KR100983256B1 - Method and system for measuring biopotential signal, and diagnostic system - Google Patents

Abstract

The present invention relates to a system for measuring bioelectrical signals and a method for processing bioelectrical signals. A system for measuring a bioelectrical signal in conjunction with an MR (magnetic resonance) image acquisition device of the present invention includes a modulator for modulating a bioelectrical signal measured from a subject into a non-electrical signal that is not affected by the MR image acquisition process. And a blocker for blocking noise caused by the MR image acquisition process. According to the present invention, the bioelectrical signal may be measured at the same time of acquiring the MR image. In particular, by simultaneously measuring the functional magnetic resonance imaging (fMRI) and galvanic skin response (GSR) signals can be confirmed at the same time the response of the central nervous system and the peripheral nervous system. It can be used for a variety of emotional studies, and can be used for various clinical studies.

Bioelectrical signals, GSR signals, MR imaging

Description

METHOD AND SYSTEM FOR MEASURING BIOPOTENTIAL SIGNAL, AND DIAGNOSTIC SYSTEM}

The present invention relates to a system for measuring a bioelectrical signal and a bioelectrical signal processing method. In particular, the bioelectrical signal is modulated into a non-electrical signal which is not affected by a magnetic resonance (MR) image acquisition process and simultaneously with MR image acquisition. It is for measuring bioelectrical signals.

Magnetic resonance (MR) images and bioelectrical signals are used as data for a variety of clinical studies, including emotional studies.

Magnetic resonance imaging (MRI) is mainly used in patients with the nervous system such as the central nervous system, head and neck, spine and spinal cord. The principles of MRI are as follows. The nucleus is usually rotating, but once placed in a strong magnetic field, precession occurs. The faster the precession is, the stronger the magnetic field is. Therefore, if an RF pulse is applied to a magnetized atomic nucleus, the atomic nucleus becomes a high energy state. After removing the RF pulses, the nucleus returns to its original state, in which the nucleus emits the same type of RF pulse as the applied RF pulse. MR images are images of the RF pulses emitted by the nucleus during this process.

Functional magnetic resonance imaging (fMRI) using the MR imaging technique can easily identify where the activity occurs in the brain. However, MR images have excellent spatial resolution, but since they take time to shoot and image, there is a problem that the time resolution indicating when an activity occurs is low.

In contrast, bioelectric signals such as electroencephalogram (EGE), electrocardiogram (EGG), galvanic skin response (GSR), skin conductance response (SCR), and photoplethysmograph (PPG) Although the spatial resolution is low, the time resolution is excellent. For example, electroencephalogram (EEG) measurements show the electrical changes occurring on the surface of the head by attaching electrodes to the scalp and observing changes in the electric field. Electroencephalogram measurements do not provide an accurate picture of where a potential change occurs, but can even pinpoint a thousandth of a second.

Therefore, MR image acquisition and bioelectrical signal measurement need to be performed at the same time. However, as described above, since magnetic fields (static and gradient magnetic fields) and RF pulses are emitted during the MR image acquisition process, when the bioelectrical signal measurement and the MR image acquisition are simultaneously performed, the magnetic and RF pulses are generated during the bioelectric signal measurement process. There is a problem of generating distortion. Similarly, the bioelectrical signal and the bioelectrical signal measuring apparatus have a problem of causing distortion in the MR image.

The present invention has been proposed to solve the above problems, and an object of the present invention is to propose a system capable of measuring bioelectrical signals simultaneously with MR image acquisition by blocking mutual noise between the MR image acquisition process and bioelectrical signal measurement.

In order to achieve the above object, the present invention provides a bioelectric signal measuring system that measures a bioelectrical signal simultaneously with an MR image acquisition process of an MR image acquisition device, and includes: a blocking unit for blocking a signal generated during the MR image acquisition process; And a modulator configured to modulate the bioelectrical signal measured from a subject who is the MR image acquisition subject into a non-electrical signal and disposed in the blocking unit.

The present invention also provides a diagnostic system in which MR image acquisition and biosignal measurement are performed simultaneously, an apparatus for acquiring an MR image from a subject, a blocker for blocking a signal generated during the MR image acquisition process, and the MR image acquisition. And a bioelectrical signal measuring device that modulates the bioelectrical signal measured from the subject, which is a subject, into a non-electrical signal, and includes a modulator disposed in the blocking unit.

The present invention also provides a method of processing a bioelectrical signal in conjunction with an MR image acquisition device, the method comprising measuring a bioelectrical signal from a subject, and modulating the bioelectrical signal measured from the subject into a non-electrical signal And delivering the non-electrical signal.

According to the present invention, by interfering noise between the MR image acquisition process and the bioelectrical signal measurement process, the bioelectrical signal may be measured simultaneously with the MR image acquisition. In particular, by simultaneously measuring the functional magnetic resonance imaging (fMRI) and the bioelectrical signal, for example, the galvanic skin response (GSR) signal can be confirmed at the same time the response of the central nervous system and the peripheral nervous system. It can be used for a variety of emotional studies and can be used for various clinical studies.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing the configuration of a bioelectrical signal measuring system to which the present invention is applied. As shown, the bioelectrical signal measuring system includes a modulator 110 and a blocker 120.

The modulator 110 modulates the bioelectrical signal 130 measured by the subject into a non-electrical signal 140 that is not affected by the MR image acquisition process and is disposed in the blocking unit. As described above, in the MR image acquisition process, signals such as magnetic fields (static and gradient magnetic fields) and RF pulses are emitted, and these signals, that is, noise, cause distortion in measuring bioelectrical signals. Therefore, the modulator modulates the bioelectric signal into a non-electrical signal that is not distorted by noise such as magnetic fields and RF pulses generated during MR image acquisition. In this case, the modulator may be located at a magnet edge of the MR image acquisition device in order to minimize the influence of the MR image acquisition process. In addition, it may be fixed in order to minimize noise caused by vibration generated in the MR image acquisition process. If a metallic material is used inside the modulator, the MR image may be affected, and the modulator may be formed as an analog device because a high frequency RF noise may be generated by a digital device such as a microphone processor to cause distortion in the MR image. .

The blocking unit 120 blocks the noise 150 by the MR image acquisition process. Noise generated during MR image acquisition may include magnetic fields (static and gradient magnetic fields) and RF pulses, and the noise may affect not only the bioelectric signal 130 but also the modulator 110 itself. When the modulator includes a material affected by the magnetic field, distortion may occur in the modulation process itself, and conversely, the modulator may cause distortion in the MR image. Therefore, the blocker 120 blocks noise 150 generated in the MR image acquisition process from being introduced into the modulator 110 and blocks the modulator from distorting the MR image. For example, the blocking unit may be manufactured as a shielding case capable of blocking noise. The shielding case will be described in detail with reference to FIG. 3. In addition, the blocking unit may surround a lead through which the bioelectrical signal is transmitted, thereby blocking noise flowing into the lead. In addition, the breaker may be used for all equipment related to measuring bioelectrical signals, such as a power supply for supplying power to a modulator. In other words, the blocking unit according to the present invention includes all means and devices for preventing noise generated in the MR image acquisition process from being introduced into the bioelectrical signal measuring process. Also included are all means, apparatus for preventing the MR image from being distorted by the bioelectrical signal and the bioelectrical signal measuring apparatus.

An example of the bioelectric signal may be a galvanic skin response (GSR) signal, and an example of the non-electrical signal may be an optical signal. The GSR signal is a kind of electrical signal that is affected by the magnetic field, while the optical signal is a non-electrical signal using light and is not affected by the magnetic field. The modulation of the signal may be performed by various methods, for example, pulse width modulation (PWM). The PWM method is a modulation method well known to those skilled in the art and generates a triangular wave having a high frequency (for example, 10 KHz) compared to the frequency band of the bioelectrical signal, and generates a pulse of square wave by comparing with the bioelectrical signal measured from the subject. to be.

Therefore, the modulator may modulate the GSR signal measured from the subject into an optical signal by a pulse width modulation (PWM) method, and in this process, all equipment of the bioelectrical signal measuring system such as a lead and a modulator is blocked. Through this, the influx of noise generated in the MR image acquisition process can be blocked.

The bioelectrical signal measuring system may further include a measuring unit. The measurement unit measures the bioelectrical signal from the subject, and may be attached to the body of the subject to measure the bioelectrical signal. In the measurement section, Ag / AgCl electrodes are generally used, but carbon electrodes may be used to minimize induced noise.

For example, the measuring unit measuring the GSR signal measures the GSR signal using a constant voltage source. The constant voltage source adds a capacitor to the zener diode to supply a constant voltage without ripple, and the input constant voltage is output with the amplification degree changed according to the change in the conductance of the skin. In this process, a low pass filter with a cutoff frequency of 30 Hz is used to cut off high frequency noise outside the GSR signal band, and a post amplifier is used to compensate for optical loss that may occur during optical communication. Offset nulling circuitry connects before the post amplifier to prevent the GSR signal from becoming saturated.

The bioelectrical signal measured by the measuring unit is transmitted to the modulator through the lead. In this case, a twisted lead may be used to cancel noise flowing into the lead. Of course, as described above, the blocking unit may block the noise flowing into the lead. In addition, the length of the lead may be appropriately adjusted to block the influence of the MR image acquisition process. Here, the influence of the MR image acquisition process includes not only magnetic fields and RF pulses generated in the MR image acquisition process, but also mutually induced noise with the MR image acquisition device magnet. If the length of the lead is too short, the mutually induced noise with the MR image acquisition device magnet may increase, and if the length of the lead is too long, noise may be formed in the bioelectrical signal due to the magnetic field flowing into the lead. Therefore, in the present invention, the length of the lead may be adjusted to an appropriate length to minimize noise. In addition, the lead may be fixed to block noise caused by vibration generated in the MR image acquisition process.

The bioelectrical signal measuring system may further include a demodulator. The demodulator recovers non-electrical signals into bioelectrical signals and is usually located outside the MR room. The non-electrical signal modulated by the modulator is transferred to the demodulator. For example, when the GSR signal is modulated into an optical signal, the GSR signal may be transmitted to the demodulator without distortion using an LED or an optical cable, and the demodulator may demodulate the optical signal into the GSR signal using a low pass filter. The demodulated GSR signal may be stored in a computer or the like and used for research purposes. For example, the GSR signal is stored in the computer using a DAQ board, and when the GSR signal is needed for research purposes, the signal stored in the computer is restored using Matlab.

2 is a view showing the configuration of a diagnostic system according to an embodiment of the present invention. As shown, the diagnostic system includes a bioelectrical signal measuring apparatus including an MR image capturing apparatus 210, a modulator 220, and a blocker 230.

The MR image acquisition device 210 is located inside the MR room. The subject is placed in the bed of the MR image acquisition device, and the bed enters into the MR image acquisition device magnet to acquire the MR image.

The modulator 220 of the bioelectrical signal measuring apparatus modulates the bioelectrical signal measured from the subject and may be positioned at the edge of the MR image acquisition magnet, as described above, to minimize the influence of noise.

The blocking unit 230 of the bioelectric signal measuring apparatus may be formed to surround the modulator as shown to block the influence of the MR image acquisition process. In addition, it may be installed to prevent distortion between the bioelectric signal measurement process and the MR image acquisition process. Just as the noise generated in the MR image acquisition distorts the bioelectrical signal, the MR image signal may be distorted by the bioelectrical signal and the modulator, so that the blocking unit not only blocks the modulator from the noise, but also It can also be used to prevent distortion.

The modulated non-electrical signal, for example, the optical signal may be transmitted through the optical cable 240. The optical signal transmitted to the outside of the MR room through the optical cable is demodulated back into the bioelectrical signal by the demodulator.

3 is a view showing the configuration of a shielding case (shielding case) according to an embodiment of the present invention. As shown, the shielding case 310 may be formed in a double.

The shielding case is a kind of protective film for protecting the device inside by blocking noise (for example, magnetic field or RF pulse) from the outside. In the present invention, a shielding case is used to protect a modulator, a power supply, and the like from noise generated during a GS image acquisition process. The shielding case is made of copper or aluminum and can be formed in duplicate.

For example, the inside of the shielding case 320 may be made of aluminum and the outside of copper. When inserting the modulator into the shielding case, make small holes in the sides of the shielding case so that the necessary lines can pass through. For example, when a modulator for modulating a GSR signal into an optical signal enters a shielding case, a hole through which a lead 340 through which a GSR signal measured from a subject is transmitted passes, and an optical cable through which a modulated optical signal passes The hole 350, and the hole 360 through which the power supply lead for supplying power to the modulator passes, are formed at the side of the shielding case. When a battery used as a power supply unit is disposed together with a modulator, mutual noise with the MR image acquisition magnet is increased. Therefore, the battery may be spaced at least a certain distance from the modulator and placed in a shielding case to minimize mutual noise with the MR imaging apparatus.

The effects of the bioelectrical signal measuring system, the diagnostic system, and the bioelectrical signal processing method of the present invention can be confirmed through experimental results of the following human body. In the experiment, GSR signal was used as bioelectrical signal and optical signal was used as non-electrical signal.

TR / TE / TI 10 / 5.7 / 300ms, field of view 220 * 220 * 192mm using three-dimensional (3D) magnetization-prepared, rapid-gradient echo (MPRAGE) technique in 3T MRI (FORTE, ISOL Technology, Korea) ^The GSR signal was measured while acquiring T1-weighted images using imaging parameters of ³ , matrix size 256 * 256 * 128, slice thickness 1.5mm, # of slices 128, and flip angle 10 °.

In addition, to obtain functional and neurological information of the brain, the Echo planar imaging (EPI) technique uses TR / TE 3000 / 30ms, field of view 240mm, matrix size 64 * 64mm ² , slice thickness 4mm, # of slices 30, flip angle The GSR signal was measured while acquiring an fMRI image using an image parameter of 80 °.

4 is a diagram illustrating an MR image obtained by an embodiment of the present invention described above.

The upper image 410 is an MR image acquired by the MPRAGE technique while measuring the GSR signal, the lower image 420 is an MR image 420 obtained by the EPI technique while measuring the GSR signal. Through this, it can be seen that the distortion does not occur even when the MR image is acquired while measuring the GSR signal.

5 is a diagram illustrating a galvanic skin response (GSR) signal according to an embodiment of the present invention.

The upper graph 510 is a GSR signal measured while acquiring an MR image using the MPRAGE technique, and the lower graph 520 is a GSR signal measured while acquiring an MR image using the EPI technique. Through this, it can be seen that the GSR signal can be stably measured without distortion even when the MR image is acquired and the GSR signal is measured at the same time.

The present invention can be utilized in various clinical studies, and in particular, it is possible to measure autonomic nervous system responses while acquiring fMRI images. Therefore, the central nervous system through fMRI and the peripheral nervous system through the GSR signal can be simultaneously measured and used for various emotional studies.

1 is a block diagram of a bioelectrical signal measuring system to which the present invention is applied.

2 is a block diagram of a diagnostic system according to an embodiment of the present invention.

3 is a block diagram of a shielding case (shielding case) according to an embodiment of the present invention.

4 is a view showing an MR image obtained by an embodiment of the present invention.

5 is a diagram illustrating a galvanic skin response (GSR) signal obtained according to an embodiment of the present invention.

Claims (26)

In the bioelectrical signal measuring system for measuring the bioelectrical signal at the same time as the MR image acquisition process of the MR image acquisition device, A blocking unit which blocks a signal generated in the MR image acquisition process; A modulator disposed in the blocking unit by modulating the bioelectrical signal measured from the subject who is the MR image acquisition subject into a non-electrical signal Bioelectrical signal measuring system comprising a. The method of claim 1, The bio-electrical signal is a galvanic skin response (GSR) signal, characterized in that the bio-electrical signal measuring system. The method of claim 1, And said non-electrical signal is an optical signal. The method of claim 3, wherein The modulator modulates the bioelectrical signal into an optical signal by pulse width modulation (PWM). A bioelectrical signal measuring system. The method of claim 1, The signal generated in the MR image acquisition process is a magnetic field or RF pulse A bioelectrical signal measuring system. The method of claim 1, The blocking unit is a bio-electrical signal measuring system, characterized in that the shielding case (shielding case) is made of copper or aluminum formed in a double. The method of claim 1, And the modulator receives the measured bioelectrical signal through a lead having a twisted structure. The method of claim 7, wherein And the length of the lead is adjustable. The method of claim 1, A demodulator for restoring the non-electrical signal to a bioelectrical signal Bioelectrical signal measuring system further comprising. In a diagnostic system in which MR image acquisition and biosignal measurement are performed simultaneously, An apparatus for acquiring an MR image from a subject, Measuring a bio-electrical signal comprising a blocker for blocking the signal generated in the MR image acquisition process, and a modulator disposed in the blocker to modulate the bioelectrical signal measured from the subject of the MR image acquisition target into a non-electrical signal Device Diagnostic system comprising a. The method of claim 10, The bio-electrical signal is a galvanic skin response (GSR) signal. The method of claim 10, And the non-electrical signal is an optical signal. The method of claim 10, And a modulator modulates the bioelectrical signal into an optical signal by pulse width modulation (PWM). The method of claim 10, The signal generated in the MR image acquisition process is a magnetic field or RF pulse Characterized by a diagnostic system. The method of claim 10, The blocking unit is a diagnostic system, characterized in that the shielding case is made of copper or aluminum formed in a double. The method of claim 10, The modulator is a diagnostic system, characterized in that for receiving the measured bioelectric signal through the lead (twist) of the twisted structure. The method of claim 16, And the length of the lid is adjustable. The method of claim 10, The biosignal measuring apparatus further includes a demodulator configured to restore the non-electrical signal to a bioelectrical signal. In the method of processing the bio-electrical signal in conjunction with the MR image acquisition device, Measuring the bioelectrical signal from the subject, Modulating a bioelectrical signal measured from the subject into a non-electrical signal; Delivering the non-electrical signal Bioelectrical signal processing method comprising a. The method of claim 19, Modulating the non-electrical signal, Is performed in a state in which a signal generated in the MR image acquisition process is blocked. A bioelectrical signal processing method. The method of claim 20, The signal generated in the MR image acquisition process is blocked by a double shielding case (shielding case) made of copper or aluminum A bioelectrical signal processing method. The method of claim 19, The bio-electrical signal processing method of the bio-electrical signal, characterized in that the galvanic skin response (GSR) signal. The method of claim 19, And said non-electrical signal is an optical signal. The method of claim 23, Modulating the non-electrical signal Modulating the bioelectrical signal into an optical signal by pulse width modulation (PWM) A bioelectrical signal processing method. The method of claim 19, The bio-electrical signal processing method of claim 1, wherein the bio-electrical signal measured from the subject is transmitted through a lead having a twisted structure. The method of claim 19, Restoring the non-electrical signal to a bioelectrical signal. Bioelectrical signal processing method characterized in that it further comprises.

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