Wireless physiological gating via reflectometer and secondary device

Abstract

The invention relates to wireless physiological gating via a reflectometer and a secondary device. Data (e.g., an electrocardiogram (ECG) waveform (902)) from a secondary device (200) (e.g., an ECG device (610)) is wirelessly transmitted to a primary device (e.g., an MRI machine), where an antenna (602) of the primary device is configured to wirelessly receive an analog physiological signal of interest (826) from the secondary device (200), where the antenna (602) of the primary device is coupled in a near field with a resonant antenna (812) of the secondary device (200), and where the resonant antenna (812) of the secondary device (200) is coupled in a near field with the resonant antenna (812) of the secondary device (200). And the secondary device (200) comprises circuitry (818) to vary the impedance of the resonant antenna of the secondary device or to vary the tuning of the resonant antenna of the secondary device in order to affect the electromagnetic environment and tuning of the antenna of the primary device, a change in the electromagnetic environment (822) is detected by the primary device and corresponds to an analog physiological signal of interest (826) from the secondary device (200).

Description

Technical Field

[0001] The present disclosure relates to wirelessly transmitting analog physiological data from a secondary device to a primary device, and more particularly to wirelessly transmitting data, such as electrocardiogram (ECG) waveform data, from a secondary device to a magnetic resonance imaging (MRI). Background Art

[0002] Magnetic resonance imaging (MRI) can be used to obtain internal physiological information of a patient, including for cardiac imaging and imaging other tissues within the patient's body. In certain areas, such as portions of the torso, it is often desirable to obtain images at specific points in a variable cycle (e.g., the respiratory cycle and / or the cardiac cycle), such as a peak of the variable cycle, to analyze the behavior during the peak. Physiological gating is an option for characterizing different properties of the organ being imaged.

[0003] Common gating techniques include cardiac gating, respiratory gating, and peripheral pulse gating, and their use in many medical applications spans diagnostic modalities such as CT, MRI, X-ray, ultrasound, and positron emission tomography (PET). For example, respiratory gating and cardiac gating are important for cardiac imaging, while imaging modalities such as CT and MRI are used to minimize motion-related artifacts caused by the patient's breathing and the motion caused by the patient's heartbeat.

[0004] Therefore, respiratory gating and / or cardiac gating are commonly used for MRI data acquisition, which relies on the detection of a specific point in the motion cycle as a trigger to repeatedly acquire data at approximately the same stage of the motion cycle. Sensor systems are used to sense respiratory activity and cardiac potentials. Respiratory monitors using bellows sensors are commonly used to detect respiratory waveforms, which use a belt and bellows including a pressure sensor to detect chest expansion. Electrocardiogram (ECG) devices with electrodes attached to the patient are commonly used to monitor the cardiac cycle. However, such monitoring methods generally require wired / cabled electrical connection to the MRI machine and extend the time for patient preparation and scanning system setup. Summary of the invention

[0005] In one embodiment, a method for wireless physiological gating in a magnetic resonance imaging (MRI) machine includes wirelessly receiving a simulated physiological signal of interest from a secondary device and a primary device, the primary device including an antenna of the MRI machine coupled in a near field to a resonant antenna of the secondary device, and the secondary device having a circuit system configured to change the impedance of the resonant antenna of the secondary device or otherwise change the tuning of the resonant antenna of the secondary device so as to affect the electromagnetic environment or tuning of the antenna of the MRI machine, the change in the electromagnetic environment being detected by the primary device and corresponding to the simulated physiological signal of interest from the secondary device.

[0006] In one embodiment, a system configured to wirelessly transmit data from a secondary device to a primary device includes a circuit system and an antenna / primary coil of a primary device configured to wirelessly receive a simulated physiological signal of interest from the secondary device, the antenna of the primary device coupled to a resonant antenna of the secondary device in a near field, and the secondary device having a circuit system configured to change the impedance of the resonant antenna of the secondary device or otherwise change the tuning of the resonant antenna of the secondary device so as to affect the electromagnetic environment or tuning of the antenna of the primary device, the changes in the electromagnetic environment being detected by the circuit system within the primary device and corresponding to the simulated physiological signal of interest from the secondary device.

[0007] In one embodiment, a system for wirelessly transmitting data from an electrocardiogram (ECG) device to a magnetic resonance imaging (MRI) machine includes a circuit system and an antenna / primary coil of the MRI machine configured to wirelessly receive a simulated physiological signal of interest from the ECG device, the antenna of the MRI machine is coupled to a resonant antenna of the ECG device in a near field, and the ECG device has a circuit system configured to change the impedance of the resonant antenna of the ECG device or otherwise change the tuning of the resonant antenna of the ECG device so as to affect the electromagnetic environment or tuning of the antenna of the MRI machine, the changes in the electromagnetic environment are detected by the circuit system within the MRI machine and correspond to the simulated physiological signal of interest from the ECG device, wherein the MRI machine includes the circuit system and one or more antennas, and the circuit system and one or more antennas are configured to detect the electromagnetic environment and measure changes in the electromagnetic environment corresponding to the simulated physiological signal of interest from the ECG device. In one aspect, the simulated physiological signal of interest includes an electrical QRS signal or an electrocardiogram (ECG) waveform, and the ECG device includes electrode connections to the patient and a resonant circuit configured to directly modulate the impedance of a resonant antenna of a secondary device or otherwise directly modulate the tuning of a resonant antenna of the secondary device to correlate with the ECG waveform. In another aspect, the ECG device is not electrically interconnected with the MRI machine and is configured such that the simulated physiological signal of interest from the ECG device can be wirelessly data transmitted to the MRI machine using a radio frequency (RF) transmitter without the ECG device.

[0008] It should be understood that the above brief description is provided to introduce in a simplified form selected concepts that are further described in the detailed description. It is not meant to identify key features or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present disclosure is described with reference to the schematic diagrams, depictions, circuit diagrams, exemplary signal and reflection coefficient shapes and graphs, and illustrations in the following drawings.

[0010] Figure 1 is a schematic diagram of an exemplary magnetic resonance imaging (MRI) system with an MRI machine and secondary equipment according to an embodiment.

[0011] Figure 2 is an illustration of an exemplary work table of an MRI system / machine according to an embodiment.

[0012] Figure 3Depicted are exemplary primary coils / antennas and matching circuitry or sensors for an MRI system / machine according to an embodiment.

[0013] Figure 4 is a circuit diagram of an exemplary coupling circuit and matching circuitry for an MRI system / machine according to an embodiment.

[0014] Figure 5 According to the implementation plan Figure 4 Circuit diagram of an exemplary resonant antenna and resonant circuit modified to provide a variable impedance / variable antenna tuning element with a secondary device.

[0015] Figure 6 is a schematic diagram of a primary coil / antenna and reflector circuit within a primary device coupled to an exemplary secondary device in the near field, according to an embodiment.

[0016] Figure 7 is a circuit diagram of an exemplary resonant antenna and a resonant circuit of a secondary device according to an embodiment.

[0017] Fig. 8A is a schematic diagram of an MRI system having a self-resonant helical antenna or similar antenna and reflector circuitry of the MRI machine coupled in a near field to a resonant antenna and resonant circuitry of a secondary device in accordance with an embodiment.

[0018] Figure 8B is a schematic diagram of an MRI system according to an embodiment, the MRI system being configured to measure a transmission path between a transmit antenna and a receive antenna of an MRI machine, wherein a resonant antenna of a secondary device couples one or both of the transmit antenna and the receive antenna in a near field.

[0019] Fig. 9 Depicted are shapes of exemplary simulated physiological signals of interest, according to embodiments.

[0020] Fig.10 A graph depicting the variation of the reflection coefficient ( S11 ) of an exemplary primary coil / antenna and reflectometer circuit according to an embodiment. DETAILED DESCRIPTION

[0021] The present disclosure describes embodiments of wirelessly receiving simulated physiological signals from a secondary device via circuitry within an MRI machine, where the simulated physiological signals may include, for example, ECG signals that may be used for gating in the MRI machine.

[0022] The inventors of the present invention have recognized that it may be desirable to have a non-contact physiological gating method in order to avoid the patient preparation time and setup time required for patient contact-based methods, such as patient preparation such as attaching an air pressure bellows, a finger (pulse) sensor, or a wired ECG cable. Other technologies such as the non-contact respiration (NCR) technology described and taught in the inventor's U.S. Patent No. 11419516B2, which is incorporated herein by reference for all purposes, do not provide a true electrical ECG waveform with minimized trigger delay. Existing wireless ECG gating solutions can provide an electrical QRS signal, however such solutions (which utilize RF transmitters and communicate via Bluetooth or Wi-Fi) are expensive, bandwidth-limited (there are processing delays and data link delays), and have limited capabilities to handle gradient noise.

[0023] The aforementioned NCR technique (described in U.S. Pat. No. 11419516 B2, as incorporated by reference above) works in a unique manner, measuring impedance changes in the orifice due to respiratory motion or other physiological motion. However, the inventors of the present invention have discovered that a higher bandwidth technique can be achieved via the aforementioned NCR measurement system, which utilizes a secondary measurement method such as an ECG amplifier with electrode connections to the patient, wherein the ECG amplifier device, for example, modulates the resonant frequency of a near-field coupled resonant antenna integrated into an ECG amplifier box or patch. The secondary device is used to make direct physiological measurements, such as ECG. The resonant coil / antenna of the secondary device is coupled to a primary resonant coil (i.e., the primary coil / antenna within the MRI machine). And, the impedance of the secondary resonant coil (i.e., the resonant coil / antenna of the secondary device) is modulated with a physiological signal to affect the S11 reflection measurement results of the primary coil.

[0024] The inventors of the present invention also realized that it is extremely difficult to wirelessly detect physiological signals such as ECG with extremely high bandwidth and low power consumption in an MRI environment to achieve gating or synchronization of MRI scans to patient physiology, which requires abnormally high bandwidth to filter / compensate for MR interference such as RF pulses and changing gradients and requires immunity to high magnetic fields and RF fields while avoiding RF interference to the MRI scan.

[0025] Therefore, the inventors of the present invention have developed a method (and system thereof) for performing wireless physiological gating in a magnetic resonance imaging (MRI) machine as disclosed in the present invention, which includes wirelessly receiving an analog physiological signal of interest from a secondary device via a reflectometer circuit and antenna of the MRI machine, the antenna of the MRI machine being coupled to a resonant antenna of the secondary device in a near field, and the secondary device having a circuit system configured to change the impedance of the resonant antenna of the secondary device or otherwise change the tuning of the resonant antenna of the secondary device so as to affect the electromagnetic environment and tuning of the antenna of the MRI machine, the change in the tuning of the antenna of the MRI machine being detected by the reflectometer circuit within the MRI machine and corresponding to the analog physiological signal of interest from the secondary device.

[0026] The inventors of the present invention have determined that the technology disclosed in the present invention provides a real-time high fidelity and high bandwidth, low cost and low power consumption ECG, which will enable a high quality physiological gating signal that is not affected by interference from the MRI scanner. In contrast to wireless protocols such as Bluetooth or Wi-Fi, the technology disclosed in the present invention also achieves relatively low latency (via a directly modulated signal), thereby improving the temporal accuracy of gating and forming clearer MR images. In addition, existing wireless ECG devices transmit RF and therefore require regulatory approval, while with the technology disclosed in the present invention, wireless ECG devices do not transmit RF and therefore do not require regulatory approval. In addition, the technology disclosed in the present invention utilizes electrical modulation of the impedance of the resonant antenna of the secondary device (rather than mechanically changing the physical / structural shape of the antenna), does not require the use of discrete switches to change the impedance of the secondary coil (i.e., the resonant antenna of the secondary device), does not work by measuring phase, and utilizes near-field coupling (rather than RF backscattering).

[0027] The inventors of the present invention have recognized that known prior art or existing physiological gating systems for MRI do not use impedance modulation or near-field interaction as a way to obtain analog physiological signals from secondary devices, known MRI accessories do not utilize "non-contact" (e.g., NCR) devices to receive information or signals from other secondary devices, and known MRI accessories do not transmit data in any form other than digital modes or protocols such as Bluetooth or Wifi.

[0028] In view of the foregoing, the inventors of the present invention developed the technology disclosed in the present invention, which, in addition to the aforementioned advantages, can also cost much lower than existing solutions and achieve much higher bandwidth than existing products (making it possible to eliminate scanning interference artifacts and achieve more accurate triggering and gating).

[0029] As an overview, Figures 1 to 4An MRI system is described which includes an MRI machine of the NCR type MRI system cited above. Figure 5 A resonant antenna with a variable impedance element for use in a secondary device such as an ECG device or patch is illustrated, the resonant antenna including a modified NCR coupling circuit that is coupled to a Figure 3 to Figure 4 The NCR MRI machine primary coil / antenna and circuit system are coupled to the waveform generator and near field driver respectively to provide Fig. 9 and Fig.10 QRS ECG waveform and graph of the changes in S11. Figure 7 A circuit diagram of an exemplary resonant circuit of a secondary device having a variable reactance diode biased by a signal of interest to change the impedance of a resonant antenna of the secondary device or otherwise change the tuning of the resonant antenna of the secondary device is depicted. Figure 6 and Fig. 8A Near-field coupling between a primary coil and reflectometer circuitry within an MRI machine and a resonant loop or antenna of a secondary device (eg, an ECG device) is illustrated.

[0030] Now turning to the attached figure, Figure 1 is a schematic diagram of an exemplary magnetic resonance imaging (MRI) system 100 with an MRI machine and a secondary device 200 according to an embodiment. In addition to the secondary device 200, an MRI (or MR imaging) machine typically includes Figure 1 (and Figure 2 ) and are referred to hereinbelow (e.g., table 171, resonance assembly 140, computer system 120, MRI system controller 130, physiological acquisition controller (PAC) 155, gradient driver 1150, sensor / motion sensor / primary coil / antenna 11, operator workstation 110, etc.) Figure 5 The secondary device 200 is described in more detail in FIG. 8 .

[0031] The operation of the MRI system 100 is controlled by an operator workstation 110, which includes an input device 114, a control panel 116, and a display 118. The input device 114 may be a joystick, a keyboard, a mouse, a trackball, a touch-activated screen, voice control, or any similar or equivalent input device. The control panel 116 may include a keyboard, a touch-activated screen, voice control, buttons, a slider, or any similar or equivalent control device. The operator workstation 110 is coupled to and communicates with a computer system 120, which enables an operator to control the generation and viewing of images on the display 118. The computer system 120 includes a plurality of components that communicate with each other via electrical and / or data connections 122. The computer system connection 122 may be a direct wired connection, an optical fiber connection, a wireless communication link, or the like. Components of the computer system 120 include a central processing unit (CPU) 124, a memory 126, and an image processor 128, and the memory 126 may include a frame buffer for storing image data. In alternative embodiments, image processor 128 may be replaced by image processing functionality implemented in CPU 124. Computer system 120 may be connected to an archival media device, permanent or backup memory storage, or a network. Computer system 120 is coupled to and in communication with a separate MRI system controller 130.

[0032] The MRI system controller 130 includes a set of components that communicate with each other via electrical and / or data connections 132. The MRI system controller connection 132 can be a direct wired connection, an optical fiber connection, a wireless communication link, etc. The components of the MRI system controller 130 include a CPU 131, a pulse generator 133, a transceiver 135, a memory 137, and an array processor 139. The pulse generator 133 is coupled to and communicates with the operator workstation 110. In an alternative embodiment, the pulse generator 133 can be integrated into the resonance assembly 140 of the MRI system 100. The MRI system controller 130 is coupled to the operator workstation 110 and receives commands from the operator workstation 110 to indicate the MRI scan sequence to be performed during the MRI scan. The MRI system controller 130 is also coupled to and communicates with the gradient drive system 1150, which is coupled to the gradient coil assembly 142 to generate magnetic field gradients during the MRI scan.

[0033] The pulse generator 133 may also receive data from a physiological acquisition controller (PAC) 155, which receives signals from a plurality of different sensors connected to an object or patient 170 undergoing an MRI scan, including respiratory signals and / or cardiac signals (e.g., ECG signals). And finally, the pulse generator 133 is coupled to and in communication with a scan room interface system 145, which receives signals from various sensors associated with the state of the resonance assembly 140. The scan room interface system 145 is also coupled to and in communication with a patient positioning system 147, which sends and receives signals to control the movement of a table 171. The table 171 is controllable to move the patient into and out of the aperture 146 and to move the patient to a desired position within the aperture 146 for an MRI scan.

[0034] The MRI system controller 130 provides gradient waveforms to the gradient driver system 1150, which includes G X Amplifier, G Y Amplifier and G Z Amplifier, etc. G X Gradient amplifier, G Y Gradient amplifier and G Z The gradient amplifiers each excite a corresponding gradient coil in a gradient coil assembly 142 to generate magnetic field gradients for spatially encoding MR signals during an MRI scan. The gradient coil assembly 142 is included in a resonance assembly 140, which also includes a superconducting magnet having superconducting coils 144 that, when in operation, provide a uniform longitudinal magnetic field B through an aperture 146. 0 , or an open cylindrical imaging volume surrounded by the resonance assembly 140. The resonance assembly 140 also includes an RF body coil 148, which provides a transverse magnetic field B in operation. 1 , the transverse magnetic field is substantially perpendicular to B through the aperture 146 0 The resonance assembly 140 may also include an RF surface coil 149 for imaging different anatomical structures of a patient undergoing an MRI scan. The RF body coil 148 and the RF surface coil 149 may be configured to operate in a transmit and receive mode, a transmit mode, or a receive mode.

[0035] An object or patient 170 undergoing an MRI scan may be positioned within the aperture 146 of the resonance assembly 140. The transceiver 135 in the MRI system controller 130 generates RF excitation pulses which are amplified by an RF amplifier 162 and provided to the RF body coil 148 and the RF surface coil 149 via a transmit / receive switch (T / R switch) 164.

[0036] As described above, the RF body coil 148 and the RF surface coil 149 and / or one or more phased array (PA) coils 150 may be used to transmit RF excitation pulses and / or receive resulting MR signals from a patient undergoing an MRI scan. For example, the PA coil 150 may be located in a table below the patient 170, such as in a region below the patient's torso 170a. The resulting MR signals emitted by the excited nuclei in the patient undergoing an MRI scan may be sensed and received by the RF body coil 148, the RF surface coil 149, or the PA coil 150. Each of the coils 148, 149, and 150 typically includes a corresponding T / R switch, and each typically includes a T / R function and a preamplifier within the surface coil / PA coil itself. Therefore, a plurality of T / R switches, collectively referred to as T / R switches 164, are included in the system. Similarly, a plurality of preamplifiers, collectively referred to as preamplifiers 166, may be included. The amplified MR signals are demodulated, filtered, and digitized in the receiver portion of the transceiver 135. Appropriate T / R switches 164 are controlled by signals from the pulse generator 133 to electrically connect the amplifier 162 to the appropriate coil 148, 149, 150 during transmit mode and to connect the corresponding preamplifier 166 to the coil 148, 149, 150 during receive mode. The transceiver 135 digitizes the resulting MR signals sensed and received by the RF body coil 148 or the PA coil 150 and transmits them to a memory 137 in the MRI system controller 130.

[0037] An MR scan is complete when an array of raw k-space data corresponding to the received MR signals has been acquired and temporarily stored in memory 137 until the data is subsequently transformed to create an image. For each image to be reconstructed, the raw k-space data is rearranged into a separate array of k-space data, and each of these separate arrays of k-space data is input to an array processor 139 which operates to Fourier transform the data into an array of image data.

[0038] The array processor 139 uses known transform methods, most commonly Fourier transforms, to create images from the received MR signals. These images are transmitted to the computer system 120, where they are stored in the memory 126. In response to commands received from the operator workstation 110, the image data may be archived in a long-term storage device, or may be further processed by the image processor 128 and transmitted to the operator workstation 110 for presentation on the display 118. In various embodiments, components of the computer system 120 and the MRI system controller 130 may be implemented on the same computer system or multiple computer systems.

[0039] A sensor or motion sensor 11 (also referred to herein as the primary coil or antenna of the MRI machine) is integrated into the resonance assembly 140 to sense the patient's motion and / or detect the electromagnetic environment and measure changes in the reflection coefficient corresponding to the simulated physiological signal of interest from the secondary device 200. The detected motion information and / or the simulated physiological signal of interest (e.g., ECG or cardiac signal) can be used to control and optimize imaging, such as to assist MR image capture based on the detected periodic motion and / or otherwise improve image quality by avoiding image degradation due to patient motion and / or, for example, patient ECG. The sensor / motion sensor 11 generates a magnetic field through which the patient's motion and / or other physiological signals can be detected, as described below. The motion / physiological information is provided to a physiological acquisition controller (PAC) 155, which provides information about the patient's periodic and / or other motion to the pulse generator 133. For example, the PAC controller 155 can generate a respiratory signal and / or ECG signal formatted for triggering MR image data acquisition performed by the MRI system controller 130.

[0040] Figure 2 1 is an illustration of an exemplary workbench of an MRI system / machine according to an embodiment. A workbench 171 is shown, which schematically illustrates an exemplary sensor / motion sensor system 10 incorporated therein. The workbench 171 is outside the aperture 146 and can be moved into the aperture 146 for patient imaging. The workbench 171 has a top surface 171a for supporting a patient 170 to be imaged. In the depicted example, the workbench includes a PA coil 150 located below the top surface 171a. In the depicted example, two sensors / motion sensors 11a and 11b are located below the PA coil and are configured to sense the patient's motion and / or wirelessly receive physiological signals of interest (e.g., ECG signals) from a secondary device 200. In other embodiments, the sensors / motion sensors 11a, 11b may be positioned elsewhere in the system 140, such as directly below the top surface 171a or elsewhere relative to the patient, such as to the side or above the patient in the aperture 146.

[0041] The sensors / motion sensors 11a, 11b may each include a resonant coil 16a, 16b and a corresponding coupling loop 18a, 18b. Each coupling loop 18a, 18b is configured to generate a drive RF signal to excite the corresponding resonant coil 16a, 16b to radiate a magnetic field having a predefined resonant frequency. The coupling loop 18a, 18b is further configured to receive a reflected RF signal from the corresponding resonant coil 16a, 16b.

[0042] In other embodiments, different drive methods can be utilized, such as via a directly connected driver / receiver. In the case of a direct drive configuration, sensing of S11 will also be achieved through a direct drive connection. In one such embodiment, a self-resonant spiral (SRS) coil 36 may be composed of two spiral elements staggered 180 degrees rotated from each other. Each staggered spiral element has a center end and an outer end. A voltage source may be used to directly drive the end closest to the center of the coil 36 so as to excite the self-resonant spiral (SRS) coil to generate a magnetic field. Receiving RF signals and sensing S11 therefrom will also be accomplished through a direct connection. Therefore, in a direct drive embodiment, the coupling loop may be eliminated.

[0043] The sensors / motion sensors 11a, 11b may each be positioned so that a relevant portion of the patient 170 is within a region of a strong magnetic field relative to the sensors 11a, 11b. In the case where respiratory motion is detected by the motion sensors 11a, 11b, the sensors / motion sensors 11a, 11b may be positioned so that at least a portion of the torso 170a of the patient 170 is within a region of a sufficiently strong magnetic field so that the motion of the torso 170a due to breathing may be detected. The time-varying load of the magnetic field (H field) due to changes in absorption of the patient's tissue within the field may be measured and corresponds to the respiratory cycle.

[0044] In one embodiment, this change is detected by measuring the reflection coefficient (S11) of the RF source power emitted by the coupling loops 18a, 18b into the resonant coils 16a, 16b. The reflection coefficient S11 indicates how much power is reflected from the resonant coils 16a, 16b, which will be affected by changes in absorption caused by the patient's breathing. Therefore, a breathing signal can be determined based on the change in the reflection coefficient during the breathing cycle.

[0045] exist Figure 2In the embodiment at, two sensors / motion sensors 11a, 11b are included. In other embodiments, only one sensor / motion sensor 11 may be included, or more than two sensors / motion sensors 11 may be included. One or more sensors / motion sensors in the sensors / motion sensors 11a, 11b may be selected via switch 20. In the depicted example, only one sensor / motion sensor in the sensors / motion sensors 11a or 11b may be selected by connecting the corresponding coupling loops 18a, 18b to a controller (in this example, a PAC controller 155). Based on the direction of the patient to be imaged (i.e., whether the patient is positioned to move into the orifice 146 with the head first or the foot first), the appropriate sensor / motion sensor 11a or 11b is selected. In this example, the sensor / motion sensor 11a is positioned closer to the front end 172 (the end that enters the orifice first) of the workbench 171, and the sensor / motion sensor 11b is positioned closer to the rear end 173 (the end that enters the orifice later) of the workbench 171. If the patient is positioned head first, wherein the patient's head is at the front end 172 of the table 171, then the sensor / motion sensor 11a will be utilized. Specifically, the sensor / motion sensor 11a is positioned so that it is aligned with the patient's torso 170a when the patient is positioned head first toward the aperture 146. Alternatively, if the patient is positioned feet first toward the aperture 146, then the sensor / motion sensor 11b may be selected via the switch 20, which is positioned to align with the patient's torso 170a when the patient is in the feet first position.

[0046] In one example, selection of the appropriate sensor / motion sensor 11a or 11b by the switch 20 may be controlled based on whether the patient 170 to be imaged is positioned head first or feet first. The patient position is known, for example, by the MRI system controller 130, and is a parameter used for a number of control purposes within the MRI system 100. In one embodiment, actuation of the switch 20 to control selection of the sensor / motion sensor 11a or 11b may be performed by providing a predefined DC bias on the drive signal coaxial cable, wherein a different predefined DC bias is associated with each of the sensors / motion sensors 11a and 11b.

[0047] The sensors / motion sensors 11a and 11b may be connected to a controller 155, such as via a coaxial cable 22. The controller 155 may be a PAC controller 155 that includes a respiratory and / or physiological signal (e.g., ECG signal from the secondary device 200) detection subcontroller 24 that includes circuitry and software for filtering and digitizing analog reflectometer measurements provided by the sensors / motion sensors 11a, 11b and software for processing the digitized signals to generate respiratory and / or physiological signals that may be used to control MR image acquisition.

[0048] Likewise, if Figure 2 As shown, one or more passive coupling elements 26a, 26b may be included and positioned adjacent to the active coils 16a, 16b to increase the magnitude of the magnetic field along the Z-axis (which extends from the head to the feet along the length of the table 171 and relative to the patient). For example, the coupling element may be a passive SRS coil and therefore does not have a corresponding coupling loop, but rather is inductively coupled via the magnetic field radiated by the driven SRS coil 36.

[0049] Figure 3 Depicted are exemplary primary coils / antennas and matching circuitry or sensors for an MRI system / machine according to an embodiment. Figure 3 One embodiment is depicted in which the resonant coil 16 is a self-resonant spiral (SRS) coil 36. In other embodiments, the resonant coil 16 may be replaced by a circular coil or air coil positioned closer to the back of the patient 170. In one embodiment, the self-resonant spiral provides for greater H-field generation due to its multi-turn nature, where the tuning capacitance is dominated by the distributed capacitance between the turns of the spiral. For example, this allows the SRS coil 36 to be positioned farther away from the patient than other types of resonant coils, while still providing useful detection of the patient's loading with a magnetic field that is sensitive enough to provide good detection of the patient's breathing. The SRS coil 36 with multiple turns is driven at a frequency lower than the frequency of the proton scan or the Larmor frequency to produce a strong H-field with a large penetration depth into the scanner object that will not form an interference with MR imaging.

[0050] Figure 3One embodiment of an SRS coil 36 is depicted. The exemplary SRS coil 36 includes 13 turns between a first end 37 and a second end 38 of a conductor or wire comprising the coil. In this example, the circular coil is always spaced apart, with the spacing S being another parameter that affects the resonant frequency and H-field magnitude. In other examples, and depending on the application, different numbers of turns and / or different spacings may be utilized, and the spacing may vary depending on the shape of the SRS coil 36. For example, for an elliptical coil, the spacing will vary depending on the angle of rotation about the center of the coil and depending on the eccentricity of the ellipse. For example, the inventors have recognized that various numbers of turns, such as 10 to 15 turns, may be appropriate depending on the desired resonant frequency and the required H-field magnitude (e.g., which may depend on placement within a workbench). Figure 3 In the example at , the SRS coil 36 is elliptical. In other embodiments, different shapes may be used. For a given excitation current, an elliptical self-resonant spiral coil can generate a stronger magnetic field. In addition, the elliptical coil may have an additional advantage, that is, it can be installed in a narrow space, which may be beneficial for installing the sensor 11 in a crowded space on the workbench 171.

[0051] like Figure 3 As shown, the SRS coil 36 may be disposed on a layer / plate 30, which is illustrated transparently (illustrated in FIG. Figure 3 ) below (or behind) a layer / plate 40 including a coupling loop 18 and associated coupling circuitry 41. The coupling loop 18 is inductively coupled to an SRS coil 36 or other resonant coil 16. The coupling loop 18 is configured to generate a drive RF signal to excite the SRS coil to radiate a magnetic field at a predefined frequency. In one embodiment, it is desirable to use a 27 MHz SRS coil 36 because the SRS coil provides for large H-field generation due to its multi-turn nature, where the tuning capacitance is dominated by the distributed capacitance between the turns of the spiral. 27 MHz is beneficially within the Industrial, Scientific and Medical (ISM) band. In other embodiments, a different predefined resonant frequency may be utilized, which may be a different ISM band frequency. To provide an example, the predefined resonant frequency may be in the ISM band between 26.975 MHz and 27.283 MHz, or may be between 40.66 MHz and 40.7 MHz, or in yet other embodiments, may be between 13.553 MHz and 13.567 MHz. In other embodiments, the predetermined resonant frequency may be different and / or outside of those ISM frequency bands.In certain examples, it may be beneficial to utilize a predetermined resonant frequency that is lower than the proton scanning frequency.

[0052] The coupling loop 18 also receives a reflected RF signal from the SRS coil 36, so that breathing or other patient motion can be detected by measuring changes in the reflected RF signal due to changes in the load experienced by the patient against the RF H field. For example, when the patient breathes, the amount of power reflected by the SRS coil 36 will change. In one embodiment, a motion signal, such as a breathing signal, is determined based on the reflection coefficient S11 of the SRS coil 36. Figure 4 In the depicted embodiment, a dual-logarithmic power detection integrated circuit is used in conjunction with a directional coupler to measure the reflected power (i.e., reflected RF signal) delivered at 27 MHz divided by the forward power (i.e., driving RF signal). The reflection coefficient S11 can then be calculated according to the following formula:

[0053] S11 = log 10 (P refl )-log 10(P drv )

[0054] Figure 4 is a circuit diagram of an exemplary coupling circuit and matching circuitry for an MRI system / machine according to an embodiment. Figure 4 One embodiment of a coupling plate 40 for detecting patient motion based on changes in reflected RF signals is depicted, the coupling plate comprising a coupling loop and a coupling circuit 41. The coupling loop 18 may be, for example, a 3D-type RF circuit having a specified diameter d. cl To provide only one example, the diameter d of the coupling loop 18 is cl can be 50mm, and the gap between the ends of the coupling ring 18 is g cl It can be, for example, 5 mm. The coupling circuit 41 includes a blocking network 43 that blocks other resonant frequencies except the resonant frequency at 27 MHz or a predefined resonant frequency. It also includes a lattice balance-unbalance circuit 45 that converts the differential output of the loop into a single-ended coaxial feed line. The lattice balance-unbalance can effectively make the sensor assembly insensitive to frequency shift. It also includes a filtering circuit 47 such as a duplexer to filter the output reflectometer measurement signal before transmitting it to the controller 155. The resulting signal is provided to a socket 49 such as a coaxial connector.

[0055] Figure 5 According to the implementation plan Figure 4 1 is a circuit diagram of an exemplary resonant antenna and resonant circuit 500 modified to provide a variable impedance / variable antenna tuning element 506, 508 with a secondary device (such as for the secondary device 200 in the MRI system 100). Figure 5 The exemplary resonant antenna and resonant circuit 500 shown may include: Figure 3 and Figure 4 Shown and referenced Figure 3 and Figure 4 The resonant antenna or loop antenna 502 is depicted in which the lumped element balun components are removed and two BBY-40 variable reactance diodes 506, 508 (eg, Figure 5 As depicted, arranged cathode to cathode), a pair of 49.9 kOhm resistors 510, 512 are arranged to connect to a reverse bias waveform input 514 (e.g., which may include an SMA connector). As shown, an additional 100 pF capacitor may be added to set the process tuning. The resulting circuit system includes a resonant circuit with a variable impedance element and a resonant antenna, whereby a signal of interest (such as a simulated physiological signal, including, for example, a QRS signal or an ECG waveform) may be introduced at the input 514.

[0056] The inventors of the present invention have determined that by modulating the resonant antenna of the secondary device to effectively form a Figure 1 and Figure 2 The described prototype and demonstration of such characteristics of the MRI system with secondary equipment, reflectometry, near field coupling, and wireless reception of simulated physiological signals such as simulated ECG waveforms can be achieved using a modified NCR antenna assembly (i.e., a reference Figure 3 and Figure 4 The described NCR antenna assembly was modified to include Figure 5 The resonant antenna and resonant circuit shown) and the use of an arbitrary waveform generator with adjustable amplitude and offset to modulate the (secondary device) resonant coil / loop antenna 502 tuning are achieved. The waveform generator can be configured to provide, for example, a 3VDC bias + / -3V pk-pk analog signal of interest, including Fig. 9 Example QRS signal or ECG waveform.

[0057] The above test setup may include positioning the resonant coil / loop antenna 502 at a position similar to Figure 3 and Figure 4 Shown and referenced Figure 3 and Figure 4 The self-resonant coil 36 and reflectometer circuitry are described as being at a distance of 25 cm, so that the resonant antenna 502 is coupled in the near field to the self-resonant coil 36 (or the antenna of the primary device / MRI machine). The network analyzer can then be compared with the reference Figure 3 and Figure 4 The NCR antenna assembly described is connected to drive the reflectometer circuit system and measure the change in reflection coefficient S11, and then Fig.10 As illustrated, the change in the reflection coefficient S11 is shown as an S11 measurement result having, for example, a 0.2 dB pk-pk S11 change.

[0058] Using the above test setup, the inventors of the present invention have demonstrated that a reflectometer circuit and antenna (such as Figures 1 to 4 In an embodiment described herein, an antenna of an MRI machine (such as a secondary device 200) wirelessly receives an analog physiological signal of interest (e.g., a QRS signal or an ECG waveform) from a secondary device (such as secondary device 200). Figure 3 and Figure 4 The secondary device is coupled in the near field to a resonant antenna (such as a resonant antenna or loop antenna 502) of the secondary device, and the secondary device has a circuit system configured to (such as Figure 5 ) changes the impedance of the resonant antenna 502 of the secondary device 200 or otherwise changes the tuning of the resonant antenna of the secondary device to affect the electromagnetic environment and tuning of the antenna 16, 36 of the MRI machine, the changes in the tuning of the antenna of the MRI machine being detected by reflectometer circuitry within the MRI machine and correlated with simulated physiological signals of interest from the secondary device (such as Fig. 9 And, as described, Fig.10 A graph showing changes in the reflection coefficient ( S11 ) detected by a reflectometer circuit within an MRI machine, corresponding to an analog physical signal of interest (eg, a QRS signal or an ECG waveform) from the secondary device 200 .

[0059] Figure 6 is a schematic diagram of a system 600 according to an embodiment, the system including a primary device (such as a reference Figure 1 to Figure 2 154. The primary resonant coil 602 and reflector circuit 604 may be located within the MRI machine described herein. The primary resonant coil 602 may include, for example, a self-resonant spiral (SRS) antenna or similar antenna (e.g., SRS 36) and is driven by the reflector circuit 604 to emit (or radiate) a magnetic field 606 having a predefined resonant frequency (or tone). The resonant frequency may be, for example, between 26.957 MHz and 27.283 MHz. The reflector circuit 604 may be located within the MRI machine and configured to detect and process changes in the load of the magnetic field 606, either alone or in conjunction with a circuit system and / or controller (such as PAC 155). The operation of the reflector circuit 604 and the primary coil 602 may be substantially as described in reference to Figures 1 to 4 The MRI machine described.

[0060] The tuned secondary resonant coil or antenna 608 (of the ECG device or patch 610) affects the electromagnetic environment including the magnetic field 606. And because the primary coil or antenna 602 and the secondary coil or antenna 608 are coupled in the near field, the tuning of the secondary antenna 608 affects the tuning of the primary antenna 602. Changes in this tuning can be detected by the reflectometer circuit 604 as changes in S11 or changes in the reflection coefficient of the primary coil 602.

[0061] The ECG device 610 may include a preamplifier and / or ECG amplifier box from which electrodes extend to physically contact and connect to a patient, such as patient 170. The ECG device 610 may include a patch or flexible circuit having an adhesive or other connector for contacting and connecting to patient 170. The ECG device or patch 610 may include a pad that is specialized and manufactured as a disposable device with circuitry embedded therein. Figure 6 As shown, the ECD device or patch 610 may include circuitry or contact leads for receiving, for example, an ECG voltage, and circuitry configured to modulate the impedance or resonant frequency of the secondary coil 608 corresponding to the ECG voltage (which includes a simulated physiological signal of interest).

[0062] Figure 7 is a circuit diagram of a secondary circuit 700 of an exemplary resonant antenna and resonant circuit of a secondary device 200, 610 according to an embodiment. The secondary device may include, for example, a secondary circuit 700 including a resonant tank or antenna (or secondary coil) 702, a tuned LC circuit including an inductor 704 and a capacitor 706 element / component, and a variable impedance element 708 such as a variable reactance diode, which are connected in parallel with each other as shown and connected to a bias or reference signal (e.g., bias voltage) 714 via inductors 710 and 712. In operation, changes in the bias voltage 714 cause corresponding changes in the variable impedance element 708, which changes the impedance of the resonant tank / antenna (secondary device antenna) 702. Other configurations of the circuit system can be used to modulate the impedance of the secondary device antenna / resonant antenna 702.

[0063] for Figure 7 In the secondary circuit 700 shown, the tuning of the secondary antenna is changed by a variable impedance element, which is controlled by a signal of interest (e.g., bias voltage) 714. In one embodiment, the signal of interest is applied as a bias signal to a variable reactance diode 708, which changes the capacitance of the secondary circuit 700. This change in capacitance changes the tuning of the secondary coil 702 and changes the tuning of the primary coil (e.g., primary coil 602) through coupling and near-field interaction.

[0064] Fig. 8A 8 is a schematic diagram of an MRI system 800 having a self-resonant helical antenna or similar antenna 808 and a reflectometer circuit 806 of an MRI machine coupled in a near field to a resonant antenna 812 and a resonant circuit 818 of a secondary device 824, according to an embodiment. Fig. 8A As shown, the schematic functional blocks positioned / arranged on the left side of the radiated magnetic field 820 may be located or may reside within a primary device or an MRI machine, and the schematic functional blocks positioned / arranged on the right side of the radiated magnetic field 820 may be located or may reside within a secondary device or an ECG device.

[0065] In various embodiments, the secondary device 824 is separate from the primary device and the secondary device is not electrically interconnected with the primary device and / or the secondary device does not require any wired electrical interconnection with the primary device so that the physiological signal of interest 826 can be data transmitted from the secondary device to the primary device and / or the secondary device does not require the use of any radio frequency (RF) or other type of transmission or radiation transmitter.

[0066] In one embodiment, the primary device includes an interface for inputting and / or changing the system configuration 802. One such input may be a selection of a predetermined resonant frequency at which the primary coil or antenna of the primary device is driven or excited to radiate (transmit) a magnetic field 820. In the event that the predetermined resonant frequency (or frequency tone) is selected, a circuit system 804 for generating a tone (e.g., a phase-locked loop (PLL) or other circuit system) generates a constant frequency tone. Next, a reflectometer circuit 806 of the primary device drives the primary coil or antenna of the primary device (e.g., a self-resonant spiral (SRS) antenna or similar antenna 808) to excite the primary coil (e.g., an SRS coil) to radiate a magnetic field 820 having a predefined resonant frequency. The primary coil is excited so that the resonant coil / resonant primary antenna 808 transmits an incident wave. In one embodiment, the reflectometer circuit 806 measures the incident waveform and the reflected waveform, providing an S11 measurement result. In one embodiment, reflectometer circuit 806 compares the incident power to the reflected power, for example using a logarithmic power ratio detector to detect and measure the ratio of the incident power to the reflected power.

[0067] The secondary resonant antenna 812 is coupled to the primary antenna 808 by near-field coupling. Therefore, the impedance and resonant frequency of the primary antenna 808 depend on the tuning of the secondary antenna 812. In one embodiment, the secondary resonant antenna 812 has a device for modulating its impedance / tuning / resonant frequency. For example, a variable reactance diode or a varactor diode can be used to provide a variable capacitance controlled by a reverse bias voltage. The reverse bias can be driven to be related to a physiological signal 826 of interest such as an ECG signal. As the varactor changes capacitance, the impedance of the coupled system also changes. This effectively "transmits" real-time ECG data from the secondary device 824 (e.g., by modulating impedance, affecting the electromagnetic environment 822) to the primary device. In one embodiment, real-time ECG data is effectively "transmitted" from the secondary device to the primary device and the ADC 810 that measures the ratio of incident power to reflected power or the S11 reflection coefficient.

[0068] In one embodiment, Fig. 8A The illustrated exemplary secondary device 824 (e.g., an ECG device) is configured to: generate a simulated physiological signal of interest 826 (e.g., an ECG) via the secondary device's electrode connections or other connections to a patient (e.g., patient 170) and a resonant circuit 818, the resonant circuit being configured to directly modulate the impedance of the secondary device's resonant antenna 812 or otherwise modulate the tuning of the secondary device's resonant antenna to correlate with the simulated physiological signal of interest; and to modulate the impedance of the secondary device's resonant antenna 812 or otherwise modulate the tuning of the secondary device's resonant antenna to correlate with the simulated physiological signal of interest and to modulate the primary device (e.g., including, e.g., Figures 1 to 4 The electromagnetic environment and tuning of the SRS antenna or similar antenna of the primary equipment of the MRI machine described above are affected.

[0069] Power for the secondary device may be provided by a battery, other power delivery means such as photovoltaic / solar, MRI RF / gradient power harvesting, and / or by power harvested from the NCR primary coil. As previously described, the secondary device may include a package for a conventional wireless ECG used in conventional MR, such as a box with a battery and ports for connecting to ECG leads and other transducers or measurement sensors. Alternatively, the package may be a package with one or more wireless ECG "patches" integrated with flexible circuits capable of attaching to a patient's electrodes or sensors.

[0070] Furthermore, while the secondary device 200 is primarily described herein in the context of an ECG device, the present disclosure includes aspects applicable to other systems, other modalities, or in other situations. For example, the simulated physiological signal of interest may include a squeeze ball that may be triggered / squeezed by the patient 170 in order to gain the attention of, for example, an MRI system operator. Such a squeeze ball application may involve, for example, a resonant circuit 818 that is configured to change the impedance of a (secondary device) resonant antenna or otherwise change the tuning of a (secondary device) resonant antenna to a particular impedance change frequency and / or waveform and / or pattern.

[0071] Furthermore, in other embodiments, different modulation methods may be used, or different methods of how to detect the modulated signal may be used. For example, while the MRI system 100 previously described and described may utilize S11 or reflection coefficient measurements, different detection methods may be used (via circuitry within the MRI machine), such as S21 transmission coefficients, measuring transmission paths, power consumption, detecting resonant frequencies, or sensing transmitter current or voltage.

[0072] Figure 8B 850 is a schematic diagram of an MRI system 850 configured to measure a transmission path between a transmit antenna 852 of a primary device (e.g., an MRI machine) and a receive antenna 854 of the primary device, wherein a secondary device 824 may be (near field) coupled to the transmit antenna 852 or the receive antenna 854 (of the primary measurement system), or to both the transmit antenna 852 and the receive antenna 854. In one embodiment, (as described in reference to Fig. 8A Real-time physiological signal data of interest (e.g., ECG data) is effectively "transmitted" from the secondary device 824 to the primary device and the ADC 810 that measures the transmission path or S21 transmission coefficient. In various embodiments, Figure 8B The system configuration 802, tone generation 804, radiated magnetic field 820, modulated impedance / affected EM environment 822, and other exemplary functional blocks are shown in the same manner and function as in reference Fig. 8A In one embodiment, the receive antenna 854 may be specifically designed to detect the modulated EM environment. In another embodiment, the receive antenna 854 may include an existing MR coil of an MRI machine used for imaging.

[0073] and Fig. 8A Depicting the use of a reflectometer to detect an electromagnetic (EM) environment (illustrating one embodiment of using a reflectometer to detect an EM environment and modulating the EM environment by this secondary device), Figure 8BDepicted, for example, using separate transmit antenna 852 (of the primary device) and receive antenna 854 to probe the EM environment (which is still modulated by the secondary device 824) to measure the transmission path. In other embodiments, other methods of probing the EM environment or probing the secondary device 824 may be used.

[0074] Fig. 9 A waveform generator display 900 is depicted showing a shape 902 of an exemplary simulated physiological signal of interest according to an embodiment. The shape 902 comprises a QRS signal or an ECG waveform and is generated as an arbitrary analog waveform for input into a resonant circuit of a secondary device, such as the exemplary resonant antenna and resonant circuit 500 at the waveform input 514. As shown, the exemplary settings 904 include: sampling rate (450 samples / second), amplitude (3Vpp), offset (3.5V), samples (450), arbitrary waveform name (Cardiac.arb).

[0075] Fig.10 A network analyzer display 1000 is depicted showing a graph 1002 of changes in the reflection coefficient (S11) of an exemplary primary coil / antenna and reflectometer circuit, according to an embodiment. The vertical axis of the graph 1002 is S11 (dB), and the resonant frequency of the primary antenna of 27 MHz is used.

[0076] The present disclosure provides support for a method for wireless physiological gating in a magnetic resonance imaging (MRI) machine, the method comprising: wirelessly receiving a simulated physiological signal of interest from a secondary device and a primary device, the primary device comprising an antenna of the MRI machine, the antenna coupled in a near field to a resonant antenna of the secondary device, and the secondary device having a circuit system configured to change the impedance of the resonant antenna of the secondary device or otherwise change the tuning of the resonant antenna of the secondary device so as to affect the electromagnetic environment or tuning of the antenna of the MRI machine, the change in the electromagnetic environment being detected by the primary device and corresponding to the simulated physiological signal of interest from the secondary device. In one aspect, the primary device comprises circuitry and one or more antennas of an MRI machine configured to detect changes in the electromagnetic environment; or the antenna of the MRI machine comprises a self-resonant helical antenna or other type of antenna configured to detect the electromagnetic environment and measure changes in reflection coefficients corresponding to simulated physiological signals of interest from the secondary device when electrically driven by reflectometer circuitry of the primary device; or the MRI machine comprises circuitry and transmit and receive antennas configured to detect the electromagnetic environment and measure changes in transmission paths and / or transmission coefficients corresponding to simulated physiological signals of interest from the secondary device. In another aspect, the simulated physiological signal of interest comprises an electrical QRS signal or an electrocardiogram (ECG) waveform, and the secondary device comprises an ECG device or ECG patch with electrode connections to a patient and a resonant circuit configured to directly modulate the impedance of the resonant antenna of the secondary device or otherwise directly modulate the tuning of the resonant antenna of the secondary device to correlate with the ECG waveform. In another aspect, the secondary device is not electrically interconnected with the MRI machine and is configured so that the analog physiological signal of interest from the secondary device can be wirelessly data transmitted to the MRI machine using a radio frequency (RF) transmitter without the secondary device. In another aspect, the method includes: using a phase-locked loop (PLL) or other circuit system to generate a constant or varying frequency tone (or signal, which may include "linear frequency modulation pulses" or "sweep frequency", etc.) through a system control including the MRI machine; driving the antenna of the MRI machine via a reflectometer circuit of the MRI machine to transmit a constant or varying frequency tone or signal as an incident wave emitted by the antenna of the MRI machine; near-field coupling the antenna of the MRI machine and the resonant antenna of the secondary device; and detecting and measuring the ratio of incident power to reflected power and its reflection coefficient through the reflectometer circuit and the circuit system associated therewith, the change in the reflection coefficient corresponding to the analog physiological signal of interest from the secondary device.In another aspect, the method includes: generating a simulated physiological signal of interest via an electrode connection or other connection to a patient of a secondary device and a resonant circuit, the resonant circuit being configured to directly modulate the impedance of a resonant antenna of the secondary device or otherwise modulate the tuning of the resonant antenna of the secondary device to correlate with the simulated physiological signal of interest; and modulating the impedance of the resonant antenna of the secondary device or otherwise modulating the tuning of the resonant antenna of the secondary device to correlate with the simulated physiological signal of interest and to affect the electromagnetic environment and tuning of an antenna of an MRI machine. In another aspect, modulating the impedance of the resonant antenna of the secondary device or otherwise modulating the tuning of the resonant antenna of the secondary device includes biasing a variable impedance circuit element or a variable reactance diode or a varactor diode of the resonant circuit of the secondary device to provide a variable capacitance controlled by a reverse bias voltage, the reverse bias voltage being driven to correlate with the physiological signal of interest. In another aspect, the physiological signal of interest is an electrical QRS signal or an electrocardiogram (ECG) waveform or other physiological signal generated via an electrode connection or other connection to a patient. In another aspect, the simulated physiological signal of interest comprises a signal generated in response to a squeeze ball triggered by the patient squeezing the squeeze ball. In yet another aspect, the secondary device is powered by a battery and / or photovoltaic cell / solar power and / or power harvested from the RF / gradient power of the MRI machine and / or power harvested from the antenna / primary coil of the MRI machine.

[0077] The present disclosure also provides support for a system configured to wirelessly transmit data from a secondary device to a primary device, the system comprising: a circuit system and an antenna / primary coil of a primary device configured to wirelessly receive a simulated physiological signal of interest from the secondary device, the antenna of the primary device coupled to a resonant antenna of the secondary device in a near field, and the secondary device having a circuit system configured to change the impedance of the resonant antenna of the secondary device or otherwise change the tuning of the resonant antenna of the secondary device so as to affect the electromagnetic environment or tuning of the antenna of the primary device, the changes in the electromagnetic environment being detected by the circuit system within the primary device and corresponding to the simulated physiological signal of interest from the secondary device. In one aspect, the primary device comprises circuitry and one or more antennas configured to detect changes in the electromagnetic environment; or the antenna of the primary device comprises a self-resonant helical antenna or other type of antenna configured to detect the electromagnetic environment and measure changes in reflection coefficient corresponding to the simulated physiological signal of interest from the secondary device when electrically driven by the reflectometer circuit; or the primary device comprises circuitry and a transmitting antenna and a receiving antenna configured to detect the electromagnetic environment and measure changes in transmission paths and / or transmission coefficients corresponding to the simulated physiological signal of interest from the secondary device. In another aspect, the primary device comprises a magnetic resonance imaging (MRI) machine, wherein the simulated physiological signal of interest comprises an electrical QRS signal or an electrocardiogram (ECG) waveform, and wherein the secondary device comprises an ECG device or ECG patch with electrode connections to a patient and a resonant circuit configured to directly modulate the impedance of the resonant antenna of the secondary device or otherwise directly modulate the tuning of the resonant antenna of the secondary device to correlate with the ECG waveform. In another aspect, the secondary device is not electrically interconnected with the primary device and is configured so that the simulated physiological signal of interest from the secondary device can be wirelessly data transmitted to the primary device using a radio frequency (RF) transmitter without the secondary device. In yet another aspect, the primary device is configured to: generate a constant or varying frequency tone or signal using a phase-locked loop (PLL) or other circuit system through system control including the primary device; drive the antenna of the primary device via a reflectometer circuit of the primary device to emit a constant or varying frequency tone or signal as an incident wave emitted by the antenna of the primary device; near-field couple the antenna of the primary device and the resonant antenna of the secondary device; and detect and measure the ratio of incident power to reflected power and its reflection coefficient through the reflectometer circuit and circuit systems associated therewith, the change in the reflection coefficient corresponding to the simulated physiological signal of interest from the secondary device.In another aspect, the secondary device is configured to: generate an analog physiological signal of interest via an electrode connection or other connection of the secondary device to the patient and a resonant circuit, the resonant circuit being configured to directly modulate the impedance of the resonant antenna of the secondary device or otherwise directly modulate the tuning of the resonant antenna of the secondary device so as to be related to the analog physiological signal of interest; and modulate the impedance of the resonant antenna of the secondary device or otherwise modulate the tuning of the resonant antenna of the secondary device so as to be related to the analog physiological signal of interest and to affect the electromagnetic environment and tuning of the antenna of the primary device. In yet another aspect, modulating the impedance of the resonant antenna of the secondary device or otherwise modulating the tuning of the resonant antenna of the secondary device includes biasing a variable impedance circuit element or a variable reactance diode or varactor diode of the resonant circuit of the secondary device to provide a variable capacitance controlled by a reverse bias voltage, the reverse bias voltage being driven to be related to the physiological signal of interest.

[0078] The present disclosure also provides support for a system for wirelessly transmitting data from an electrocardiogram (ECG) device to a magnetic resonance imaging (MRI) machine, the system including: circuitry and an antenna / primary coil of the MRI machine configured to wirelessly receive an analog physiological signal of interest from the ECG device, the antenna of the MRI machine being coupled in the near field to the resonant antenna of the ECG device, and the ECG device having circuitry configured to change the impedance of the resonant antenna of the ECG device or otherwise change the tuning of the resonant antenna of the ECG device so as to affect the electromagnetic environment or tuning of the antenna of the MRI machine, the change in the electromagnetic environment being detected by circuitry within the MRI machine and corresponding to the analog physiological signal of interest from the ECG device, wherein the MRI machine includes circuitry and one or more antennas configured to detect the electromagnetic environment and measure the change in the electromagnetic environment corresponding to the analog physiological signal of interest from the ECG device. In one aspect, the analog physiological signal of interest includes an electrical QRS signal or an electrocardiogram (ECG) waveform, and wherein the ECG device includes an electrode connection to the patient and a resonant circuit configured to directly modulate the impedance of the resonant antenna of the secondary device or otherwise directly modulate the tuning of the resonant antenna of the secondary device so as to be related to the ECG waveform. In another aspect, the ECG device is not electrically interconnected with the MRI machine and is configured such that wireless data of the analog physiological signal of interest from the ECG device can be transmitted to the MRI machine using a radio frequency (RF) transmitter without the presence of the ECG device. In yet another aspect, the ECG device is powered by a battery and / or a photovoltaic cell unit / solar and / or power harvested from the RF / gradient power of the MRI machine and / or power harvested from the antenna / primary coil of the MRI machine.

[0079] As used herein, the elements or steps listed in the singular and beginning with the word "one" or "a kind of" should be understood as not excluding a plurality of said elements or steps, unless such exclusion is explicitly stated. In addition, the reference to "one embodiment" of the present invention is not intended to be interpreted as excluding the existence of additional embodiments that also include the cited features. In addition, unless explicitly stated to the contrary, "comprising", "including" or "having" an embodiment of an element or multiple elements with a specific characteristic may include additional such elements that do not have the characteristic. The terms "including" and "in..." are used as the concise language equivalents of the corresponding terms "including" and "wherein". In addition, the terms "first", "second" and "third" etc. are only used as marks, and are not intended to impose numerical requirements or specific positional order on their objects.

[0080] Figure 1 To Fig. 8 or its parts, the example configuration of the relative positioning of each component can be shown. In at least one example, if it is shown as directly contacting or directly coupling each other, such elements can be respectively referred to as directly contacting or directly coupling. Similarly, in at least one example, the elements shown as being adjacent or adjacent to each other can be adjacent or adjacent to each other respectively. For example, the components placed in coplanar contact with each other can be referred to as being in coplanar contact. For example, in at least one example, the elements positioned to be spaced apart from each other and having only space therebetween without other components can be described and quoted as such. For example, the elements shown as being located above / below each other, located on the opposite sides of each other, or located on the left / right sides of each other can be described and quoted as such relative to each other. In addition, as shown in the figure, in at least one example, the topmost element or the point of the element can be referred to as the "top" of the component, and the bottommost element or the point of the element can be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the figure, and can be used to describe the position of the elements relative to each other in the figure. Thus, in one example, elements shown as being above other elements are positioned vertically above other elements. For another example, the shapes of the elements depicted in the figures may be referred to as having those shapes (e.g., such as being round, straight, planar, curved, rounded, chamfered, angled, etc.). In addition, in at least one example, elements shown as intersecting each other may be referred to as intersecting elements or intersecting each other. In addition, in one example, elements shown as being within another element or being shown as being outside another element may be described and referenced as such.

[0081] This written description uses examples to disclose the invention, including the best mode, and also to enable a person skilled in the relevant art to practice the invention, including making and using any devices or systems and performing any included methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to a person skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insignificant differences from the literal language of the claims.

Claims

1. A method for wireless physiological gating in a magnetic resonance imaging (MRI) machine, the method comprising: Wirelessly receiving a simulated physiological signal of interest (826) from a primary device and a secondary device (200), the primary device comprising an antenna (602) of the MRI machine, the antenna being coupled in a near field to a resonant antenna (812) of the secondary device (200), and the secondary device (200) having a circuit system (818) configured to change the impedance of the resonant antenna (812) of the secondary device (200) or otherwise change the tuning of the resonant antenna of the secondary device to affect the electromagnetic environment or tuning of the antenna of the MRI machine, the changes in the electromagnetic environment (822) being detected by the primary device and corresponding to the simulated physiological signal of interest (826) from the secondary device (200).

2. The method according to claim 1, wherein: The primary device includes circuitry of the MRI machine and the antenna (602) configured to detect changes in the electromagnetic environment (822); or the antenna of the MRI machine comprising a self-resonant helical antenna or other type of antenna (808) configured to detect the electromagnetic environment and measure changes in reflection coefficient corresponding to the simulated physiological signal of interest (826) from the secondary device (200) when electrically driven by the reflectometer circuit (806) of the primary device; or The MRI machine includes circuitry and a transmit antenna (852) and a receive antenna (854) configured to detect the electromagnetic environment and measure changes in transmission paths and / or transmission coefficients corresponding to the simulated physiological signal of interest (826) from the secondary device (200).

3. The method according to claim 1, wherein: The simulated physiological signal of interest (826) comprises an electrical QRS signal or an electrocardiogram (ECG) waveform (902), and wherein the secondary device (200) comprises an ECG device or ECG patch (610) having electrode connections to a patient (170) and a resonant circuit (818), the resonant circuit being configured to directly modulate the impedance of the resonant antenna (812) of the secondary device (200) or otherwise directly modulate the tuning of the resonant antenna of the secondary device so as to correlate with the ECG waveform (902).

4. The method according to claim 1, wherein: The secondary device (200) is not electrically interconnected with the MRI machine and is configured such that the simulated physiological signal of interest (826) can be wirelessly data transmitted from the secondary device (200) to the MRI machine using a radio frequency (RF) transmitter in the absence of the secondary device (200).

5. The method according to claim 1, comprising: generating a constant or varying frequency tone (804) or signal using a phase locked loop (PLL) or other circuitry controlled by a system (100) including the MRI machine; driving the antenna (808) of the MRI machine via a reflectometer circuit (806) of the MRI machine to transmit the constant or varying frequency tone or signal as an incident wave transmitted by the antenna (808) of the MRI machine; near-field coupling the antenna (808) of the MRI machine and the resonant antenna (812) of the secondary device (200); and The reflectometer circuit (806) and associated circuitry detect and measure the ratio of incident power to reflected power and a reflection coefficient, the change in which corresponds to the simulated physiological signal (826) of interest from the secondary device (200).

6. The method according to claim 5, comprising: generating the simulated physiological signal of interest (826) via an electrode connection or other connection of the secondary device (200) to the patient (170) and a resonant circuit (818), the resonant circuit being configured to directly modulate an impedance of the resonant antenna of the secondary device or otherwise directly modulate a tuning of the resonant antenna of the secondary device to correlate with the simulated physiological signal of interest (826); as well as Modulating the impedance of the resonant antenna (812) of the secondary device (200) or otherwise modulating the tuning of the resonant antenna of the secondary device to correlate with the simulated physiological signal (826) of interest and to affect the electromagnetic environment and tuning of the antenna of the MRI machine.

7. The method according to claim 6, wherein: Modulating the impedance of the resonant antenna (812) of the secondary device (200) or otherwise modulating the tuning of the resonant antenna of the secondary device includes biasing a variable impedance circuit element or a variable reactance diode or varactor diode (708) of the resonant circuit (818) of the secondary device (200) to provide a variable capacitance controlled by a reverse bias voltage (714) driven to be related to the physiological signal of interest (826).

8. The method according to claim 1, wherein: The simulated physiological signal of interest (826) includes a signal generated by the squeeze bulb in response to being triggered by the patient (170) squeezing the squeeze bulb.

9. The method according to claim 1, wherein: The secondary device (200) is powered by batteries and / or photovoltaic cells / solar energy and / or power harvested from the RF / gradient power of the MRI machine and / or power harvested from the antenna / primary coil of the MRI machine.

10. A system (100) configured to wirelessly transmit data from a secondary device (200) to a primary device, the system comprising: The circuit system and antenna / primary coil (602) of the primary device are configured to wirelessly receive a simulated physiological signal of interest (826) from the secondary device (200), the antenna (602) of the primary device being coupled in a near field to a resonant antenna (812) of the secondary device (200), and the secondary device (200) having a circuit system (818) configured to change the impedance of the resonant antenna of the secondary device or otherwise change the tuning of the resonant antenna of the secondary device so as to affect the electromagnetic environment or tuning of the antenna of the primary device, the changes in the electromagnetic environment (822) being detected by the circuit system within the primary device and corresponding to the simulated physiological signal of interest (826) from the secondary device (200).

11. The system according to claim 10, wherein: The primary device includes circuitry and one or more antennas (602) configured to detect changes in the electromagnetic environment (822); or the antenna (602) of the primary device comprises a self-resonant helical antenna or other type of antenna (808) configured to detect the electromagnetic environment and measure changes in reflection coefficient corresponding to the simulated physiological signal of interest (826) from the secondary device (200) when electrically driven by a reflectometer circuit (806); or The primary device includes circuitry and a transmit antenna (852) and a receive antenna (854) configured to detect the electromagnetic environment and measure changes in transmission paths and / or transmission coefficients corresponding to the simulated physiological signal of interest (826) from the secondary device (200).

12. The system according to claim 10, wherein: The primary device comprises a magnetic resonance imaging (MRI) machine, wherein the simulated physiological signal of interest (826) comprises an electrical QRS signal or an electrocardiogram (ECG) waveform (902), and wherein the secondary device (200) comprises an ECG device or ECG patch (610) having electrode connections to a patient (170) and a resonant circuit (818) configured to directly modulate the impedance of the resonant antenna (812) of the secondary device (200) or otherwise directly modulate the tuning of the resonant antenna of the secondary device to correlate with the ECG waveform (902).

13. The system according to claim 10, wherein: The secondary device (200) is not electrically interconnected with the primary device and is configured such that the simulated physiological signal of interest (826) can be wirelessly data transmitted from the secondary device (200) to the primary device using a radio frequency (RF) transmitter in the absence of the secondary device (200).

14. The system according to claim 10, wherein: The primary device is configured as follows: generating a constant or varying frequency tone (804) or signal using a phase locked loop (PLL) or other circuitry controlled by a system (100) including the primary device; driving the antenna (808) of the primary device (200) via a reflectometer circuit (806) of the primary device to transmit the constant or varying frequency tone or signal as an incident wave transmitted by the antenna (808) of the primary device; near-field coupling the antenna (808) of the primary device and the resonant antenna (812) of the secondary device; and The reflectometer circuit (806) and associated circuitry detect and measure the ratio of incident power to reflected power and a reflection coefficient, the change in which corresponds to the simulated physiological signal (826) of interest from the secondary device (200).

15. The system of claim 14, wherein: The secondary device is configured to: generating the simulated physiological signal of interest (826) via an electrode connection or other connection of the secondary device (200) to the patient (170) and a resonant circuit (818), the resonant circuit being configured to directly modulate an impedance of the resonant antenna (812) of the secondary device (200) or otherwise directly modulate the tuning of the resonant antenna of the secondary device to correlate with the simulated physiological signal of interest (826); as well as Modulating the impedance of the resonant antenna (812) of the secondary device (200) or otherwise modulating the tuning of the resonant antenna of the secondary device to correlate with the simulated physiological signal of interest (826) and to affect the electromagnetic environment and tuning of the antenna (808) of the primary device.

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