an (electromagnetic) RF signal can be induced into the RF antenna. The at least one electronic component can, for example, comprise electrical capacitances, inductances, resistors, diodes, etc. The at least one electronic component can, for example, comprise a preamplifier for amplifying a received RF signal.

[0012] The at least one electronic component and the at least one RF antenna can be connected to each other, in particular, by means of an electrical line, for example, an electrically conductive wire. Furthermore, the at least one electronic component can also be electrically connected to any plug connection of the MR surface coil, which can be used to connect the MR surface coil to a magnetic resonance device. In addition to wired MR surface coils, wireless MR surface coils are also conceivable.

[0013] Preferably, the heat energy is transported away from the MR surface coil by dissipating it to the outside. This advantageously limits any potential temperature increase on the surface of the MR surface coil.

[0014] The planar distribution of the thermal energy preferably reduces local concentrations of thermal energy. Thermal hotspots can thus be advantageously avoided or reduced. The planar distribution of the thermal energy preferably occurs over a surface parallel to the surface of the MR surface coil.

[0015] The at least one heat dissipation element is advantageously thermally connected or coupled to the at least one electronic component in such a way that the thermal energy can be transported particularly quickly from the at least one electronic component to the heat dissipation element. Preferably, the heat dissipation element directly touches the at least one electronic component or is separated from it only by a thermally negligible intermediate layer. The intermediate layer is thermally negligible, for example, if it is sufficiently thin and / or if it has a high thermal conductivity (e.g., more than 2 W / (m·K)).

[0016] Preferably, the MR surface coil is flat, in particular two-dimensional. In particular, the MR surface coil has exactly two opposing surfaces, which form a large part of the total surface of the MR surface coil and are referred to below as main surfaces. In particular, the proportion of the two main surfaces to the total surface of the MR surface coil is at least 80 percent, in particular at least 90 percent. In particular, the two main surfaces are arranged parallel to each other.

[0017] In particular, the at least one electronic component comprises a plurality of electronic components. In particular, the plurality of electronic components are distributed over a surface. In particular, this surface is arranged parallel to the two main surfaces.

[0018] The MR surface coil is preferably flexible. The MR surface coil is preferably variable in shape. The MR surface coil is advantageously adaptable to the shape of the examination subject. The MR surface coil is preferably stretchable and / or elastic and / or flexible. The MR surface coil is, for example, blanket-shaped. The MR surface coil can advantageously be placed over the examination subject like a blanket.

[0019] Preferably, the at least one heat dissipation element comprises at least one, in particular thermal, distribution layer, which is arranged between the at least one electronic component and the casing and is designed to distribute at least part of the thermal energy over a surface of the MR surface coil. This advantageously reduces, and ideally prevents, heat hotspots.

[0020] Preferably, the at least one distribution layer is planar, in particular two-dimensional. In particular, the distribution layer has a surface A and an edge of length L delimiting the surface, where L 2 / A > 20, especially L 2 / A > 50, especially L 2 / A > 100.

[0021] Preferably, the at least one distribution layer, in particular its surface A, is arranged parallel to the two main surfaces. Advantageously, the thermal energy is thereby distributed over at least one of the two main surfaces.

[0022] The at least one distribution layer preferably comprises a fire-resistant fleece, a thermal fleece, a heat-resistant film, a coated textile, and / or a foam material. These materials are advantageously particularly well suited for distributing the thermal energy. The at least one distribution layer preferably has a low thermal conductivity (e.g., less than 5 W / (m·K), in particular less than 2 W / (m·K), in particular less than 1 W / (m·K)). The at least one distribution layer preferably inhibits heat propagation toward the surface, in particular the main surface, of the MR surface coil. Instead, the thermal energy is preferably distributed more strongly in a lateral direction, i.e., parallel to the surface, in particular the main surface, of the MR surface coil.

[0023] Advantageously, the introduction of at least one distribution layer is very flexible. In particular, their geometry can be easily adjusted. Thicker distribution layers are preferably used at higher temperatures. The use of distribution layers on a wide variety of coil shapes is conceivable, since the shape of the distribution layers can advantageously be adapted as desired.

[0024] A very lightweight material can advantageously be used for the at least one distribution layer. Furthermore, it advantageously represents a cost-effective implementation of a heat dissipation element. Design modifications are typically not required for the subsequent introduction of the at least one distribution layer. Advantageously, the at least one distribution layer also provides (possibly additional) padding for the at least one electronic component.

[0025] Preferably, the at least one distribution layer is designed to be flexible. In particular, the at least one distribution layer is made of a flexible material. This advantageously prevents negative influences, such as stiffening of the MR surface coil, so that the flexibility of the entire MR surface coil is maintained.

[0026] Preferably, the heat dissipation element comprises at least one heat conductor, in particular a thread, which is arranged at least partially within the sheath and which is designed to conduct at least part of the heat out of the MR surface coil along the heat conductor.

[0027] For example, the at least one heat conductor can be combined with the at least one distribution layer. In particular, the at least one heat conductor is connected, in particular thermally, to the at least one distribution layer, in particular brought into direct contact.

[0028] For example, the at least one heat conductor can have a meandering structure, particularly in sections. In particular, the at least one heat conductor can have a meandering structure in the vicinity of the at least one electronic component.

[0029] Preferably, the at least one heat dissipation element comprises at least one replaceable cooling pack. Advantageously, the cooling pack is designed to absorb thermal energy. Advantageously, the at least one cooling pack can reduce thermal energy specifically at the location of the at least one electronic component.

[0030] Advantageously, the cooling pack can be repeatedly inserted into the MR surface coil in a cool state and removed again in a warm state; for example, it can then be replaced with another cooling pack that is in a cool state. This advantageously ensures continuous heat dissipation.

[0031] The MR surface coil, for example, has at least one resealable opening through which the at least one cooling pack can be inserted into the MR surface coil. This at least one resealable opening can, for example, have a zipper and / or a hook-and-loop fastener.

[0032] Preferably, the at least one heat dissipation element comprises at least one fastening element arranged outside the sheath for fastening the MR surface coil to the patient and / or to the patient table, wherein the at least one fastening element is designed to absorb at least part of the thermal energy.

[0033] The fastening element can be a belt, for example. The belt preferably has a particularly high thermal conductivity in the area of ​​the at least one electronic component. Belts are typically already available components that can be used flexibly. Belts are preferably already inserted into defined positions that can enable temperature control.

[0034] Preferably, the at least one heat dissipation element comprises at least one heat transfer element which is arranged between the at least one electronic component and the casing and is designed to transfer at least part of the thermal energy to at least one counterpart arranged outside the MR surface coil.

[0035] Preferably, the at least one heat transfer element has a particularly high thermal conductivity. The at least one heat transfer element preferably comprises a material having a thermal conductivity λ of at least 10 W / (m·K), in particular 30 W / (m·K), in particular 100 W / (m·K). Possible materials include, in particular, aluminum or copper.

[0036] The MR surface coil preferably comprises at least one first positioning unit for positioning the at least one heat transfer element as precisely as possible relative to the at least one counterpart arranged outside the MR surface coil. The at least one first positioning unit can, for example, comprise an optical marker and / or a mechanical guide.

[0037] Furthermore, a system is proposed which comprises at least one MR surface coil as described above and a patient table, wherein the patient table has the at least one counterpart which is suitable for absorbing at least part of the thermal energy from the at least one heat transfer element.

[0038] Advantageously, this ensures particularly effective heat dissipation, so that even electronic components with high heat generation can be used.

[0039] Furthermore, a system is proposed which comprises at least one MR surface coil as described above and a patient table, wherein the patient table has at least one heat dissipation element, wherein the at least one heat dissipation element is designed to absorb at least part of the heat energy when the MR surface coil is arranged on the patient table.

[0040] The patient table is preferably suitable for supporting the examination subject during a magnetic resonance examination, in particular magnetic resonance measurement.

[0041] The patient table preferably comprises at least one second positioning unit for positioning the at least one MR surface coil as precisely as possible relative to the patient table. The at least one second positioning unit can, for example, comprise an optical marker and / or a mechanical guide. In particular, the at least one first positioning unit of the MR surface coil can interact with the at least one first positioning unit of the patient table.

[0042] For example, optical markings of the at least one first positioning unit of the MR surface coil and the at least one second positioning unit of the patient table can be arranged such that correct relative positioning is ensured when the markings overlap. For example, the at least one first positioning unit of the MR surface coil can engage with the at least one second positioning unit of the patient table.

[0043] Furthermore, a magnetic resonance apparatus with at least one MR surface coil and / or a system as described above is proposed.

[0044] Further advantages, features, and details of the invention will become apparent from the exemplary embodiments described below and from the drawings. Corresponding parts are provided with the same reference numerals in all figures.

[0045] They show: Fig. 1 a magnetic resonance device with a patient table and an MR surface coil, Fig. 2 and Fig. 3 an MR surface coil with several distribution layers as heat dissipation elements, Fig. 4 an MR surface coil with several heat conductors as heat dissipation elements, Fig. 5 an MR surface coil with several cooling packs as heat dissipation elements, Fig. 6 a system comprising an MR surface coil and a patient table.

[0046] In Fig. 1 schematically shows a magnetic resonance apparatus 10. The magnetic resonance apparatus 10 comprises a magnet unit 11 having a main magnet 12 for generating a strong and, in particular, temporally constant main magnetic field 13. In addition, the magnetic resonance apparatus 10 comprises a patient receiving area 14 for receiving a patient 15. The patient receiving area 14 in the present exemplary embodiment is cylindrical and is surrounded in a circumferential direction by the magnet unit 11. In principle, however, a different design of the patient receiving area 14 is conceivable at any time. The patient 15 can be pushed into the patient receiving area 14 by means of a patient support device 16 of the magnetic resonance apparatus 10. For this purpose, the patient support device 16 has a patient table 17 designed to be movable within the patient receiving area 14 for supporting the patient 15.

[0047] The magnet unit 11 further comprises a gradient coil unit 18 for generating magnetic field gradients used for spatial encoding during imaging. The gradient coil unit 18 is controlled by a gradient control unit 19 of the magnetic resonance device 10. The magnet unit 11 further comprises a radio-frequency antenna unit 20, which in the present exemplary embodiment is designed as a body coil permanently integrated into the magnetic resonance device 10. The radio-frequency antenna unit 20 is controlled by a radio-frequency antenna control unit 21 of the magnetic resonance device 10 and radiates radio-frequency magnetic resonance sequences into an examination space, which is essentially formed by a patient receiving area 14 of the magnetic resonance device 10. As a result, the main magnetic field 13 generated by the main magnet 12 excites atomic nuclei.Magnetic resonance signals are generated by the relaxation of the excited atomic nuclei. The radio-frequency antenna unit 20 is also designed to receive the magnetic resonance signals.

[0048] The magnetic resonance apparatus 10 has a system control unit 22 for controlling the main magnet 12, the gradient control unit 19, and the radio-frequency antenna control unit 21. The system control unit 22 centrally controls the magnetic resonance apparatus 10, such as performing a predetermined imaging gradient echo sequence. The system control unit 22 also includes an evaluation unit (not shown in detail) for evaluating the magnetic resonance signals acquired during the magnetic resonance examination. Furthermore, the magnetic resonance apparatus 10 includes a user interface 23 connected to the system control unit 22. Control information, such as imaging parameters, as well as reconstructed magnetic resonance images, can be displayed on a display unit 24, for example, on at least one monitor, of the user interface 23 for medical personnel.Furthermore, the user interface 23 has an input unit 25 by means of which information and / or parameters can be entered by the medical operating personnel during a measurement process.

[0049] The magnetic resonance device further comprises an MR surface coil 100, which is configured to transmit RF signals, in particular excitation pulses, and / or to receive RF signals, in particular magnetic resonance signals. The MR surface coil 100 is arranged directly on the body of the patient 15, here on the upper body. The MR surface coil 100 is preferably flexible so that it can be easily adapted to the shape of the patient 15. Due to the proximity to the location where the magnetic resonance signals are generated, the magnetic resonance signals received by the MR surface coil 100 advantageously have a particularly high signal-to-noise ratio.

[0050] The MR surface coil 100 comprises, in particular, at least one RF antenna for transmitting and / or receiving RF signals, at least one heat-generating electronic component that is electrically connected to the at least one RF antenna, a shell within which the at least one RF antenna and the at least one electronic component are arranged, and at least one heat dissipation element that is thermally connected to the at least one electronic component, wherein the at least one heat dissipation element is designed to dissipate thermal energy from the at least one electronic component to the outside and / or to distribute it over a surface.

[0051] Fig. 2 shows a possible embodiment of the MR surface coil 100 in a plan view. The MR surface coil 100 includes several RF antennas 110 for transmitting and / or receiving RF signals. (In Fig. 4-6, the RF antennas 110 are not shown for clarity. The RF antennas 110 are electrically connected to a plurality of electronic components 120. In the example shown, each RF antenna 110 is connected to a respective electronic component 120. However, it is also conceivable for the MR surface coil 100 to have more or fewer electronic components 120 per RF antenna 110. Electronic components 120 ensure, for example, that the magnetic resonance signals received by the RF antennas 110 are amplified and / or that the resonant frequency of the MR surface coil 100 is detuned when RF signals are transmitted by the radio-frequency antenna unit 20.

[0052] The electronic components are in turn electrically connected to a connector 140, with which the MR surface coil 100 can be connected to the magnetic resonance device.

[0053] The MR surface coil 100 comprises distribution layers 103a as heat dissipation elements. As shown in Fig. As can be seen in Figure 3, the distribution layers 130a are arranged between the electronic components 120 and the casing 150. These ensure that at least part of the thermal energy is distributed over a surface, in particular a main surface S, of the MR surface coil 100.

[0054] In the example shown here, the distribution layers 130a are arranged on both sides between the centrally arranged electronic components 120 and the outer casing 150. However, it is also conceivable for the distribution layers 130a to be arranged on only one side between the electronic components 120 and the casing 150. This side is preferably the side facing away from the patient 15.

[0055] The RF antennas 110, electronic components 120 and the distribution layers 130a can, for example, be embedded in a foam structure 170.

[0056] By introducing the distribution layers 103a, temperature peaks that occur in the area of ​​the electronic components 120 can be avoided. The temperature is distributed over the surface by means of the distribution layers 130a, specifically redirected, and / or dissipated. The edge surface should be as large as possible in order to provide the largest possible area for convection. Preferably, the distribution layers 103a each have a surface with an area A and an edge delimiting the surface with a length L, where L 2 / A > 20, especially L 2 / A > 50, especially L 2 / A > 100.

[0057] The distribution layers 103a can be made of various materials. Examples include fire-resistant nonwovens, foams, thermal nonwovens, heat-resistant films, and / or coated textiles.

[0058] In Fig. Figure 4 shows a possible embodiment of the MR surface coil 100, according to which the surface coil 100 comprises heat conductors 130d arranged within the shell as heat dissipation elements. The heat conductors 130d are designed as temperature filaments that extend out of the MR surface coil 100 and transfer the temperature in a targeted manner.

[0059] Fig. Figure 5 shows an example of an MR surface coil 100 with insertable or replaceable cooling packs 130c as heat dissipation elements. The cooling packs 130c are preferably arranged at the temperature hotspots of the MR surface coil 100, in particular at the heat-generating electronic components 120. The cooling packs 130c can be inserted and removed again via an opening 160.

[0060] Another way to dissipate heat is by Fig.6. The MR surface coil 100 has heat transfer elements 130b, in particular heat transfer pads, as heat dissipation elements. The heat transfer elements 130b can be coupled to counterparts 200 arranged outside the MR surface coil 100 on the patient table 17. Via these contact points and / or coupling points, which are particularly highly thermally conductive, the heat is specifically transferred from the MR surface coil 100 into the patient table 15 and dissipated. The heat transfer elements 130b preferably comprise a material having a thermal conductivity λ of at least 2 W / (m·K), in particular 4 W / (m·K), in particular 10 W / (m·K).

[0061] Furthermore, it would be possible to use conventionally available fastening materials for the MR surface coil 100, particularly straps, for targeted temperature control. Preferably, particularly thermally conductive materials and / or shielding are used for this purpose.

[0062] Finally, it should be noted once again that the MR surface coils and the magnetic resonance device described in detail above are merely exemplary embodiments that can be modified in a variety of ways by a person skilled in the art without departing from the scope of the invention. Furthermore, the use of the indefinite articles "a" or "an" does not exclude the possibility that the respective features may be present in multiple instances. Likewise, the term "unit" does not exclude the possibility that the respective components consist of several interacting subcomponents, which may also be spatially distributed.

Claims

[1] MR surface coil comprising: - at least one RF antenna for transmitting and / or receiving RF signals, - at least one electronic component that is electrically connected to the at least one RF antenna, - a shell within which the at least one RF antenna and the at least one electronic component are arranged, - at least one heat dissipation element which is thermally connected to the at least one electronic component, wherein the at least one heat dissipation element is designed to dissipate heat energy from the at least one electronic component to the outside and / or to distribute it over a surface. [2] MR surface coil according to claim 1, wherein the MR surface coil is flexible. [3] MR surface coil according to one of claims 1 or 2, wherein the at least one heat dissipation element comprises at least one distribution layer arranged between the at least one electronic component and the shell and configured to distribute at least part of the thermal energy on a surface of the MR surface coil. [4] MR surface coil according to claim 3, wherein the at least one distribution layer has a surface with an area A and an edge delimiting the surface with an edge length L, where L 2 / A > 20, especially L 2 / A > 50, especially L 2 / A > 100. [5] MR surface coil according to one of claims 3 or 4, wherein the at least one distribution layer has a thermal conductivity λ of less than 5 W / (m·K), in particular less than 2 W / (m·K), in particular less than 1 W / (m·K). [6] MR surface coil according to one of claims 3 to 5, wherein the at least one distribution layer comprises a fire-resistant nonwoven, a thermal nonwoven, a heat-resistant film, a coated textile and / or a foam material. [7] MR surface coil according to one of claims 3 to 6, wherein the at least one distribution layer is flexible and in particular consists of a flexible material. [8] MR surface coil according to one of the preceding claims, wherein the at least one heat dissipation element comprises at least one heat conductor, in particular a thread, which is arranged at least partially within the sheath and which is designed to conduct at least part of the heat out of the MR surface coil along the heat conductor. [9] MR surface coil according to one of the preceding claims, wherein the at least one heat dissipation element comprises at least one replaceable cooling pack. [10] MR surface coil according to one of the preceding claims, wherein the at least one heat dissipation element comprises at least one fastening element arranged outside the sheath, in particular at least one belt, for fastening the MR surface coil to the patient and / or to the patient table, wherein the at least one fastening element is designed to absorb at least part of the thermal energy. [11] MR surface coil according to one of the preceding claims, wherein the at least one heat dissipation element comprises at least one heat transfer element which is arranged between the at least one electronic component and the casing and is designed to transfer at least part of the thermal energy to at least one counterpart arranged outside the MR surface coil. [12] MR surface coil according to claim 11, wherein the at least one heat transfer element comprises a material having a thermal conductivity λ of at least 10 W / (m·K), in particular at least 30 W / (m·K), in particular at least 100 W / (m·K). [13] A system comprising an MR surface coil according to any one of claims 10 to 12 and a patient table, wherein the patient table has the at least one counterpart adapted to absorb at least part of the thermal energy from the at least one heat transfer element. [14] System comprising at least one MR surface coil according to one of claims 1 to 12 and a patient table, wherein the patient table has at least one heat dissipation element, wherein the at least one heat dissipation element is designed to absorb at least part of the heat energy when the MR surface coil is arranged on the patient table. [15] Magnetic resonance apparatus with at least one MR surface coil according to one of claims 1 to 12 and / or a system according to claim 13 and / or a system according to claim 14.

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