Radio frequency cable trap assembly with indicator circuitry

Abstract

Disclosed herein is a radio frequency cable trap assembly 100 having a radio frequency cable trap circuit 102. The radio frequency cable trap is configured to suppress induction of alternating current energy at a predetermined magnetic resonance imaging operating frequency in a cable 200 for a magnetic resonance imaging coil 302, 310, 314. The assembly 100 further includes an indication circuit 104 having an output unit 111 configured to output an indication signal upon reaching a predetermined upper threshold by the suppressed energy. The indication circuit 104 is configured to determine reaching of the predetermined upper threshold using a portion of the suppressed energy transferred from the radio frequency cable trap circuit 102 to the indication circuit 104 via an energy transfer coupling between the radio frequency cable trap circuit 102 and the indication circuit 104.

Description

[Technical Field]

[0001] The present invention relates to magnetic resonance imaging, and more particularly to radio frequency traps for cables of magnetic resonance imaging coils. [Background technology]

[0002] Unwanted currents, such as common mode currents, that can flow along the shielding of cables in magnetic resonance systems can adversely affect the performance of radio frequency coils, for example by affecting the decoupling and tuning of the coils. Furthermore, energy dissipated from the cables can generate heat that poses a risk of causing burns to the patient. Summary of the Invention [Problem to be solved by the invention]

[0003] To suppress such currents, radio frequency cable trap circuits can be used which introduce a high impedance to the common mode currents on the cable. There are several known designs for radio frequency cable trap circuits in magnetic resonance systems, e.g., tank circuits and bazooka baluns. [Means for solving the problem]

[0004] The present invention provides a radio frequency cable trap assembly, a cable for a magnetic resonance imaging coil having such a radio frequency cable trap assembly, a magnetic resonance imaging coil having such a cable, and a magnetic resonance imaging system having such a magnetic resonance imaging coil.

[0005] In one aspect, the present invention provides a radio frequency cable trap assembly having a radio frequency cable trap circuit configured to suppress induction of alternating current energy in a cable to a magnetic resonance imaging coil at a predetermined magnetic resonance imaging operating frequency.

[0006] The assembly further comprises an indicating circuit having an output unit configured to output an indicating signal upon reaching of a predetermined upper threshold by the suppressed energy, i.e. the energy resulting from the suppression, wherein for outputting the indicating signal the indicating circuit uses a portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicating circuit via the energy transfer coupling between the radio frequency cable trap circuit and the indicating circuit.

[0007] The reaching of a predetermined upper threshold by the suppressed energy may be sensed and / or measured, for example, via direct or indirect sensing and / or measurement. For example, the suppressed energy may be sensed and / or measured using a suitable sensor, and / or other physical quantities indicative of the suppressed energy, such as power, current, voltage, and / or temperature resulting from the suppressed energy, may be sensed and / or measured using a suitable sensor. The suppressed energy and / or other physical quantities resulting from the suppressed energy, such as power, current, voltage, and / or temperature, may be sensed and / or measured, for example, within the radio frequency cable trap circuit. For example, physical quantities indicative of the suppressed energy, such as power, current, voltage, and / or temperature resulting from the suppressed energy due to energy transferred from the radio frequency cable trap circuit to the indicator circuit via an energy transfer coupling, may be sensed and / or measured within the indicator circuit.

[0008] The indicator signal indicates that a predetermined upper threshold has been reached by the suppressed energy. Depending on the sensing and / or measurements performed within the radio frequency cable trap assembly, the indicator signal may additionally indicate other sensory values ​​sensed and / or measured within the radio frequency cable trap assembly.

[0009] A portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicator circuit may be used, for example, to supply energy to an output unit to output an indicator signal. A portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicator circuit may be used, for example, to activate an output mode of an output unit. A portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicator circuit may be used, for example, to indicate reaching a predetermined upper threshold.

[0010] The indicator circuit may be configured to determine the reaching of a predetermined upper threshold, for example, using a portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicator circuit via an energy transfer coupling between the radio frequency cable trap circuit and the indicator circuit.

[0011] The indicator signal may take different forms in different examples, for example, a visual, acoustic and / or radio signal to alert the operator of the magnetic resonance system that a predetermined upper threshold has been reached by the suppressed energy. In other examples, the indicator signal may be used to trigger other components of the magnetic resonance imaging system. In one example, the indicator signal may automatically trigger the cessation of a magnetic resonance scan performed by the magnetic resonance imaging system.

[0012] Although described in the context of cables for magnetic resonance imaging coils, the radio frequency cable trap assemblies described herein may be used in any galvanic connection located or intended to be located within the B1 field of a magnetic resonance imaging system.

[0013] Magnetic resonance imaging (MRI) is an imaging technique based on the principle of nuclear magnetic resonance, i.e., atomic nuclei with non-zero spin possess a magnetic moment. In medical magnetic resonance imaging, the non-zero spin nuclei are typically the nuclei of hydrogen atoms present in the human or animal body. Radio frequency (RF) waves forming a B1 excitation field are directed at the nuclei in an external magnetic field, leading to the excitation of protons and their subsequent relaxation process. The relaxation of the protons results in radio frequency signals emitted by the nuclei that can be sensed and processed to form an image.

[0014] A typical magnetic resonance imaging system generally includes a magnet (e.g., a superconducting electromagnet) that generates a strong static magnetic field, gradient coils that generate linear variations in the static magnetic field, a radio frequency transmit coil that generates a B1 excitation field, and a radio frequency receiver coil that senses the magnetic resonance radio frequency signals emitted by relaxing atomic nuclei. Typically, cables, such as coaxial cables, are used in the magnetic resonance system for controlled transmission of the radio frequency signals within the coils. Furthermore, the coils of the magnetic resonance system, as well as the radio frequency coils, are connected via cable transmission lines, e.g., coaxial cable transmission lines, to a computer unit that controls the magnetic resonance system and processes the acquired magnetic resonance signals.

[0015] In magnetic resonance imaging systems, cables placed within the system can unintentionally couple into the radio frequency transmission magnetic field, or B1 field, and act like unwanted antennas. This is referred to as the antenna effect. Wires, and generally any elongated conductive object, placed within the B1 field can act like antennas, capturing electromagnetic waves and extracting energy from them. Antennas can generate standing wave patterns of voltage and current that are maximized when their length is half the radio frequency wavelength. Such currents can cause radio frequency induction heating of the antenna, e.g., the cable, and can pose a risk of burns to patients near the heated antenna.

[0016] For example, a coaxial cable has an outer shield and an inner conductor separated from each other by a dielectric material. Together, they form a radio frequency transmission line with defined and stable propagation characteristics, such as velocity and characteristic impedance. This allows the outer shield to prevent picking up undesired frequencies. Magnetic resonance signals acquired by a radio frequency coil of a magnetic resonance system may be transmitted over the coaxial cable, for example, in a differential mode on the inner surfaces of the inner and outer conductors.

[0017] However, sources external to the coaxial cable can induce unintended currents in the outer shield, thus generating unintended signals that can adversely affect, for example, the signal-to-noise ratio of a radio frequency receiver coil. In high magnetic fields, the outer surface of the coaxial cable's outer conductor can electromagnetically couple to the radiated or radio frequency transmitted magnetic field, i.e., the B1 field. This coupling can induce undesired common-mode currents. Due to the skin effect, the inner and outer surfaces of the coaxial shield can be effectively separated at radio frequencies. Nevertheless, common-mode currents can cause problems by coupling to nearby dielectrics, such as the patient and the radio frequency coil. Residual coupling of common-mode currents into the receive signal path can result in the cable itself acting like an unwanted antenna, which can cause patient burns. Furthermore, coil fill factor and power efficiency can be reduced. Furthermore, depending on the cable's wiring, common-mode currents can generate high local electric fields, which can cause superficial burns to the patient's body.

[0018] For these reasons, radio frequency cable trap circuits are used with cables in magnetic resonance systems. Radio frequency cable trap circuits can have the beneficial effect of introducing high impedance. This impedance can enable the suppression of AC energy, e.g., AC current, at a given magnetic resonance imaging operating frequency. For example, impedance can be introduced to common-mode currents on the cable. In magnetic resonance imaging systems, such AC energy, e.g., in the form of common-mode currents, can be induced through the body coil during the transmission of radio frequency pulses. Common-mode current refers to the portion of the conductor current that is not matched by an equal and opposite current. This is the portion of the total current that causes the feedline to behave like a single wire line. Currents flowing in the common mode can be reduced by a sufficiently high common-mode impedance. Therefore, increasing the common-mode impedance can reduce, or suppress, common-mode currents on the cable or any other galvanic connection, such as a twin-ax or twisted-pair connection.

[0019] The radio frequency cable trap circuit may, for example, form a resonant structure having at least one electrical energy reservoir and at least one magnetic energy reservoir that forms a high impedance to common modes on the cable. This may be achieved, for example, by forming the resonant structure directly from a portion of the transmission line, or, for example, primarily by inductive coupling between the resonant structure and the cable.

[0020] An MR-compatible cable trap circuit may be based on a resonant structure that stores both electrical and magnetic energy. Different methods can be used to construct such a resonant trap structure. For example, a coil may be made from a transmission line with a common mode sensed inductor. The inductor may be connected to a parallel capacitor, for example, to form a parallel resonant circuit. However, the capacitor does not have to be realized by a lumped component. The capacitive coupling between the windings of the coil may, for example, function as an electrical energy reservoir. The coil may, for example, be formed by another structure and primarily inductively coupled to, for example, the cable. Alternatively, a coaxial structure may be used to form an inductively coupled structure instead of a coil. This may, for example, directly use the cable as an internal component. The length may be selected to be, for example, a quarter wavelength, to form a monopole resonator structure known as a bazooka balun.

[0021] The radio frequency cable trap assembly is designed without magnetic materials to ensure magnetic resonance compatibility. A resonant structure is used to form a high impedance at a predetermined magnetic resonance imaging operating frequency. For narrowband pulses used in magnetic resonance imaging systems, a high impedance at the predetermined magnetic resonance imaging operating frequency may be sufficient. In special cases, multiple nuclei may also be used for imaging. Then, for example, a multi-resonant radio frequency cable trap circuit resonating with multiple different magnetic resonance imaging operating frequencies, or multiple radio frequency cable trap assemblies resonating with different magnetic resonance imaging operating frequencies, may be used. Furthermore, a multi-tenant structure combining two or more modes may be realized.

[0022] Even when a radio frequency cable trap circuit is used, errors and / or problems may occur. These errors and / or problems may, for example, cause insufficient suppression of induced AC energy by the radio frequency cable trap circuit. A predetermined upper threshold may be defined so that adverse effects on the patient, e.g., due to heating caused by induced energy exceeding a safe temperature, are excluded or at least made unlikely. Thus, when the suppressed energy reaches the predetermined upper threshold, the resulting risk may be indicated by an indicator signal output by an indicator circuit. The predetermined upper threshold may be defined, for example, as a temperature threshold. When the respective temperature threshold is reached, it may be concluded that the suppression of the induction of AC energy is insufficient. Furthermore, it may be concluded that an error and / or problem has occurred. Such errors and / or problems may include, for example, non-ideal adjustment of the radio frequency cable trap circuit, defects in the radio frequency cable trap circuit, defects in the cable, and / or critical placement of the cable. These errors and / or problems may be corrected, or the radio frequency cable trap circuit and / or the cable may be replaced. The modifications may include, for example, modifying the tuning of the radio frequency cable trap circuitry and / or modifying the placement of the cable.

[0023] Such errors and / or problems can also occur for unconnected coils in magnetic resonance imaging systems. In the event of errors and / or problems, the cables and / or radio frequency cable trap circuits present risks, such as the risk of skin burns due to electromagnetic coupling, resulting in the induction of AC energy that may be too large and / or insufficiently suppressed. These examples may therefore increase patient safety for both connected and unconnected coils.

[0024] Critical operations of the magnetic resonance imaging system can result in high voltages being induced across the radio frequency cable trap circuit, which can generate high currents within the radio frequency cable trap circuit.

[0025] Suppressed energy refers to the energy resulting from suppression, i.e., the amount of residual energy remaining after suppression.

[0026] For example, a power threshold indicative of a predetermined upper threshold can be sensed, for example, by the radio frequency cable trap circuit and / or the indicator circuit using a power sensor circuit configured by the radio frequency cable trap assembly. The power sensor circuit is configured to sense, for example, the power resulting from the suppressed energy, i.e., the amount of suppressed energy induced in the radio frequency cable trap circuit per unit time. The power sensor circuit is configured to sense, for example, the power resulting from the transmitted portion of the suppressed energy, i.e., the amount of suppressed energy transmitted from the radio frequency cable trap circuit to the indicator circuit per unit time via the energy transmission coupling between the radio frequency cable trap circuit and the indicator circuit.

[0027] For example, the predetermined upper threshold as the energy threshold, or another energy threshold indicating the predetermined upper threshold, may be sensed, for example, by the radio frequency cable trap circuit and / or the indicator circuit using an energy sensor circuit configured by the radio frequency cable trap assembly. The energy sensor circuit may be configured, for example, to sense suppressed energy induced in the radio frequency cable trap circuit. The energy sensor circuit may be configured, for example, to sense a portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicator circuit via an energy transfer coupling between the radio frequency cable trap circuit and the indicator circuit.

[0028] For example, a current threshold indicative of a predetermined upper threshold may be sensed, for example, by the radio frequency cable trap circuit and / or the indicator circuit using a current sensor circuit configured by the radio frequency cable trap assembly. The current sensor circuit may be configured to sense, for example, a current resulting from suppressed energy induced in the radio frequency cable trap circuit. The current sensor circuit may be configured to sense, for example, a current resulting from a portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicator circuit via an energy transfer coupling between the radio frequency cable trap circuit and the indicator circuit.

[0029] For example, a voltage threshold indicative of a predetermined upper threshold may be sensed, for example, by the radio frequency cable trap circuit and / or the indicator circuit using a voltage sensor circuit configured by the radio frequency cable trap assembly. The voltage sensor circuit may be configured to sense a voltage resulting from, for example, suppressed energy induced in the radio frequency cable trap circuit. The voltage sensor circuit may be configured to sense a voltage resulting from, for example, a portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicator circuit via an energy transfer coupling between the radio frequency cable trap circuit and the indicator circuit.

[0030] For example, a temperature threshold indicative of a predetermined upper threshold may be sensed, for example, by the radio frequency cable trap circuit and / or the indicator circuit using a temperature sensor circuit configured by the radio frequency cable trap assembly. The temperature sensor circuit may be configured to sense a temperature resulting from, for example, suppressed energy induced in the radio frequency cable trap circuit. The temperature sensor circuit may be configured to sense a temperature resulting from, for example, a portion of suppressed energy transferred from the radio frequency cable trap circuit to the indicator circuit via an energy transfer coupling between the radio frequency cable trap circuit and the indicator circuit.

[0031] Embodiments may have the beneficial effect of enabling detection of critical trap heating of a cable in which a radio frequency cable trap circuit and / or radio frequency cable trap assembly is used. Such heating may result from induced alternating current energy. The reaching of potential critical or at least undesirable heating may be determined based on the reaching of a predetermined upper threshold by the suppressed energy. This threshold may indicate energy large enough to potentially cause an undesirable or critical level of heating. Accordingly, an indicator signal output in response to the reaching of the predetermined upper threshold by the suppressed energy may indicate an undesirable or critical level of heating. The output may therefore enable the stopping of a magnetic resonance imaging scan before the patient is damaged by the heating, e.g., burns. The magnetic resonance imaging scan may be automatically stopped, for example, upon receipt of the indicator signal by a receiver portion of a magnetic resonance imaging system performing the magnetic resonance imaging scan. For example, a system-integrated body coil connected to the receive chain may be used. The body coil may enable sensing of signals within or slightly outside the MR bandwidth without requiring additional hardware. The receiver may forward the received indicator signal to a control unit of the magnetic resonance imaging system, which may then stop the execution of the magnetic resonance imaging scan. When the magnetic resonance imaging scan is stopped, induction of AC energy at a predetermined magnetic resonance imaging operating frequency in the cable may be stopped. Accordingly, further heating of the cable and / or radio frequency cable trap circuitry may be stopped, and the cable and / or radio frequency cable trap circuitry may cool again. Alternatively, the magnetic resonance imaging scan may be stopped by an operator operating the magnetic resonance imaging system upon receipt of the output indicator signal. The indicator signal may indicate, for example, a detected problem with the radio frequency cable trap circuitry and / or sensor values. The detected problem and / or sensor values ​​may be transmitted, for example, to a cloud server and / or written to a log file for later use, such as for services.

[0032] When the magnetic resonance imaging scan is stopped, the cable and / or radio frequency cable trap circuit may be checked for potential errors, such as non-ideal adjustment of the radio frequency cable trap circuit, defects in the radio frequency cable trap circuit, defects in the cable, and / or non-critical placement of the cable. If errors occur, they may, for example, be corrected or the radio frequency cable trap circuit and / or the cable may be replaced. Correction may include, for example, correcting the adjustment of the radio frequency cable trap circuit and / or correcting the placement of the cable.

[0033] Embodiments may have the beneficial effect of preventing heating of the cable and / or radio frequency cable trap assembly to a level that could potentially be harmful to the patient. Thus, by stopping the magnetic resonance imaging scan, for example, the patient being scanned may be protected from any hazards, such as burns, that may result from heating of the cable and / or radio frequency cable trap circuitry. This may be particularly beneficial for protecting sedated patients who may be unable to report any problematic heating that occurs during sedation.

[0034] In another embodiment, the indicator circuit has a passive switch controlled by the fraction of the suppressed energy transferred via the energy transfer coupling and configured to activate an output mode of the indicator circuit to output an indicator signal when the suppressed energy reaches a predetermined upper threshold. An embodiment may have the beneficial effect that the output mode of the indicator circuit, e.g., activating an output unit of the indicator circuit, may be controlled based on the fraction of the suppressed energy transferred and thus based on the induced suppressed energy. For example, the output unit may be in a sleep mode and activated only when the suppressed energy reaches a predetermined upper threshold.

[0035] In another embodiment, the indicator circuit includes a comparator configured to compare a parameter describing the portion of the suppressed energy transferred via the energy transfer coupling with a reference parameter describing the reaching of a predetermined upper threshold. The indicator circuit is configured to activate an output mode upon determining using the comparator that the suppressed energy has reached the predetermined upper threshold. An embodiment may have the beneficial effect that the output mode of the indicator circuit, e.g., activating an output unit of the indicator circuit, may be controlled based on the portion of the suppressed energy transferred, and thus based on the suppressed energy induced. For example, the output unit may be in a sleep mode and be activated only when the suppressed energy reaches the predetermined upper threshold.

[0036] In another embodiment, the energy transfer coupling is an inductive coupling. Inductive or magnetic coupling refers to a coupling in which a change in current through one wire induces a voltage between the ends of the other wire by electromagnetic induction. The changing current through the first wire generates a changing magnetic field around it by Ampere's law of circuits. The changing magnetic field induces an electromotive force in the second wire by Faraday's law of electromagnetic induction.

[0037] For example, a radio frequency cable trap circuit may inductively couple via its local magnetic field to an indicator circuit having a pickup loop for picking up the induced voltage. The radio frequency cable trap circuit may, for example, suppress alternating current in the cable at a predetermined magnetic resonance imaging operating frequency, e.g., the 1.5 T Larmor frequency. For sufficiently high power absorbed in the radio frequency cable trap circuit, the induced voltage in the indicator circuit may be large enough to allow significant energy harvesting of energy transferred from the radio frequency cable trap circuit by the indicator circuit. The harvested energy may be large enough to power the transmission of an indicator signal by the indicator circuit to, for example, a magnetic resonance imaging system.

[0038] For example, an AC voltage may be induced in the indicator circuit by energy transfer. The induced AC voltage may be used to generate a DC voltage, for example, by rectification. The resulting DC voltage may be used to power an oscillator, e.g., a quartz oscillator, configured to transmit a pilot tone as an indicator signal. The pilot tone may be transmitted, for example, within a receiver bandwidth of a receiver of the magnetic resonance imaging system. For example, the pilot tone may indicate detection of heating of the radio frequency cable trap circuit reaching a predetermined upper threshold. The magnetic resonance imaging system may be configured to detect the pilot tone transmitted within the receiver bandwidth using the receiver. By detecting reception of the pilot tone, the magnetic resonance imaging system may detect heating of the radio frequency cable trap circuit reaching a predetermined upper threshold.

[0039] Additionally, the indicator circuit may include, for example, a microcontroller, which may be powered using energy harvesting, which may enable the indicator circuit to collect and transmit additional data, such as, for example, the temperature, power level, etc., of the radio frequency cable trap circuit and / or the indicator circuit.

[0040] In another embodiment, the energy transfer coupling is capacitive coupling. Capacitive coupling refers to the transfer of energy in an electrical network by displacement currents between circuit nodes induced by an electric field. In its simplest implementation, capacitive coupling may be achieved by placing a capacitor between the nodes.

[0041] In another embodiment, the indicator circuit includes an energy harvesting circuit configured to recover a portion of the suppressed energy transferred via the energy transfer coupling, the indicator circuit configured to use the harvested energy to output the indicator signal.

[0042] The embodiment may have the beneficial effect of integrating an energy harvesting function into the radio frequency cable trap assembly. This energy harvesting function may be used to supply energy to the indicating circuit, allowing the indicating circuit to output an indicating signal using the output unit. Thus, the indicating circuit may not require an independent energy supply, but may be provided with energy via energy harvesting whenever a portion of the suppressed energy is transferred from the radio frequency cable trap circuit to the partial indicating circuit via the energy transfer coupling. Since the purpose of the indicating circuit is to ensure that the suppressed energy reaches a predetermined upper threshold, the indicating circuit may only require a power supply when there is non-negligible suppressed energy, i.e., when a non-negligible amount of energy is induced despite the suppression by the radio frequency cable trap circuit. Such non-negligible suppressed energy may provide energy to the indicating circuit via energy harvesting. Thus, the power supply of the indicating circuit may be guaranteed when necessary. Therefore, the power supply of the indicating circuit may be independent of any additional connection of the radio frequency cable trap assembly to an external power source. It may also function when the cable and / or magnetic resonance imaging coil provided with the radio frequency cable trap assembly are not connected to a power source.

[0043] Critical operations of the magnetic resonance imaging system may result in high voltages being induced across the radio frequency cable trap circuit, generating high currents within the radio frequency cable trap circuit. Such high currents may further result in high radio frequency magnetic fields being generated internally within the radio frequency cable trap circuit. This locally generated radio frequency magnetic field may be sufficiently high to be used for energy harvesting by an indicator circuit of the intelligent radio frequency cable trap assembly. The indicator circuit may be configured to harvest energy, for example, using a voltage induced in the indicator circuit by the radio frequency magnetic field generated by the radio frequency cable trap circuit. As soon as this voltage harvested by the indicator circuit reaches a critical limit, i.e., a predetermined upper threshold, which may be defined as a voltage threshold, the indicator circuit may communicate with the magnetic resonance imaging system indicating the reaching of the predetermined upper threshold and / or requesting the cessation of magnetic resonance imaging data acquisition by the magnetic resonance imaging system. In further embodiments, additional information, such as temperature, current, force, magnetic field, etc., may be sensed using appropriate sensors configured by the intelligent radio frequency cable trap assembly and transmitted to the magnetic resonance imaging system as well.

[0044] For example, the harvested energy may be employed by the indicator circuit to power an on-board transmitter to transmit data regarding the state of the radio frequency trap circuit to a host system, such as a magnetic resonance imaging system.

[0045] The radio frequency cable trap circuit is intended to sufficiently suppress the induction of AC energy in the cable. Unless an error or other problem occurs, energy induced in the cable by radio frequency radiation, particularly pulses having a predetermined magnetic resonance imaging operating frequency, can be effectively suppressed by the radio frequency cable trap circuit. Therefore, a predetermined upper threshold of the suppressed energy can be reached only in the event of an error. Such errors may include, for example, non-ideal adjustment of the radio frequency cable trap circuit, defects in the cable in which the radio frequency cable trap assembly is used, or critical placement. In such cases, it may still occur that large energy, e.g., strong currents, are induced in the cable and / or the radio frequency cable trap circuit. Such large energy induced despite the suppression may, for example, lead to critical heating of the cable and / or the radio frequency cable trap circuit.

[0046] Such error scenarios, in which the indicating circuit is required, may also include errors related to the power source. For example, some components of a magnetic resonance imaging system in which the radio frequency cable trap circuit assembly is used may not be connected to a power source. For example, the cable and / or the magnetic resonance imaging coil using the radio frequency cable trap circuit assembly may not be connected. Using energy harvesting to provide energy to the indicating circuit may have the beneficial effect of making the power supply of the indicating circuit independent of errors related to connecting to an external power source. Such errors related to the external power source may result, for example, from an operational error. For example, an operator may simply forget to plug in such an external power source. An indicating circuit powered using energy harvesting may be independent of such operational errors.

[0047] In another embodiment, the indicating circuit has a battery unit configured to provide energy for outputting the indicating signal. This embodiment may have the beneficial effect of providing a self-sufficient power supply for the indicating circuit together with the battery unit. Energy harvesting and the battery unit may be combined, and during normal operation, the energy harvesting may be configured, for example, to recharge the battery unit, potentially consuming only a small amount of energy over time without any impact on normal operation, i.e., backlash. It may thus be ensured that the battery unit remains charged to provide energy for outputting the indicating signal as needed. When a predetermined upper threshold is reached by the withdrawn energy, for example, a passive switch may trigger output of the indicating signal powered from the charged battery unit.

[0048] In another embodiment, the indication signal comprises a visual signal. The output unit has a visual signal emitting circuit configured to emit the visual signal.

[0049] In another embodiment, the indication signal comprises an acoustic signal. The output unit comprises an acoustic signal emitting circuit configured to emit the acoustic signal.

[0050] In another embodiment, the instruction signal comprises a wireless signal. The output unit has a wireless signal transmitting circuit configured to transmit the wireless signal.

[0051] In another embodiment, the instruction circuit is configured to transmit a radio signal in a radio frequency band that at least partially overlaps with, is within or near a predetermined magnetic resonance imaging operating frequency bandwidth that includes the predetermined magnetic resonance imaging operating frequency.

[0052] For example, the radio frequency band is a frequency band defined by the magnetic resonance imaging bandwidth. A receiver component of the magnetic resonance imaging system, e.g., one or more receiver coils, may be configured to receive magnetic resonance signals, i.e., radio frequency signals, within the magnetic resonance imaging bandwidth. Transmitting radio signals at a radio frequency having the magnetic resonance imaging bandwidth, i.e., the magnetic resonance imaging bandwidth, by a radio frequency cable trap assembly disposed within the magnetic resonance imaging system may have the beneficial effect of enabling the magnetic resonance imaging receiver component to receive and process the radio frequency signals. The receiver component of the magnetic resonance imaging system may be highly sensitive to receive radio frequency signals within the magnetic resonance imaging bandwidth.

[0053] A magnetic resonance imaging system may include a main magnet configured to generate a main magnetic field for polarizing a sample, one or more shim coils for correcting shifts in the uniformity of the main magnetic field, a gradient system used to identify the region to be scanned, and a radio frequency system configured to excite the sample using radio frequency pulses and detect magnetic resonance signals resulting from the excitation. Magnetic resonance signals in magnetic resonance imaging are generated by a resonance process resulting from excitation by radio frequency pulses. The radio frequency system may include a transmit component, i.e., one or more transmitter coils configured to generate the radio frequency pulses used to excite the sample. Nuclei of interest for acquiring magnetic resonance imaging data have unique resonant frequencies in the radio frequency portion of the electromagnetic spectrum. Radio frequency pulses are transmitted to excite the nuclei of interest using these resonant frequencies as the magnetic resonance imaging operating frequency. The radio frequency system may also include a receiver component, i.e., one or more receiver coils configured to receive magnetic resonance signals within the magnetic resonance imaging bandwidth. The receiver coils detect radio frequency-excited oscillations generated by precession of the magnetic moments of atomic nuclei within the sample. Thus, the magnetic resonance signals acquired by the receiver coils are induced electromagnetic fields oscillating within the magnetic resonance imaging bandwidth.

[0054] For example, the indicator circuitry may be configured to transmit a radio signal in a radio frequency band that does not include the predetermined magnetic resonance imaging operating frequency.

[0055] In another embodiment, the indicating circuitry is configured to transmit said wireless signal in a frequency band outside a predetermined magnetic resonance imaging operating frequency band that includes the predetermined magnetic resonance imaging operating frequency.

[0056] For example, RFID technology may be used to transmit the indicator signal. The indicator circuit may include, for example, an RFID chip. For example, power obtained by the indicator circuit from the radio frequency cable trap circuit may be high enough to trigger and / or power the RFID chip. The RFID chip may be configured to submit a unique ID assigned to the RFID chip and, therefore, to the radio frequency cable trap assembly including the RFID chip. The unique ID may be encoded in the radio frequency signal transmitted by the RFID chip as the indicator signal. The signal transmitted by the RFID chip may be transmitted in a radio frequency band separate from the magnetic resonance imaging bandwidth and received by a receiver component of the magnetic resonance imaging system configured to receive magnetic resonance signals for magnetic resonance imaging data acquisition. The signal transmitted by the RFID chip may be received by a dedicated radio frequency receiver. This dedicated radio frequency receiver may be configured by the magnetic resonance imaging system. For example, the dedicated radio frequency receiver may be mounted on the patient table or the bore of the magnetic resonance imaging system. The unique ID constituted by the indicator signal transmitted by the RFID chip may enable a receiver, e.g., a magnetic resonance imaging system having a dedicated radio frequency receiver, to identify the radio frequency cable trap assembly that triggered the issuance of the respective indicator signal, i.e., the origin of the indicator signal. Receipt of the indicator signal may, for example, cause the magnetic resonance imaging system or a computer system controlling the magnetic resonance imaging system to stop the magnetic resonance imaging scan performed by the magnetic resonance imaging system. Furthermore, a request may be output, for example, requesting an operator to relocate a cable having a radio frequency cable trap assembly identified by the unique ID. If an induced signal is repeatedly received for the same radio frequency cable trap assembly, a repair action may be triggered. For example, a repair request may be output, requesting an operator to repair the identified radio frequency cable trap assembly and / or the cable having the identified radio frequency cable trap assembly.For example, a counter may be used to count the number of indication signals issued to a radio frequency cable trap assembly identified by a unique ID, and a repair request may be triggered when a predetermined threshold is reached by the counter.

[0057] In another embodiment, the indicating circuit includes one or more sensor circuits for acquiring sensor data and a microcontroller configured to control the acquisition of the sensor data and the transmission of the acquired sensor data by wireless signal.

[0058] Using a microcontroller, the indicator circuitry may be enabled to collect and transmit additional sensor data acquired by the sensor circuitry, for example.

[0059] In another embodiment, the one or more sensor circuits are configured to obtain sensor data for one or more of the following parameters: temperature of the radio frequency cable trap assembly; voltage in the radio frequency cable trap circuit resulting from the suppressed energy; voltage in the indicator circuit resulting from the transmitted portion of the suppressed energy; current in the radio frequency cable trap circuit resulting from the suppressed energy; current in the indicator circuit resulting from the transmitted portion of the suppressed energy; magnetic field strength; environmental temperature; and environmental humidity.

[0060] For example, the indicator circuit, such as a pickup circuit, may be configured such that when the suppressed energy induced in the radio frequency cable trap circuit reaches a predetermined upper threshold, the power picked up by the indicator circuit is high enough to provide sufficient power to drive the microcontroller. The microcontroller may be configured to detect, for example, an electromagnetic field, an environmental parameter such as temperature or humidity, or motion. The microcontroller may further be configured to wirelessly report the sensing results to a remote router, for example, via Wi-Fi, Bluetooth (LE), or any other power-efficient wireless communication method. The submitted data may be used to control the magnetic resonance imaging system, particularly to prevent dangerous situations for the patient, such as those described above. Such dangerous situations may be prevented, for example, by automatically stopping the magnetic resonance imaging scan operation performed by the magnetic resonance imaging system.

[0061] The temperature and / or power may be measured using, for example, a sensor with a local bolometer, a thermistor, or a switch controlled by a thermally dependent mechanical expansion. The thermally dependent mechanical expansion may be implemented, for example, using a bimetallic component. The bimetallic component comprises layers of different metals with at least different thermal expansion coefficients. Due to the difference in the thermal expansion coefficients, a temperature change is converted into a mechanical displacement. The bimetallic component may, for example, have the shape of a strip or a disk.

[0062] The indicator circuit may, for example, include a voltage sensor configured to measure a voltage on the radio frequency cable trap circuit. Further, a comparator may be provided configured to compare the voltage sensed on the radio frequency cable trap circuit by the voltage sensor with a predetermined voltage threshold. When the sensed voltage reaches the predetermined voltage threshold, an indicator signal may be issued by the indicator circuit to, for example, prompt a scan controller of the magnetic resonance imaging system to stop the scan being performed by the magnetic resonance imaging system.

[0063] In another embodiment, the transmitted radio signal includes a radio frequency cable trap assembly ID that identifies the radio frequency cable trap assembly transmitting the radio signal.

[0064] The radio frequency cable trap assembly may be used to prevent and / or detect currents on galvanic structures in an MRI system. It may be applied, for example, to a magnetic resonance imaging coil, particularly an MRI receive coil. For example, the radio frequency cable trap may be connected to the magnetic resonance imaging coil or may be implemented in any type of cable connected to the magnetic resonance imaging coil.

[0065] In another aspect, the present invention provides a cable for a magnetic resonance imaging coil having a radio frequency cable trap assembly according to any of the aforementioned embodiments of the radio frequency cable trap assembly, the cable being, for example, a coaxial cable.

[0066] In another aspect, the present invention provides a magnetic resonance imaging coil having any of the aforementioned embodiments of a cable with a radio frequency cable trap assembly.

[0067] In another aspect, the present invention provides a magnetic resonance imaging system having a magnetic resonance imaging coil of any of the preceding embodiments of the magnetic resonance imaging coil, wherein the magnetic resonance imaging coil is provided with a cable having a radio frequency cable trap assembly.

[0068] It will be understood that one or more of the above-described embodiments of the present invention can be combined, as long as the combined embodiments are not mutually exclusive.

[0069] As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as an apparatus, a method, or a computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which may be referred to generally herein as a "circuit," "module," or "system." Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer-readable medium(s) having computer-executable code embodied therein.

[0070] Any combination of one or more computer-readable media may be utilized. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. As used herein, "computer-readable storage medium" encompasses any tangible storage medium capable of storing instructions executable by a processor or computing system of a computing device. The computer-readable storage medium may also be referred to as a computer-readable non-transitory storage medium. The computer-readable storage medium may also be referred to as a tangible computer-readable medium. In some embodiments, the computer-readable storage medium may be capable of storing data that can be accessed by the computing system of a computing device. Examples of computer-readable storage media include, but are not limited to, floppy disks, magnetic hard disk drives, solid-state hard disks, flash memory, USB thumb drives, random access memory, read-only memory (ROM), optical disks, magneto-optical disks, and computing system register files. Examples of optical disks include compact discs (CDs) and digital versatile discs (DVDs), such as CD-ROM, CD-RW, CD-R, DVD-ROM, DVD-RW, or DVD-R discs. The term computer-readable storage medium also refers to various types of storage media that can be accessed by a computer device over a network or communications link. For example, data may be retrieved via a modem, the Internet, or a local area network. Computer-executable code embodied on a computer-readable medium may be transmitted using any suitable medium, including, but not limited to, wireless, wired, fiber optic cable, RF, or any suitable combination of the foregoing.

[0071] A computer-readable signal medium may include a propagated data signal having computer-executable code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electromagnetic, optical, or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium, such computer-readable medium being other than a computer-readable storage medium, capable of communicating, propagating, or transmitting a program for use by or in connection with an instruction execution system, apparatus, or device.

[0072] "Computer memory" or "memory" is an example of a computer-readable storage medium. Computer memory is memory that is directly accessible to a computing system. "Computer storage" or "storage" is a further example of a computer-readable storage medium. Computer storage is any non-volatile computer-readable storage medium. In some embodiments, computer storage may be computer memory, or vice versa.

[0073] As used herein, a "computing system" encompasses electronic components capable of executing programs or machine-executable instructions or computer-executable code. References to a computing system, including examples of "computing system," should be interpreted as potentially including more than one computing system or processing core. A computing system may be, for example, a multi-core processor. A computing system may refer to a collection of computing systems within a single computer system or distributed across multiple computer systems. The term computing system should also be interpreted as potentially referring to a collection or network of computing devices, each having a processor or computing system. Machine-executable code or instructions may be executed by multiple computing systems or processors, which may be within the same computing device or distributed across multiple computing devices.

[0074] Machine-executable instructions or computer-executable code may include instructions or programs that cause a processor or other computing system to perform an aspect of the present invention. Computer-executable code for performing operations for aspects of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages, such as the "C" programming language or similar programming languages, compiled into machine-executable instructions. In some examples, the computer-executable code may be in the form of a high-level language or pre-compiled, or may be used in conjunction with an interpreter that generates machine-executable instructions on the fly. In other examples, the machine-executable instructions or computer-executable code may be in the form of programming for a programmable logic gate array.

[0075] The computer executable code may run entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter situation, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet Service Provider).

[0076] Aspects of the present invention will be described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block or portion of a block in the flowcharts, illustrations, and / or block diagrams, where applicable, can be implemented by computer program instructions in the form of computer-executable code. It will further be understood that blocks in different flowcharts, illustrations, and / or block diagrams can be combined, if not mutually exclusive. These computer program instructions may be supplied to a general-purpose computer, a special-purpose computer, or other programmable data processing device computing system, such that the instructions, when executed via the computer or other programmable data processing device computing system, produce a machine that generates means for performing the functions / acts specified in one or more blocks of the flowcharts and / or block diagrams.

[0077] These machine-executable instructions or computer program instructions may be stored on a computer-readable medium that can instruct a computer, other programmable data processing apparatus, or other device to function in a particular manner, such as to produce an article of manufacture including instructions that implement the functions / acts specified in one or more blocks of the flowcharts and / or block diagrams, where the instructions stored on the computer-readable medium.

[0078] The machine-executable instructions or computer program instructions may also be loaded into a computer, other programmable data processing apparatus, or other device to perform a series of operational steps on the computer, other programmable data processing apparatus, or other device to generate a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide a process for performing the functions / acts specified in one or more blocks of the flowcharts and / or block diagrams.

[0079] As used herein, a "user interface" is an interface that allows a user or operator to interact with a computer or computer system. A "user interface" may also be referred to as a "human interface device." A user interface may provide information or data to an operator and / or receive information or data from an operator. A user interface may allow input from an operator to be received by a computer and may provide output from the computer to a user. In other words, a user interface may allow an operator to control or manipulate a computer, and the interface may allow a computer to indicate the effects of the operator's control or manipulation. The display of data or information on a display or graphical user interface is an example of providing information to an operator. A keyboard, mouse, trackball, touchpad, pointing stick, graphics tablet, joystick, gamepad, webcam, headset, pedals, wired gloves, remote control, and receiving data via an accelerometer are all examples of user interface components that allow receiving information or data from an operator.

[0080] As used herein, a "hardware interface" includes an interface that allows a computing system of a computer system to interact with and / or control external computing devices and / or equipment. A hardware interface may allow a computing system to send control signals or instructions to external computing devices and / or equipment. A hardware interface may also allow a computing system to exchange data with external computing devices and / or equipment. Examples of hardware interfaces include, but are not limited to, a universal serial bus, an IEEE 1394 port, a parallel port, an IEEE 1284 port, a serial port, an RS-232 port, an IEEE-488 port, a Bluetooth connection, a wireless local area network connection, a TCP / IP connection, an Ethernet connection, a control voltage interface, a MIDI interface, an analog input interface, and a digital input interface.

[0081] As used herein, "display" or "display device" encompasses an output device or user interface configured to display images or data. A display can output visual, auditory, and / or tactile data. Examples of displays include, but are not limited to, computer monitors, television screens, touchscreens, tactile electronic displays, Braille screens, cathode ray tubes (CRTs), memory tubes, bi-stable displays, electronic paper, vector displays, flat panel displays, vacuum fluorescent displays (VFs), light-emitting diode (LED) displays, electroluminescent displays (ELDs), plasma display panels (PDPs), liquid crystal displays (LCDs), organic light-emitting diode displays (OLEDs), projectors, and head-mounted displays.

[0082] Preferred embodiments of the invention will now be described, by way of example only, with reference to the drawings in which: [Brief explanation of the drawings]

[0083] [Figure 1] 1 illustrates an example of a radio frequency cable trap assembly. [Figure 2] 1 illustrates a further example of a radio frequency cable trap assembly. [Figure 3] 1 illustrates a further example of a radio frequency cable trap assembly. [Figure 4] 1 illustrates a further example of a radio frequency cable trap assembly. [Figure 5] 1 shows an example of a cable with a radio frequency cable trap assembly. [Figure 6] 6 illustrates an example of a coil connected to the example cable of FIG. 5. [Figure 7] 7 illustrates an example of a magnetic resonance imaging system having the coil of FIG. 6. [Figure 8] 10 illustrates a further example of a radio frequency cable trap assembly with inductive coupling. [Figure 9] 9 illustrates the functional behavior of the radio frequency cable trap assembly of FIG. 8. [Figure 10] 10 illustrates a further example of a radio frequency cable trap assembly with capacitive coupling. [Figure 11] 11 illustrates the functional behavior of the radio frequency cable trap assembly of FIG. 10. [Figure 12] 1 illustrates an example of a radio frequency cable trap assembly with a battery unit. [Figure 13] 1 illustrates a further example of a radio frequency cable trap assembly with a battery unit. [Figure 14] 1 illustrates a further example of a magnetic resonance imaging system. [Figure 15] 1 illustrates a further example of a magnetic resonance imaging system. DETAILED DESCRIPTION OF THE INVENTION

[0084] Like numbered elements in these figures are either equivalent elements or perform the same function. An element described above is not necessarily described in a subsequent figure if the function is equivalent.

[0085] FIG. 1 illustrates an exemplary radio frequency cable trap assembly 100. The radio frequency cable trap assembly 100 includes a radio frequency cable trap circuit 102 and an indicator circuit 104. The radio frequency cable trap circuit 102 is configured to suppress induction of alternating current energy at a predetermined magnetic resonance imaging operating frequency in a cable. The cable may be, for example, a cable of a magnetic resonance imaging coil of an MRI system. The indicator circuit 104 includes an output unit 111 configured to output an indicator signal when the suppressed energy reaches a predetermined upper threshold. To output the indicator signal, the indicator circuit 104 uses a portion of the suppressed energy transferred from the radio frequency cable trap circuit 102 to the indicator circuit 104 via an energy transfer coupling between the radio frequency cable trap circuit 102 and the indicator circuit 104. The coupling may be, for example, an inductive or capacitive coupling. The transferred portion of the suppressed energy may be used to provide energy for operating the output unit 111, for example, by an energy harvesting circuit 106 of the indicator circuit. The energy harvesting circuit 106 is configured to harvest the transmitted portion of the suppressed energy for outputting the indicator signal.

[0086] The indication signal may be output in the form of, for example, a visual signal, an acoustic signal, and / or a wireless signal. To output the indication signal, the output unit 111 may include, for example, one or more of a visual signal emitting circuit 112 configured to emit a visual signal, an acoustic signal emitting circuit 114 configured to emit an acoustic signal, and a wireless signal transmitting circuit 116 configured to transmit a wireless signal. The visual signal emitting circuit 112 may include, for example, one or more LEDs. The acoustic signal emitting circuit 114 may include, for example, a buzzer or a loudspeaker. The wireless signal transmitting circuit 116 may include, for example, a radio frequency transmitter. The radio frequency transmitter may be configured to transmit a wireless signal in a radio frequency band receivable by, for example, a receiver component of an MRI system configured to receive MR radio frequency signals. The radio frequency transmitter may be configured, for example, as an RFID chip. The RFID chip may be configured to transmit a radio frequency signal receivable by a dedicated receiver. The radio frequency transmitter may be configured to transmit, for example, a WIFI signal or, for example, a Bluetooth (LE) signal that can be received by a remote router addressed by the transmitted signal.

[0087] FIG. 2 shows another exemplary radio frequency cable trap assembly 100. The radio frequency cable trap assembly 100 of FIG. 2 corresponds to the radio frequency cable trap assembly 100 of FIG. 1. The only difference is that the radio frequency cable trap assembly 100 of FIG. 2 includes a battery unit 108 configured to provide energy for outputting an indication signal by an output unit 111 instead of an energy harvesting circuit. According to an alternative embodiment (not shown), the energy harvesting circuit 106 of the radio frequency cable trap assembly 100 of FIG. 1 may be combined with the battery unit 108 of the radio frequency cable trap assembly 100 of FIG. 2. In that case, energy may be provided by energy harvesting using the battery unit 108 and the energy harvesting circuit 106, for example, for outputting an indication signal by the output unit 111.

[0088] The output unit 111 may enter a sleep mode to conserve energy. The transmitted portion of the suppressed energy may control the passive switch 110. When the suppressed energy reaches a predetermined upper threshold, the resulting transmitted portion of the suppressed energy may be large enough to enable the passive switch, thereby activating the battery-powered output unit 111. Accordingly, an output mode of the indicator circuit 104 may be activated, which outputs an indicator signal using the battery-powered output unit 111, upon reaching the predetermined upper threshold by the suppressed energy in the radio frequency cable trap 102. A voltage exceeding a predetermined activation threshold supplied to a trigger pin of the output unit 111 may activate the unit and place it in an active mode. In the active mode, the output unit 111 may output an indicator signal with significantly higher power consumption than in the sleep mode. For example, a comparator may be configured in the indicator circuit 104 to compare a parameter describing the transmitted portion of the suppressed energy, e.g., a voltage, with a reference parameter, e.g., a reference voltage, describing the reaching of the predetermined upper threshold. The indication circuit 104 may be configured to activate the output mode of the output unit 111 when it determines, using the comparator, that the suppressed energy reaches a predetermined upper threshold.

[0089] Figure 3 shows another exemplary radio frequency cable trap assembly 100. The radio frequency cable trap assembly 100 of Figure 3 corresponds to the radio frequency cable trap assembly 100 of Figure 1. The radio frequency cable trap assembly 100 of Figure 3 further comprises a microcontroller unit 118 and one or more sensor circuits 120 for acquiring sensor data. The microcontroller may be configured, for example, to control the acquisition of the sensor data using the one or more sensor circuits 120 and to transmit the acquired sensor data via an instruction signal in the form of a wireless signal using the wireless signal transmitting circuit 116 of the output unit 111. The one or more sensor circuits 120 may be configured to obtain sensor data for, for example, one or more of the following parameters: temperature of the radio frequency cable trap assembly, i.e., temperature of the radio frequency cable trap circuit 102 and / or the indicator circuit 104; voltage of the radio frequency cable trap circuit 102 resulting from the suppressed energy; voltage of the indicator circuit 104 resulting from the transmission portion of the suppressed energy; current in the radio frequency cable trap circuit 102 resulting from the transmission portion of the suppressed energy; current in the indicator circuit 104 resulting from the transmission portion of the suppressed energy; magnetic field strength; environmental temperature; and environmental humidity.

[0090] Figure 4 shows another exemplary radio frequency cable trap assembly 100. The radio frequency cable trap assembly 100 of Figure 4 corresponds to the radio frequency cable trap assembly 100 of Figure 2. The radio frequency cable trap assembly 100 of Figure 4 further includes a microcontroller unit 118 and one or more sensor circuits 120 for acquiring sensor data. The microcontroller may be configured, for example, to control the acquisition of the sensor data using the one or more sensor circuits 120 and to transmit the acquired sensor data via an instruction signal in the form of a wireless signal using the wireless signal transmitting circuit 116 of the output unit 111. The one or more sensor circuits 120 may be configured to obtain sensor data for, for example, one or more of the following parameters: temperature of the radio frequency cable trap assembly, i.e., temperature of the radio frequency cable trap circuit 102 and / or the indicator circuit 104; voltage of the radio frequency cable trap circuit 102 resulting from the suppressed energy; voltage of the indicator circuit 104 resulting from the transmission portion of the suppressed energy; current in the radio frequency cable trap circuit 102 resulting from the transmission portion of the suppressed energy; current in the indicator circuit 104 resulting from the transmission portion of the suppressed energy; magnetic field strength; environmental temperature; and environmental humidity.

[0091] FIG. 5 illustrates an exemplary cable 200. The cable 200 includes or is provided with a radio frequency cable trap assembly 100. The radio frequency cable trap assembly 100 may be configured, for example, as any of the exemplary radio frequency cable trap assemblies 100 shown in FIGS. 1-4. The cable 200 may be, for example, a cable for a magnetic resonance imaging coil used in an MRI system. For example, the cable 200 may be a coaxial cable. The connection to the receive coil may include, for example, several coaxial cables, as well as wires for power and control (e.g., detuning) lines. These components of the connection to the receive coil may, but need not, have external shielding. For example, multiple traps may be placed along the cable depending on the frequency, i.e., a distance significantly less than half the free-space wavelength.

[0092] 6 shows an exemplary magnetic resonance imaging coil 302 provided with, i.e., connected to, the cable 200 of FIG. 5 with a radio frequency cable trap assembly 100. The magnetic resonance imaging coil 302 may be, for example, any receive coil of an MRI system, particularly a flexibly positioned surface receive coil.

[0093] FIG. 7 illustrates an exemplary magnetic resonance imaging system 300 having the magnetic resonance imaging coil 302 of FIG. 6 connected to the cable 200 having the radio frequency cable trap assembly 100. The magnetic resonance imaging device 300 may further include a receiver component 350 configured to receive an indication signal transmitted by an output unit of the indication circuit of the radio frequency cable trap assembly 100. The receiver component 350 may be, for example, a receiving radio frequency coil of the magnetic resonance imaging system 300 configured to receive MR signals within the MR bandwidth. The receiver component 350 may be, for example, a dedicated receiver configured to receive an indication signal transmitted in the form of an RFID signal. The receiver component 350 may be, for example, a remote router configured to receive an indication signal transmitted in the form of a wireless signal, e.g., via Wi-Fi, Bluetooth (LE), or any other power-efficient wireless communication scheme. The remote router may be configured to forward the indication signal to, for example, a controller of the magnetic resonance imaging device 300 or a remote server. For example, the remote server may forward the indication signal to the controller of the magnetic resonance imaging device 300.

[0094] FIG. 8 illustrates an exemplary radio frequency cable trap assembly 100 for a cable 200 including a radio frequency cable trap circuit 102 and an indicator circuit 104. The cable is represented at the bottom with a path through L1, which forms a coil inductor connected in parallel to C1. The voltage supply represents excitation via a transmit coil in an MRI system. The radio frequency cable trap circuit 102 includes an inductance L1, e.g., in the form of a loop, a capacitor C1, and a resistor R1, which inductively couples to a pickup loop L2 of the indicator circuit 104 via the local magnetic field. In the example of FIG. 8, the following values ​​are used for illustrative purposes: R1 = 0.1 Ω, R2 = 1 kΩ, R3 = 50 Ω, C1 = 61.85 pF, C2 = 100 nF, L1 = 100 nH, L2 = 100 nH, and k = 0.01 (coupling between L1 and L2). Graph A of FIG. 9 shows the suppression of AC current in cable 200 measured by Pr1 at a frequency of 64 MHz, i.e., the Larmor frequency of 1.5 T. The frequency was varied from 54 MHz to 74 MHz. Graph B of FIG. 9 shows the power absorbed in the radio frequency cable trap circuit 102, P=0.5*R1*Pr2.I^2, where Pr2.I is the AC current measured by Pr2. A parameter sweep for different B1 amplitudes, i.e., different parameters for V1, is shown. For high absorbed power P, the voltage across harvesting coil L2, shown in graph C of FIG. 9, plotting the harvesting voltage Pr3.dV measured by Pr3, becomes large enough to power an energy harvesting unit to transmit data to, for example, an MRI system.

[0095] FIG. 10 shows an exemplary radio frequency cable trap assembly 100 for a cable 200 having a radio frequency cable trap circuit 102 and an indicator circuit 104. The voltage supply represents excitation via a transmit coil in an MRI system. In contrast to the inductive coupling between the radio frequency cable trap circuit 102 and the indicator circuit 104 of the radio frequency cable trap assembly 100 of FIG. 8, the radio frequency cable trap circuit 102 and the indicator circuit 104 of the radio frequency cable trap assembly 100 of FIG. 10 are inductively coupled via capacitors C3 and C4. Capacitive coupling may be implemented, for example, by lumped capacitors or by placing a lower capacitor C5 close to an upper capacitor C1 of the radio frequency cable trap circuit 102. Here, capacitor C1 has been slightly reduced because capacitive coupling slightly detunes the resonance. In the example of FIG. 10, for illustrative purposes, the following values ​​are used: R1 = 0.1 Ω, R2 = 1 kΩ, R3 = 50 Ω, C1 = 61.3 pF, C2 = 100 nF, C3 = 1 pF, C4 = 1 pF, C5 = 50 pF, and L1 = 100 nH. Graph A of FIG. 11 shows the suppression of AC current in cable 200 measured by Pr1 at a frequency of 64 MHz, i.e., the Larmor frequency of 1.5 T. The frequency was varied from 54 MHz to 74 MHz. Graph B of FIG. 11 shows the power absorbed by radio frequency cable trap circuit 102, P = 0.5 * R1 * Pr2.I^2, where Pr2.I is the AC current measured by Pr2. A parameter sweep for different B1 amplitudes, i.e., different parameters for V1, is shown. For high absorbed power P, the voltage across the harvesting coil L2 shown in graph C of Figure 11, which plots the harvesting voltage Pr3.dV measured by Pr3, becomes large enough to power the energy harvesting and unit to transmit data to, for example, an MRI system.

[0096] FIG. 12 illustrates an exemplary radio frequency cable trap assembly 100 having a battery unit 108. The radio frequency cable trap assembly 100 includes a radio frequency cable trap circuit 102 and an indicator circuit 104. The radio frequency cable trap assembly 100 is configured to transfer energy from the radio frequency cable trap circuit 102 to the indicator circuit 104 via an inductive energy transfer coupling. The indicator circuit 104 includes a passive switch 110 controlled by a portion of the suppressed energy transferred from the radio frequency cable trap circuit 102 to the indicator circuit 104 via the inductive energy transfer coupling. When the transferred energy is sufficient to enable the passive switch 110, the switch 110 activates an output mode of the indicator circuit 104 to output an indicator signal using an output unit 111. For example, the transferred energy may be sufficient to enable the passive switch when a predetermined upper threshold is reached. The output unit 111 may be powered by the battery unit 108. The output unit 111, which may have, for example, a microcontroller unit, is in a sleep mode with low power consumption, allowing the output unit 111 to remain passive for long periods of time, e.g., years. A voltage resulting from the transferred energy exceeding a predetermined wake-up threshold supplied to a trigger pin may wake up the output unit 111 and place it in an active, i.e., output, mode. Once in the output mode, the output unit 111 may output an instruction signal that consumes power provided by the battery unit 108. For example, energy harvesting and battery-powered operation may be combined; in normal operation, energy harvesting may be configured to recharge the battery unit, which may consume only a small amount of energy over time without any impact, i.e., backlash, on normal operation; then, when a threshold is reached, the switch 110 may trigger the required action, powered from the charged battery unit.

[0097] The indication signal may be output by the battery-powered output unit 111 in the form of, for example, a visual signal, an acoustic signal, and / or a wireless signal. To output the indication signal, the output unit 111 may include, for example, one or more of a visual signal emitting circuit configured to emit a visual signal, an acoustic signal emitting circuit configured to emit an acoustic signal, and a wireless signal transmitting circuit configured to transmit a wireless signal. The visual signal emitting circuit may include, for example, one or more LEDs. The acoustic signal emitting circuit may include, for example, a buzzer or a loudspeaker. The wireless signal transmitting circuit may include, for example, a radio frequency transmitter. The radio frequency transmitter may be configured to transmit a wireless signal in a radio frequency band receivable by, for example, a receiver component of an MRI system configured to receive the MR radio frequency signal. The radio frequency transmitter may be, for example, a crystal oscillator. The radio frequency transmitter may be configured, for example, as an RFID chip. The RFID chip may be configured to transmit a radio frequency signal receivable by a dedicated receiver. The radio frequency transmitter may be configured to transmit, for example, a WIFI or Bluetooth (LE) signal that can be received by a remote router addressed by the transmitted signal.

[0098] FIG. 13 illustrates another exemplary radio frequency cable trap assembly 100 having a battery unit 108. The radio frequency cable trap assembly 100 includes a radio frequency cable trap circuit 102 and an indicator circuit 104. The radio frequency cable trap assembly 100 is configured to transfer energy from the radio frequency cable trap circuit 102 to the indicator circuit 104 via a capacitive energy transfer coupling. The indicator circuit 104 includes a passive switch 110 controlled by a portion of the suppressed energy transferred from the radio frequency cable trap circuit 102 to the indicator circuit 104 via the capacitive energy transfer coupling. When the transferred energy is large enough to enable the passive switch 110, the switch 110 activates an output mode of the indicator circuit 104 to output an indicator signal using an output unit 111. For example, the transferred energy may be large enough to enable the passive switch when it reaches a predetermined upper threshold. The output unit 111 may be powered by the battery unit 108. The output unit 111, which may comprise, for example, a microcontroller unit, is in a sleep mode with low power consumption, allowing the output unit 111 to remain passive for long periods of time, e.g., years. A voltage resulting from the transferred energy exceeding a predetermined activation threshold supplied to a trigger pin may activate the output unit 111 and place it in an active, i.e., output, mode. When placed in the output mode, the output unit 111 may output an instruction signal that consumes power supplied by the battery unit 108.

[0099] The indication signal may be output by the battery-powered output unit 111 in the form of, for example, a visual signal, an acoustic signal, and / or a wireless signal. To output the indication signal, the output unit 111 may include, for example, one or more of a visual signal emitting circuit configured to emit a visual signal, an acoustic signal emitting circuit configured to emit an acoustic signal, and a wireless signal transmitting circuit configured to transmit a wireless signal. The visual signal emitting circuit may include, for example, one or more LEDs. The acoustic signal emitting circuit may include, for example, a buzzer or a loudspeaker. The wireless signal transmitting circuit may include, for example, a radio frequency transmitter. The radio frequency transmitter may be configured to transmit a wireless signal in a radio frequency band receivable by, for example, a receiver component of an MRI system configured to receive the MR radio frequency signal. The radio frequency transmitter may be configured, for example, as an RFID chip. The RFID chip may be configured to transmit a radio frequency signal receivable by a dedicated receiver. The radio frequency transmitter may be configured to transmit a WIFI signal or a Bluetooth (LE) signal receivable by, for example, a remote router addressed by the transmitted signal.

[0100] 14 shows an example of a magnetic resonance imaging system 300 controlled by a computer 400. The magnetic resonance imaging system 300 comprises a magnet 304. The magnet 304 is a cylindrical superconducting magnet having a bore 306 therethrough. Different types of magnets can be used, for example both segmented cylindrical magnets and so-called open magnets.

[0101] Within the bore 306 of the cylindrical magnet 304 is an imaging zone 308 where the magnetic field is sufficiently strong and uniform to perform magnetic resonance imaging. A region of interest 309 is shown within the imaging zone 308. Acquired magnetic resonance data is typically acquired about the region of interest 309. A subject 318 is shown supported by a subject support 320 such that at least a portion of the subject 318 is within the imaging zone 308 and the region of interest 309.

[0102] Also present within the magnet bore 306 is a set of magnetic field gradient coils 310, which are used to acquire preliminary magnetic resonance data for spatially encoding magnetic spins within the imaging zone 308 of the magnet 304. The magnetic field gradient coils 310 are connected to a magnetic field gradient coil power supply 312. The magnetic field gradient coils 310 are intended to be exemplary. Typically, the magnetic field gradient coils 310 include three separate coil sets for spatial encoding in three orthogonal spatial directions. The magnetic field gradient power supply 312 supplies current to the magnetic field gradient coils 310. The current supplied to the magnetic field gradient coils 310 is controlled as a function of time and may be ramped or pulsed.

[0103] Adjacent to the imaging zone 308 is a radio frequency coil 314 for manipulating the orientation of magnetic spins within the imaging zone 308 and receiving radio frequency transmissions from the spins within the imaging zone 308. The radio frequency coil 314 may include multiple coil elements. The radio frequency coil 314 may also be referred to as an antenna. The radio frequency coil 314 is connected to a radio frequency transceiver 316, for example, via a cable 200. The cable 200 may include, for example, a radio frequency cable trap assembly 100 having a radio frequency cable trap circuit and an indicator circuit. The radio frequency coil 314 and radio frequency transceiver 316 may be replaced, for example, with separate transmit and receiver coils and separate transmitters and receivers. Alternatively, one or more receiver coils connected to a radio frequency receiver, for example, via a cable, may be configured by the magnetic resonance imaging system 300 in addition to the radio frequency coil 314 and transceiver 316 shown. The radio frequency coil 314 and radio frequency transceiver 316 are understood to be representative. The radio frequency coil 314 is also intended to represent a dedicated transmit antenna and a dedicated receive antenna. Similarly, the transceiver 316 may represent separate transmitters and receivers. The radio frequency coil 314 may have multiple receive / transmit elements, and the radio frequency transceiver 316 may have multiple receive / transmit channels. For example, if a parallel imaging technique such as SENSE is implemented, the radio frequency coil 314 will have multiple coil elements.

[0104] The instruction signal output by the radio frequency cable trap assembly may be output as a radio signal at a radio frequency within the MR bandwidth to be received by, for example, the radio frequency coil 314 of the magnetic resonance imaging system 300, e.g., another receiving coil. For example, the magnetic resonance imaging system 300 may have a dedicated receiver 350 configured to receive the instruction signal transmitted in the form of an RFID signal. The dedicated receiver 350 may be located, for example, on the subject support 320, in the bore 306, or elsewhere within the RF shielded room. For example, the receiver may be provided in the form of a remote router configured to receive the instruction signal transmitted in the form of a radio signal, e.g., via Wi-Fi, Bluetooth (LE), or any other power-efficient wireless communication scheme. The remote router may be configured to forward the instruction signal, for example, to a computer 400 controlling the magnetic resonance imaging system 300 or a remote server. For example, the remote server may forward the instruction signal to the computer 400 of the magnetic resonance imaging device 300.

[0105] The transceiver 316 and gradient controller 312 are shown as connected to a hardware interface 406 of the computer 400 .

[0106] The computer 400 is intended to represent one or more calculation or computing devices. The computer 400 is configured to acquire medical imaging data as part of the control system of the magnetic resonance imaging system 300. The computer 400 is shown as having a calculation system 404. The calculation system 404 is intended to represent one or more processors, processing cores, or other calculation systems located in one or more locations. The calculation system 404 is shown as connected to an optional hardware interface 406, a user interface 408, and a memory 410. The hardware interface 406 may enable the calculation system 404 to exchange commands and data with other components, if present.

[0107] The optional hardware interface 406 may, for example, allow the computing system 404 to control other components, such as the magnetic resonance imaging system 300. The computing system 404 is further shown as connected to an optional user interface 408, for example, allowing an operator to control and operate the computer 400 and, via the computer 400, the magnetic resonance imaging system 300. The optional user interface 408 may, for example, have output and / or input devices that allow a user to interact with the computer 400. The output device may, for example, include a display device configured to display magnetic resonance imaging and / or instruction data 428 constituted by instruction signals received from an output unit of the radio frequency cable trap assembly 100. The input device may, for example, include a keyboard and / or a mouse that allow a user to control the computer 400 and, via the computer 400, to input control commands for controlling the magnetic resonance imaging system 300. The computing system 404 is further shown as connected to a memory 410. The memory 410 is intended to represent different types of memory that may be connected to the computing system 404 and may, for example, be a non-transitory storage medium.

[0108] The memory is shown as including machine-executable instructions 420. The machine-executable instructions 420 enable the computing system 404 to perform tasks such as controlling other components to perform numerical tasks and performing various data and image processing tasks. The machine-executable instructions 420 may, for example, enable the computing system 404 to control the magnetic resonance imaging system 300. For example, the machine-executable instructions 420 may be configured to stop an MRI scan performed by the magnetic resonance imaging device 300 in response to receiving an instruction signal 428 from an output unit of the radio frequency cable trap assembly 100.

[0109] The memory 410 is further shown as including pulse sequence commands 422. The pulse sequence commands 422 are commands or data that can be converted into commands configured to control the magnetic resonance imaging system 300 to acquire magnetic resonance imaging data 424 from the region of interest 309. The acquired magnetic resonance imaging data 424 is used to reconstruct a magnetic resonance image 426.

[0110] The memory 410 is further shown as including indication data 428 provided by the received indication signal and indicative of the reaching of a predetermined upper threshold by the suppressed energy in the radio frequency cable trap assembly 100. The indication data 428 may be processed and / or stored by the computer 400. The indication signal may be received from an output unit of the radio frequency cable trap assembly 100. Upon receiving the indication signal, the indication data 428 conveyed by the indication signal may be processed by the computing system 404, which may, for example, automatically stop an MRI scan performed by the magnetic resonance imaging system 300 upon receiving the indication data 428. The indication data 428 provided by the received indication signal may include additional information, such as, for example, sensor data acquired by a sensor of the radio frequency cable trap assembly 100.

[0111] FIG. 15 illustrates another example of a magnetic resonance imaging system 300. The magnetic resonance imaging system 300 of FIG. 15 corresponds to the magnetic resonance imaging system 300 of FIG. 14, except that the radio frequency coil and transceiver are replaced with separate transmit coils 311 and receive coils 317, as well as separate transmitters 313 and receivers 317. The array of receive coils 317 is connected to a receiver 315, for example, via a cable 200. The cable 200 may include one or more radio frequency cable trap assemblies 100, for example, including a radio frequency cable trap circuit and an indicator circuit. Such traps 100 may be particularly useful in capturing the B1 field from the transmit coil 311, i.e., within the bore 306. A first trap may also be located, for example, inside the receive coil 317. The coil 317 may be configured for, for example, a locally flexible placement. For example, the receive coil 317 may be located near or directly on the subject 318. Similar to the receive coil 317, the transmit coil 311 may include multiple coil elements and may be implemented, for example, in the form of a coil array. The receiver 315 and transmitter 313 are shown as connected to a hardware interface 406 of the computer 400.

[0112] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments.

[0113] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. A computer program can be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems. Any reference signs in the claims should not be construed as limiting the scope. [Explanation of symbols]

[0114] 100 Radio Frequency Cable Trap Assembly 102 Radio Frequency Cable Trap Circuit 104 Indication circuit 106 Energy Harvesting Circuit 108 Battery Unit 110 Switch 111 Output Unit 112 Visual signal transmission circuit 114 Acoustic signal transmission circuit 116 Radio signal transmitting circuit 118 Microcontroller Unit 120 Sensor Circuit 200 Cable 300 Magnetic Resonance Imaging System 302 Coil 304 Magnet 306 Magnet Bore 308 Imaging Zone 309 Areas of Interest 310 Magnetic Gradient Coil 311 Radio Frequency Transmitting Coil 312 Magnetic field gradient coil power supply 313 Transmitter 314 Radio Frequency Coil 315 Receiver 316 Transmitter / Receiver 317 Radio Frequency Receiving Coil 318 subjects 320 Target Support 350 Receiver Components 400 computers 404 Computing Systems 406 Optional Hardware Interface 408 Optional User Interface 410 memory 420 machine-executable instructions 422 Pulse Sequence Commands 424 Magnetic Resonance Imaging Data 426 Magnetic Resonance Imaging 428 Instruction Data

Claims

1. a radio frequency cable trap configured to suppress induction of alternating current energy at a predetermined magnetic resonance imaging operating frequency in a cable for a magnetic resonance imaging coil; an indicating circuit having an output unit configured to output an indication signal in response to the reaching of a predetermined upper threshold by the suppressed energy using a portion of the suppressed energy transferred from the radio frequency cable trap circuit to the indicating circuit via an energy transfer coupling between the radio frequency cable trap circuit and the indicating circuit, the indicating circuit having an energy harvesting circuit configured to harvest a portion of the suppressed energy transferred via the energy transfer coupling, the indicating circuit being configured to use the harvested energy for outputting the indication signal; A radio frequency cable trap assembly comprising:

2. the indicator circuit comprises a passive switch controlled by the portion of the suppressed energy transferred via the energy transfer coupling and configured to activate an output mode of the indicator circuit to output the indicator signal when the suppressed energy reaches the predetermined upper threshold; or the indication circuit has a comparator configured to compare a parameter describing the portion of the suppressed energy transferred via the energy transfer coupling with a reference parameter describing reaching of the predetermined upper threshold, and the indication circuit is configured to activate the output mode when it determines using the comparator that the suppressed energy has reached the predetermined upper threshold.

10. The radio frequency cable trap assembly of claim 1.

3. the energy transfer coupling is an inductive coupling; or the energy transfer coupling is a capacitive coupling; 3. A radio frequency cable trap assembly according to claim 1 or 2.

4. 4. A radio frequency cable trap assembly according to claim 1, wherein the indicating circuit comprises a battery unit configured to provide energy for outputting the indicating signal.

5. 5. The radio frequency cable trap assembly according to claim 1, wherein the indication signal comprises a visual signal, and the output unit comprises a visual signal emitting circuit configured to emit the visual signal.

6. 6. The radio frequency cable trap assembly according to claim 1, wherein the indication signal comprises an acoustic signal, and the output unit comprises an acoustic signal emitting circuit configured to emit the acoustic signal.

7. 7. The radio frequency cable trap assembly according to claim 1, wherein the instruction signal comprises a radio signal, and the output unit comprises a radio signal transmitting circuit configured to transmit the radio signal.

8. the indicating circuitry is configured to transmit the radio signal in a radio frequency band that at least partially overlaps a predetermined magnetic resonance imaging operating frequency band that includes the predetermined magnetic resonance imaging operating frequency; or the indicating circuitry is configured to transmit the wireless signal in a radio frequency band outside the predetermined magnetic resonance imaging operating frequency band.

9. The radio frequency cable trap assembly of claim 8.

9. 10. The radio frequency cable trap assembly according to claim 8, wherein the indicating circuit comprises one or more sensor circuits for acquiring sensor data, and a microcontroller for controlling the acquisition of the sensor data and the transmission of the acquired sensor data by the radio signal.

10. The one or more sensor circuits measure the following parameters: - the temperature of said radio frequency cable trap assembly; - a voltage in the radio frequency cable trap circuit resulting from the suppressed energy; - a voltage in the indicator circuit resulting from the transmitted portion of the suppressed energy; - a current in the radio frequency cable trap circuit resulting from the suppressed energy; - a current in the indicator circuit resulting from the transmitted portion of the inhibited energy; - magnetic field strength, - environmental temperature, - environmental humidity, 10. The radio frequency cable trap assembly of claim 9, configured to acquire sensor data for one or more of:

11. 11. The radio frequency cable trap assembly of claim 7, wherein the transmitted radio signal includes an ID of the radio frequency cable trap assembly that identifies the radio frequency cable trap assembly transmitting the radio frequency signal.

12. A cable for a magnetic resonance imaging coil comprising a radio frequency cable trap assembly according to any one of claims 1 to 10.

13. A magnetic resonance imaging coil comprising the cable of claim 12.

14. A magnetic resonance imaging system comprising a magnetic resonance imaging coil according to claim 13.

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