KR101084718B1 - System for measuring motion signal - Google Patents

Abstract

The present invention relates to a motion signal measuring system, and provides a motion signal measuring system that does not affect an MR image at the same time without being affected by a static magnetic field, a gradient magnetic field rapidly changing with time, and an RF pulse. Has its characteristic purpose.
The present invention for achieving this object is made of a plurality of three-axis acceleration sensor, the acceleration sensor unit is fixed to a predetermined portion of the body to measure the operation signal; An amplifier which receives and amplifies an operation signal measured by the acceleration sensor unit and modulates it into an optical signal; An optical signal transmitter for transmitting the optical signal modulated by the amplifier to an outside of the MR room; A demodulator for receiving a modulated optical signal from the optical signal transmitter and restoring an operation signal which is an original signal; A DAQ board unit for converting an operation signal restored by the demodulator to a digital value; And a control unit for transmitting a control signal to the acceleration sensor unit, the amplifier unit, the optical signal transmitter, the demodulator unit, and the DAQ board unit, and receiving, storing, and displaying the digitized operation signal from the DAQ board unit. Characterized in that it comprises a.

Description

Motion signal measuring system {SYSTEM FOR MEASURING MOTION SIGNAL}

The present invention relates to a motion signal measuring system, and more particularly, to a motion signal measuring system capable of minimizing mutual interference between an MR image and a motion signal when acquiring an MR image and a motion signal of a body.

Human operations are performed by a complex combination of nerves, muscles, and skeletal systems (NMS). Numerous studies have been conducted in terms of biomechanical and motor control to study human motion.

In recent years, research on the functional aspects of brain using functional magnetic resonance imaging (fMRI) has been attempted.

Initially, due to the limiting factor of the magnetic resonance (MR) environment, a motion signal was not obtained, and a brain function study was mainly performed based on simple variables such as speed of motion. For example, only changes in brain activation area and amount were observed for simple motion tasks such as the task of changing the speed of the fingers and wrist, the task of coordinating the thumb of both hands, and the imaginary finger-sequencing task.

However, at this time, since the motion signal was not acquired along with the fMRI image acquisition, an accurate interpretation between the human motion and the brain function was not achieved.

Recently, in order to investigate the interrelationship between motion and brain function, research has been conducted on the development of a system for measuring motion signals simultaneously with fMRI. A system was developed to measure the grip force using a force transducer using hydraulic pressure.

In addition to acquiring MR images using an accelerometer and a potentiometer, a study of measuring the movement of one finger only in one axial direction has been conducted.

However, these systems could not directly extract kinematic variables and had limitations that only measured the accuracy of the movement for repetition of simple movements.

In addition, a study was conducted to measure the angular velocity of the movement of five fingers only in one axial direction and to extract jerk information using the angular velocity sensor.

However, the accuracy was lowered because only the angular velocity information was measured using the yaw rate sensor and the jerk information was extracted. Therefore, the difference in brain activation due to advanced variables such as jerk and softness is limited. there was.

The motion signal sensor used in these previous studies caused a lot of noise from the MR system and at the same time degraded the MR image quality. In addition, in the previous research, there was a limit in extracting accurate kinematic variables by measuring motion signals of only one axis.

The present invention has been made in view of the above problems, and does not affect the MR image at the same time without being affected by the static magnetic field, the gradient magnetic field and the RF pulse that rapidly change with time when the MR image is acquired. Its purpose is to provide a motion signal measuring system.

The present invention for achieving the above technical problem, relates to a motion signal measuring system, consisting of a plurality of three-axis acceleration sensor, is fixed to a predetermined body part acceleration sensor unit for measuring the operation signal; An amplifier which receives and amplifies an operation signal measured by the acceleration sensor unit and modulates it into an optical signal; An optical signal transmitter for transmitting the optical signal modulated by the amplifier to an outside of the MR room; A demodulator for receiving a modulated optical signal from the optical signal transmitter and restoring an operation signal which is an original signal; A DAQ board unit for converting an operation signal restored by the demodulator to a digital value; And a control unit for transmitting a control signal to the acceleration sensor unit, the amplifier unit, the optical signal transmitter, the demodulator unit, and the DAQ board unit, and receiving, storing, and displaying the digitized operation signal from the DAQ board unit. Characterized in that it comprises a.

In addition, the acceleration sensor unit is characterized in that the band type using a Velcro.

In addition, the amplification unit is composed of an analog element, characterized in that the amplification rate is variable up to 2 to 10 times.

In addition, the amplifying unit, using the pulse width modulation (PWM) method of generating a pulse of the square wave by comparing the operation signal measured in the MR room with a high frequency triangular wave compared to the frequency band of the operation signal, the operation signal It characterized in that the modulated to an optical signal.

In addition, the acceleration sensor unit and the amplification unit is connected through a lead wire, the lead wire, characterized in that the twisted form in order to prevent the generation of the electromagnetic field.

The amplification unit may be installed at an edge of an MR scanner magnet through the lead wire.

In addition, a power supply unit connected to the amplifier through the lead wire to supply power; It characterized in that it further comprises.

In addition, the power supply, characterized in that installed in the MR room spaced apart from the amplifier 3m or more.

In addition, the amplifier and the power supply is characterized in that provided in the double shield case.

In addition, the double shielding case is characterized in that the outer surface formed of copper and the inner surface formed of aluminum overlapped.

The optical signal transmitter may include a light emitting diode that receives an optical signal modulated by the amplifier and emits light into light; And an optical cable for receiving an optical signal from the light emitting diode and transmitting the optical signal to the outside. Characterized in that it comprises a.

The demodulator may demodulate the optical signal received through the optical signal transmitter by using a low pass filter to restore an operation signal.

According to the present invention as described above, by minimizing the interaction noise through the strict electromagnetic shielding, there is an effect that can stably and accurately extract the advanced kinematic variables such as jerk and at the same time the MR image acquisition.

In addition, according to the present invention, it is possible to stably measure a motion signal while acquiring an MR image, and there is also an effect that can be actively used to study the relationship between various kinematic variables and brain function.

1 is an overall configuration diagram conceptually showing a motion signal measuring system according to the present invention.
2 is an actual photograph showing a state in which a band type acceleration sensor unit is fixed to a finger using a velcro according to the present invention.
3 is an exemplary view showing a lead wire between an acceleration sensor unit and an amplifying unit having a twisted shape according to the present invention.
4 is a graph showing operation signals measured while acquiring an MR image using the operation signal measuring system according to the present invention;
Figure 5 is an exemplary view showing a state in which the acceleration sensor is attached to the phantom to observe whether the acceleration sensor unit causes noise in the MR image according to the present invention.
6 is an exemplary view showing that the acceleration sensor unit according to the present invention does not cause distortion in the MR image.
7 is an exemplary view showing three types of MR images obtained while measuring the operation signal through the operation signal measuring system according to the present invention.
8 is a graph showing an operation signal measured by an operation signal measuring system according to the present invention while acquiring an MR image using an EPI technique.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. In the meantime, when it is determined that the detailed description of the known functions and configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, it should be noted that the detailed description is omitted.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

The operation signal measuring system according to the present invention will be described with reference to FIGS. 1 to 8 as follows.

1 is an overall configuration diagram conceptually showing an operation signal measuring system S according to the present invention, and as shown, an acceleration sensor unit 100, an amplifier unit 200, a power supply unit 300, and an optical signal transmission The unit 400 includes a demodulator 500, a DAQ board unit 600, and a controller 700.

The acceleration sensor unit 100 is composed of a plurality of three-axis acceleration sensor 110, and is fixed to a predetermined body part to perform a function of measuring the operation signal.

In this case, the examinee is positioned inside the scanner of the MR room 10 to take an MR image, and the acceleration sensor unit 100 is fixed to the examinee's finger through the Velcro.

In this embodiment, although the acceleration sensor unit 100 is shown as being fixed to the finger, the acceleration sensor unit 100 according to the present invention is a band type using a velcro, as shown in Figure 2, It is fixed to various parts such as wrists, toes, and ankles as well as fingers, and can measure motion signals.

In addition, the amplifier 200 receives and amplifies the operation signal measured by the acceleration sensor unit 100, and performs a function of modulating the optical signal.

The digital device generates high frequency RF noise, which may cause noise in the MR image. Accordingly, the amplification unit 200 according to the present invention has an amplification circuit composed of only analog elements, and can vary the amplification factor up to 10 times so as to obtain an optimum gain.

The amplification unit 200 compares an operation signal measured in the MR room 10 with a triangular wave having a high frequency (10KHz) compared to a frequency band of the operation signal to generate a pulse of square wave (Pulse Width Modulation) : PWM) modulates the operation signal into an optical signal.

On the other hand, the acceleration sensor unit 100 and the amplifier 200 is connected via a lead (lead) (20). In this case, when the length of the lead wire 20 is shortened, the amplifier 200 becomes close to the center of the magnet of the MR scanner 30 so that the induced noise may increase in the operation signal, and at the same time, may cause noise in the MR image.

In addition, when the length of the lead wire 20 is long, noise may be generated in the operation signal due to the electromagnetic field induced by the lead wire 20. Accordingly, the amplifier 200 is installed at the edge of the magnet of the MR scanner 30 so that a stable operation signal can be measured without generating noise in the MR image.

In addition, the lead wire 20 between the acceleration sensor unit 100 and the amplifying unit 200 has a twisted shape (see FIG. 3) to prevent the generation of an electromagnetic field, and the lead wire 20 is caused by vibration generated during MR imaging. It is fixed at a certain position to minimize noise.

In addition, the power supply unit 300 is connected through the amplifier 200 and the lead wire 20 performs a function for supplying power. In this case, the power supply unit 300 is installed in the MR room 10 to be spaced apart from the amplification unit 200 by more than 1m to 5m, preferably 3m or more in order to prevent the noise from the amplifier 200.

On the other hand, when measuring the operation signal simultaneously with the MR image acquisition, when the amplification unit 200 is installed in the MR room (10), the metallic material inside the amplification unit 200 affects the MR image, MR field And RF pulses cause noise in the motion measurement circuit.

In order to solve this problem, in the present invention, the power supply unit 300 including the amplification unit 200 is provided inside the double shielding case overlapped with copper (outer side) and aluminum (inner side).

In addition, the optical signal transmitter 400 transmits the optical signal modulated by the amplifier 200 to the outside of the MR room 10. As shown in FIG. Light Emitting Diode (LED) 410 which receives the optical signal modulated by the light emitting diode 200 and emits light into the light, and an optical cable 420 which receives the optical signal from the LED 410 and transmits it to the outside. Include.

In addition, the demodulator 500 receives a modulated optical signal from the optical signal transmitter 400 and restores the original signal to an operation signal.

At this time, the demodulator 500 demodulates the optical signal using a low pass filter to restore the optical signal to an operation signal.

In addition, the DAQ board unit 600 performs a function of converting the operation signal restored by the demodulator 500 into a digital value.

For reference, DAQ (Data Acquisition) is an analog physical quantity measurement such as voltage, current, temperature, pressure, speed, acceleration, displacement (length), torque, etc. In this case, it means a process of converting a physical quantity, which is an analog value, into a digital value to be recognized by a computer.

In addition, the control unit 700 controls the control signal to the acceleration sensor unit 100, the amplifier 200, the power supply unit 300, the optical signal transmitter 400, the demodulator 500, and the DAQ board unit 600. Transmits and receives and stores and displays the digitized operation signal from the DAQ board unit 600.

FIG. 4 is a graph showing an operation signal measured while acquiring an MR image using the operation signal measuring system according to the present invention, x during arm extension and flexion (0.5 times / second) operation; FIG. The operation signals on the y, z axes were measured at 300 samples / sec.

Meanwhile, in order to observe whether the acceleration sensor according to the present invention causes noise in the MR image, the MR image was obtained after attaching the acceleration sensor to the phantom as shown in FIG. 5.

A marker was attached to confirm the contact area with the sensor, and phantom images of the cross section passing through the marker and the front and rear cross sections were obtained. TR / TE 400 / 7ms, field of view 250mm, matrix 256 × 256, slice thickness 5mm, # of slices 10, flip angle 90 ° by gradient echo (GE) method in 3.0 Tesla MR system (FORTE, ISOL Technology, Korea) Images were acquired using imaging parameters. As shown in FIG. 6, it was confirmed that the sensor did not cause distortion in the MR image.

MR images were obtained from humans, and motion signals were measured to observe interaction effects. When the arm extension and flexion (0.5 times / sec) were performed after the accelerometer was attached to the wrist, MR images were acquired using the following three imaging techniques and the motion signals on the x, y, and z axes were measured simultaneously. Images were acquired using fast spin echo (FSE) imaging parameters of TR / TE 800 / 14ms, field of view 250mm, matrix size 256 × 256, slice thickness 5mm, # of slices 25, flip angle 90 °, Gradient echo (GE) method was used to obtain images using TR / TE 600 / 7ms, field of view 250mm, matrix size 256 × 256, slice thickness 5mm, # of slices 25, flip angle 90 °. In addition, Echo Planar Imaging (EPI) is a method for obtaining functional information of the brain.It is TR / TE 3000 / 35ms, field of view 250mm, matrix size 64 × 64, slice thickness 5mm, # of slices 10, flip angle 90 ° Images were acquired using imaging parameters.

7 is an exemplary view showing three types of MR images obtained while measuring the operation signal through the operation signal measuring system according to the present invention. As an MR image obtained by using the FSE technique, the GE technique, and the EPI technique as described above, no distortion was generated in the image as shown.

FIG. 8 is a graph showing an operation signal measured by an operation signal measuring system according to the present invention while acquiring an MR image using an EPI technique. Although the baseline noise is slightly increased compared to that shown in FIG. It was confirmed that the operation signal can be measured stably in the axial direction.

The motion signal measuring system according to the present invention having the above-described configuration and characteristic functions enables measurement of acceleration in three directions using a three-axis sensor unlike the conventional method, and thus information such as position and angle in space Could get In addition, various kinematic variables such as jerk can be extracted accurately.

In addition, the housing by the band type using a velcro (velcro) to enable not only the wrist, but also the measurement of the operation signal of the finger or toe.

Since the current system uses 15 channels, it is possible to simultaneously measure information about three axes in each of five fingers. However, by extending the channel of the DAQ board, it is possible to extend the number of operation signals that can be measured simultaneously.

The apparatus can measure an operation signal stably while acquiring an MR image. Therefore, it is expected that it can be actively used to study the relationship between various kinematic variables and brain function.

As described above and described with reference to a preferred embodiment for illustrating the technical idea of the present invention, the present invention is not limited to the configuration and operation as shown and described as described above, it is a deviation from the scope of the technical idea It will be understood by those skilled in the art that many modifications and variations can be made to the invention without departing from the scope of the invention. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

100: acceleration sensor unit 200: amplification unit
300: power supply unit 400: optical signal transmission unit
500: demodulation unit 600: DAQ board unit
700: control unit 110: three-axis acceleration sensor
410: light emitting diode 420: optical cable
10: MR room 20: Lead wire
30: MR scanner

Claims (12)

In the system for measuring the operation signal of the subject taking the MR image,
An acceleration sensor unit comprising a plurality of three-axis acceleration sensors and fixed to a predetermined part of the body to measure an operation signal;
An amplifier which receives and amplifies an operation signal measured by the acceleration sensor unit and modulates it into an optical signal;
An optical signal transmitter for transmitting the optical signal modulated by the amplifier to an outside of the MR room;
A demodulator for receiving a modulated optical signal from the optical signal transmitter and restoring an operation signal which is an original signal;
A DAQ board unit for converting an operation signal restored by the demodulator to a digital value; And
A control unit which transmits a control signal to the acceleration sensor unit, amplifying unit, optical signal transmitter, demodulator and DAQ board unit, receives, stores and displays the digitized operation signal from the DAQ board unit; Operation signal measurement system comprising a.
The method of claim 1,
The acceleration sensor unit,
Motion signal measuring system characterized in that the band type using a velcro (velcro).
The method of claim 1,
The amplification unit,
An operating signal measuring system, comprising an analog element, wherein the amplification rate is varied from 2 to 10 times.
delete The method of claim 1,
The acceleration sensor unit and the amplification unit operating signal measuring system, characterized in that connected via a lead wire.
The method of claim 5, wherein
The amplification unit, the operation signal measuring system, characterized in that installed on the edge of the MR scanner magnet through the lead.
The method of claim 1,
A power supply unit connected to the amplifier and a lead wire to supply power; Motion signal measuring system further comprises.
The method of claim 7, wherein
The power supply unit,
Operating signal measuring system, characterized in that installed in the MR room spaced apart from the amplifier a predetermined distance.
The method of claim 7, wherein
The amplifying unit and the power supply unit, the operation signal measuring system, characterized in that provided in the double shield case.
delete The method of claim 1,
The optical signal transmission unit,
A light emitting diode that receives the optical signal modulated by the amplifier and emits light; And
An optical cable for receiving an optical signal from the light emitting diode and transmitting the optical signal to the outside; Operation signal measuring system comprising a.
The method of claim 1,
The demodulation unit,
And a demodulating the optical signal received through the optical signal transmission unit by using a low pass filter to restore the optical signal to an operation signal.

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