Wireless gating system for magnetic resonance imaging

Abstract

An exemplary magnetic resonance imaging (MRI) system uses a magnetic field and radio frequency to generate anatomical images of a biological organism such as, for example, the human body. The exemplary MRI system may implement prospective gating techniques, such as cardiac gating and / or respiratory gating to name a few, to improve the image quality of the anatomical images. The prospective gating techniques utilize one or more physiological events of the biological organism to trigger the exemplary MRI system to image the biological organism at a specific point in time, and to compensate for, for example, interference that may be introduced by the magnetic field and / or radio frequency, in order to improve the image quality of the anatomical images. TIFF2025519068000002.tif88170

Description

Background Art

[0001] Background Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate anatomical images of biological organisms. MRI is widely used in hospitals and clinics for the medical diagnosis, staging, and follow-up of various diseases. MRI can be used by medical personnel to examine the brain, spinal cord, bones, joints, heart, blood vessels, and other internal organs of biological organisms. For example, MRI may be used by medical personnel to evaluate the structures of the heart and aorta to detect aneurysms or ruptures. As another example, MRI may be used by medical personnel to evaluate glands and organs within the abdomen of a biological organism and can provide accurate information about the structures of joints, soft tissues, and bones of the biological organism.

Summary of the Invention

[0002]

Brief Description of the Drawings

[0003] The accompanying drawings, which are incorporated herein and constitute a part of this specification, illustrate the present disclosure and, together with the description of the present disclosure, serve to explain the principles of the present disclosure so that those skilled in the art can utilize it. The aspects of the present disclosure are best understood by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practices in the industry, the features are not of uniform scale. In fact, the dimensions of the features may be arbitrarily increased or reduced for clarity of explanation. The drawings are as follows.

[0004]

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[0005] In the accompanying drawings, like reference numerals indicate identical or functionally similar elements. Additionally, the leftmost digit of a reference numeral identifies the drawing in which the reference numeral first appears. DETAILED DESCRIPTION

[0006] Detailed Description The following disclosure provides numerous different aspects or examples for implementing different features of the subject matter provided. To simplify the present disclosure, specific examples of components and arrangements are described below. These are of course only examples and are not intended to be limiting. For example, if in the following description a first feature is formed on top of a second feature, this may include aspects where the first and second features are formed in direct contact, and also aspects where additional features may be formed between the first and second features so that the first and second features are not in direct contact. Additionally, the present disclosure may repeat reference numerals and / or letters in the examples. This repetition itself does not define a relationship between the aspects and / or configurations being discussed.

[0007] Overview An exemplary magnetic resonance imaging (MRI) system uses a magnetic field and radio frequency to generate anatomical images of a biological organism, such as, by way of example, the human body. The image quality of the anatomical images generated by the exemplary MRI system, such as contrast and spatial resolution, may be sub-optimal due to one or more physiological events of the biological organism, such as the heartbeat and / or respiration of the biological organism. As will be described in more detail below, the exemplary MRI system may implement prospective gating techniques, such as, by way of example, cardiac gating and / or respiratory gating, to improve the image quality of the anatomical images. The prospective gating techniques utilize one or more physiological events of the biological organism to trigger the exemplary MRI system to image the biological organism at a particular point in time to improve the image quality of the anatomical images. However, the magnetic field and / or radio frequency may interfere with the prospective gating techniques. As will be described in more detail below, the exemplary MRI system compensates for the interference introduced by the magnetic field and / or radio frequency.

[0008] Exemplary Magnetic Resonance Imaging (MRI) System FIG. 1 illustrates a simplified block diagram of an exemplary magnetic resonance imaging (MRI) system in accordance with some exemplary aspects of the present disclosure. In the exemplary aspect illustrated in FIG. 1, imaging system 100 represents a magnetic resonance imaging (MRI) system that uses magnetic fields and radio frequencies to generate anatomical images of a biological organism, such as a human body by way of example. Although imaging system 100 is described in FIG. 1 as being a magnetic resonance imaging (MRI) system, the teachings herein are equally applicable to other types of imaging systems, such as, by way of example, a computed tomography (CT) imaging system, a computed axial tomography (CAT) imaging system, and / or a positron emission tomography (PET) imaging system, without departing from the spirit and scope of the present disclosure, as will be recognized by those of ordinary skill in the art. As illustrated in FIG. 1, imaging system 100 includes a patient transport table 102, an imaging machine 104, an MRI computer control system 106, an administrative workstation 108, a gating signal transmitter 110, and a gating signal receiver 112. Although imaging machine 104 is illustrated in FIG. 1 as being a standard imaging machine having a long cylinder with a narrow tube portion, also referred to as a bore, at its center, the teachings herein are equally applicable to other types of imaging machines, such as, by way of example, a short bore imaging machine, an open imaging machine having a bore with an opening, and / or a wide bore imaging machine, without departing from the spirit and scope of the present disclosure, as will be recognized by those of ordinary skill in the art.

[0009] Patient transport table 102 positions patient 116 on patient transport table 102 within imaging machine 104. In some aspects, patient transport table 102 may be adjustable in three dimensions, such as, for example, raised, pitched, rolled, and / or yawed, to slide the patient into imaging machine 104. As illustrated in FIG. 1, patient 116 is positioned on patient transport table 102 that can be adjusted to position patient 116 within imaging machine 104, such as, for example, by sliding.

[0010] Imaging machine 104 performs magnetic resonance imaging (MRI) imaging of patient 116 using a combination of magnetic fields and radio frequencies. In an exemplary embodiment illustrated in FIG. 1, imaging machine 104 generates a strong and stable primary magnetic field, for example, from about 0.5 tesla (T) to about 3.0 T. In some embodiments, when patient 116 is positioned within imaging machine 104, the primary magnetic field surrounds patient 116. In these embodiments, the primary magnetic field aligns subatomic particles, such as protons, within the tissue of patient 116. In these embodiments, the protons are often protons of hydrogen atoms that are abundantly present within living organisms, particularly within water and fat cells within these organisms.

[0011] Imaging machine 104 generates one or more variable secondary magnetic fields, such as gradient magnetic field pulses, which slightly distort the primary magnetic field and enable imaging of different spatial positions, such as slices, of patient 116. These gradient magnetic field pulses may be directed towards that particular spatial position to image a particular spatial position, or slice, of patient 116. In some embodiments, the gradient magnetic field pulses may cause a frequency variation at that particular spatial position so that a particular spatial position, or slice, of patient 116 can be excited by radio frequencies.

[0012] The imaging machine 104 may generate radio frequency, such as a radio frequency pulse, which is directed towards the patient 116 to image a specific spatial location of the patient 116. In some embodiments, subatomic particles within the tissue of the patient 116 at the specific spatial location absorb the radio frequency pulse. In these embodiments, the subatomic particles absorb energy from the radio frequency pulse, which causes these particles to rotate away from the primary magnetic field. In these embodiments, when the frequency of the radio frequency pulse matches the precession frequency at which these subatomic particles rotate, the subatomic particles rotate away from the primary magnetic field. In these embodiments, the imaging machine 104 may deactivate the radio frequency pulse to slowly return these subatomic particles to alignment within the primary magnetic field; thereby, the energy absorbed from the radio frequency pulse is released. Generally, the amount of energy released by the subatomic particles is related to the chemical properties of the tissue of the patient 116. In some embodiments, the imaging machine 104 may detect the amount of released energy using, for example, a coil (not illustrated in FIG. 1) placed around the patient 116. In these embodiments, the imaging machine 104 may then convert the detected released energy into an electrical signal to provide an image data signal to the control system 106 that is indicative of the composition of the tissue of the patient 116 at the specific spatial location.

[0013] The control system 106 may include one or more computing devices, such as one or more desktop computers, one or more rack-mounted computers, one or more computer hardware servers, and / or any other computing device having one or more processors, which would be recognized by those skilled in the art without departing from the spirit and scope of the present disclosure. Although not illustrated in FIG. 1, the control system 106 may include or be connected to other hardware components for operating the imaging machine 104, such as, by way of example, one or more waveform generators, one or more amplifiers, one or more radio frequency transmitters, one or more radio frequency receivers, one or more digital-to-analog converters (DACs), one or more analog-to-digital converters (ADCs), one or more mixers, one or more power supplies, one or more water pumps, pumps for one or more supercooled fluids such as, by way of example, liquid helium or liquid nitrogen, and / or one or more supercooled fluid storage tanks. These other hardware components are well known to those skilled in the art and will not be discussed in further detail.

[0014] In some embodiments, the control system 106 may configure gradient magnetic field pulses and / or radio frequency pulses that are applied to the imaging machine 104 to image the patient 116 in order to acquire an image data signal. For example, the control system 106 may configure gradient magnetic field pulses to excite a particular spatial location of the patient 116 being imaged, such as a slice, and / or may configure various radio frequency pulses to image these particular spatial locations. In some embodiments, the control system 106 may control one or more waveform generators that generate gradient magnetic field pulses and / or radio frequency pulses, and / or one or more amplifiers that amplify gradient magnetic field pulses and / or radio frequency pulses. In these embodiments, the one or more waveform generators, and / or the one or more amplifiers, may be implemented as stand-alone or discrete devices, and / or may be incorporated into or coupled to the control system 106.

[0015] In some embodiments, the control system 106 may analyze the image data signal provided by the imaging machine 104 to generate an anatomical image of the patient 116. In these embodiments, the anatomical image of the patient 116 depicts the tissue composition of the patient 116 at the spatial location. In some embodiments, the control system 106 may transform the image data signal using a mathematical transform, such as a Fourier transform, to mathematically transform the image data signal into an anatomical image of the patient 116. In these embodiments, the Fourier transform enables the image data signal to be decomposed into a combination of sine waves of different frequencies, phases, and amplitudes that can be used to generate an anatomical image of the patient 116, as would be recognized by those skilled in the art without departing from the spirit and scope of the present disclosure.

[0016] The administrative workstation 108 may display one or more of the anatomical images of the patient 116 generated by the control system 106. In some embodiments, the administrative workstation 108 may be used to change the characteristics of the anatomical images of the patient 116, such as, by way of example, windowing and / or magnification; to reformat one or more of the anatomical images of the patient 116; or to further process one or more of the anatomical images of the patient 116 to display a particular view of the patient 116 from the anatomical images of the patient 116. In some embodiments, the administrative workstation 108 may be installed within a dedicated location within the imaging system 100 that is electrically and / or magnetically isolated from the imaging machine 104 and / or the control system 106.

[0017] In an exemplary aspect illustrated in FIG. 1, the image quality of the anatomical images generated by the control system 106, such as contrast and spatial resolution, may be sub-optimal due to one or more physiological events of the patient 116, such as the heartbeat and / or respiration of the patient 116. In the exemplary aspect illustrated in FIG. 1, the control system 106 may implement one or more gating techniques, such as prospective gating techniques that are cardiac gating and / or respiratory gating, and / or retrospective gating techniques, to improve the image quality of the anatomical images. The one or more gating techniques utilize the one or more physiological events of the patient 116 to trigger the imaging machine 104 to image the patient 116 at a specific point in time, for example, to improve the temporal resolution of the anatomical images and / or to minimize imaging artifacts caused by the one or more physiological events of the patient 116, thereby improving the image quality of the anatomical images. For example, the control system 106 may trigger the imaging machine 104 to image the patient 116 during a specific portion of the cardiac cycle, such as diastole when the ventricles are passively filled, when performing cardiac gating. As another example, the control system 106 may predict the phase of the respiratory cycle of the patient 116 while the patient 116 is breathing freely when performing respiratory gating, which may improve the contrast and spatial resolution of the anatomical images.

[0018] As illustrated in FIG. 1, one or more sensors 118 may be placed on patient 116 to provide one or more physiological event signals that can be used to measure the one or more physiological events of patient 116. In some embodiments, the one or more sensors 118 may include one or more cardiac activity electrodes placed on the chest, wrists, and / or legs of patient 116 to provide one or more electrocardiogram (ECG) signals that are accompanied by characteristic P waves, Q waves, R waves, S waves, T waves, and U waves, as well as any other signal deflections represented in a given waveform, along with the associated QRS complex. In these embodiments, control system 106 may measure the electrical activity of patient 116's heart based on the one or more ECG signals, as would be recognized by those skilled in the art without departing from the spirit and scope of the present disclosure. In some embodiments, the one or more sensors 118 may include a pulse oximeter placed on one of patient 116's fingers to provide a photoplethysmogram (PPG) signal. In these embodiments, control system 106 may measure the heart rate of patient 116 based on the PPG signal, as would be recognized by those skilled in the art without departing from the spirit and scope of the present disclosure. In some embodiments, the one or more sensors 118 may include a respiratory sensor, such as a chest belt, bellows, or cushion, placed around the abdomen and / or chest of patient 116 to provide a respiration (RESP) signal. In these embodiments, control system 106 may measure the respiratory expansion of patient 116's abdomen and / or chest based on the RESP signal, as would be recognized by those skilled in the art without departing from the spirit and scope of the present disclosure. In the exemplary embodiment illustrated in FIG. 1, control system 106 may utilize the one or more ECG signals, PPG signals, and / or RESP signals to trigger imaging machine 104 according to various prospective gating techniques that would be recognized by those skilled in the art without departing from the spirit and scope of the present disclosure.

[0019] The one or more physiological event signals may be transmitted to the gating signal transmitter 110 using one or more lead wires 120. In some embodiments, the one or more lead wires 120 may be implemented as simple conductors such as, by way of example, tin, copper, and / or silver, or as more complex conductors shielded using, by way of example, polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), thermoplastic elastomer (TPE), thermoplastic rubber (TPR), thermoplastic polyurethane (TPU), fluorinated ethylene propylene (FEP), and / or ethylene-tetrafluoroethylene (ETFE). In an exemplary embodiment illustrated in FIG. 1, the gradient magnetic field pulses and / or radio frequency pulses used by the imaging machine 104 may interfere with the one or more physiological event signals. In some embodiments, the gradient magnetic field pulses and / or radio frequency pulses may introduce gradient pulse interference and / or signal offsets, such as common mode offsets, into the one or more physiological event signals. In these embodiments, the gradient magnetic field pulses may couple onto the one or more lead wires 120 when the one or more physiological event signals are transmitted by the one or more lead wires 120. In these embodiments, the radio frequency pulses may be demodulated and become common mode interference, which may affect the bus and / or high impedance circuit nodes of the imaging system 100 and introduce unwanted noise, such as, by way of example, amplitude modulation (AM) noise, into the one or more physiological event signals.

[0020] In an exemplary aspect illustrated in FIG. 1, the gating signal transmitter 110 compensates for interference introduced onto the one or more physiological event signals by a gradient magnetic field pulse and / or a radio frequency pulse. In some aspects, the gating signal transmitter 110 may process the one or more physiological event signals to reduce interference introduced onto the one or more physiological event signals by a gradient magnetic field pulse and / or a radio frequency pulse, such as, by way of example and not limitation, gradient pulse interference and / or signal offset. In some aspects, as will be described in more detail below, the gating signal transmitter 110 may compensate for gradient pulse interference. In these aspects, the gating signal transmitter 110 may use non-linear separation techniques, such as, by way of example and not limitation, a median filter, an average value filter, a wavelet filter or a ranklet filter, a phase detector, a frequency mixer, an oscillator, a modulator, or any combination thereof, to reduce gradient pulse interference. In some aspects, as will be described in more detail below, the gating signal transmitter 110 may compensate for signal offset. In these aspects, the gating signal transmitter 110 may evaluate an interference cost function, to be described in more detail below, to reduce signal offset. As illustrated in FIG. 1, the gating signal transmitter 110 provides the one or more physiological event signals to a gating signal receiver 112 for delivery to a control system 106. In some aspects, the gating signal receiver 112 may be implemented as a stand-alone or discrete device, as illustrated in FIG. 1, and / or may be incorporated into or coupled to the control system 106. Exemplary aspects of the gating signal transmitter 110 and the gating signal receiver 112 will be described in more detail below.

[0021] Exemplary Physiological Event Signals within an Exemplary MRI Imaging System FIG. 2 illustrates various signals within an exemplary MRI imaging system according to some exemplary aspects of the present disclosure. As described above, in order to provide an electrocardiogram (ECG) signal 200 as illustrated in FIG. 2, cardiac activity electrodes may be placed on the chest, wrists, and / or legs of a patient, such as patient 116, as described above with respect to FIG. 1. The ECG signal 200 represents a clean ECG signal that is free from interference from the gradient magnetic field pulses and / or radio frequency pulses being used to image the patient, as illustrated in FIG. 2. In the exemplary aspect illustrated in FIG. 2, interference from the gradient magnetic field pulses and / or radio frequency pulses is illustrated as an unwanted noise signal 210. As illustrated in FIG. 2, the unwanted noise signal 210 may include a low-speed gradient interference pulse 212 resulting from the switching of the gradient magnetic field pulses, and a high-speed gradient interference pulse 214 resulting from the switching of the radio frequency pulses. In some aspects, the low-speed gradient interference pulse 212 and / or the high-speed gradient interference pulse 214 may introduce gradient pulse interference and / or a signal offset into the ECG signal 200 in a manner substantially similar to that described above with respect to FIG. 1, to provide a noisy ECG signal 220. In some aspects, the noisy ECG signal 220 may include, for example, high-speed pulses having a duration of about 0.1 milliseconds (ms) to about 4 ms, and / or long signal offsets, such as, for example, about 50 milliseconds (ms) to about 200 ms, superimposed on the ECG signal 200.

[0022] Exemplary Gating Transmitter that can be Implemented within an Exemplary MRI Imaging System FIG. 3 illustrates a block diagram of an exemplary gating transmitter that may be implemented within an exemplary MRI imaging system in accordance with some illustrative aspects of the present disclosure. Gradient magnetic field pulses and / or radio frequency pulses used by an imaging machine such as the imaging machine 104 described above with respect to FIG. 1 may interfere with one or more physiological event signals used to measure one or more physiological events of a patient in a manner substantially similar to that described above with respect to FIGS. 1 and 2. As will be described in more detail below, the gating signal transmitter 300 can compensate for interference introduced onto the one or more physiological event signals by the gradient magnetic field pulses and / or radio frequency pulses. As illustrated in FIG. 3, the gating signal transmitter 300 may include an analog processing circuitry 302, an analog-to-digital (ADC) converter 304, a digital processing circuitry 306, and / or a communication transmitter 308. In some aspects, the gating signal transmitter 300 may represent an exemplary aspect of the gating signal transmitter 110 described above with respect to FIG. 1.

[0023] The analog processing circuitry 302 may process the noisy physiological event signal 350 in the analog signal domain, e.g., through amplification and / or signal conditioning, to provide the processed physiological event signal to the ADC 304. As illustrated in FIG. 3, the noisy physiological event signal 350 may include an electrocardiogram (ECG) signal 350.1, a photoplethysmogram (PPG) signal 350.2, and a respiration (RESP) signal 350.3. In some aspects, the ECG signal 350.1, the PPG signal 350.2, and / or the RESP signal 350.3 may be generated by placing one or more sensors, such as one or more of the sensors 118 described above with respect to FIG. 1, on a patient, such as the patient 116 described above with respect to FIG. 1, in substantially the same manner as described above with respect to FIG. 1. In these aspects, one or more lead wires, such as one or more of the lead wires 120 described above with respect to FIG. 1, may be connected between the one or more sensors and the analog processing circuitry 302 to transmit the ECG signal 350.1, the PPG signal 350.2, and / or the RESP signal 350.3 to the analog processing circuitry 302. In some aspects, the ECG signal 350.1 may be characterized as a relatively fast electrical signal, the PPG signal 350.2 may be characterized as a relatively slow electrical signal, and the RESP signal 350.3 may be characterized as an optical signal. In these aspects, it may be assumed that the PPG signal 350.2 and / or the RESP signal 350.3 are not affected by interference from gradient magnetic field pulses and / or radio frequency pulses as compared to the ECG signal 350.1. Therefore, the gating signal transmitter 300 compensates for interference from gradient magnetic field pulses and / or radio frequency pulses introduced into the ECG signal 350.1, as will be described in more detail below.However, as will be understood by those skilled in the art, the teachings described herein for compensating for interference from gradient magnetic field pulses and / or radio frequency pulses introduced into the ECG signal 350.1 are equally applicable to compensating for interference from gradient magnetic field pulses and / or radio frequency pulses introduced into the PPG signal 350.2 and / or the RESP signal 350.3 without departing from the spirit and scope of the present disclosure. In some embodiments, the ECG signal 350.1, the PPG signal 350.2, and / or the RESP signal 350.3 may represent one or more differential signals.

[0024] The analog processing circuit network 302 includes an ECG analog front end (AFE) 310.1, a PPG AFE 310.2, and a RESP AFE 310.3 for receiving an ECG signal 350.1, a PPG signal 350.2, and a RESP signal 350.3, respectively. In an exemplary embodiment illustrated in FIG. 3, the ECG AFE 310.1, the PPG AFE 310.2, and the RESP AFE 310.3 may process the ECG signal 350.1, the PPG signal 350.2, and the RESP signal 350.3, respectively, in the analog signal domain, for example, through amplification and / or signal conditioning. In some embodiments, the ECG AFE 310.1, the PPG AFE 310.2, and / or the RESP AFE 310.3 may include a signal converter, such as an opto - electrical converter, for converting the ECG signal 350.1, the PPG signal 350.2, and / or the RESP signal 350.3 into an electrical signal. In some embodiments, the ECG AFE 310.1, the PPG AFE 310.2, and the RESP AFE 310.3 may each include various amplifiers, such as operational amplifiers (op - amps) and / or differential amplifiers, for amplifying the ECG signal 350.1, the PPG signal 350.2, and the RESP signal 350.3, respectively. In some embodiments, the ECG AFE 310.1, the PPG AFE 310.2, and the RESP AFE 310.3 may each include various filters, such as low - pass filters, band - pass filters, high - pass filters, and / or anti - aliasing filters, for conditioning the ECG signal 350.1, the PPG signal 350.2, and the RESP signal 350.3, respectively.

[0025] In some embodiments, the ECG AFE 310.1, the PPG AFE 310.2, and / or the RESP AFE 310.3 may process the ECG signal 350.1, the PPG signal 350.2, and the RESP signal 350.3, respectively, in different ways in the analog signal domain. For example, the ECG AFE 310.1 may include an anti-aliasing filter having a bandwidth of about 1 kilohertz (kHz) coupled to an amplifier having a gain of 1, also referred to as a buffer amplifier. The 1 kHz bandwidth of the anti-aliasing filter is sufficient to capture interference from gradient magnetic field pulses and / or radio frequency pulses introduced into the ECG signal 350.1. As another example, the PPG AFE 310.2 may include a first-order bandpass filter having a bandwidth of about 500 hertz (Hz) to about 10 kHz coupled to an amplifier having a gain of about 1000, which is in turn coupled to a third-order low-pass filter having a bandwidth of about 12 Hz. As a further example, the RESP AFE 310.3 may include a first-order low-pass filter having a bandwidth of about 7 Hz coupled to an amplifier having a gain of about 1000, which is in turn coupled to a second-order low-pass filter having a bandwidth of about 5 Hz. The 7 Hz bandwidth of the first-order low-pass filter and the 5 Hz bandwidth of the second-order low-pass filter are sufficient to remove interference from gradient magnetic field pulses and / or radio frequency pulses introduced into the RESP signal 350.3. In some embodiments, the ECG AFE 310.1, the PPG AFE 310.2, and the RESP AFE 310.3 may include various radio frequency interference (RFI) and / or electrostatic discharge (ESD) circuitry to protect the ECG AFE 310.1, the PPG AFE 310.2, and the RESP AFE 310.3 from RFI and / or ESD events. In these embodiments, the RFI and / or ESD circuitry may be implemented using analog circuits and / or circuitry for protecting the ECG AFE 310.1, the PPG AFE 310.2, and the RESP AFE 310.3 from RFI and / or ESD events that would be apparent to those of ordinary skill in the art without departing from the spirit and scope of the present disclosure.

[0026] The ADC 304 converts the processed physiological event signal received from the analog processing circuitry 302 from the analog signal domain to the digital signal domain in order to provide the digital physiological event signal to the digital processing circuitry 306. In an exemplary aspect illustrated in FIG. 3, the ADC 304 includes ADCs 312.1, 312.2, and 312.3. In some aspects, ADCs 312.1, 312.2, and / or 312.3 may be implemented as stand-alone or discrete devices and / or may be incorporated into or coupled to the digital processing circuitry 306. As will be described in more detail below, the digital processing circuitry 306 may be implemented using a dedicated processor chip, such as, by way of example, a digital signal processor (DSP) or an application specific integrated circuit (ASIC). In some aspects, the dedicated processor chip may include an on-chip ADC. In these aspects, ADCs 312.1, 312.2, and / or 312.3 may be implemented as discrete devices within the gating signal transmitter 300 and / or using the on-chip ADC of the dedicated processor chip.

[0027] ADC 312.1, ADC 312.2, and ADC 312.3 each convert the processed ECG signal provided by ECG AFE 310.1, the processed PPG signal provided by PPG AFE 310.2, and the processed RESP signal provided by RESP AFE 310.3 from the analog signal domain to the digital signal domain. In some embodiments, ADC 312.1, ADC 312.2, and / or ADC 312.3 may each be implemented as a wideband ADC having a sampling rate of, for example, approximately 8 kHz to capture interference introduced into ECG signal 350.1, PPG signal 350.2, and RESP signal 350.3. In an exemplary embodiment illustrated in FIG. 3, ADC 312.1 may be implemented as a wideband ADC having a higher sampling rate compared to the sampling rates of ADC 312.2 and ADC 312.3, for example, approximately 1 kHz. In some embodiments, ADC 312.1, ADC 312.2, and / or ADC 312.3 may be implemented with different resolutions. For example, ADC 312.1 may be implemented with a resolution of 24 bits compared to the resolutions of ADC 312.2 and ADC 312.3, for example, 12 bits. In some embodiments, interference from gradient magnetic field pulses and / or radio frequency pulses introduced into ECG signal 350.1 may be significantly larger compared to ECG signal 350.1 itself. In these embodiments, the higher resolution of ADC 312.1 compared to ADC 312.2 and ADC 312.3 enables ADC 312.1 to adequately sample ECG signal 350.1 to capture interference from gradient magnetic field pulses and / or radio frequency pulses introduced into ECG signal 350.1.

[0028] The digital processing circuitry network 306 may process the digital physiological event signal received from the ADC 304 in the digital signal domain, for example, through signal conditioning, to provide a clean physiological event signal to the communication transmitter 308. In an exemplary embodiment illustrated in FIG. 3, the digital processing circuitry network 306 includes a gradient offset filter 314, a gradient blocking filter 316, a digital filter 318, a downsampler 320, and a combination circuitry network 322. In some embodiments, the gradient offset filter 314, the gradient blocking filter 316, the digital filter 318, the downsampler 320, and the combination circuitry network 322 may be implemented as stand-alone or discrete devices within the digital processing circuitry network 306 and / or may be incorporated into or coupled to a dedicated processor chip as described above.

[0029] In some embodiments, as described above, it can be assumed that the PPG signal 350.2 and / or the RESP signal 350.3 are not affected by interference from gradient magnetic field pulses and / or radio frequency pulses as compared to the ECG signal 350.1. In these embodiments, the digital PPG signal and the digital RESP signal received from the ADC 312.2 and the ADC 312.3 respectively represent clean signals that are not significantly affected by interference from gradient magnetic field pulses and / or radio frequency pulses. In these embodiments, as will be described in more detail below, the digital processing circuitry network 306 may process the digital ECG signal received from the ADC 312.1 in the digital signal domain, for example, through signal conditioning, to provide a clean ECG signal free from interference from gradient magnetic field pulses and / or radio frequency pulses.

[0030] Gradient offset filter 314 may compensate for signal offsets, such as common mode offsets, introduced into the ECG signal 350.1 by gradient magnetic field pulses and / or radio frequency pulses. In some aspects, gradient offset filter 314 may process samples of the digital ECG signal provided by ADC 312.1 in the digital signal domain to reduce signal offsets introduced into the ECG signal 350.1 by gradient magnetic field pulses and / or radio frequency pulses. In some aspects, gradient offset filter 314 accumulates samples of the digital ECG signal provided by ADC 312.1 over an interference time window. In these aspects, the interference time window has a duration of, for example, about 2 ms. In some aspects, gradient offset filter 314 evaluates samples of the digital ECG signal provided by ADC 312.1 accumulated in each time interference window according to an interference cost function to identify samples in each time interference window that best represent the ECG signal 350.1. In these aspects, the interference cost function may evaluate the volatility of samples of the digital ECG signal provided by ADC 312.1, the direction change of samples of the digital ECG signal provided by ADC 312.1, and / or the offset between samples of the digital ECG signal provided by ADC 312.1 for each time interference window to identify samples with the lowest cost that best represent the ECG signal 350.1 without interference from gradient magnetic field pulses and / or radio frequency pulses. An exemplary aspect of gradient offset filter 314 will be described in more detail below with respect to FIG. 4.

[0031] Gradient rejection filter 316 may compensate for gradient pulse interference introduced into the ECG signal 350.1 by gradient magnetic field pulses and / or radio frequency pulses. In some embodiments, gradient rejection filter 316 may process samples of the digital ECG signal provided by gradient offset filter 314 in the digital signal domain to reduce gradient pulse interference introduced into the ECG signal 350.1 by gradient magnetic field pulses and / or radio frequency pulses. In some embodiments, gradient rejection filter 316 may use a non-linear separation technique, such as, for example, a digital median filter, on samples of the digital ECG signal provided by gradient offset filter 314 to compensate for gradient pulse interference. In some embodiments, gradient pulse interference may be characterized as impulse noise, such as, for example, salt-and-pepper noise or speckle noise, that can be compensated for by gradient rejection filter 316. In some embodiments that use, for example, a median filter, the median filter may analyze adjacent samples out of the samples from the ECG signal provided by gradient offset filter 314 to determine a median value of these samples, which is also referred to as a median window. In these embodiments, the median filter may use the median value of the median window in place of that sample. The median filter may iteratively advance the median window to other samples of the ECG signal provided by gradient offset filter 314 to compensate for gradient pulse interference.

[0032] The digital filter 318 further filters the digital ECG signal received from the gradient rejection filter 316. In some embodiments, the digital filter 318 may be characterized as a linear filter, a causal filter, a non-causal filter, a time-invariant filter, a stable filter, an unstable filter, a finite impulse response (FIR) filter, and / or any other type of digital filter that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. The digital filter 318 may include a digital low-pass filter, a digital high-pass filter, a digital band-pass filter, a digital band-stop filter, and / or any other digital filter topology that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In some embodiments, the digital filter 318 may remove high-frequency noise, such as impulse noise, flicker noise, and / or white noise, for example, above 150 Hz, from the digital ECG signal received from the gradient rejection filter 316. In some embodiments, the digital filter 318 is optional.

[0033] The downsampler 320 samples the digital ECG signal received from the gradient rejection filter 316, or the digital ECG signal received from the digital filter 318, to the sampling rate of ADC 312.1 and / or ADC 312.2. In some embodiments, the downsampler 320 downsamples the sampling rate of the digital ECG signal received from the gradient rejection filter 316, or the digital ECG signal received from the digital filter 318, for example, 8 kHz, to match the sampling rate of the digital PPG signal received from ADC 312.2, and / or the digital RESP signal received from ADC 312.3, for example, 1 kHz. In some embodiments, the downsampler 320 is optional, such as when the sampling rates of ADC 312.1, ADC 312.2, and ADC 312.3 are the same.

[0034] The combination circuit network 322 combines the digital ECG signal received from the gradient blocking filter 316, the digital filter 318, or the downsampler 320; the digital PPG signal received from the ADC 312.2; and the digital RESP signal received from the ADC 312.3 to provide a physiological event signal for transmission. In some embodiments, the combination circuit network 322 may be implemented as a digital adder, such as a full adder, a half adder, a carry-propagate adder, a carry-lookahead adder, a carry-save adder, a quantum full adder, and / or any other suitable digital circuit capable of combining digital signals that would be apparent to those skilled in the art without departing from the spirit and scope of the present disclosure.

[0035] The communication transmitter 308 formats the physiological event signal from the combination circuitry 322 to provide a clean physiological event signal 352 for transmission to a communication receiver such as the gating signal receiver 112 described above with respect to FIG. 1. In some aspects, the communication transmitter 308 may communicate the clean physiological event signal 352 over a wireless communication network, a wired communication network, and / or any combination thereof that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In these aspects, the wireless communication network may be, for example, one version of Institute of Electrical and Electronics Engineers (I.E.E.E.) 802.11, collectively referred to as Wi-Fi, such as 802.11a, 802.11b / g / n, 802.11h, and / or 802.11ac; one version of the Bluetooth communication standard; and / or any other wireless communication standard or protocol that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In these aspects, the wired communication network may be, for example, one version of a standard or protocol such as IEEE 802.10, also known as Ethernet; and / or any other wired communication standard or protocol that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure.

[0036] Exemplary Gradient Offset Filter that can be Implemented within an Exemplary Gating Transmitter FIG. 4 illustrates a block diagram of an exemplary gradient offset filter that may be implemented within an exemplary gating transmitter according to some exemplary aspects of the present disclosure. The gradient magnetic field pulses and / or radio frequency pulses used by an imaging machine such as the imaging machine 104 described above with respect to FIG. 1 may interfere with one or more physiological event signals used to measure one or more physiological events of a patient in a substantially similar manner as described above with respect to FIGS. 1-3. In some aspects, the gradient magnetic field pulses and / or radio frequency pulses may introduce a signal offset, such as a common mode offset, into the one or more physiological event signals. In these aspects, the signal offset may be from about 50 milliseconds (ms) to about 200 ms. As will be described in more detail below, the gradient offset filter 400 may compensate for the signal offset introduced onto the one or more physiological event signals by the gradient magnetic field pulses and / or radio frequency pulses. In some aspects, the gradient offset filter 400 may evaluate an interference cost function to identify samples of the one or more physiological event signals that best represent the one or more physiological event signals without interference from the gradient magnetic field pulses and / or radio frequency pulses. In these aspects, the interference cost function may evaluate the volatility of samples of the one or more physiological event signals, the change in direction of samples of the one or more physiological event signals, and / or the offset between samples of the one or more physiological event signals to identify samples that best represent the one or more physiological event signals without interference from the gradient magnetic field pulses and / or radio frequency pulses.

[0037] As illustrated in FIG. 4, the gradient offset filter 400 may include a sample queue 402, a statistical module 404, digital adder circuits 406-410, a monotonicity module 412, a cost function module 414, and a cost analysis module 416. As used herein, references to "module" are to be understood as including at least one of software; firmware; hardware such as one or more circuits, microchips, and / or electronic devices, to name a few; and / or any combination thereof. In some embodiments, the sample queue 402, the statistical module 404, the digital adder circuits 406-410, the monotonicity module 412, the cost function module 414, and / or the cost analysis module 416 may be implemented as discrete devices within the gradient offset filter 400 and / or may be incorporated within a dedicated processor chip as described above. In some embodiments, the gradient offset filter 400 may represent an exemplary embodiment of the gradient offset filter 314 described above with respect to FIG. 3.

[0038] The sample queue 402 accumulates samples of the digital ECG signal 450, such as the digital ECG signal provided by the ADC 312.1 described above with respect to FIG. 3 for example. The following description of FIG. 4 is explained in terms of the ECG signal, but those skilled in the art will recognize that the teachings herein are equally applicable to compensating for signal offsets introduced onto PPG signals and / or RESP signals by gradient magnetic field pulses and / or radio frequency pulses without departing from the spirit and scope of the present disclosure. In the exemplary embodiment illustrated in FIG. 4, the sample queue 402 accumulates N samples of the digital ECG signal 450 over an interference time window, for example, a group of samples of the digital ECG signal provided by the ADC 312.1. In these embodiments, the interference time window has a duration of, for example, about 2 ms. In some embodiments, the sample queue 402 may be implemented as one or more first-in-first-out (FIFO) queues, one or more circular buffers, and / or any other suitable architecture that would be apparent to those skilled in the art without departing from the spirit and scope of the present disclosure.

[0039] The statistical module 404 calculates one or more statistical measurements of the samples of the digital ECG signal 450 accumulated in the sample queue 402. In some embodiments, the one or more statistical measurements may include, for example, moving mean, moving median, moving average, root mean square, root mean square of the moving average, moving variance, and / or moving norm of the samples of the digital ECG signal 450 accumulated in the sample queue 402. In some embodiments, the statistical module 404 calculates one or more statistical measurements of the samples of the digital ECG signal 450 accumulated in the sample queue 402 during the interference time window.

[0040] Digital adder circuits 406-410 combine various samples of the digital ECG signal 450 stored in sample queue 402 and / or one or more of the statistical measurements provided by statistical module 404 to provide various input signals to monotonicity module 412 and / or cost function module 414. In an exemplary aspect illustrated in FIG. 4, digital adder circuit 406 subtracts the i-th sample of the digital ECG signal 450 stored in sample queue 402 from one or more of the statistical measurements, such as a moving average, to provide an offset signal (OFFSET) to cost function module 414. In some aspects, the offset signal represents the deviation or offset of the i-th sample from one or more of the statistical measurements, such as a moving average, provided by statistical module 404. In an exemplary aspect illustrated in FIG. 4, digital adder circuit 408 subtracts the (i+1)-th sample of the digital ECG signal 450 from the i-th sample of the digital ECG signal 450 stored in sample queue 402, and digital adder circuit 410 subtracts the (i+2)-th sample of the digital ECG signal 450 from the (i+1)-th sample of the digital ECG signal 450 stored in sample queue 402 to provide a first derivative signal (DV_0) and a second derivative signal (DV_1), respectively, to monotonicity module 412 and cost function module 414. In some aspects, the first derivative signal and the second derivative signal can be used to indicate the trend of the samples of the digital ECG signal 450 stored in sample queue 402, e.g., whether these samples are increasing, decreasing, and / or changing direction.

[0041] The monotonicity module 412 determines the monotonicity of the samples of the digital ECG signal 450 accumulated in the sample queue 402, i.e., whether these samples are increasing, decreasing, and / or changing direction. In some embodiments, the interference time window may be of sufficient duration to capture the interference introduced onto the digital ECG signal 450 by a plurality of gradient magnetic field pulses and / or radio frequency pulses. In these embodiments, when the (i + 2)-th sample from the i-th sample of the digital ECG signal 450 is decreasing, these samples indicate the presence of a single gradient magnetic field pulse and / or radio frequency pulse. In these embodiments, when the (i + 2)-th sample from the i-th sample of the digital ECG signal 450 is changing direction, these samples indicate the presence of a plurality of gradient magnetic field pulses and / or radio frequency pulses. In an exemplary embodiment illustrated in FIG. 4, when the sign of the first derivative signal (DV_0) is not equal to the sign of the second derivative signal (DV_1), the monotonicity module 412 determines that the (i + 2)-th sample from the i-th sample of the digital ECG signal 450 is changing direction. As illustrated in FIG. 4, the monotonicity module 412 provides a monotonicity signal (MONO) having different integer values to the cost function module 414 based on whether the (i + 2)-th sample from the i-th sample of the digital ECG signal 450 is changing direction. In some embodiments, when the (i + 2)-th sample from the i-th sample of the digital ECG signal 450 is changing direction, the monotonicity module 412 sets the monotonicity signal to a relatively large integer value, e.g., 10. In these embodiments, that relatively large integer value is selectively chosen to effectively exclude the i-th sample of the digital ECG signal 450 so that it is not selected as the sample that best represents the digital ECG signal 450 without interference from gradient magnetic field pulses and / or radio frequency pulses. In some embodiments, when the (i + 2)-th sample from the i-th sample of the digital ECG signal 450 is not changing direction, the monotonicity module 412 sets the monotonicity signal to a relatively small integer value, e.g., 1.In these embodiments, the relatively small integer value is selectively chosen to effectively enable the i-th sample of the digital ECG signal 450 to be selected as the sample that best represents the digital ECG signal 450 without interference from the gradient magnetic field pulse and / or the radio frequency pulse.

[0042] The cost function module 414 may implement an interference cost function that maps the i-th sample of the digital ECG signal 450 onto a real number (weight (WEIGHT)) representing the estimated difference between the digital ECG signal 450 and the digital ECG signal 450 without interference from the gradient magnetic field pulse and / or the radio frequency pulse. In some embodiments, the interference cost function may evaluate the volatility of the samples of the digital ECG signal 450, the change in direction of the samples of the digital ECG signal 450, and / or the offset between the samples of the digital ECG signal 450. In these embodiments, the interference cost function may be represented by the following equation: Weight = ((|DV_0| + |DV_1| * MONO) + |offset|) (1) In the above equation, the weight represents the estimated difference described above, |DV_0| and |DV_1| represent the absolute values of the first derivative signal and the second derivative signal respectively, MONO represents the monotonicity signal, and |offset| represents the absolute value of the offset signal. Similarly, as an illustrative example, a general cost function may be useful in some cases with weighting factors such as derivative signals, offset signals, or monotonicity signals. Therefore, in some use cases, (a * x + b * y + c * z) may represent the cost function, where x, y, and z represent the derivative signal, the offset signal, and the monotonicity signal respectively, and a, b, and c represent weights that may have different values for each signal.

[0043] The cost analysis module 416 analyzes the weights for samples of the digital ECG signal 450 to identify samples of the digital ECG signal 450 that best represent the digital ECG signal 450 without interference from gradient magnetic field pulses and / or radio frequency pulses. In some embodiments, the cost analysis module 416 analyzes the weights for samples of the digital ECG signal 450 within a time interference window to identify samples of the digital ECG signal 450 within the time interference window that best represent the digital ECG signal 450 without interference from gradient magnetic field pulses and / or radio frequency pulses. In some embodiments, the cost analysis module 416 analyzes the weights for samples of the digital ECG signal 450 to identify, as the one that best represents the digital ECG signal 450 without interference from gradient magnetic field pulses and / or radio frequency pulses within the time interference window, the sample of the digital ECG signal 450 within the time interference window that has the minimum weight. In these embodiments, the cost analysis module 416 accumulates the weights for samples of the digital ECG signal 450 within the time interference window and selects, as the sample of the digital ECG signal 450 within the time interference window that best represents the digital ECG signal 450 without interference from gradient magnetic field pulses and / or radio frequency pulses within the time interference window, the sample of the digital ECG signal 450 within the time interference window that has the minimum weight.

[0044] In some embodiments, rather than using a cost function with a sliding window, the gradient offset filter may be implemented using a selection filter or an algorithm therefor. Such algorithms that emphasize selection based on the derived signal and the offset criterion, as opposed to retaining the best sample within the sliding window, may reduce the complexity in implementation and may also provide other advantages such as efficiency improvement and reduction of computational overhead. Thus, the selection filter algorithm may be desirable for implementation in, for example, certain low-power embedded systems.

[0045] For an exemplary selection filter, in a manner similar to that described elsewhere in this specification, an offset signal may represent the deviation or offset of the i-th sample from one or more statistical measurements, such as a moving average, etc., which may be provided by a statistical module or its equivalent. In one aspect, a digital adder circuit or its equivalent may subtract the (i - 1)-th sample of the digital ECG signal 450, accumulated within a sample queue or within any smaller memory, such as a circular buffer, etc., from the i-th sample of the digital ECG signal 450 to provide a first derived signal (DV_0). Further, that adder circuit or its equivalent may subtract the (i - 2)-th sample of the digital ECG signal 450, accumulated within the sample queue or buffer, from the i-th sample of the digital ECG signal 450 to provide a second derived signal (DV_1). Similar to other aspects described elsewhere in this specification, the first and second derived signals may be useful for indicating trends in the samples of the corresponding digital ECG signal 450, such as whether these samples are increasing, decreasing, and / or changing direction.

[0046] Thus, in some aspects, a selection filter may be used to select a sample as an acceptable output if certain conditions are met with respect to a selection criterion. For example, as predefined values related to the selection criterion, an offset reference value (REF) and a derived limit (DV_LIMIT) may be set. A sample, such as the i-th sample from the one or more statistical measurements, may be evaluated for any or all of the conditions specified by the predefined selection criterion. These conditions may include, by way of example, each of |DV_0| and |DV_1| being less than DV_LIMIT, and an offset value defined by the difference between the sample value and the offset reference value (e.g., BUF[i] - REF; where "i" refers to the position of the i-th sample stored within the buffer vector or array BUF[]).

[0047] As a result of performing these calculations on the selection filter, outliers may be rejected while more reliable samples may be retained; this also facilitates implementation and improves computational efficiency. Other advantages of this embodiment and its equivalents are readily recognized, and other embodiments may be contemplated to achieve other trade - offs within the various constraints of other computing devices such as, for example, embedded systems. The examples provided herein are not intended to be exhaustive but are illustrative in the context of rejecting a particular offset, outlier, or gradient trend in specific sample data.

[0048] Exemplary Gating Receiver that can be Implemented within an Exemplary MRI Imaging System FIG. 5 illustrates a block diagram of an exemplary gating receiver that may be implemented within an exemplary MRI imaging system based on some exemplary aspects of the present disclosure. As will be described in more detail below, the gating signal receiver 500 may recover a physiological event signal provided by a gating signal transmitter such as the gating signal transmitter 110 described above with respect to FIG. 1. In some aspects, the gating signal receiver 500 may generate various clocking signals, such as a triggering signal, for example, that can be used to synchronize the physiological event signal to one or more physiological events of a patient, such as the patient's heartbeat and / or respiration, from these physiological event signals. In the exemplary aspect illustrated in FIG. 5, the gating signal receiver 500 may include a communication receiver 502, an analog processing circuitry 504, a trigger generation circuitry 506, and a communication transmitter 508.

[0049] The communication receiver 502 may receive one or more physiological event signals 550 provided by the gating signal transmitter. In some embodiments, the one or more physiological event signals 550 may include an ECG signal, a PPG signal, and / or a RESP signal. In these embodiments, the communication receiver 502 may recover an ECG signal, a PPG signal, and / or a RESP signal from the one or more physiological event signals 550. In some embodiments, the communication receiver 502 may receive the one or more physiological event signals 550 over a wireless communication network, a wired communication network, and / or any combination thereof that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In these embodiments, the wireless communication network may comply with, for example, one version of the Wi-Fi communication standard; one version of the Bluetooth communication standard; and / or any other wireless communication standard or protocol that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In these embodiments, the wired communication network may comply with, for example, one version of the Ethernet communication standard; and / or any other wired communication standard or protocol that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure.

[0050] The analog processing circuit network 504 may process the one or more physiological event signals 550 in the analog signal domain, for example, through amplification and / or signal conditioning, to provide the processed physiological event signals to the ADC 304. In some embodiments, the analog processing circuit network 504 may include one or more analog filters for parsing or separating the ECG signal, PPG signal, and / or RESP signal from each other. In some embodiments, the one or more analog filters may include an analog low-pass filter, an analog high-pass filter, an analog band-pass filter, an analog band-stop filter, and / or any other analog filter topology that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. For example, the one or more analog filters may include a high-pass filter having a cutoff between about 0.1 Hz and a low-pass filter having a cutoff between about 10 Hz to separate the ECG signal from the PPG signal and the RESP signal. As another example, the one or more analog filters may include a high-pass filter having a cutoff between about 0.05 Hz and a low-pass filter having a cutoff between about 10 Hz to separate the PPG signal from the ECG signal and the RESP signal. As a further example, the one or more analog filters may include a high-pass filter having a cutoff between about 0.1 Hz and a low-pass filter having a cutoff between about 3 Hz to separate the ECG signal from the PPG signal and the RESP signal. In some embodiments, the analog processing circuit network 504 may include one or more automatic gain control (AGC) circuits to adjust the magnitude of the ECG signal, PPG signal, and / or RESP signal. In these embodiments, the one or more AGC circuits may adjust the magnitude of the ECG signal, PPG signal, and / or RESP signal to be substantially similar to each other.In some embodiments, the analog processing circuitry 504 may include a combination circuitry for combining ECG signals, PPG signals, and / or RESP signals for transmission to, for example, the MRI computer control system 106 described above with respect to FIG. 1.

[0051] The trigger generation circuitry 506 may process the one or more physiological event signals 550 in the analog signal domain, e.g., through amplification and / or signal conditioning, to provide one or more physiological event triggering signals. In some embodiments, the trigger generation circuitry 506 may include one or more analog filters for parsing or separating an ECG signal, a PPG signal, and / or a RESP signal from each other. In some embodiments, the one or more analog filters may include an analog low-pass filter, an analog high-pass filter, an analog band-pass filter, an analog band-stop filter, and / or any other analog filter topology that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. For example, the one or more analog filters may include a band-pass filter having a bandwidth of from about 2 Hz to about 30 Hz to separate an ECG signal from a PPG signal and a RESP signal. As another example, the one or more analog filters may include a band-pass filter having a bandwidth of from about 0.1 Hz to about 10 Hz to separate a PPG signal from an ECG signal and a RESP signal. As a further example, the one or more analog filters may include a band-pass filter having a bandwidth of from about 0.1 Hz to about 3 Hz to separate an ECG signal from a PPG signal and a RESP signal. In some embodiments, the trigger generation circuitry 506 may include one or more trigger circuits for generating the one or more physiological event triggering signals from an ECG signal, a PPG signal, and / or a RESP signal. In these embodiments, the one or more physiological event triggering signals may include an ECG trigger signal and a PPG trigger signal that can be used to synchronize the ECG signal and the PPG signal, respectively, to the patient's heartbeat as would be recognized by one of ordinary skill in the art without departing from the spirit and scope of the present disclosure.In these aspects, the one or more physiological event triggering signals may include a RESP trigger signal that can be used to synchronize the RESP signal with the patient's respiration, as would be recognized by one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In some aspects, the one or more trigger circuits may be characterized as converting ECG signals, PPG signals, and RESP signals from the analog signal domain to provide a triggering signal or a clocking signal in the digital signal domain. In some aspects, the trigger generation circuit network 506 may include a combination circuit network for combining an ECG trigger signal, a PPG trigger signal, and / or a RESP trigger signal for transmission to, for example, the MRI computer control system 106 described above with respect to FIG. 1.

[0052] The communication transmitter 508 formats the ECG signal, PPG signal, and / or RESP signal from the analog processing circuitry 504, and / or the ECG trigger signal, PPG trigger signal, and / or RESP trigger signal from the trigger generation circuitry 506 for transmission to a communication receiver that is internal to or coupled to, for example, the MRI computer control system 106 described above with respect to FIG. 1. In some aspects, the communication transmitter 508 may communicate these signals over a wireless communication network, a wired communication network, and / or any combination thereof that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In these aspects, the wireless communication network may comply with, for example, one version of the Wi-Fi communication standard; one version of the Bluetooth communication standard; and / or any other wireless communication standard or protocol that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In these aspects, the wired communication network may comply with, for example, one version of the Ethernet communication standard; and / or any other wired communication standard or protocol that would be apparent to one of ordinary skill in the art without departing from the spirit and scope of the present disclosure. In some aspects, the communication transmitter 508 may include a signal converter, such as an electro-optical converter, for converting signals from the analog processing circuitry 504 and / or signals from the trigger generation circuitry 506 into optical signals for transmission to the communication receiver.

[0053] Exemplary Computer System that can be Utilized to Implement Electronic Devices within an Exemplary MRI Imaging System FIG. 6 illustrates a simplified block diagram of a computer system suitable for use with the aspects described herein, in accordance with some exemplary aspects of the present disclosure. Various electronic devices, such as the MRI computer system 106 and / or the administrative workstation 108 described above with respect to FIG. 1, may be implemented in hardware, firmware, software, or any combination thereof. The description of FIG. 6 below describes an exemplary computer system 610 that can be used with these electronic devices.

[0054] In the exemplary aspect illustrated in FIG. 6, the computer system 610 typically includes at least one processor 614 that communicates with several peripheral devices via a bus subsystem 612. Typically, the at least one processor 614 is any one of or includes a microprocessor, a graphics processing unit, or a digital signal processor, and their electronic processing equivalents, such as an application specific integrated circuit (“ASIC”) or a field programmable gate array (“FPGA”). As used herein, the term “processor” refers to a physical data and information processing device that typically uses sequence conversion (also called “operation”) to physically transform data and information. The data and information may be physically represented by electrical, magnetic, optical, or acoustic signals that can be stored, accessed, transferred, combined, compared, or otherwise manipulated by the processor. The term “processor” may refer to a single processor and may potentially refer to a multi-core system or a multi-processor array, which includes a graphics processing unit, a digital signal processor, a digital processor, or a combination of these elements. The processor may be electronic, such as comprising a digital logic network (e.g., binary logic), or may be analog (e.g., an operational amplifier).

[0055] The processor may also access or host any application and / or data through any delivery paradigm, including but not limited to remote or distributed cloud computing solutions; local or on-premises software, and operate a client or server, and, in "cloud computing", or any "as a service" model (e.g., software as a service (SaaS), managed software as a service (MSaaS), platform as a service (PaaS), desktop as a service (DaaS), framework as a service (FaaS), backend as a service (BaaS), mobile backend as a service (MBaaS), infrastructure as a service (IaaS), database as a service (DBaaS), etc.), and / or any combination of the foregoing examples or other services or delivery paradigms, and support the performance of related operations according to a hybrid model.

[0056] As a further example, at least a portion of the operations may be performed by a group of processors available in a distributed or remote system, which processors are accessible via a communication network (e.g., the Internet) and via one or more software interfaces (e.g., application program interfaces (APIs)); such APIs include, without limitation, Document Object Model (DOM), Discovery Service (DS), NSUserDefaults, Web Services Description Language (WSDL), Message Exchange Pattern (MEP), Web Distributed Data Exchange (WDDX), Web Hypertext Application Technology Working Group (WHATWG), HTML5 Web Messaging, Representational State Transfer (REST or RESTful web services), Extensible User Interface Protocol (XUP), Simple Object Access Protocol (SOAP), XML Schema Definition (XSD), XML Remote Procedure Call (XML-RPC), or any other open or proprietary mechanism capable of achieving similar functions and results.

[0057] Any applicable data structure, file format, and schema may be derived from various standards; such standards include, without limitation, JavaScript Object Notation (JSON), Extensible Markup Language (XML), Yet Another Markup Language (YAML), Extensible Hypertext Markup Language (XHTML), Wireless Markup Language (WML), MessagePack, XML User Interface Language (XUL), or any other functionally similar representation, alone or in combination. Alternatively, proprietary data structures, file formats, and schemas may be used exclusively or in combination with known or open standards.

[0058] Such files may conform to a data model, which includes, without limitation, a Universal Data Model (UDM), an entry-attribute-value (EAV) model, an object-attribute-value (OAV) model, a vertical database model, an open schema, a closed schema, or any other standard, non-standard, or proprietary data model. Configuration data may be in the form of a structured database, an unstructured database, a flat file database, a column-oriented database, a row-oriented database, or other types of database formats.

[0059] Any related data, files, and / or databases may be stored, retrieved, accessed, and / or transmitted in a human-readable format, such as, but not limited to, numerical formats, text formats, graphic formats, or multimedia formats, which may further include various types of markup languages. Alternatively or in combination with the above formats, data, files, and / or databases may be stored, retrieved, accessed, and / or transmitted in a binary format, an encoded format, a compressed format, and / or an encrypted format, or any other machine-readable format.

[0060] A computer system typically includes an operating system or other low-level system software that supports higher-level application software and interfaces with system hardware and peripheral devices to manage, for example, memory access, input / output (I / O), and process scheduling.

[0061] As illustrated in FIG. 6, these peripheral devices may include a storage subsystem 624 including a memory subsystem 626 and a file storage subsystem 628, a user interface input device 622, a user interface output device 620, and a network interface subsystem 616. The input and output devices enable interaction between the computer system 610 and the user. In the exemplary embodiment illustrated in FIG. 6, the network interface subsystem 616 provides an interface to an external network, including an interface to a communication network 618, and is coupled via the communication network 618 to a corresponding interface device within another computer system or machine. The communication network 618 may comprise a number of interconnected computer systems, machines, and communication links. These communication links may be wired links, optical links, wireless links, or any other device for communicating information. The communication network 618 may be any suitable computer network, such as a wide area network such as the Internet and / or a local area network such as Ethernet. The communication network 618 may be wired and / or wireless, and the communication network may use encryption and decryption methods such as those available in a virtual private network. The communication network uses one or more communication interfaces capable of receiving and transmitting data with other systems. Exemplary aspects of the communication interface typically include an Ethernet card, a modem (e.g., telephone, satellite, cable, or ISDN), an (asynchronous) digital subscriber line (DSL) unit, an IEEE 1394 (Firewire) interface, and a USB interface. One or more communication protocols such as HTTP, TCP / IP, RTP / RTSP, IPX, and / or UDP may be used.

[0062] The user interface input device 622 may include an alphanumeric keyboard; a keypad; a pointing device such as a mouse, trackball, touchpad, stylus, or graphics tablet; a scanner; a touch screen incorporated in a display; an auditory input device such as a voice recognition system or a microphone; eye gaze recognition; electroencephalogram pattern recognition; and other types of input devices. Such devices may be connected to the computer system either wired or wirelessly. Generally, the use of the term "input device" is intended to include all possible types of devices and methods for inputting information into the computer system 610 or onto the communication network 618. The user interface input device 622 typically enables a user to select objects, icons, and text, etc., that appear on some type of user interface output device, such as a display subsystem.

[0063] The user interface output device 620 may include a non-visual display such as a display subsystem, a printer, a fax machine, or an auditory output device. The display subsystem may include a cathode ray tube (CRT); a flat panel device such as a liquid crystal display (LCD), a projection device; or any other device for creating a visual image, such as a virtual reality system. The display subsystem may also provide a non-visual display via an auditory output device or a tactile output (e.g., vibration) device. Generally, the use of the term "output device" is intended to include all possible types of devices and methods for outputting information from the computer system 610 to the user or another machine or computer system.

[0064] Memory subsystem 626 typically includes several memories, including a main random access memory ("RAM") 630 (or other volatile storage device) for storing instructions and data during program execution, as well as a read-only memory ("ROM") 632 in which fixed instructions are stored. File storage subsystem 628 provides persistent storage for program and data files and may include a hard disk drive, a floppy disk drive with associated removable media, a CD-ROM drive, an optical drive, a flash memory, or a removable media cartridge. Databases and modules implementing the functionality of certain aspects may be stored by file storage subsystem 628.

[0065] Bus subsystem 612 is a device for enabling the various components and subsystems of computer system 610 to communicate with each other as intended. Bus subsystem 612 is shown schematically as a single bus, but multiple buses may be used in alternative aspects of the bus subsystem. For example, a RAM-based main memory may communicate directly with the file storage system using a direct memory access ("DMA") system.

[0066] Conclusion The detailed description has been made with reference to the accompanying drawings in order to illustrate exemplary aspects consistent with the present disclosure. References to "one exemplary aspect" in the present disclosure indicate that the described exemplary aspect may include a particular feature, structure, or characteristic, but not all exemplary aspects necessarily include that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same exemplary aspect. Moreover, any feature, structure, or characteristic described with respect to one exemplary aspect may be included, independently or in any combination, with the features, structures, or characteristics of other exemplary aspects, whether or not explicitly described.

[0067] The detailed description is not intended to be limiting. Rather, the scope of the present disclosure is defined only by the appended claims and their equivalents. It should be recognized that the detailed description section, rather than the summary section, is intended to be used to interpret the claims. The summary section may describe one or more exemplary aspects of the present disclosure, but not all exemplary aspects, and thus is not intended to limit the present disclosure, the appended claims, and their equivalents in any way.

[0068] The exemplary aspects described within the present disclosure are provided for illustrative purposes and are not intended to be limiting. Other exemplary aspects are possible and modifications to the exemplary aspects may be made while remaining within the spirit and scope of the present disclosure. The present disclosure is described with the aid of functional building blocks that illustrate embodiments of the specified functions and their relationships. The boundaries of these functional building blocks are arbitrarily defined herein for convenience of description. Alternative boundaries may be defined as long as the specified functions and their relationships are properly performed.

[0069] Aspects of the present disclosure may be implemented in hardware, firmware, software applications, or any combination thereof. Aspects of the present disclosure may also be implemented as instructions stored on a machine-readable medium that can be read and executed by one or more processors. The machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing circuitry). For example, the machine-readable medium may include non-transitory machine-readable media such as read-only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; and flash memory devices. As another example, the machine-readable medium may include transitory machine-readable media such as electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.). Further, firmware, software applications, routines, instructions may be described herein as performing certain actions. However, such descriptions are for convenience only; and it should be recognized that such actions result from computing devices, processors, controllers, or other devices that execute firmware, software applications, routines, instructions, etc.

[0070] The detailed description of the exemplary aspects has sufficiently revealed the general nature of the present disclosure such that others can, by applying the knowledge of those skilled in the art, readily modify and / or adapt such exemplary aspects for various applications without departing from the spirit and scope of the present disclosure and without undue experimentation. Accordingly, such adaptations and modifications are intended to be within the meaning and range of equivalents of the exemplary aspects based upon the teachings and guidance presented herein. It should be understood that the syntax or terminology herein is for the purpose of description and not limitation, and will be interpreted by those skilled in the art in light of the teachings herein.

Claims

1. A magnetic resonance imaging (MRI) system for generating anatomical images of a patient, comprising: The imaging machine configured to apply a magnetic field and radio frequency to the patient within the imaging machine to obtain an image data signal that is an indicator of the tissue composition within the patient's spatial position; A gating signal transmitter configured to compensate for signal offset and gradient pulse interference introduced by the magnetic field and radio frequency on a physiological event signal related to the physiological event of the patient to generate a physiological event signal with noise, A digital gradient offset filter configured to identify a first plurality of samples of the physiological event signal with noise that best represent the physiological event signal from among a second plurality of samples of the physiological event signal with noise to compensate for the signal offset; A digital gradient blocking filter configured to perform a non-linear separation technique on the first plurality of samples of the physiological event signal with noise to provide a third plurality of samples of the physiological event signal with noise to compensate for the gradient pulse interference; The gating signal transmitter comprising the above; and A control system, Triggering the imaging machine to obtain the image data signal based on the third plurality of samples of the physiological event signal with noise, and Converting the image data signal into an anatomical image to illustrate the composition of the tissue within the spatial position of the patient. The control system configured as such. The MRI system comprising the above.

2. The MRI system according to claim 1, wherein the digital gradient offset filter is configured to identify the first plurality of samples of the physiological event signal with noise in a plurality of interference time windows, and each sample from among the first plurality of samples of the physiological event signal with noise corresponds to one of the plurality of interference time windows.

3. The MRI system according to claim 1, wherein the digital gradient offset filter is further configured to evaluate an interference cost function to identify the first plurality of samples of the physiological event signal with noise.

4. The MRI system according to claim 3, wherein the interference cost function is configured to evaluate the volatility of samples from among the second plurality of samples of the physiological event signal with noise, the directional change of samples from among the second plurality of samples of the physiological event signal with noise, and the offset between samples from among the second plurality of samples of the physiological event signal with noise to identify the first plurality of samples of the physiological event signal with noise.

5. The MRI system according to claim 4, wherein the interference cost function is configured to evaluate the volatility of samples from among the second plurality of samples of the physiological event signal with noise, the directional change of samples from among the second plurality of samples of the physiological event signal with noise, and the offset between samples from among the second plurality of samples of the physiological event signal with noise to determine a plurality of costs for the second plurality of samples of the physiological event signal with noise.

6. The digital gradient offset filter is configured to identify the first plurality of samples of the physiological event signal with noise as samples from among the second plurality of samples of the physiological event signal with noise that have the minimum cost among the plurality of costs in a plurality of time interference windows.

7. The digital gradient blocking filter is as follows: A median filter, configured to analyze adjacent samples among the samples from the first plurality of samples of the physiological event signal with noise to determine the median of the adjacent samples, and configured to use the median of the adjacent samples in place of the sample from among the first plurality of samples of the physiological event signal with noise to provide the third plurality of samples of the physiological event signal with noise. The median filter thus configured is provided in the MRI system according to claim 1.

8. A gating signal transmitter, which is as follows: An analog processing circuit network configured to process an ECG signal, a PPG signal, and a RESP signal received from a plurality of sensors attached to a patient to provide a processed ECG signal, a processed PPG signal, and a processed RESP signal; A plurality of analog-to-digital converters (ADCs) configured to convert the processed ECG signal, the processed PPG signal, and the processed RESP signal from the analog signal domain to the digital signal domain to provide a digital ECG signal, a digital PPG signal, and a digital RESP signal; A digital processing circuit network, configured to process the digital ECG signal in the digital signal domain to compensate for interference introduced into the ECG signal by gradient magnetic field pulses and radio frequency pulses to provide a clean ECG signal, and configured to combine the clean ECG signal, the digital PPG signal, and the digital RESP signal to provide a physiological event signal the digital processing circuit network; and A communication transmitter configured to format the physiological event signal for transmission to a communication receiver The gating signal transmitter comprising.

9. The analog processing circuit network is as follows: A first plurality of analog filters and a first amplifier configured to perform signal conditioning and amplification on the ECG signal to provide the processed ECG signal; A second plurality of analog filters and a second amplifier configured to perform signal conditioning and amplification on the PPG signal to provide the processed PPG signal; and A third plurality of analog filters and a third amplifier configured to perform signal conditioning and amplification on the RESP signal to provide the processed RESP signal The gating signal transmitter according to claim 8, comprising.

10. The plurality of ADCs are as follows: A first ADC configured to convert the processed ECG signal from the analog signal domain to the digital signal domain to provide the digital ECG signal; A second ADC configured to convert the processed PPG signal from the analog signal domain to the digital signal domain to provide the digital PPG signal; and A third ADC configured to convert the processed RESP signal from the analog signal domain to the digital signal domain to provide the digital RESP signal The gating signal transmitter according to claim 8, comprising:

11. The sampling rate of the first ADC is greater than the sampling rates of the second ADC and the third ADC, The resolution of the first ADC is greater than the resolutions of the second ADC and the third ADC, and The digital processing circuitry includes the following: A downsampler configured to match the sampling rate of the clean ECG signal to the sampling rates of the digital PPG signal and the digital RESP signal The gating signal transmitter according to claim 10, comprising:

12. The digital processing circuitry includes the following: A digital gradient offset filter configured to identify a first plurality of samples of the digital ECG signal that best represents the ECG signal from among a second plurality of samples of the digital ECG signal to compensate for a signal offset introduced onto the ECG signal by a magnetic field and radio frequency; and A digital gradient rejection filter configured to perform a non-linear separation technique on the first plurality of samples of the digital ECG signal to provide a third plurality of samples of the digital ECG signal as the clean ECG signal to compensate for gradient pulses introduced onto the ECG signal by a magnetic field and radio frequency The gating signal transmitter according to claim 8, comprising:

13. The digital gradient offset filter is configured to identify the first plurality of samples of the digital ECG signal among a plurality of interference time windows, and each sample from among the first plurality of samples of the digital ECG signal corresponds to one of the plurality of interference time windows from among the plurality of interference time windows. The gating signal transmitter according to claim 8.

14. The gating signal transmitter according to claim 8, wherein the digital gradient offset filter is further configured to evaluate an interference cost function to identify the first plurality of samples of the digital ECG signal.

15. The gating signal transmitter according to claim 14, wherein the interference cost function is configured to evaluate the volatility of samples from among the second plurality of samples of the digital ECG signal, the directional change of samples from among the second plurality of samples of the digital ECG signal, and the offset between samples from among the second plurality of samples of the digital ECG signal to identify the first plurality of samples of the digital ECG signal.

16. The digital gradient offset filter is configured to identify the first plurality of samples of the digital ECG signal as samples from among the second plurality of samples of the digital ECG signal having the minimum cost among the plurality of costs in a plurality of time interference windows.

17. The digital gradient blocking filter is as follows: A median filter, configured to analyze adjacent samples among samples from among the first plurality of samples of the digital ECG signal to determine the median of the adjacent samples, and configured to use the median of the adjacent samples in place of the sample from among the first plurality of samples of the digital ECG signal to provide the third plurality of samples of the digital ECG signal. The median filter comprised by the gating signal transmitter according to claim 8.

18. A digital gradient offset filter for compensating for a signal offset introduced onto an electrical signal, as follows: A first digital adder configured to subtract a first sample of the electrical signal from among the plurality of samples of the electrical signal from a moving average of the plurality of samples to provide an offset signal; A second digital adder configured to subtract a second sample of the electrical signal from among the plurality of samples of the electrical signal from the first sample to provide a first derivative signal; A third digital adder configured to subtract a third sample of the electrical signal from among the plurality of samples of the electrical signal from the second sample to provide a second derived signal; A monotonicity module configured to set a monotonicity signal to a first value when the sign of the first derived signal is not equal to the sign of the second derived signal, or to a second value when the sign of the first derived signal is equal to the sign of the second derived signal; A cost function module for implementing an interference cost function that maps the first sample of the electrical signal to a certain weight using the offset signal, the first derived signal, the second derived signal, and the monotonicity signal, wherein the weight represents an estimated difference between the first sample of the electrical signal and the first sample of the electrical signal without interference; and A cost analysis module configured to compare the weight with other weights of other samples from among the plurality of samples of the electrical signal to determine a sample from among the plurality of samples that best represents the electrical signal without interference The digital gradient offset filter comprising the same.

19. The interference cost function is weight = ((|DV_0| + |DV_1| * MONO) + |offset|) including In the above formula, |DV_0| and |DV_1| respectively represent the absolute values of the first derived signal and the second derived signal, MONO represents the monotonicity signal, and |offset| represents the absolute value of the offset signal, The digital gradient offset filter according to Claim 18.

20. The digital gradient offset filter according to Claim 18, wherein the cost analysis module is configured to determine the sample from among the plurality of samples that best represents the electrical signal without interference as the sample from among the plurality of samples having the minimum weight.

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