TW202203845A - 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

Using Periodic Physiological Signals to Generate Resistive Antibody Layer Imaging Method and Device

The present invention relates to a resistive antibody tomography technology, and more particularly, to a method and device for generating resistive antibody tomography by utilizing periodic physiological signals.

In most medical institutions, common internal imaging techniques are X-ray, computed tomography, nuclear magnetic resonance, and ultrasound. However, X-ray and computed tomography have radiation concerns. Although nuclear magnetic resonance and ultrasound are non-radiation detection instruments, they cannot be popularized in non-research hospitals due to their high cost and large size.

Electrical impedance tomography (EIT) technology is a non-radiative, non-invasive medical imaging technology, which uses the voltage signal outside the measured object to analyze the conductivity distribution inside the object. Therefore, the electrical impedance imaging technology has the advantages of being portable and low-cost in development. In recent years, the research of electrical impedance imaging technology in the image measurement of the human body has proposed many solutions for improving the image resolution, such as the design of composite electrodes, the improvement of the front-end analog circuit, the improvement of the conversion resolution of the 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 remains at the size of the organ level, such as the application of lung and kidney imaging.

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

According to an embodiment, a method for generating resistive antibody layer imaging using periodic physiological signals is provided, comprising: measuring the periodic physiological signals, and detecting characteristic points in each cycle of the periodic physiological signals; The characteristic point in each cycle of the sexual physiological signal is triggered to capture an electrical impedance imaging (EIT) signal, and the EIT signal is measured for a predetermined number of times; the EIT signal for the predetermined number of times 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 measurement of the EIT signal may be to measure 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 with the pulse of the heart. The physiological signals accompanying the heart pulsation may include electrocardiogram signals, photoplethysmography signals, blood oxygen signals, and heart sound signals. The periodic physiological signal may also include a breathing signal.

In the above method, the characteristic points may include signal peaks, signal troughs or R-peaks in each cycle of the periodic physiological signal. In the above method, each measurement of the EIT signal may be performed with a predetermined data length.

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

In the above-mentioned device, the EIT signal measurement may be to measure 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 device, the periodic physiological signal may include a physiological signal generated along with the pulse of the heart. The physiological signals accompanying the heart pulsation may include electrocardiogram signals, photoplethysmography signals, blood oxygen signals, and heart sound signals. The periodic physiological signal may also include a breathing signal.

In the above device, the characteristic points may include signal peaks, signal troughs or R-peaks in each cycle of the periodic physiological signal. In the above apparatus, each measurement of the EIT signal may be performed with a predetermined data length. In addition, the resistive tomographic imaging device using periodic physiological signals can be configured as a wearable device.

Through the above-mentioned electrical impedance imaging technology for synchronizing the measurement of periodic physiological signals (eg, ECG signals), the image resolution can be increased, and the quality of medical testing can also be improved.

The present invention utilizes the characteristics of periodic physiological signals to perform synchronous measurement with the electrical impedance imaging technology, thereby marking and defining the electrical impedance signal of each beat. The periodic physiological signal may be, for example, an electrocardiogram (ECG) signal, after which the electrical impedance signal of each beat is averaged to eliminate internal noise and obtain a template of the electrical impedance signal. The template of this near noise-free electrical impedance signal is input to the back-end imaging software to obtain high-resolution images.

1A to 1E are schematic diagrams for illustrating the effect of multiple averaging of periodic physiological signals. As shown in Figure 1, which shows the measurement of the continuous beats of the ECG signal, it can be seen from the figure that an R-peak of the R wave appears at each beat of the ECG signal. In FIG. 1B , the measurer can mark the R-wave peak of each beat, which is marked with a triangle in the figure. Then, when the R-wave peak of each beat is used as the alignment reference, the ECG signal waveform after the temporary superposition of each beat is shown in FIG. 1C . Finally, after averaging the ECG signals of each segment, the waveform shown in Figure 1D is obtained. As shown in FIG. 1D , the final averaged ECG signal template is shown as a thick line, and the ECG signal of each beat is shown as a dashed line.

Because the in-band noise in the ECG signal of each beat can be regarded as random, the random in-band noise can be almost eliminated after averaging the ECG signals of multiple beats , and presents a 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, there will be a pressure wave passing through the blood vessel, and 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 FIG. 1E , the PPG signal can also be similar to the above-mentioned ECG signal. After averaging the measurements of each beat, the internal random noise can also be canceled to obtain a PPG signal template with almost no noise.

Next, a method for generating a resistive tomography device using periodic physiological signals according to an embodiment of the present invention will be described. In this method, periodic physiological signals are used to synchronize measurements of resistive tomography. According to this embodiment, the periodic physiological signal can be, for example, a periodic signal related to the heart beat, such as a blood pressure signal, an electrocardiogram (ECG) signal, a photoplethysmography (PPG) signal, a blood oxygen signal, a heart sound signal, and the like. In addition to the signals related to the heart, breathing signals can also be used as periodic physiological signals.

In addition, according to this embodiment, the characteristic points in each cycle of the periodic physiological signal 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 peak and trough of the signal, etc. It can also be selected as a feature point of this embodiment. This feature point can be used to trigger 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 tomography device using periodic physiological signals according to an embodiment of the present invention. First, the method of the present embodiment will be briefly described with reference to FIG. 2 . In addition, in the following embodiments, the ECG signal is used as an example of the periodic physiological signal, but 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 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 measuring 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 the reference to trigger the EIT signal measurement. By using this feature point to trigger to capture the EIT signal, the measurement of the EIT signal can be synchronized with the periodic physiological signal.

In addition, an EIT device is set on the hands of the subject 10 to perform electrical impedance imaging. In this embodiment, in each cycle of the previously measured ECG signal, when the R-wave peak of the R-wave of the ECG signal is detected (an example of a feature point), the EIT device is triggered to start capturing the EIT signal, so as to perform Measure. Extracting the EIT signal can extract 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 times K, for example, 10 times of measurement may 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.

Next, the measurement of the EIT signal of each cycle in FIG. 2 is averaged to obtain the template 20 . Finally, electrical impedance imaging is performed using this template 20 to obtain an EIT image 30 . In the EIT image 30, images of the inside 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.

FIG. 3 is a schematic flowchart of a method for generating a resistive tomography device using periodic physiological signals according to an embodiment of the present invention. Next, the method of the resistive tomography apparatus of the present embodiment will be further described with reference to the flowchart shown in FIG. 3 .

As shown in FIGS. 2 and 3 , first, in step S100 , the periodic physiological signals of the subject 10 are measured. Here, examples of periodic physiological signals include periodic signals related to heart beating, such as blood pressure signal, ECG signal, PPG signal, blood oxygen signal, heart sound signal, and the like. Besides, besides the signals related to the heart, breathing signals can also be used as periodic physiological signals.

Then, in step S102, the characteristic points in each cycle of the periodic physiological signal are detected. For example, when the ECG signal is used as the periodic physiological signal, the R-wave peak of the R wave in the ECG signal can be used. Here, only this feature point is distinguishable 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 feature point.

After detecting the characteristic point of the periodic physiological signal, step S104 is executed; otherwise, if no characteristic point is detected, then go back to step S100 to continue to detect the characteristic point from the measured periodic physiological signal. In step S104, the EIT imaging unit is triggered to capture the EIT signal based on the characteristic points (R-wave peaks) in each cycle of the periodic physiological signal (ECG signal). In this way, when the EIT signal is captured in this embodiment, the ECG signal can be synchronized.

Next, in step S106, after the EIT signal is captured for EIT signal measurement, it is determined whether the EIT signal measurement has been performed for 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 times K, go to step S108 , otherwise, go back to step S100 , and continue the above steps S100 to S104 until the 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 EIT signal measurements will be further described later. Next, in step S110, according to the template, the resistive antibody layer image is generated by the EIT imaging unit. Because the 10 measurements are synchronized with periodic physiological signals, random errors in each measurement can be averaged to generate a nearly error-free template, thereby producing high-resolution EIT images.

4A to 4D illustrate waveform diagrams and spatial distribution diagrams of various stages in the EIT imaging process. When starting EIT imaging, firstly, 8 electrodes (refer to the electrodes 112 on the wrist 110 of FIG. 7 ) are attached to the wrist (an example) of the subject 10 as shown in FIG. Measurements were made to obtain 16 pairs of raw signals (signal pairs 0-16) as shown in Figure 4A. This original signal can basically appear as a sine wave.

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

5A to 5D are schematic diagrams illustrating a method for measuring the average EIT signal. In this embodiment, the EIT signals measured in synchronization with the physiological signals in each cycle are superimposed and then averaged to generate a template. In this embodiment, the averaging can be performed according to signals of different stages of EIT imaging. As shown in FIGS. 4A to 4D , the EIT imaging process mainly has four stages, ie, 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 measurements.

First, as shown in Figure 5A, the source of the averaged signal is the raw signal (sine wave) from the EIT measurement. As shown in FIG. 5A, for each cycle of the R-peak of the ECG signal, trigger to capture the EIT signal. Each measurement can be performed with a predetermined data length. In this embodiment, the predetermined data length can be set as N frames (N is a natural number). After, for example, 10 measurements, 10 original signals with a data length of N frames are obtained. Afterwards, the 10 original signals are averaged to obtain a template 20 based on the original signal and having a data length of N frames. Because the 10 measurements are synchronized with periodic physiological signals (in this case, ECG signals), random errors in each measurement can be averaged to generate a template with almost no errors, which can produce high resolution EIT imaging.

In addition, as shown in FIG. 5B, the RMS voltage signal as shown in FIG. 4B is used for averaging. Similarly, in this method, 10 RMS voltage signals with a data length of N frames are finally obtained. Then, 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 periodic physiological signals (in this case, ECG signals), random errors in each measurement can be averaged to generate a template with almost no errors, which can produce high resolution EIT imaging. The example shown in FIG. 5C uses the conduction value signal shown in FIG. 4C for averaging. In this way, a template 24 based on the conductive value signal and having a data length of N frames can be obtained. For the same reason as described above, high-resolution EIT imaging can also be produced. 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. For the same reason as described above, a high-resolution EIT image can also be generated.

FIG. 6 is a block diagram illustrating a resistive tomographic imaging device using periodic physiological signals according to an embodiment of the present invention. The resistive tomography apparatus 100 includes at least a processor 102 and an EIT imaging unit 104 . The resistive tomography apparatus 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. The ECG signal can be measured by any ECG module, for example, to provide a stable ECG signal measurement without baseline shift. The resistive tomography device 100 may 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 times K based on the R-wave peak of the ECG signal. The K measurements of the EIT signal can then be averaged to obtain a nearly noise-free template. Finally, the EIT image is output according to this template. The processor 102 and the EIT imaging unit 104 of the resistive tomography apparatus 100 can cooperate to execute the flow chart of the method for generating a resistive tomography apparatus using periodic physiological signals described in FIG. 3 , and the EIT signals described in FIGS. 5A to 5D . The average method of measurement will not be repeated here.

FIG. 7 is a schematic diagram of an EIT imaging device. The specific EIT imaging device 100 may have various designs, and the present invention does not limit the specific circuit structure of the EIT imaging device 100 .

The EIT imaging device 100 may be provided with electrical impedance imaging electrodes 112, for example, 8 electrodes are evenly distributed on the part to be measured, such as the wrist 110, of the subject 10.

The EIT imaging device 100 further includes a current source 124, which can provide a current output of 0.14 mA, 10KHz, for example. The EIT imaging device 100 further includes two multiplexers 120 and 122 for the current source discharge path selection, wherein the input terminal of the multiplexer 120 is connected to the current source, and the input terminal of the multiplexer 122 is connected to the ground. (DAQ device) 126 controls its digital output for the purpose of current path selection. The DAQ device 126 may use, for example, an NI MyDAQ (trade name) device, which is used to generate digital outputs for logic control of the multiplexers 120, 122 to achieve current path selection. In addition, the DAQ device 126 can continuously capture the 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 peripheral voltage of the wrist 110 received by the DAQ device 126 to obtain a distribution map of the internal conductivity, and output the EIT image accordingly.

To sum up, the above-mentioned electrical impedance imaging technology for synchronizing the measurement of periodic physiological signals (eg, 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 towards clinical application. Make it a non-radiative, low-cost image detection system. In the short-term development, this patent 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 and worn on the wrist to detect the radial artery, and then achieve Long-term cardiovascular health monitoring. In addition, the electrical impedance imaging technology of periodic physiological signals (eg, ECG signals) in this embodiment is also beneficial to improve the quality of medical testing.

10: Subjects 12: ECG electrodes 20, 22, 24, 26: Templates 30: EIT Image 32: Bones 34: Arteries 100: Resistive antibody tomography device 102: Processor 104: EIT imaging unit 110: wrist 112: Electrodes 124: Current source 120, 122: Multiplexer 126:DAQ device S100~S110: each process step

1A to 1E are schematic diagrams for illustrating the effect of multiple averaging of periodic physiological signals. FIG. 2 is a schematic diagram of waveforms at various stages of a method for generating a resistive tomography device using periodic physiological signals according to an embodiment of the present invention. FIG. 3 is a schematic flowchart of a method for generating a resistive tomography device using periodic physiological signals according to an embodiment of the present invention. 4A to 4D illustrate waveform diagrams and spatial distribution diagrams of various stages in the EIT imaging process. 5A to 5D are schematic diagrams illustrating a method for measuring the average EIT signal. FIG. 6 is a block diagram illustrating a resistive tomographic imaging device using periodic physiological signals according to an embodiment of the present invention. FIG. 7 is a schematic diagram of an EIT imaging unit.

S100~S110: each process step

Claims (21)

A method for generating resistive antibody tomography using periodic physiological signals, comprising: measuring periodic physiological signals, and detecting characteristic points in each cycle of the periodic physiological signals; triggering to capture an electrical impedance imaging (EIT) signal based on the feature point in each cycle of the periodic physiological signal, and performing the EIT signal measurement a predetermined number of times; averaging the predetermined number of measurements of the EIT signal to generate a template; and From the template, resistive antibody layer images are generated. The method for generating resistive tomography using periodic physiological signals as claimed in claim 1, wherein the EIT signal measurement is to measure the original signal of the EIT signal. The method for generating resistive tomography using periodic physiological signals as claimed in claim 1, wherein the EIT signal measurement is to measure a root mean square voltage signal generated based on the EIT signal. The method for generating resistive tomography imaging using periodic physiological signals as claimed in claim 1, wherein the EIT signal measurement is to measure a conductive value signal generated based on the EIT signal. The method for generating resistive tomography imaging using periodic physiological signals according to claim 1, wherein the EIT signal measurement is to measure an EIT image generated based on the EIT signal. The method for generating resistive tomography using periodic physiological signals as claimed in claim 1, wherein the periodic physiological signals include physiological signals generated along with the pulse of the heart. The method for generating resistive antibody tomography using periodic physiological signals according to claim 6, wherein the physiological signals accompanying the heart pulsation include electrocardiogram signals, photoplethysmography signals, blood oxygen signals, and heart sound signals. The method for generating resistive tomography using periodic physiological signals as claimed in claim 1, wherein the periodic physiological signals include breathing signals. The method for generating resistive tomography using periodic physiological signals as claimed in 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 tomography using periodic physiological signals as claimed in claim 1, wherein each measurement of the EIT signal is performed with a predetermined data length. A device for generating resistive tomography using periodic physiological signals, comprising: A resistive tomographic imaging unit for generating resistive tomographic imaging; A processor configured to perform the following steps: receiving periodic physiological signals, and detecting characteristic points in each cycle of the periodic physiological signals; triggering the resistive tomographic imaging unit to capture electrical impedance imaging (EIT) signals based on the feature points in each cycle of the periodic physiological signal, and performing the EIT signal measurement a predetermined number of times; averaging the predetermined number of measurements of the EIT signal to generate a template; and From the template, the resistive antibody layer image is generated. The resistive tomographic imaging device using periodic physiological signals as claimed in claim 11, wherein the EIT signal measurement is to measure the original signal of the EIT signal. The resistive tomographic imaging device using periodic physiological signals as claimed in claim 11, wherein the EIT signal measurement is to measure a root mean square voltage signal generated based on the EIT signal. The resistive tomographic imaging device using periodic physiological signals as claimed in claim 11, wherein the EIT signal measurement is to measure a conductive value signal generated based on the EIT signal. The resistive tomographic imaging device using periodic physiological signals as claimed in claim 11, wherein the EIT signal measurement is to measure an EIT image generated based on the EIT signal. The resistive tomographic imaging device using periodic physiological signals as claimed in claim 11, wherein the periodic physiological signals include physiological signals generated along with heart pulsation. The resistive tomography device using periodic physiological signals as claimed in claim 16, wherein the physiological signals accompanying the heart pulsation include electrocardiogram signals, photoplethysmography signals, blood oxygen signals, and heart sound signals. The resistive tomographic imaging device using periodic physiological signals as claimed in claim 11, wherein the periodic physiological signals include breathing signals. The resistive tomographic imaging device using periodic physiological signals as claimed in claim 11, wherein the characteristic points include signal peaks, signal troughs or R-wave peaks in each cycle of the periodic physiological signals. The resistive tomography apparatus using periodic physiological signals as claimed in claim 11, wherein each measurement of the EIT signal is performed with a predetermined data length. The resistive tomographic imaging device using periodic physiological signals as claimed in claim 11, wherein the resistive tomographic imaging device using periodic physiological signals is configured as a wearable device.

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