TWI740586B - Method and device for generating eit image using periodic biomedical signal - Google Patents

Abstract

Provided are a method and a device for generating an EIT image using periodic biomedical signal. The method includes measuring a periodic biomedical signal and detecting a feature point in each period of the periodic biomedical signal; triggering to acquire an EIT signal based on the feature point in each period of the periodic biomedical signal, and performing EIT signal measurements for a predetermined times; averaging the EIT signal measurements to generate a template; and generating an EIT image based on the template.

Description

Method and device for generating resistive antibody layer imaging using periodic physiological signals

The present invention relates to a resistive antibody layer imaging technology, and particularly relates to a method and device for generating resistive antibody layer imaging using periodic physiological signals.

In most medical institutions, common internal human body imaging techniques include X-rays, computed tomography, nuclear magnetic resonance, and ultrasound. However, X-ray and computer tomography have radiation doubts. Although nuclear magnetic resonance and ultrasound are non-radiative testing instruments, they cannot be popularized in non-research hospitals due to their high cost and bulkiness.

Electrical impedance tomography (EIT) technology is a non-radiative, non-invasive medical imaging technology that uses the external voltage signal of the measured object to analyze the electrical conductivity distribution inside the object. Therefore, electrical impedance imaging technology has the advantages of portability and low cost in development. In recent years, the research of electrical impedance imaging technology on human body image measurement has proposed many refined solutions for image resolution, such as composite electrode design, improvement of front-end analog circuits, enhancement of conversion resolution of analog-to-digital converter (ADC), Back-end imaging software algorithm optimization and image post-modification to improve the resolution of electrical impedance imaging. However, in practical applications, the resolution still stays at the level of analyzing organs, such as the application of lung and kidney imaging.

At present, in the application of human body imaging, there is no mention of using synchronized physiological signal measurement to eliminate noise, thereby improving the resolution of electrical impedance imaging.

According to one embodiment, a method for generating resistive antibody layer imaging using periodic physiological signals is provided, including: measuring periodic physiological signals, and detecting characteristic points in each period of the periodic physiological signals; based on the period The characteristic point in each cycle of the sexual physiological signal is triggered to capture electrical impedance imaging (EIT) signals, and the EIT signal measurement is performed a predetermined number of times; the predetermined number of the EIT signal is measured Averaging is performed to generate a template; and based on the template, a resistive antibody layer image is generated.

In the above method, the EIT signal measurement can be the original signal of the EIT signal, the root mean square voltage signal generated based on the EIT signal, the conduction value signal generated based on the EIT signal, and the signal generated based on the EIT signal. EIT image.

In the above method, the periodic physiological signal may include a physiological signal generated along with the pulse of the heart. The physiological signals accompanying the heart pulse may include electrocardiogram signals, photoplethysmogram signals, blood oxygen signals, and heart sound signals. The periodic physiological signal may also include a breathing signal.

In the above method, the characteristic point may include a signal peak, a signal trough, or an R-wave peak in each cycle of the periodic physiological signal. In the above method, each EIT signal measurement can be performed with a predetermined data length.

According to another embodiment, there is provided a resistive antibody layer imaging device using periodic physiological signals, which includes: a resistive antibody layer imaging unit for generating resistive antibody layer imaging; and a processor configured to perform the following steps: receiving periodicity Physiological signal, and detect the characteristic points in each cycle of the periodic physiological signal; based on the characteristic points in each cycle of the periodic physiological signal, trigger the resistive antibody layer imaging unit to capture Electrical Impedance Imaging (EIT) signal, and perform the EIT signal measurement for a predetermined number of times; average the EIT signal measurement of the predetermined number of times to generate a template; and generate the resistance according to the template Antibody layer imaging.

In the above device, the EIT signal measurement can be the original signal of the measurement EIT signal, the root mean square voltage signal generated based on the EIT signal, the conduction value signal generated based on the EIT signal, and the signal generated based on the EIT signal. EIT image.

In the above device, the periodic physiological signal may include a physiological signal generated along with the heart pulse. The physiological signals accompanying the heart pulse may include electrocardiogram signals, photoplethysmogram signals, blood oxygen signals, and heart sound signals. The periodic physiological signal may also include a breathing signal.

In the above device, the characteristic point may include a signal peak, a signal trough, or an R-wave peak in each cycle of the periodic physiological signal. In the above device, each EIT signal measurement can be performed with a predetermined data length. In addition, the imaging device using periodic physiological signals to generate the resistive antibody layer can be configured as a wearable device.

The electrical impedance imaging technology that synchronizes the measurement of periodic physiological signals (such as electrocardiographic signals) can increase the resolution of images, and is also conducive to improving the quality of medical testing.

The present invention utilizes the characteristics of periodic physiological signals to perform synchronous measurement with electrical impedance imaging technology, so as to conveniently mark and define the electrical impedance signal of each beat. The periodic physiological signal can be, for example, an electrocardiography (ECG) signal. The electrical impedance signal of each beat is averaged to eliminate internal noise and obtain a template of the electrical impedance signal. Input this almost noise-free electrical impedance signal template into the back-end imaging software to obtain a high-resolution image.

Figures 1A to 1E are schematic diagrams illustrating the effects of averaging periodic physiological signals multiple times. As shown in Figure 1, it shows the measurement of the continuous beats of the ECG signal. From the figure, it can be seen that the R-peak of the R wave appears at each beat of the ECG signal. In Figure 1B, the measurer can mark the R-wave peak of each beat, which is marked by the triangle in the figure. Then, when the R-wave peak of each beat is used as the alignment reference, the ECG signal waveform after temporarily superimposing each beat is as shown in FIG. 1C. Finally, after averaging each segment of the ECG signal, the waveform shown in Figure 1D is obtained. As shown in Figure 1D, the final average ECG signal template is shown by the thick line, and the ECG signal of each beat is shown by the dotted line.

Because the in-band noise in the ECG signal of each beat can be regarded as random, after averaging the ECG signals of multiple beats, the random in-band noise can be almost eliminated , And presents pseudo noise (pseudo noise) signal. Therefore, taking the characteristic points of each beat of the periodic physiological signal (such as the above-mentioned R-wave peak) as the alignment reference, and averaging the beats of the periodic physiological signal, a template with almost no noise can be obtained.

In addition, FIG. 1E shows another example of a periodic physiological signal, which uses a photoplethysmography (PPG) signal. Generally, with the heartbeat, a pressure wave will pass through the blood vessel. This wave will slightly change the diameter of the blood vessel. PPG uses this change and is mainly used for blood volume description. As shown in Figure 1E, the PPG signal can also be the same as the above-mentioned ECG signal. After the measurement of each beat is averaged, the internal random noise can also be offset to obtain a PPG signal template with almost no noise.

Next, a method for generating a resistive antibody layer imaging device using periodic physiological signals according to an embodiment of the present invention will be described. In this method, periodic physiological signals will be used to synchronize the measurement of resistive antibody layer imaging. According to this embodiment, the periodic physiological signal can be used as a periodic signal related to the heart beat, such as blood pressure signal, electrocardiogram (ECG) signal, photoplethysmogram (PPG) signal, blood oxygen signal, heart sound signal, etc. In addition to signals related to the heart, breathing signals can also be used as periodic physiological signals.

In addition, according to this embodiment, the characteristic points of the periodic physiological signal in each week are not limited to the R-wave peak of the above-mentioned R wave. In each week of the periodic physiological signal, as long as the point is distinctive, it can be selected as the characteristic point of this embodiment. Therefore, in addition to the R-wave peak of the R wave in the above ECG signal, the signal's peak, trough, etc., It can also be selected as the characteristic point of this embodiment. This feature point can be used to trigger the EIT signal measurement. In this way, the EIT signal measurement can be synchronized with the periodic physiological signal.

FIG. 2 is a schematic diagram of waveforms at various stages of a method for generating a resistive antibody layer imaging device using periodic physiological signals according to an embodiment of the present invention. First, the method of this embodiment will be briefly explained with reference to FIG. 2. In addition, in the following embodiments, the ECG signal is used as an illustrative example of the periodic physiological signal. However, as mentioned above, the periodic physiological signal is not limited to the ECG signal, as long as it has periodic characteristics.

As shown in FIG. 2, for example, three pieces of electrode pads 12 for ECG measurement are placed on the subject 10 so that the ECG signal of the subject 10 can be measured by the ECG measurement device. As shown in the figure, the ECG signal exhibits periodic characteristics, and the R-wave peak of the R wave is used as the characteristic point, that is, the characteristic point is used as a reference to trigger the EIT signal measurement. By using this characteristic point to trigger to capture the EIT signal, the EIT signal measurement can be synchronized with the periodic physiological signal.

In addition, an EIT device is installed on the hand of the subject 10 to perform electrical impedance imaging. In this embodiment, in each cycle of the previously measured ECG signal, when the R peak of the R wave of the ECG signal is detected (an example of a characteristic point), the EIT device is triggered to start capturing the EIT signal to perform Measure. Retrieving the EIT signal can retrieve a predetermined data length, such as N frames, where N is a natural number. The acquisition and measurement of the EIT signal will continue for a predetermined number of K, for example, 10 measurements can be performed in this embodiment. The predetermined number of times K is not particularly limited, and can be set according to requirements such as resolution.

Then, the EIT signal quantity of each cycle in FIG. 2 is measured and averaged to obtain the template 20. Finally, the template 20 is used for electrical impedance imaging to obtain an EIT image 30. In the EIT image 30, the internal images of the human body such as bones 32 or arteries 34 can be clearly seen. In the EIT image 30 obtained in this way, since the noise can be almost eliminated, the EIT image 30 with high resolution can be obtained.

3 is a schematic flowchart of a method for generating a resistive antibody layer imaging device using periodic physiological signals according to an embodiment of the present invention. Next, referring to the flowchart shown in FIG. 3, the method of the resistive antibody layer imaging device of this embodiment will be further described.

As shown in FIGS. 2 and 3, first, in step S100, the periodic physiological signal of the subject 10 is measured. Here, as examples of periodic physiological signals, there are periodic signals related to the heartbeat, such as blood pressure signal, ECG signal, PPG signal, blood oxygen signal, heart sound signal, etc. In addition, in addition to signals related to the heart, breathing signals can also be used as periodic physiological signals.

Next, in step S102, the characteristic points in each cycle of the periodic physiological signal are detected. For example, when an ECG signal is used as a periodic physiological signal, the R-wave peak of the R wave in the ECG signal can be used. Here, only this characteristic point is distinctive enough to be used to explicitly trigger to capture the EIT signal. For example, signal peaks or troughs in a cycle can also be used as this characteristic point.

After detecting the characteristic points of the periodic physiological signal, step S104 is changed to execute. On the contrary, if the characteristic point is not detected, the process returns to step S100 to continue to detect the characteristic point from the measured periodic physiological signal. In step S104, based on the characteristic point (R-wave peak) in each cycle of the periodic physiological signal (ECG signal), the EIT imaging unit is triggered to capture the EIT signal. In this way, in this embodiment, when the EIT signal is captured, it can be synchronized with the ECG signal.

Then, in step S106, after the EIT signal is captured to perform the EIT signal measurement, it is determined whether the EIT signal measurement has been performed a predetermined number of times K. In this embodiment, 10 measurements are taken as an example. If the EIT signal measurement has reached the predetermined number of K, step S108 is executed, otherwise, it returns to step S100, and the steps from S100 to S104 are continued until K times of measurement are completed.

In step S108, the above K times of EIT signal measurements are averaged to generate a template. In addition, the averaging of the EIT signal measurement will be further explained later. Next, in step S110, based on this template, the EIT imaging unit generates resistive antibody layer imaging. Because these 10 measurements are synchronized with periodic physiological signals, random errors in each measurement can be averaged to produce a template with almost no errors, which can produce high-resolution EIT imaging.

4A to 4D show waveform diagrams and spatial distribution diagrams of various stages in the EIT imaging process. At the beginning of EIT imaging, first, for example, 8 electrodes are attached to the wrist of the subject 10 (an example) as shown in FIG. 2 (refer to the electrodes 112 on the wrist 110 in FIG. 7), and the electrodes are used to perform the imaging. Measure to obtain 16 pairs of original signals (signal pairs 0-16) as shown in Figure 4A. This original signal can basically present a sine wave.

Then, the measured original signal is converted into a root mean square (RMS) voltage waveform as shown in FIG. 4B. After that, it is converted from the root mean square graph to the spatial distribution graph of the conductivity value as shown in Fig. 4C. From the partial enlarged view in Fig. 4C, it can be seen the distribution of the conduction value of each grid in the space. Finally, according to the spatial distribution map of the conductivity value, imaging is performed to generate an EIT image as shown in Figure 4D.

5A to 5D show schematic diagrams of the average EIT signal measurement method. In this embodiment, the EIT signal measured in synchronization with the physiological signal in each cycle is superimposed and then averaged to generate a template. In this embodiment, the averaging can be performed according to the signals of different stages of EIT imaging. As shown in Figures 4A to 4D, the EIT imaging process mainly has four stages, namely the original signal, the RMS voltage signal, the conductivity value, and the EIT image. Therefore, the four-stage signal can be used to average the EIT signal measurement.

First, as shown in FIG. 5A, the signal source for this averaging is the original signal (sine wave) from the EIT measurement. As shown in FIG. 5A, for each cycle of the R-wave peak of the ECG signal, trigger to acquire the EIT signal. Each measurement can be performed with a predetermined data length. In this embodiment, the predetermined data length can be set to N frames (N is a natural number). After, for example, 10 measurements, 10 original signals with a data length of N frames are obtained. After that, the 10 original signals are averaged to obtain a template 20 based on the original signals and having a data length of N frames. Because the 10 measurements are synchronized with the periodic physiological signal (in this case, the ECG signal), the random errors in each measurement can be averaged to produce almost error-free templates, which can generate high resolution EIT imaging.

In addition, as shown in FIG. 5B, it uses the RMS voltage signal shown in FIG. 4B for averaging. Similarly, in this method, 10 RMS voltage signals with a data length of N frames will be obtained at the end. After that, the 10 RMS voltage signals are averaged to obtain a template 22 based on the RMS voltage signal and having a data length of N frames. Because the 10 measurements are synchronized with the periodic physiological signal (in this case, the ECG signal), the random errors in each measurement can be averaged to produce almost error-free templates, which can generate high resolution EIT imaging. The example shown in FIG. 5C uses the conductivity signal shown in FIG. 4C for averaging. In this way, a template 24 based on the conductivity signal and having a data length of N frames can be obtained. The same reason as the above-mentioned reason can also produce high-resolution EIT imaging. In addition, the example shown in FIG. 5D uses the EIT image shown in FIG. 4D for averaging. In this way, a template 26 based on the EIT image signal and having a data length of N frames can be obtained. The same reason as the above-mentioned reason can also produce high-resolution EIT imaging.

6 is a schematic block diagram of an imaging device for generating a resistive antibody layer using periodic physiological signals according to an embodiment of the present invention. The resistive antibody layer imaging device 100 at least includes a processor 102 and an EIT imaging unit 104. The resistive antibody layer imaging device 100 can receive the ECG signal, and accordingly trigger the EIT imaging unit 104 to start capturing the EIT signal of the subject 10. The EIT imaging unit 104 may be provided on the wrist of the subject 10, for example. This ECG signal, for example, can use any ECG module to measure the subject, and provide stable ECG signal measurement without baseline deviation. The resistive antibody layer imaging device 100 can also use other periodic physiological signals.

After that, the processor 102 can control the EIT imaging unit 104 to trigger the EIT imaging unit 104 to perform a predetermined number of K based on the R-wave peak of the ECG signal. Then, the K times of EIT signal measurement can be averaged to obtain a template with almost no noise. Finally, the EIT image is output according to this template. The processor 102 and the EIT imaging unit 104 of the resistive antibody layer imaging device 100 can cooperatively execute the above-described method of generating a resistive antibody layer imaging device using periodic physiological signals as described in FIG. 3, and the EIT signal described in FIGS. 5A to 5D The averaging method of the measurement will not be detailed here.

Fig. 7 shows a schematic diagram of the EIT imaging device. The specific EIT imaging device 100 may have various design methods, and the present invention does not limit the specific circuit structure of the EIT imaging device 100.

The EIT imaging device 100 can be provided with electrical impedance imaging electrodes 112, for example, 8 electrodes are used to evenly distribute the test site of the subject 10, such as the wrist 110.

The EIT imaging device 100 further includes a current source 124, which can provide a current output of 0.14 mA, 10 KHz, for example. The EIT imaging device 100 further includes two multiplexers 120 and 122 as current source discharge path selection. The input terminal of the multiplexer 120 is connected to the current source, and the input terminal of the multiplexer 122 is grounded. (DAQ device) 126 controls its digital output to achieve the purpose of current path selection. The DAQ device 126 can use, for example, an NI MyDAQ (trade name) device, which is used to generate digital output as the logic control of the multiplexers 120 and 122 to achieve current path selection. In addition, the DAQ device 126 can continuously capture 16-pole peripheral voltage from the wrist 110 and convert the voltage from an analog to a digital signal (DAC).

Finally, in this embodiment, for example, the imaging software Matlab EIDORS toolbox (trade name) can be used to internally solve the DAQ device 126 receiving the peripheral voltage of the wrist 110 to obtain the internal conductivity distribution map, and output the EIT image accordingly.

In summary, the synchronized electrical impedance imaging technology through the measurement of the above-mentioned periodic physiological signals (such as ECG signals) can increase the image resolution. Therefore, in the long-term development, it is conducive to the development of electrical impedance imaging technology, and it is more advanced in clinical application. Make it a non-radiation, low-cost image detection system. In the short-term development, with this patent, it can improve its image analysis ability and detect its blood vessel images. In the development of wearable devices, it can be made into a wristband to be worn on the wrist to detect the radial artery and achieve Long-term cardiovascular health monitoring. In addition, the electrical impedance imaging technology for periodic physiological signals (such as ECG signals) of this embodiment is also beneficial to improve the quality of medical testing.

10: Subject 12: ECG electrode 20, 22, 24, 26: template 30: EIT image 32: Bones 34: Artery 100: Resistance antibody layer imaging device 102: processor 104: EIT imaging unit 110: wrist 112: Electrode 124: current source 120, 122: multiplexer 126: DAQ device S100~S110: Each process step

Figures 1A to 1E are schematic diagrams illustrating the effects of averaging periodic physiological signals multiple times. FIG. 2 is a schematic diagram of waveforms at various stages of a method for generating a resistive antibody layer imaging device using periodic physiological signals according to an embodiment of the present invention. 3 is a schematic flowchart of a method for generating a resistive antibody layer imaging device using periodic physiological signals according to an embodiment of the present invention. 4A to 4D show waveform diagrams and spatial distribution diagrams of various stages in the EIT imaging process. 5A to 5D show schematic diagrams of the average EIT signal measurement method. 6 is a schematic block diagram of an imaging device for generating a resistive antibody layer using periodic physiological signals according to an embodiment of the present invention. Fig. 7 shows a schematic diagram of the EIT imaging unit.

S100~S110: Each process step

Claims (21)

A method for generating resistive antibody layer imaging using periodic physiological signals, including: Measuring periodic physiological signals, and detecting characteristic points in each cycle of the periodic physiological signals; Triggering to acquire electrical impedance imaging (EIT) signals based on the characteristic points in each cycle of the periodic physiological signal, and performing the EIT signal measurement with a predetermined number of times; Averaging the EIT signal measurements of the predetermined number of times to generate a template; and According to the template, an image of the resistive antibody layer is generated. The method for generating resistive antibody layer imaging using periodic physiological signals as described in claim 1, wherein the EIT signal measurement is to measure the original signal of the EIT signal. The method for generating resistive antibody layer imaging using periodic physiological signals according to claim 1, wherein the EIT signal measurement is to measure the root mean square voltage signal generated based on the EIT signal. The method for generating a resistive antibody layer imaging method using periodic physiological signals as described in claim 1, wherein the EIT signal measurement is to measure a conductivity signal generated based on the EIT signal. The method for generating resistive antibody layer imaging using periodic physiological signals as described in claim 1, wherein the EIT signal measurement is to measure the EIT image generated based on the EIT signal. The method for generating resistive antibody layer imaging using periodic physiological signals as described in claim 1, wherein the periodic physiological signals include physiological signals generated along with heart pulse. According to claim 6, the method for generating resistive antibody layer imaging using periodic physiological signals, wherein the physiological signals following the heart pulse include electrocardiogram signals, photoplethysmogram signals, blood oxygen signals, and heart sound signals. The method for generating resistive antibody layer imaging using periodic physiological signals as described in claim 1, wherein the periodic physiological signals include respiratory signals. The method for generating resistive antibody layer imaging using periodic physiological signals according to claim 1, wherein the characteristic points include signal peaks, signal troughs, or R-wave peaks in each cycle of the periodic physiological signals. The method for generating resistive antibody layer imaging using periodic physiological signals as described in claim 1, wherein each measurement of the EIT signal is performed with a predetermined data length. An imaging device for generating a resistive antibody layer by using periodic physiological signals, including: The resistive antibody layer imaging unit is used to produce resistive antibody layer imaging; The processor is structured to perform the following steps: Receiving periodic physiological signals, and detecting characteristic points in each cycle of the periodic physiological signals; Based on the characteristic points in each cycle of the periodic physiological signal, trigger the resistive antibody layer imaging unit to capture electrical impedance imaging (EIT) signals, and perform the EIT signal measurement with a predetermined number of times; Averaging the EIT signal measurements of the predetermined number of times to generate a template; and According to the template, an image of the resistive antibody layer is generated. According to claim 11, the resistive antibody layer imaging device using periodic physiological signals, wherein the EIT signal measurement is to measure the original signal of the EIT signal. According to claim 11, the resistive antibody layer imaging device using periodic physiological signals, wherein the EIT signal measurement is to measure the root mean square voltage signal generated based on the EIT signal. According to claim 11, the resistive antibody layer imaging device using periodic physiological signals, wherein the EIT signal measurement is a measurement of a conductivity signal generated based on the EIT signal. According to claim 11, the resistive antibody layer imaging device using periodic physiological signals, wherein the EIT signal measurement is to measure an EIT image generated based on the EIT signal. According to claim 11, the apparatus for generating a resistive antibody layer using periodic physiological signals, wherein the periodic physiological signals include physiological signals generated along with heart pulsation. The imaging device for generating a resistive antibody layer using periodic physiological signals according to claim 16, wherein the physiological signals following the heart pulse include electrocardiogram signals, photoplethysmogram signals, blood oxygen signals, and heart sound signals. According to claim 11, the apparatus for generating a resistive antibody layer using periodic physiological signals, wherein the periodic physiological signals include respiration signals. The imaging device for generating a resistive antibody layer using a periodic physiological signal according to claim 11, wherein the characteristic point includes a signal peak, a signal trough, or an R-wave peak in each cycle of the periodic physiological signal. According to claim 11, the resistive antibody layer imaging device using periodic physiological signals, wherein each measurement of the EIT signal is performed with a predetermined data length. The imaging device for generating a resistive antibody layer using periodic physiological signals according to claim 11, wherein the imaging device for generating a resistive antibody layer using periodic physiological signals is configured as a wearable device.

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