Magnetic resonance device

Abstract

The utility model relates to a magnetic resonance device, which comprises a control system and a pressure sensor. The control system comprises a processing unit, wherein the pressure sensor is configured to obtain pressure information of a component of the magnetic resonance device that is cryogenically cooled, and wherein the processing unit is configured to determine a pressure rate based on the pressure information, wherein the control system is configured to identify a change in an operating condition of the magnetic resonance device according to the pressure rate, and wherein the magnetic resonance device is configured to execute the change in the operating condition.

Description

Technical Field

[0001] Magnetic resonance imaging represents a well-known imaging method for acquiring images of the interior of an object under examination. In order to perform magnetic resonance measurements, the object under examination is usually positioned in a strong and uniform static magnetic field (B0 field) of a magnetic resonance device. The static magnetic field may include a magnetic field strength of 0.2 Tesla to 7 Tesla, so that the nuclear spins inside the object under examination are aligned along the static magnetic field. In order to trigger the so-called nuclear spin resonance, a radio frequency excitation pulse is emitted into the object under examination. Each radio frequency excitation pulse causes the nuclear spins in the object under examination to be magnetized to deviate from the static magnetic field by a certain amount, which is called the flip angle. The radio frequency excitation pulse may include an alternating (electric) magnetic field, the frequency of which corresponds to the Larmor frequency at the corresponding static magnetic field strength. The excited nuclear spins may exhibit a rotating and decaying magnetization (nuclear magnetic resonance), which can be detected using a dedicated radio frequency antenna. In order to spatially encode the measurement data, a rapidly switched magnetic gradient field is superimposed on the static magnetic field.

[0002] The received nuclear magnetic resonances are usually digitized and stored as complex values ​​in a k-space matrix. The k-space matrix can be used as a basis for reconstructing magnetic resonance images and for determining spectral data. Magnetic resonance images are usually reconstructed by means of a multidimensional Fourier transform of the k-space matrix. Background Art

[0003] Magnetic resonance devices may use superconducting magnets to generate a uniform static magnetic field. Superconducting magnets must be cooled below a critical temperature to maintain a superconducting state. Typically, superconducting magnets are cooled with a cryogenic coolant fluid or refrigerant, which may be a gas or liquid.

[0004] In the superconducting state, the resistivity of a superconducting magnet is very close to zero. However, in the event of a fault, a superconducting magnet can suddenly change its state from superconducting to normal. This process is called a "quench". A quench requires the immediate abandonment of all applied power and the dissipation of the electromagnetic energy of the superconducting magnet into a dedicated load or protection circuit. It is important to detect the quench in time to avoid damage to the superconducting magnet, the magnetic resonance device, and the surrounding environment of the magnetic resonance device.

[0005] The detection of a quench can be performed by different methods, such as voltage detection using a voltage tap, detection of acoustic emissions (i.e. a rupture and / or delamination of parts of the superconducting magnet) or temperature detection. In conventional magnetic resonance devices, a corresponding threshold is defined. If the threshold is exceeded, the superconducting magnet is switched off, thus preventing potential damage, but also rendering the magnetic resonance device inoperable for a long period of time.

[0006] Particularly in magnet designs with low amounts of cryogen, conventional methods for detecting quenches may interfere with intentional rundowns caused by the user or the magnetic resonance apparatus. For example, intentional rundowns may cause a voltage drop and / or temperature rise in the superconducting magnet, thus triggering a process that shuts down the superconducting magnet in the event of a quench, rendering the magnetic resonance apparatus inoperable for hours or even days. Utility Model Content

[0007] It is therefore an object of the present invention to improve the detection of a quench in a superconducting magnet in a magnetic resonance apparatus.

[0008] This object is achieved by a magnetic resonance device according to the invention. Further advantageous embodiments are specified in the dependent claims.

[0009] The inventive magnetic resonance device comprises a control system and a pressure sensor, wherein the control system comprises a processing unit.

[0010] The inventive magnetic resonance apparatus can be implemented as a closed-bore or open-bore scanner. In particular, the inventive magnetic resonance apparatus can be configured to acquire magnetic resonance data from an object located within an imaging region of the magnetic resonance apparatus. Preferably, the magnetic resonance apparatus is configured to acquire magnetic resonance image data or diagnostic magnetic resonance image data from an object located within the imaging region. The object can be a patient, in particular a human or an animal.

[0011] The magnetic resonance apparatus may include a superconducting magnet comprising one or more superconducting coils. The one or more superconducting coils may include wires having negligible electrical resistance at (or below) superconducting temperatures.

[0012] The magnetic resonance apparatus may further comprise a refrigerator or a cryocooler. The cryocooler may be configured to cool components of the magnetic resonance apparatus. For example, the cryocooler may be configured to cool a superconducting magnet, a gradient system, a shielding structure, a buffer unit, a cryogen vessel and / or a cryostat of the magnetic resonance apparatus.

[0013] Preferably, the cryocooler is configured to provide a temperature below the superconducting temperature of the superconducting material of the superconducting magnet. The cryocooler may include a cold head including one or more stages with different temperature levels. For example, the cryocooler may be implemented as a pulse tube refrigerator, a Gifford-McMahon refrigerator, a Stirling cryocooler, a Joule-Thomson cooler, etc.

[0014] The inventive magnetic resonance apparatus may further comprise a cryostat. The cryostat may comprise a sealed container or a vacuum vessel configured to store or preserve a coolant fluid, preferably a refrigerant, at a predefined temperature level. The predefined temperature level may substantially correspond to the superconducting temperature of the superconducting magnet. For example, the superconducting temperature of the superconducting magnet may be in the range of 3K to 100K, preferably in the range of 3K to 5K, 30K to 60K or 60K to 90K.

[0015] The cryostat may include insulation configured to reduce input of thermal energy from components of the magnetic resonance apparatus, the patient bore, and / or the surrounding environment of the magnetic resonance apparatus. For example, the cryostat may include an outer shell and an inner shell configured to reduce the amount of thermal radiation from the outer shell into the interior volume of the cryostat. The cryostat may enclose a vacuum chamber that surrounds other components of the cryostat such as a cryogen vessel, shielding structures, and a superconducting magnet.

[0016] In certain embodiments, the inventive magnetic resonance apparatus may represent a “wet system.” In a “wet system,” a superconducting magnet, in particular a superconducting coil of a superconducting magnet, may be immersed in a cryogen within a cryogen vessel.

[0017] In other embodiments, the inventive magnetic resonance imaging apparatus may represent a "dry system" that includes a minimal volume of cryogen or no cryogen at all. In a preferred embodiment of a "dry system", the cryogen vessel is omitted and the superconducting magnet is cooled entirely via thermal conduction. The "dry system" may still include a vacuum chamber that surrounds at least the shielding structure and the superconducting magnet.

[0018] In a "wet system" or a system with a small amount of refrigerant, the cryostat may include a refrigerant vessel containing a coolant fluid or refrigerant with a low boiling point. For example, the refrigerant may be argon, nitrogen, neon, helium, hydrogen, etc. The refrigerant may be a liquid or a gas. The superconducting coil may be disposed in or immersed in the refrigerant contained in the refrigerant vessel. However, in some embodiments, direct contact between the superconducting coil and the refrigerant may be avoided (i.e., in a magnetic resonance device with a small amount of refrigerant). In these cases, the superconducting coil may be thermally connected to the refrigerant vessel via a solid thermal conductor and / or a heat pipe.

[0019] In one embodiment of the magnetic resonance device, the refrigerant, the pressure sensor and the superconducting coil are arranged in a refrigerant vessel. The wire from the pressure sensor can leave the refrigerant vessel, i.e. leave the refrigerant vessel via a dedicated feedthrough, and be connected to the control system via a suitable signal line. It is also conceivable that the pressure sensor is arranged in the refrigerant vessel, and the superconducting coil is connected to the refrigerant vessel via a solid thermal conductor and / or a thermal pipe.

[0020] However, the present innovative magnetic resonance device may also represent a "dry system" including a minimum amount of refrigerant or no refrigerant at all. For example, the superconducting magnet may be cooled only via thermal conduction. The magnetic resonance device may still include a vacuum vessel or a suitable thermal insulation configured to reduce the amount of thermal energy deposited in the superconducting magnet and maintain the superconducting magnet at a desired temperature level. The pressure sensor may be arranged in a separate refrigerant vessel thermally connected to the superconducting coil and / or the cold head protective sleeve. However, the pressure sensor may also be directly attached or bonded to the superconducting magnet, in particular the superconducting coil. Therefore, thermal expansion or contraction of the superconducting coil may be detected via the pressure sensor.

[0021] In one embodiment, components of the magnetic resonance device, such as cryogen vessels, shielding structures, superconducting coils, etc., are thermally connected to the cold head via solid thermal conductors and / or thermal pipes.

[0022] A magnetic resonance device with a small amount of refrigerant is characterized by a refrigerant vessel that is significantly smaller than the superconducting coil being cooled. The refrigerant vessel can be thermally connected to the superconducting coil via a solid thermal conductor and / or a heat pipe. A cryocooler (also called a refrigeration cooler or refrigerator) can be thermally connected to the refrigerant vessel through one or more tubes forming a thermal siphon arrangement. For example, the refrigerant in the refrigerant vessel can absorb heat from the superconducting coil and evaporate or vaporize. The vaporized refrigerant can rise through a tube toward a heat exchanger cooled by the cryocooler. The vaporized refrigerant can be cooled and condensed by the cryocooler and flow back into the refrigerant vessel along the tube, whether it is the same tube or a different tube.

[0023] The shielding structure may be configured to reduce the transmission of thermal energy to the superconducting magnet. In a preferred embodiment, the shielding structure comprises at least or consists of a dedicated thermal shield configured to reduce the transmission of thermal energy to the superconducting magnet. The transmission of thermal energy may be characterized by heat transfer mechanisms such as thermal conduction, thermal radiation, and thermal convection.

[0024] The control system can be integrated into a main control unit of the magnetic resonance device. However, the control system can also represent a separate or independent component. In the case where the control unit is an independent component, the control unit can be connected to the main control unit of the magnetic resonance device via a signal connection or signal line.

[0025] The pressure sensor is configured to acquire pressure information of a cryogenically cooled component of the magnetic resonance apparatus.

[0026] The pressure sensor may be implemented as a force sensing resistor, a force sensing capacitor, a soft potentiometer, an acoustic sensor, a MEMS sensor, a continuous pressure sensor, or the like.

[0027] In particular, the pressure sensor may be configured to generate an output in accordance with pressure waves caused by changes in temperature and / or phase conditions of a refrigerant contained within the magnetic resonance device or a component of the magnetic resonance device. For example, in the event of a magnet quench, thermal energy provided by the superconducting coils may vaporize or evaporate the liquid refrigerant, thereby causing thermal expansion of the refrigerant. The thermal expansion and / or evaporation of the refrigerant may cause pressure waves that travel through the refrigerant and may be detected by the pressure sensor.

[0028] It is also conceivable that the pressure sensor is configured to generate an output based on strain and / or deformation of a component of the magnetic resonance apparatus. For example, the pressure sensor may be configured to provide an output based on deformation of a cryogen vessel wall or a superconducting coil surface caused by thermal expansion.

[0029] The control system may include a dedicated interface configured to obtain output and / or pressure information from the pressure sensor. The control system may also include a storage unit configured to store pressure information and / or any data based on the output of the pressure sensor. The processing unit may be configured to obtain, process and / or store the pressure information, for example by using the interface and / or the storage unit. Preferably, the control system is configured to continuously monitor the condition of the refrigerant based on the pressure information provided via the pressure sensor.

[0030] The pressure information may include information and / or data indicative of pressure. For example, the pressure information may provide an indication of an absolute pressure or a relative pressure. It is contemplated that the pressure information is characterized by a strain applied to the pressure sensor. In particular, the pressure information may be proportional to the strain applied to the pressure sensor. The pressure information may also be associated with the strain applied to the pressure sensor in a known manner.

[0031] The control system may be configured to obtain pressure information from the pressure sensor as an electrical signal. For example, a signal line connecting the pressure sensor and the control system may be configured to transmit the pressure information as an analog signal or a digital signal.

[0032] In a preferred embodiment, the magnetic resonance apparatus comprises a cryogen vessel including a cryogen disposed in the cryogen vessel. The superconducting coil may be disposed in the cryogen vessel or thermally connected to the cryogen vessel. Preferably, the pressure sensor is disposed in the cryogen vessel. Thus, the pressure sensor may advantageously detect pressure waves generated in the cryogen when heat energy is transferred from the superconducting coil to the cryogen.

[0033] In another embodiment, the refrigerant is provided in a refrigerant channel or cooling path provided in the superconducting magnet. In such an embodiment, the pressure sensor may be provided in the refrigerant channel.

[0034] According to an embodiment of the inventive magnetic resonance device, the pressure sensor is selected from the group consisting of a force sensing resistor, a force sensing capacitor, a soft potentiometer, an acoustic sensor, a MEMS sensor and a continuous pressure sensor.

[0035] MEMS sensors and acoustic sensors may represent discrete (or digital) sensors. Discrete sensors may be configured to output digital signals (ie, 0 / 1 or on / off), thereby advantageously allowing a programmable logic controller to ignore analog thresholds, deadbands, detection speeds, and / or other requirements.

[0036] Force sensing resistors, force sensing capacitors, and soft potentiometers may represent continuous or analog sensors. A continuous sensor may be configured to vary output depending on mechanical forces, such as lateral forces (pressure), bending forces, etc., applied to the sensitive surface of the continuous sensor.

[0037] The pressure sensor may be configured to detect the application of pressure or changes in pressure applied to a sensitive surface of the pressure sensor.

[0038] The control system may not be able to detect the location of the quench using pressure information obtained from a single pressure sensor. To determine the location of the quench, the control system may include multiple pressure sensors that provide pressure information from different locations on the superconducting magnet.

[0039] Preferably, the pressure sensor is arranged in the refrigerant vessel and / or the refrigerant channel of the magnetic resonance device. However, in particular in a "dry system", the pressure sensor can also be mounted on the surface of the superconducting coil and / or the wall of the magnet winding. Therefore, the pressure sensor can be used in a dry superconducting magnet system or a wet superconducting magnet system.

[0040] The processing unit is configured to determine a pressure rate based on the pressure information. The control system is configured to identify a change in an operating condition of the magnetic resonance apparatus based on the pressure rate.

[0041] In one embodiment, the control system comprises a storage unit, such as a local data storage (i.e. hard drive, solid state drive, flash drive, etc.), a network storage device, a cloud storage, etc. The control system, in particular the processing unit, may be configured to store the pressure information on the storage unit.

[0042] Preferably, the processing unit is configured to determine the pressure rate based on the pressure information received from the pressure sensor. For example, the processing unit may be configured to determine the pressure rate based on the change of the pressure information within a predefined time interval. The processing unit may be configured to store the time-dependent pressure information in the storage unit.

[0043] The pressure rate may be characterized by the average rate of change of the pressure information. However, the pressure rate may also be characterized by the instantaneous rate of change of the pressure information. Preferably, the pressure rate is characterized by the change of the pressure information within a predefined time period.

[0044] According to an embodiment, the pressure rate is characterized by the degree of change of the pressure information within a time period of less than 25 s, less than 20 s, less than 15 s or preferably 10 s.

[0045] A time period of less than 25 seconds may advantageously allow for differentiation between a pressure increase associated with a quench and a pressure increase associated with an intentional de-fielding of the superconducting magnet, while still reacting fast enough to prevent potential damage to the superconducting magnet in the event of a quench. Typically, in the event of a quench, the pressure may rise suddenly, whereas in the event of an intentional de-fielding, the pressure may rise slowly and / or gradually.

[0046] The magnetic resonance apparatus is configured to perform a change in operating conditions.

[0047] In a preferred embodiment, the control system is configured to perform all necessary steps to perform an intentional field drop of the magnetic resonance apparatus or an emergency shutdown of the magnetic resonance in the event of a quench. However, the control system may also be configured to transmit a signal indicating an intentional field drop or an emergency shutdown to a main control unit of the magnetic resonance apparatus.

[0048] When the inventive pressure sensor is provided, the pressure within the magnetic resonance device can be monitored in a simple and robust manner. Furthermore, the need to mount the sensor on the electrical conductors (i.e. voltage taps) of the superconducting magnet can be advantageously avoided. Thus, the manufacture of the superconducting magnet and the magnetic resonance system can advantageously be facilitated.

[0049] Furthermore, the pressure sensor may be configured to detect a temperature increase and / or a phase change of the refrigerant in a fast and reliable manner.Therefore, the risk of damaging the superconducting magnet in the event of a quench may advantageously be reduced.

[0050] According to an embodiment of the inventive magnetic resonance apparatus, the change in operating conditions is an intentional field reduction condition or a quench condition.

[0051] Preferably, the magnetic resonance device is configured to perform a field reduction of the superconducting magnet and / or the magnetic resonance system in dependence on the pressure information. For example, the control system may be configured to transmit a signal indicating a change in the operating condition to a main control unit of the magnetic resonance device when the pressure rate exceeds a predefined threshold. However, the control system may also be configured to autonomously initiate a change in the operating condition of the magnetic resonance device in dependence on the pressure information. For example, the control system may be configured to control the magnetic resonance device and / or components of the magnetic resonance device to perform a controlled shutdown when the pressure rate exceeds a predefined threshold. However, the control system may also be configured to initiate other changes in the operating condition of the magnetic resonance device in dependence on the pressure information.

[0052] The inventive magnetic resonance apparatus may advantageously allow a reliable distinction between an intentional field reduction and a magnet quench. Thus, an automatic ramp-up of the superconducting magnet may be performed after an intentional field reduction, which is usually excluded in the case where the magnetic resonance apparatus has been shut down due to a presumed detected magnet quench. Thus, the downtime of the entire system may advantageously be reduced, and patient throughput may be increased.

[0053] According to an embodiment of the inventive magnetic resonance apparatus, the pressure sensor is disposed in the cryogen vessel, in the cold head protective sleeve and / or near the surface of the superconducting coil of the magnetic resonance apparatus.

[0054] The pressure information may include information indicative of pressure within the cryogen vessel, within the cold head protective jacket, and / or strain acting on the surface of the superconducting coil of the magnetic resonance apparatus.

[0055] As mentioned above, the pressure sensor may be arranged in the cryogen vessel, the cold head protection sleeve and / or in a cryogen channel or cooling path arranged in the superconducting magnet.Preferably, the magnetic resonance apparatus comprises a plurality of pressure sensors arranged in one or more components of the magnetic resonance apparatus.

[0056] In a "wet system", the pressure sensor may be disposed within the cryogen vessel and / or cryogen channels of the superconducting magnet.

[0057] In a "dry system", the pressure sensor may be attached to the surface of the superconducting coil and / or the surface of the resin covering the superconducting coil. For example, the pressure sensor may include a strain gauge attached to the surface of the superconducting coil, i.e., a strain gauge attached to the surface of the superconducting coil via an adhesive, preferably a non-conductive adhesive.

[0058] In an embodiment of the magnetic resonance apparatus, the control system comprises a plurality of pressure sensors, and the processing unit is configured to determine the pressure rate based on pressure information of each pressure sensor.

[0059] A plurality of pressure sensors may be connected to an interface of a control system via a suitable signal connection. For example, the plurality of sensors may be connected to a control system via a signal line, in particular an electrical connection and / or an optical connection.

[0060] The control system may be configured to identify the location of a quench of a superconducting magnet and / or superconducting coil based on pressure information from a plurality of pressure sensors. For example, a plurality of pressure sensors may be arranged at uniform or non-uniform intervals along an extension of the superconducting magnet. A magnet quench may result in a local pressure rise, which may be detected by a pressure sensor near the quench location, while a more distant pressure sensor may not yet be able to detect the pressure change. Based on the time delay of the pressure rise detected by the plurality of pressure sensors, the location of the quench may be determined.

[0061] In another embodiment, a plurality of pressure sensors are arranged in or on different components of the magnetic resonance apparatus, ie, a cryogen vessel, a cold head protective sleeve, a superconducting magnet, a cryogen channel in a superconducting magnet, etc.

[0062] When multiple pressure sensors are provided, the accuracy and / or confidence of determining the pressure rise can advantageously be increased.In addition, multiple pressure sensors can advantageously allow the location of the quench to be determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Other advantages and details of the present invention can be recognized from the following embodiments and the accompanying drawings. The accompanying drawings show:

[0064] Figure 1 is an embodiment of the innovative magnetic resonance device,

[0065] Figure 2 This is an implementation of the innovative magnetic resonance device. DETAILED DESCRIPTION

[0066] Figure 1 An embodiment of a magnetic resonance apparatus 10 according to the utility model is shown. The magnetic resonance apparatus 10 is configured to acquire magnetic resonance image data from an object located in an imaging region 14. For example, the object may be an animal or a human patient 15. The magnetic resonance apparatus 10 may include a field generating unit 11, which includes a superconducting magnet 12 that provides a uniform static magnetic field 13 (B0 field). The imaging region 14 may be defined by a hole configured to accommodate an object during an imaging examination or magnetic resonance measurement. In particular, the imaging region 14 may be surrounded or enclosed by the field generating unit 11 in a circumferential direction. In some embodiments, the magnetic resonance apparatus 10 may be a cylindrical or closed-bore scanner. In other embodiments, the magnetic resonance apparatus 10 may be a C-type or open-bore scanner.

[0067] Preferably, the magnetic resonance apparatus 10 comprises a patient support 16 , which comprises a patient table 17 and is configured for transporting a patient 15 into the imaging region 14 , in particular into an isocenter (not shown) within the imaging region 14 .

[0068] The magnetic resonance apparatus 10 may include a gradient system 18 configured to provide a magnetic gradient field for spatially encoding magnetic resonance signals acquired during magnetic resonance measurement. The gradient system 18 is enabled or controlled by a gradient controller 19 via appropriate current signals. It is conceivable that the gradient system 18 includes one or more gradient coils for generating gradient magnetic fields in different, preferably orthogonally oriented spatial directions.

[0069] The magnetic resonance apparatus 10 may further include a high frequency system including a radio frequency antenna 20 (body coil), which may be integrated into the magnetic resonance apparatus 10. The radio frequency antenna 20 is operated via a radio frequency controller 21, which controls the radio frequency antenna 20 to generate a high frequency magnetic field and transmit radio frequency excitation pulses into the imaging region 14.

[0070] exist Figure 1 In the embodiment shown in , the magnetic resonance apparatus 10 includes a local coil 26, which is positioned near a diagnostically relevant region of an object, namely a patient 15. The local coil 26 can be configured to transmit radio frequency excitation pulses to the patient 15 and / or receive magnetic resonance signals from the patient 15. It is conceivable that the local coil 26 is controlled via a radio frequency controller 21.

[0071] In the illustrated embodiment, the local coil 26 is a head coil. Preferably, the head coil includes one or more antenna elements (not shown) configured to receive magnetic resonance signals from the head region of the patient 15 and transmit the detected magnetic resonance signals to the processing unit 28 and / or the control unit 22 via a suitable signal line 27. The head coil 26 can also be configured to transmit radio frequency signals and excite nuclear spins in a diagnostically relevant region of the patient 15.

[0072] The magnetic resonance device 10 includes at least one pressure sensor 31. The pressure sensor 31 may be disposed in a cooled component of the field generating unit 11, such as a cold head protective cover 260, a refrigerant container 240 (see Figure 2 ) and / or in a refrigerant channel extending along the superconducting coil of the superconducting magnet 12. The pressure sensor 31 is electrically connected to the control system 40 via a signal line 27.

[0073] The magnetic resonance apparatus 10 further comprises a control unit 22 configured for controlling the magnetic resonance apparatus 10. The control unit 22 may comprise a processing unit 28 configured for processing magnetic resonance image data and reconstructing magnetic resonance images. The processing unit 28 may also be configured to process input from a user of the magnetic resonance apparatus 10 and / or to provide output to the user. For this purpose, the processing unit 28 and / or the control unit 22 may be connected to the output unit 24 and the input unit 25 via suitable signals.

[0074] For the preparation of the magnetic resonance imaging measurement, preparation information, such as imaging parameters or patient information, can be provided to the user via the output unit 24. Preferably, the output unit 24 is configured to output control information, such as imaging parameters of the magnetic resonance measurement. The output unit 24 can also be configured to output pressure rate, pressure information and / or information based on the pressure information acquired via the pressure sensor 31. The input unit 25 can be configured to receive information and / or imaging parameters from the user. However, the input unit 25 can also be configured to enable the user to perform changes in the operating conditions of the magnetic resonance device 10, such as intentional field reduction.

[0075] In the depicted example, the control system 40 is integrated into the control unit 22 of the magnetic resonance apparatus 10. Likewise, the processing unit of the control system 40 is integrated into the processing unit 28 of the magnetic resonance apparatus 10. In alternative embodiments, the control system 40 may be a separate or independent component connected to the control unit 22 via a suitable signal connection.

[0076] The control system 40 may include a local storage device. The local storage device may contain instructions that, when executed by the processing unit, enable the system to perform the functions described herein. Examples of these functions are determining a pressure rate or changing an operating condition of the magnetic resonance device 10 based on pressure information obtained from the pressure sensor 31. The local storage device may be a non-volatile memory, such as a flash ROM, an electrically erasable ROM, or other suitable device. In other embodiments, the local storage device may be a volatile memory, such as a RAM or a DRAM. In the case where the control system 40 is implemented as a stand-alone device, the control system 40 may include a user input device, such as a keyboard, a mouse, a touch screen, etc. The control system 40 may also include a display device, such as a computer screen, an LED display, a monitor, or a touch screen. The user input device and the display device may communicate with the processing unit.

[0077] The magnetic resonance apparatus 10 may comprise a user interface 23 comprising an output unit 24 and an input unit 25. The user interface 23 may be configured to enable a user to control the acquisition of magnetic resonance image data via the magnetic resonance apparatus 10.

[0078] like Figure 1 As illustrated in FIG. 1 , the processing unit 28 may be connected to a storage unit 29 of the magnetic resonance apparatus 10. Optionally, the processing unit 28 may be connected to a cloud 30. The processing unit 28 may be configured to store the pressure information and / or the pressure rate in the storage unit 29 and / or the cloud 30 (i.e., cloud storage). In the case where the control system 40 is a separate component, the processing unit of the control system 40 may be connected to a local storage unit and / or the cloud in a similar manner.

[0079] The processing unit 28 may be configured to determine the pressure rate based on pressure information stored in the local storage unit 29 and / or the cloud 30. However, the pressure rate may also be obtained from a pressure sensor. The processing unit 28 may be configured to continuously monitor the pressure rate and coordinate changes in the operating conditions of the magnetic resonance device 10 based on the pressure rate.

[0080] The magnetic resonance device 10 may of course comprise other components usually associated with magnetic resonance devices. It is conceivable that the field generating unit 11 of the magnetic resonance device 10 has a cylindrical design or a C-shaped design. However, the field generating unit 11 may also have a triangular design or an asymmetrical design.

[0081] Figure 2 An embodiment is illustrated in which the magnetic resonance apparatus 10 includes a "low cryogen quality type" superconducting magnet. In the depicted example, the superconducting coil 100 is mounted within an outer vacuum vessel ("OVC") that includes an inner bore tube 120 and an outer shell 140. A pump-out port 160 may be provided for removing gas from the interior of the OVC to create the desired vacuum.

[0082] A heat shield is located between the superconducting coil 100 and the OVC, the heat shield comprising a heat shielding bore tube 180 and a heat shielding housing 200. A cooling path 220 is provided. The cooling path 220 may represent a relatively high conductivity path extending along one side of the superconducting coil 100. In one embodiment, the cooling path 220 comprises a solid thermal conductor. However, the cooling path 220 may also comprise a channel or conduit containing a refrigerant. The cooling path may be thermally connected to a refrigerant vessel 240. In particular, the cooling path 220 may be configured to transfer thermal energy from the superconducting coil 100 to the refrigerant vessel 240. A certain amount of refrigerant is provided in the refrigerant vessel 240.

[0083] A cold head protective cover 260 is disposed on the OVC, and the cold head protective cover 260 is used to accommodate a cold head 280 (ie, an electrically driven low temperature refrigerator). A gas buffer (not shown) may be connected to the cold head protective cover 260 through a connection port.

[0084] In the depicted embodiment, the tube 300 connects the refrigerant vessel 240 to the cold head protective sleeve 260, thereby providing a thermosyphon arrangement. A first tube connects the upper end of the refrigerant vessel 240 to the cold head protective sleeve 260 for conveying vaporized refrigerant vapor. A second tube connects the lower end of the cold head protective sleeve 260 to the refrigerant vessel 240, thereby providing a return flow from the cold head protective sleeve 260 to the refrigerant vessel 240 for liquefied or cooled refrigerant. Thus, the refrigerant can circulate through the thermosyphon defined by the refrigerant vessel 240, the cold head protective sleeve 260 and the tube 300.

[0085] According to an embodiment, the cold head 280 is configured to recondense the vaporized refrigerant gas into a liquid, which flows downward into the refrigerant vessel 240 via the tube 300. In the refrigerant vessel 240, the liquid refrigerant can absorb thermal energy from the superconducting coil 100 thermally connected to the refrigerant vessel 240 via the cooling path 220. By absorbing thermal energy from the superconducting coil 100, the refrigerant can evaporate and rise through the tube 300 until the refrigerant reaches the heat exchanger of the cold head 280 (i.e., the lower end of the cold head protective cover 260), thereby providing a (continuous) cycle.

[0086] In the depicted embodiment, pressure sensors 31a and 31b are disposed within the cold head protective sleeve 260 and the cryogen vessel 240. Additionally, one or more pressure sensors 31 may be disposed within the cooling path 220 (not shown). It is also conceivable that one or more pressure sensors 31 are attached to the surface of the superconducting coil 100. The pressure sensor 31 attached to the surface of the superconducting coil 100 may be a sensor configured to detect thermal expansion or deformation of a solid material, such as a force sensing resistor, a strain gauge, a force sensing capacitor, etc.

[0087] According to an embodiment, the pressure sensors 31a and 31b can be implemented as MEMS (micro-electromechanical system) sensors. The pressure sensors 31a and 31b can be connected to the interface of the control system 40 via a signal line (not shown) passing through the external vacuum container and / or the thermal shield. It is also conceivable that the path of the signal line is through the wall of the cryogen vessel 240 and / or the wall of the cold head protective sleeve 260.

[0088] The control system 40 may include a dedicated resistance meter and / or a voltmeter configured to determine pressure information from the output signal of the pressure sensor 31. However, this function may also be implemented via a processing unit of the control system 40. A plurality of pressure sensors 31 may be distributed along the cooling path 220, but may also be distributed within the cryogen vessel 240 and / or the cold head protective sleeve 260. Therefore, the location of the quench may be identified via the processing unit of the control system 40.

[0089] The present disclosure is not limited in scope by the specific embodiments described herein. In fact, according to the foregoing description and the accompanying drawings, in addition to the various embodiments and modifications described herein, other various embodiments and modifications of the present disclosure will be obvious to those of ordinary skill in the art. Therefore, such other embodiments and modifications are intended to fall within the scope of the present disclosure.

Claims

1. A magnetic resonance device, characterized in that: The magnetic resonance apparatus comprises a control system and a pressure sensor, the control system comprising a processing unit, wherein the pressure sensor is configured to acquire pressure information of a cryogenically cooled component of the magnetic resonance apparatus, and wherein the processing unit is configured to determine a pressure rate based on the pressure information, wherein the control system is configured to identify a change in an operating condition of the magnetic resonance apparatus based on the pressure rate, and wherein the magnetic resonance apparatus is configured to perform the change in the operating condition.

2. The magnetic resonance apparatus according to claim 1, characterized in that The change in operating conditions is an intentional down-field condition or a quench condition.

3. The magnetic resonance apparatus according to claim 1 or 2, characterized in that: The pressure sensor is arranged in a refrigerant container, in a cold head protection cover and / or near the surface of the superconducting coil of the magnetic resonance device.

4. The magnetic resonance apparatus according to claim 3, characterized in that The pressure rate is characterized by the degree of change of the pressure information within a time period of less than 25 seconds, less than 20 seconds, or less than 15 seconds.

5. The magnetic resonance apparatus according to claim 4, characterized in that The pressure rate is characterized by the degree of change of the pressure information within a period of 10 seconds.

6. The magnetic resonance apparatus according to any one of claims 1, 2, 4 and 5, characterized in that: The control system comprises a plurality of pressure sensors, and wherein the processing unit is configured to determine a pressure rate based on the pressure information of each pressure sensor.

7. The magnetic resonance apparatus according to any one of claims 1, 2, 4 and 5, characterized in that: The pressure sensor is selected from the group consisting of a force sensing resistor, a force sensing capacitor, a soft potentiometer, an acoustic sensor, a micro-electromechanical system switch, and a continuous pressure sensor.

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