System for monitoring electrocardiogram pulses using virtual ground - Patents.com

Abstract

The system for acquiring ECG pulses includes a common node configured to form a virtual ground, measurement nodes connectable to corresponding ECG electrodes attached to a subject, and an ECG module. The measurement nodes are connected to the virtual ground of the common node through short conductive paths. Each measurement node includes an ADC for converting an ECG signal from a corresponding ECG electrode into a digital signal, an optical converter for converting the digital signal into an optical signal output via an output optical fiber cable, a DC power converter for converting modulated optical pulses with an embedded clock signal received via an input optical fiber cable into DC power, where the DC power is supplied to the ADC and the digital-to-optical converter, and a clock recovery circuit for recovering the embedded clock signal from the modulated optical pulses, where the recovered clock signal is supplied to the ADC and the optical converter for synchronization.

Description

[Technical field]

[0001] Electrocardiogram (ECG) systems monitor the functioning of a subject's heart by acquiring and measuring ECG pulses via ECG electrodes placed in contact with the subject. [Background technology]

[0002] ECG systems are useful for monitoring subjects in potentially stressful situations during medical diagnosis and treatment. For example, during a magnetic resonance imaging (MRI) examination, the subject is confined to the relatively small diameter bore of the MRI scanner for an extended period of time, which can cause anxiety. Therefore, ECG electrodes are attached to the subject within the bore during the MRI examination to provide real-time ECG pulses and therefore information about the subject's health. Summary of the Invention [Problem to be solved by the invention]

[0003] However, MRI scanners are a harsh environment for detecting the small millivolt ECG pulses generated by the heart. Conventional ECG systems are implemented with long electrical ECG leads that individually connect the ECG electrodes to an ECG module, which acts as an analog front end for the ECG electrodes, including amplification and analog-to-digital conversion of the ECG pulses. The ECG leads are susceptible to MRI noise that is picked up during active scanning, resulting in degradation of the ECG signal. The ECG leads may also be a source of radio frequency (RF) heating induced by the RF coil of the MRI scanner, which can cause burns to the subject if the ECG leads are not placed correctly. [Means for solving the problem]

[0004] According to a representative embodiment, a system for acquiring electrocardiogram (ECG) pulses from a subject is provided. The system includes a common node configured to form a virtual ground, and a plurality of measurement nodes each connectable to a corresponding ECG electrode attachable to the subject. The measurement nodes are each connected to the virtual ground at the common node via a short conductive path. Each measurement node of the plurality of measurement nodes includes an analog-to-digital converter (ADC) configured to convert an ECG signal from the corresponding ECG electrode to a digital signal, an optical converter configured to convert the digital signal from the ADC to an optical signal and output the optical signal via an output fiber optic cable, a direct current (DC) power converter configured to receive a modulated optical signal with an embedded clock signal via an input fiber optic cable, recover (regenerate) DC power from the modulated optical signal, and provide the DC power to at least the ADC and the optical converter, and a clock recovery circuit configured to receive a modulated optical signal with the embedded clock signal via an input fiber optic cable, recover the embedded clock signal from the modulated optical signal, and provide the recovered clock signal to at least the ADC and the optical converter for synchronization. The common node may or may not be configured as a measurement node.

[0005] According to another representative embodiment, a system for acquiring electrocardiogram (ECG) pulses from a subject is provided, the system includes a common node configured to form a virtual ground, and a plurality of measurement nodes each in contact with a corresponding ECG electrode attachable to the subject, the measurement nodes each being connected to the virtual ground at the common node via a short conductive path, each measurement node of the plurality of measurement nodes includes an analog front end configured to receive and process an ECG signal from the corresponding ECG electrode, a DC power converter configured to receive a modulated optical signal with an embedded clock signal via an input fiber optic cable, regenerate DC power from the modulated optical signal, and provide the DC power to the analog front end, and a clock recovery circuit configured to receive a modulated optical signal with an embedded clock signal via an input fiber optic cable, regenerate the embedded clock signal from the modulated optical signal, and provide the regenerated clock signal to the analog front end.

[0006] According to another representative embodiment, a measurement node connectable to electrocardiogram (ECG) electrodes attachable to a body of a subject is provided for measuring electrocardiogram (ECG) pulses from the subject. The measurement node includes an analog-to-digital converter (ADC) configured to convert ECG signals from the ECG electrodes to digital signals, an optical converter configured to convert the digital signals from the ADC to optical signals and output the optical signals to an ECG monitor via an output fiber optic cable, a DC power converter configured to receive a modulated optical signal with an embedded clock signal from an ECG monitor via an input fiber optic cable, regenerate DC power from the modulated optical signal and provide the DC power to at least the ADC and the optical converter, and a clock recovery circuit configured to receive a modulated optical signal with an embedded clock signal via an input fiber optic cable, regenerate the embedded clock signal from the modulated optical signal and provide the regenerated clock signal to at least the ADC and the optical converter for synchronization. The ADC, the optical converter, the DC power converter and the clock recovery circuit are connected to a virtual ground generated by the common node attachable to the body of a subject via a short conductive path between the measurement node and a common node. [Brief description of the drawings]

[0007] The illustrative embodiments are best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that the various features are not necessarily drawn to scale. In fact, dimensions may be arbitrarily increased or decreased for clarity of discussion. Wherever applicable and practical, like reference numerals refer to like elements. [Figure 1] FIG. 1 is a simplified block diagram illustrating a set of measurement nodes for monitoring electrocardiogram (ECG) signals from a subject, according to a representative embodiment. [Diagram 2] FIG. 2 is a simplified block diagram illustrating an ECG system for monitoring ECG pulses from a subject implemented within a magnetic resonance imaging (MRI) system, according to a representative embodiment. [Diagram 3] FIG. 3 is a simplified block diagram illustrating an exemplary measurement node for monitoring an ECG signal from a subject, according to a representative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the following detailed description, for purposes of explanation and not limitation, representative embodiments disclosing specific details are described to provide a thorough understanding of the embodiments according to the present teachings. Descriptions of known systems, devices, materials, methods of operation and manufacturing methods may be omitted to avoid obscuring the description of the representative embodiments. However, systems, devices, materials and methods within the scope of those skilled in the art are within the scope of the present teachings and can be used by the representative embodiments. It is to be understood that the terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. Defined terms are given the technical and scientific meanings of the defined terms that are commonly understood and accepted in the art of the present teachings.

[0009] In this specification, terms such as first, second, third, etc. are used to describe various elements or components, but it should be understood that these elements or components should not be limited by these terms. These terms are used only to distinguish one element or component from another element or component. Thus, a first element or component described below can be called a second element or component without departing from the teaching of the inventive concept.

[0010] The terms used herein are merely for the purpose of describing particular embodiments and are not intended to be limiting. When used in this specification and the appended claims, unless otherwise clear from the context, they are intended to include both the singular and the plural, even if a plurality is not stated. In addition, the terms "comprises", "having", and / or similar terms specify the presence of stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0011] Unless otherwise stated, when an element or component is said to be "connected," "coupled," or "adjacent" to another element or component, it is understood that the element or component may be directly connected or coupled to the other element or component, or there may be intervening elements or components present. That is, these terms and similar terms encompass the cases where one or more intermediate elements or components may be used to connect the two elements or components. However, when an element or component is said to be "directly connected" to another element or component, this only encompasses the cases where the two elements or components are connected to each other without any intermediate or intervening elements or components.

[0012] Thus, the present disclosure is intended to reveal one or more of the advantages as specifically described below through one or more of its various aspects, embodiments and / or specific features or dependent components. For purposes of explanation and not limitation, exemplary embodiments disclosing specific details are described to provide a thorough understanding of embodiments according to the present teachings. However, other embodiments consistent with the present disclosure that depart from the specific details disclosed herein are within the scope of the appended claims. Furthermore, descriptions of known devices and methods may be omitted so as not to obscure the description of the exemplary embodiments. Such methods and devices are within the scope of the present disclosure.

[0013] In general, various embodiments described herein provide an ECG system including synchronized measurement nodes configured to digitize and transmit ECG pulses acquired from a subject via corresponding ECG electrodes attached to the subject's body. Each measurement node includes all the necessary components of the corresponding ECG electrode attached to digitize the ECG pulses. This eliminates the need for conductive ECG leads to connect the measurement nodes to an ECG module. In the absence of conductive ECG leads, the measurement nodes reduce signal degradation caused by noise in the bore of an MRI system, for example, as caused by conventional measurement nodes and ECG modules. Each measurement node includes an analog-to-digital converter (ADC) for converting the ECG pulses to a digital signal, a pair of fiber optic cables for communicating DC power, clocks, and ECG pulse data with the ECG module, and a short conductive path for connecting to a common measurement node that forms a common electrical reference. These measurement nodes may snap or clip onto existing ECG electrodes or may incorporate dedicated ECG electrodes.

[0014] FIG. 1 is a simplified block diagram illustrating a set of measurement nodes for monitoring electrocardiogram (ECG) signals from a subject, according to a representative embodiment.

[0015] 1, an exemplary set of measurement nodes 100 can be attached to a subject's skin, for example, using adhesive tape, to acquire ECG pulses generated by the subject's heartbeat. The set of measurement nodes 100 includes a measurement node 110 (e.g., a left arm (LA) measurement node), a measurement node 120 (e.g., a left leg (LL) measurement node), a measurement node 130 (e.g., a right arm (RA) measurement node), and a common node 140 (e.g., a right leg (RL) measurement node). As described below, the measurement nodes 110, 120, and 130 include the necessary components to receive and digitize ECG pulses, convert the digitized ECG pulses to optical ECG pulses, and communicate the optical pulses via optical fiber, thus eliminating the need for electrical ECG leads. In various configurations, the number of measurement nodes in the set of measurement nodes 100 can be varied (e.g., up to a total of 12) to provide unique advantages for any particular situation or to meet application-specific design requirements of various embodiments, as will be apparent to one of ordinary skill in the art.

[0016] Common node 140 forms a common electrical reference for the set of measurement nodes 100, referred to as a virtual ground (V-gnd). In one embodiment, common node 140 may be a measurement node having the same configuration as measurement nodes 110, 120, and 130. In this case, common node 140 is also used to receive and digitize ECG pulses, convert the digitized ECG pulses to optical ECG pulses, and communicate the optical ECG pulses via optical fiber. Alternatively, common node 140 may not have the functionality of a measurement node and may simply form a virtual ground.

[0017] Since common node 140 forms a virtual ground, measurement nodes 110, 120 and 130 are connected to common node 140 via short conductive paths relative to the length of the subject's body, and therefore have a common ground potential without needing to be electrically grounded via, for example, long ECG leads. A short conductive path is less than a quarter of the length of the subject's body, whereas a long ECG lead exceeds the length of the subject's body. In particular, measurement node 110 is connected to common node 140 via conductive path 115, measurement node 120 is connected to common node 140 via conductive path 125, and measurement node 130 is connected to common node 140 via conductive path 135. Each of short conductive paths 115, 125 and 135 is formed from a highly conductive material, such as copper, aluminum, gold or silver, and is, for example, about 12 cm long or less.

[0018] In the illustrated embodiment, each of the measurement nodes 110, 120, and 130 is connected to a corresponding ECG electrode attached to the subject's skin at a specific location on the subject's body to acquire ECG pulses generated from the subject's heartbeat. In particular, measurement node 110 is connected to ECG electrode 118, measurement node 120 is connected to ECG electrode 128, and measurement node 130 is connected to ECG electrode 138. Common node 140 is shown as optionally connected to ECG electrode 148 (shown in dashed lines), which occurs when common node 140 also has the functionality of a measurement node, as described above. Measurement nodes 110, 120, and 130 can be removably connected to ECG electrodes 118, 128, and 138, in which case conventional ECG electrodes may be used. For example, the measurement nodes 110, 120 and 130 may snap or clip onto the top surface (facing away from the subject's body) of the corresponding ECG electrodes 118, 128 and 138, respectively. Alternatively, the ECG electrodes 118, 128 and 138 may be physically integrated within the measurement nodes 110, 120 and 130, respectively.

[0019] Measurement nodes 110, 120 and 130 are further configured to communicate with an ECG module (not shown), which will be described below with reference to FIG. 2. In general, the ECG module provides DC power and clock signals to measurement nodes 110, 120 and 130 via input fiber optic cables, and processes ECG signals provided by measurement nodes 110, 120 and 130 via output fiber optic cables. In particular, measurement node 110 is connected to input fiber optic cable 111 and output fiber optic cable 112, measurement node 120 is connected to input fiber optic cable 121 and output fiber optic cable 122, and measurement node 130 is connected to input fiber optic cable 131 and output fiber optic cable 132. Common node 140 is shown as optionally connected to input fiber optic cable 141 and output fiber optic cable 142 (shown in dashed lines). As discussed above, this is because common node 140 may be configured as a measurement node for acquiring ECG signals.

[0020] 2 illustrates an ECG system for monitoring ECG pulses from a subject implemented within a magnetic resonance imaging (MRI) system, according to a representative embodiment. Although depicted with an MRI system for illustrative purposes, it will be understood that the ECG system may be implemented with an ECG system by itself or with any other type of medical imaging or medical examination system without departing from the scope of the present teachings.

[0021] 2, the ECG system 200 is combined with a representative MRI system 210 to monitor the ECG pulses of a subject 201 during an MRI examination. The MRI system 210 can be any type of MRI system, and the following description of the MRI system 210 is intended to be exemplary and not limiting. In the illustrated example, the MRI system 210 includes a magnet 212 with a bore 213. The magnet 212 may be, for example, a superconducting cylindrical magnet, although different types of magnets such as, for example, split cylindrical magnets and open magnets, are possible. An imaging zone 214 is provided within the bore 213 where the magnetic field generated by operation of the magnet 212 is strong and uniform enough to perform magnetic resonance imaging.

[0022] A subject 201 is placed on a support 203 and positioned within a bore 213 that is imaged during an MRI examination. The support 203 is attached to an (optional) actuator 204 that is configured to move the support 203 so that the subject 201 can move through an imaging zone 214. This allows most of the subject 201 or the entire subject 201 to be imaged.

[0023] The ECG system 200 includes the set of measurement nodes 100 as described above, whereby ECG electrodes 118, 128 and 138 corresponding to the measurement nodes 110, 120 and 130, respectively, are attached to the skin of the subject 201 for ECG monitoring during an MRI examination. For convenience, only the measurement node 130 is shown in FIG. 2. As described above, the common node 140 (not shown) forms a virtual ground, and the measurement node 130 is connected to the common node 140 by a short conductive path 135 to provide a common electrical reference for the measurement node 130. As described above, the other measurement nodes 110 and 120 (not shown) are similarly connected to the virtual ground provided by the common node 140. In one embodiment, the common node 140 is also a measurement node and is connected to the corresponding ECG electrode 148.

[0024] The MRI system 210 includes a set of magnetic field gradient coils 216 configured to acquire magnetic resonance data to spatially encode magnetic spins within an imaging zone 214. A magnetic field gradient coil power supply 218 supplies electrical current to the magnetic field gradient coils 216. The current may be controlled as a function of time, e.g., ramped or pulsed. Although two magnetic field gradient coils 216 are shown, it will be understood that additional magnetic field gradient coils may be included, e.g., to enable spatial encoding in three orthogonal spatial directions.

[0025] The MRI system 210 further includes an RF coil 217 disposed within the bore 213. The RF coil 217 is configured to steer the orientation of magnetic spins within the imaging zone 214 and also receive RF transmissions from the spins within the imaging zone 214. The RF coil 217 may represent dedicated transmit and receive antennas or may include multiple transmit and receive coil elements. The RF coil 217 is shown connected to an RF transceiver 219 that transmits and receives RF signals to and from the RF coil 217 during an MRI examination. In various configurations, the RF coil 217 and the RF transceiver 219 may be replaced by, for example, separate transmit and receive coils and separate transmitters and receivers.

[0026] The actuator 204, the power supply 218 of the magnetic field gradient coils, and the RF transceiver 219 are connected to a hardware interface 221 and a controller 222. The controller 222 includes a processor 224, a memory 226, and a user interface 228. The memory 226 represents one or more non-transitory memories and / or data storage devices, which are further described below. The memory 226 can store instructions for pulse sequences executed by the processor 224 to perform an MRI examination. The memory 226 may also include data storage devices for storing magnetic resonance data and / or reconstructed magnetic resonance images acquired during an MRI examination. The hardware interface 221 enables the controller 222 to interact with, control, and / or exchange data with at least the actuator 204, the power supply 218 of the magnetic field gradient coils, and the RF transceiver 219. The hardware interface 221 may include, for example, one or more of a USB, 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 LAN connection, a TCP / IP connection, an Ethernet® connection, a CV (control voltage) interface, a MIDI interface, an analog input interface, and a digital input interface.

[0027] Processor 224 represents one or more processing devices and may be implemented using any combination of hardware, software, firmware, hardwired logic circuitry, or combinations thereof, by a general purpose computer, a central processing unit, a computer processor, a microprocessor, a microcontroller, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a state machine, a programmable logic device, or combinations thereof. A processor may refer to a collection of processors within a single computer system or distributed across multiple computer systems, for example, in a cloud-based or other multi-site application.

[0028] Memory 226 may be implemented, for example, by any number, type, and combination of random access memory (RAM) and read-only memory (ROM) to store various types of information, such as software algorithms, artificial intelligence (AI) machine learning models, and computer programs, all of which are executable by processor 224. The various types of ROM and RAM may include any number, type, and combination of non-transitory computer-readable storage media, such as disk drives, flash memory, electrically programmable read-only memory (EPROM), electrically erasable and programmable read-only memory (EEPROM), registers, hard disks, removable disks, tapes, CD-ROMs, DVDs, floppy disks, Blu-ray disks, USB drives, or any other form of storage media known in the art. In this specification, the term transient should be interpreted as a characteristic of a state that lasts for a period of time, rather than a permanent characteristic of a state. The term non-transitory expressly negates a fleeting characteristic, such as a characteristic of a carrier wave or signal, or other form that exists only temporarily at any time and in any place.

[0029] The user interface 228 allows a user or operator to interact with the controller 222, receiving input from the operator that is received by the processor 224 and providing output from the processor 224 to the user. That is, the user interface 228 can provide information or data to the operator and / or receive information or data from the operator. Displaying data or information on a display or graphical user interface is an example of providing information to an operator. Receiving data via a keyboard, mouse, trackball, touchpad, pointing stick, graphics tablet, joystick, gamepad, webcam, headset, pedals, wired gloves, remote control, and accelerometer are all examples of components of the user interface 228 that allow for receiving information or data from the operator.

[0030] In addition to the set of measurement nodes 100, the ECG system 200 further includes an ECG module 230 and an output 240. In the illustrated embodiment, the ECG module 230 includes an optical modulator 231, an optical demodulator 232, and a processor 233. The optical modulator 231 is configured to receive a clock signal from a clock 237 and an optical signal from an optical source 238, modulate the optical signal and the clock signal using any compatible modulation technique, and output modulated optical signals with the embedded clock signal to the measurement nodes 110, 120, and 130 via the respective input optical fiber cables 111, 121, and 131, respectively. The optical source 238 may be, for example, a laser or a light emitting diode (LED). In one embodiment, the optical modulator 231 may provide a pulse width modulated (PWM) optical signal with the embedded clock signal, e.g., embedded via optical pulses. Alternatively, the optical modulator 231 may provide a frequency modulated or amplitude modulated optical signal with the embedded clock signal. For example, the frequency and / or width of the optical pulses in the PWM optical signal and the embedded clock signal may be adjusted to suit the MRI scanning environment. For example, certain frequencies must be avoided to avoid interference with the MR scanned images. The adjustable configuration of the ECG module 230 allows all frequencies to be selected or avoided.

[0031] The optical demodulator 232 is configured to receive optical ECG signals from the measurement nodes 110, 120 and 130 via respective output fiber optic cables 112, 122 and 132, respectively, and convert these ECG signals into corresponding electrical signals. The processor 233 is configured to execute instructions stored in a non-transitory memory (not shown) to process the electrical signals and provide corresponding ECG waves at output 240. The instructions further cause the processor 233 to determine characteristics of the ECG signal, such as the QRS complex, average beats, heart rate variability, RR intervals, PR intervals, and pulse rate. The memory may be one or more non-transitory memories and / or data storage devices, as described above with reference to the memory 226.

[0032] Processor 233 represents one or more processing devices and may be implemented using any combination of hardware, software, firmware, hardwired logic circuitry, or combinations thereof, by a general purpose computer, a central processing unit, a computer processor, a microprocessor, a microcontroller, an FPGA, an ASIC, a state machine, a programmable logic device, or combinations thereof. A processor may refer to a collection of processors within a single computer system or distributed across multiple computer systems, for example, in a cloud-based or other multi-site application.

[0033] Output 240 may include any type of visual display of the ECG tracing. For example, output 240 may include a display for displaying the ECG waves, such as a computer monitor, a television, a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a flat panel display, a solid state display, a cathode ray tube (CRT) display, a touch screen, or an electronic whiteboard. Alternatively or additionally, output 240 may include a printer, such as a thermal printer or an inkjet printer, for example, for printing the ECG waves. The ECG waves may be displayed and / or printed along with text and / or graphic information classifying and / or interpreting the ECG waves.

[0034] In the illustrated embodiment, measurement nodes 110, 120, and 130 are physically connected to ECG module 230 via input fiber optic cables 111, 121, and 131 and output fiber optic cables 112, 122, and 132, respectively. However, in an alternative embodiment, measurement nodes 110, 120, and 130 may be connected via input fiber optic cables 111, 121, and 131 and output fiber optic cables 112, 122, and 132, respectively, to a transceiver and antenna (not shown), which is configured to communicate wirelessly with ECG module 230. In this case, ECG module 230 would similarly include a transceiver and antenna (not shown) for transmitting DC power and clock signals and receiving ECG signals.

[0035] As described above, the measurement nodes 110, 120, and 130 have the same configuration. In various implementations, the common node 140 may also have the same configuration as the measurement nodes 110, 120, and 130 (except for the conductive paths). Figure 3 is a simplified block diagram illustrating an exemplary measurement node for monitoring an ECG signal from a subject, according to a representative embodiment. In particular, for purposes of illustration, Figure 3 illustrates the measurement node 130 as representative of all measurement nodes.

[0036] Referring to FIG. 3, the measurement node 130 includes a DC power converter 310 and a clock recovery circuit 315 connected to the input fiber optic cable 131. The DC power converter 310 is configured to receive a modulated optical signal from the optical modulator 231 of the ECG module 230 via the input fiber optic cable 131 and convert the modulated optical signal into a corresponding electrical signal. By converting the modulated optical signal into an electrical signal, the DC power converter 310 recovers the DC power embedded within the modulated optical signal. For example, if the modulated optical signal is a PWM optical signal, the magnitude of the DC power is indicated by the frequency and / or width of the optical pulses. The DC power converter 310 may be, for example, a photocell that directly converts an optical signal into an electrical signal using the photovoltaic effect. The clock recovery circuit 315 recovers the embedded clock signal from the modulated optical signal. The clock recovery circuit 315 may be, for example, an edge detector, a phase detector, or a frequency detector. The detector of the clock recovery circuit depends on how the clock was optically encoded, as known in the art. The recovery of DC power and the embedded clock signal can occur in any order or simultaneously. DC power conversion 310 outputs DC power (Vcc) and clock recovery circuit 315 outputs a recovered clock signal (Clk) to other components of measurement node 130, described below.

[0037] Measurement node 130 is shown connected to ECG electrodes 138 attached to the skin of subject 201 to receive small analog ECG pulses in the μV-mV range. Measurement node 130 provides an analog front end for ECG electrodes 138, including an optional programmable gain amplifier (PGA) 320 and an analog-to-digital converter (ADC) 330 (shown in dashed lines), as well as an optical converter 340. As shown, PGA 320, ADC 330, and optical converter 340 each receive DC power (Vcc) from DC power converter 310 and the recovered clock signal (Clk) from clock recovery circuit 315. Thus, PGA 320, ADC 330, and optical converter 340 are powered using the DC power (Vcc) and are synchronized with each other using the recovered clock signal (Clk) without having a power supply.

[0038] The PGA 320 receives analog ECG pulses from the ECG electrodes 138, which are electrical signals. The ADC 330 converts the ECG pulses into digital ECG signals at a predetermined sampling frequency (e.g., 300 Hz). The optical converter 340 receives the digital ECG signals and converts them into optical ECG signals. The optical converter 340 may be, for example, a laser or LED light source. The optical converter 340 outputs the optical ECG signals to the optical demodulator 232 of the ECG module 230 via the output fiber optic cable 132.

[0039] Additionally, the grounds of each of the DC power converter 310, the clock recovery circuit 315, the PGA 320, the ADC 330, and the optical converter 340 are connected to the virtual ground (V-gnd) formed by the common node 140 via conductive path 135. Thus, the DC power converter 310, the clock recovery circuit 315, the PGA 320, the ADC 330, and the optical converter 340 are grounded to a common potential along with the components of the other measurement nodes (e.g., measurement nodes 110, 120) without needing to be electrically grounded anywhere within the ECG system 200. The regenerated DC power and virtual ground of the measurement node 130 eliminates the need for electrical leads connecting the measurement node 130 to an external power source and ground.

[0040] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of various embodiments. These illustrations are not intended to serve as a complete description of all of the elements and features of the present disclosure described herein. Upon review of this disclosure, many other embodiments may become apparent to those skilled in the art. Other embodiments may be utilized and derived from this disclosure, such that structural and logical substitutions and modifications are made without departing from the scope of the present disclosure. Furthermore, these illustrations are merely representational and may not be drawn to scale. Certain proportions within these illustrations are exaggerated, while others are minimized. Thus, the present disclosure and the drawings should be considered illustrative rather than limiting.

[0041] One or more embodiments of the present disclosure may be referred to herein, individually and / or collectively, by the term "invention" merely for convenience and without any intention to spontaneously limit the scope of the present application to any particular invention or inventive concept. Furthermore, although specific embodiments have been illustrated and described herein, it should be understood that any subsequent configurations designed to achieve the same or similar purpose may be substituted for the specific embodiment shown. The present disclosure is intended to cover any and all subsequent adaptations or modifications of the various embodiments. Combinations of the above embodiments with other embodiments not specifically described herein will be apparent to those of skill in the art upon consideration of this description.

[0042] This Abstract of the Disclosure is provided for purposes of compliance with United States Patent Regulations, Title 37, Code of Federal Regulations, §1.72(b), and is submitted with the understanding that this Abstract will not be used to interpret or limit the scope or meaning of the claims. Moreover, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all of the features of any of the disclosed embodiments. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter.

[0043] The above description of the disclosed embodiments is provided to enable those skilled in the art to practice the concepts described in this disclosure. Accordingly, the subject matter disclosed above should be considered as illustrative and not limiting, and the appended claims are intended to cover all such modifications, improvements and other embodiments that fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent permitted by law, the scope of the present disclosure should be determined by the broadest permissible interpretation of the following claims and their equivalents, and should not be limited or restricted by the above detailed description.

Claims

1. 1. A system for obtaining electrocardiogram (ECG) pulses from a subject, the system comprising: a common node configured to form a virtual ground; and a plurality of measurement nodes each connectable to a corresponding plurality of ECG electrodes attachable to the subject; each of the plurality of measurement nodes is connected to the virtual ground at the common node via a short conductive path, and each measurement node of the plurality of measurement nodes is an analog-to-digital converter (ADC) configured to convert ECG signals from the corresponding ECG electrodes into digital signals; an optical converter configured to convert the digital signal from the ADC into an optical signal and output the optical signal via an output fiber optic cable; a DC power converter configured to receive a modulated optical signal with an embedded clock signal via an input fiber optic cable, recover DC power from the modulated optical signal, and provide the DC power to at least the ADC and the optical converter; and a clock recovery circuit that receives a modulated optical signal having the embedded clock signal via the input optical fiber cable, recovers the embedded clock signal from the modulated optical signal, and provides the recovered clock signal to at least the ADC and the optical converter for synchronization; A system having:

2. 2. The system of claim 1, further comprising an ECG module configured to provide the modulated optical signals to the plurality of measurement nodes via the input fiber optic cable, respectively, receive the optical signals from the plurality of measurement nodes via the output fiber optic cable, and convert the optical signals into the ECG pulses.

3. 3. The system of claim 1, wherein the common node is configured as a measurement node connectable to a corresponding ECG electrode attachable to the subject.

4. 4. The system of claim 3, wherein the plurality of measurement nodes comprises a left arm (LA) measurement node, a right arm (RA) measurement node, and a left leg (LL) measurement node, and the common node comprises a right leg (RL) measurement node.

5. The system of claim 1 , wherein the DC power converter at each measurement node of the plurality of measurement nodes comprises a photovoltaic cell.

6. 2. The system of claim 1, wherein each measurement node of the plurality of measurement nodes further comprises a programmable gain amplifier (PGA) connected to an input of the ADC and configured to amplify the ECG signal.

7. The system of claim 2 , further comprising a monitor configured to display the ECG pulses output by the ECG module.

8. The system of claim 1 , wherein the subject is positioned within a magnetic resonance imaging (MRI) bore while acquiring the ECG pulses.

9. The system of claim 1 , wherein the modulated optical signal comprises a pulse-width modulated (PWM) optical signal.

10. The system of claim 1 , wherein the modulated optical signal comprises a frequency-modulated signal or an amplitude-modulated optical signal.

11. 1. A system for obtaining electrocardiogram (ECG) pulses from a subject, the system comprising: a common node configured to form a virtual ground; and a plurality of measurement nodes each in contact with a corresponding plurality of ECG electrodes attachable to the subject, the measurement nodes each connected to the virtual ground at the common node via a short conductive path; and each measurement node of the plurality of measurement nodes has: an analog front end configured to receive and process ECG signals from the corresponding ECG electrodes; a DC power converter configured to receive a modulated optical signal comprising an embedded clock signal via an input fiber optic cable, recover DC power from the modulated optical signal, and provide the DC power to the analog front end; and a clock recovery circuit configured to receive the modulated optical signal comprising the embedded clock signal via the input fiber optic cable, recover the embedded clock signal from the modulated optical signal, and provide the recovered clock signal to the analog front end. A system having:

12. 12. The system of claim 11, wherein the modulated optical signal comprises a pulse-width modulated (PWM) optical signal, a frequency-modulated optical signal, or an amplitude-modulated optical signal.

13. 13. The system of claim 11 or 12, wherein the DC power converter of each measurement node of the plurality of measurement nodes comprises a photovoltaic cell.

14. The analog front end of each measurement node of the plurality of measurement nodes a programmable gain amplifier (PGA) configured to amplify the ECG signal; and an analog-to-digital converter (ADC) connected to an output of the PGA and configured to digitize the amplified ECG signal; The system of claim 11 further comprising:

15. 12. The system of claim 11, further comprising an ECG module configured to provide the modulated optical signals to the plurality of measurement nodes via the input fiber optic cable, respectively, receive the optical signals from the plurality of measurement nodes via the output fiber optic cable, and convert the optical signals into the ECG pulses.

16. The system of claim 11 , wherein the common node is configured as a measurement node connectable to a corresponding ECG electrode attachable to the subject.

17. 17. The system of claim 16, wherein the plurality of measurement nodes comprises a left arm (LA) measurement node, a right arm (RA) measurement node, and a left leg (LL) measurement node, and the common node comprises a right leg (RL) measurement node.

18. The system of claim 11 , wherein each measurement node of the plurality of measurement nodes is configured to snap or clip onto a top surface of the corresponding ECG electrode.

19. The system of claim 11 , wherein each measurement node of the plurality of measurement nodes further comprises the corresponding ECG electrode physically integrated within the measurement node.

20. a measurement node connectable to electrocardiogram (ECG) electrodes attachable to a body of a subject for measuring ECG pulses from the subject, the measurement node comprising: an analog-to-digital converter (ADC) configured to convert ECG signals from the ECG electrodes into digital signals; an optical converter configured to convert the digital signal from the ADC into an optical signal and output the optical signal to an ECG monitor via an output fiber optic cable; a DC power converter configured to receive a modulated optical signal with an embedded clock signal from the ECG monitor via an input fiber optic cable, recover DC power from the modulated optical signal, and provide the DC power to at least the ADC and the optical converter; and a clock recovery circuit configured to receive a modulated optical signal comprising the embedded clock signal via the input optical fiber cable, recover the embedded clock signal from the modulated optical signal, and provide the recovered clock signal to at least the ADC and the optical converter. a measurement node, the ADC, the optical converter, the DC power converter, and the clock recovery circuit being connected to a virtual ground formed by the common node, which is attachable to the body of the subject, via a short conductive path between the measurement node and a common node.

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