CN114224313B - Electrical impedance imaging method and computer-readable storage medium - Google Patents
Electrical impedance imaging method and computer-readable storage medium Download PDFInfo
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- CN114224313B CN114224313B CN202111614122.6A CN202111614122A CN114224313B CN 114224313 B CN114224313 B CN 114224313B CN 202111614122 A CN202111614122 A CN 202111614122A CN 114224313 B CN114224313 B CN 114224313B
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- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
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Abstract
The invention provides an electrical impedance imaging method, which comprises the following steps: acquiring a plurality of continuous signal amplitude vectors; respectively calculating an electrode impedance value corresponding to each signal amplitude vector according to the current value and the signal amplitude vector; dividing a plurality of signal amplitude vectors into a plurality of groups according to a preset rule, wherein the signal amplitude vectors of the plurality of groups are arranged according to the acquired time sequence; selecting the minimum electrode impedance value from the electrode impedance values corresponding to each group of signal amplitude vectors as a standard impedance value; taking a signal amplitude vector corresponding to the standard impedance value as a standard amplitude vector; respectively calculating corresponding equipotential point impedance value vectors according to each signal amplitude vector in each group of signal amplitude vectors and the standard amplitude vector corresponding to the previous group of signal amplitude vectors; and generating an electrical impedance image according to the equipotential impedance value vector. In addition, the invention also provides a computer readable storage medium. The technical scheme of the invention is used for generating the electrical impedance image according to the signal amplitude vector.
Description
Technical Field
The present invention relates to the field of electrical impedance imaging technology, and in particular, to an electrical impedance imaging method and a computer-readable storage medium.
Background
Electrical Impedance Tomography (EIT) is a technique for imaging using Electrical Impedance characteristics of organs and tissues of the human body. The electrical impedance tomography uses the resistivity distribution in the human body as a target to reconstruct a tissue image in the human body. When an organ or tissue of a human body is diseased, the impedance of the diseased region is different from the impedance of a region where no disease occurs, and thus, the disease of the organ or tissue of the human body can be diagnosed by measuring the impedance. In the process of electrical impedance tomography, a certain number of electrodes are fixed on a human body, and data for generating images are acquired by exciting two electrodes in turn and measuring the potential difference between the other electrodes.
Therefore, how to generate an image based on the potential difference is an issue that needs to be solved.
Disclosure of Invention
The invention provides an electrical impedance imaging method and a computer readable storage medium, which are used for generating electrical impedance images according to signal amplitude vectors.
In a first aspect, an embodiment of the present invention provides an electrical impedance imaging method, where the electrical impedance imaging method includes:
acquiring a plurality of continuous signal amplitude vectors, wherein each signal amplitude vector comprises sub-signal amplitudes between the rest two electrodes when two electrodes in all the electrodes are sequentially used as excitation electrode pairs;
respectively calculating an electrode impedance value corresponding to each signal amplitude vector according to the current value and the signal amplitude vector;
dividing the signal amplitude vectors into a plurality of groups according to a preset rule, wherein the signal amplitude vectors of the plurality of groups are arranged according to the acquired time sequence;
selecting the minimum electrode impedance value from the electrode impedance values corresponding to each group of signal amplitude vectors as a standard impedance value;
taking the signal amplitude vector corresponding to the standard impedance value as a standard amplitude vector;
respectively calculating corresponding equipotential point impedance value vectors according to each signal amplitude vector in each group of signal amplitude vectors and the standard amplitude vector corresponding to the previous group of signal amplitude vectors; and
and generating an electrical impedance image according to the equipotential impedance value vector.
In a second aspect, embodiments of the invention provide a computer readable storage medium for storing program instructions executable by a processor to implement an electrical impedance imaging method as described above.
According to the electrical impedance imaging method and the computer readable storage medium, the sub-signal amplitude obtained by each measurement forms a corresponding signal amplitude vector, the electrode impedance value is calculated according to the signal amplitude vector and the current value, the standard amplitude vector is obtained according to the electrode impedance value, and the equipotential point impedance value vector is calculated according to the signal amplitude vector and the standard amplitude vector, so that an electrical impedance image is generated. When the electrical impedance image is generated according to the equipotential line back projection algorithm, a signal amplitude vector obtained by measuring a uniform medium is required to be used as a standard amplitude vector for calculating an equipotential point impedance value vector. However, in practice, the signal amplitude vector corresponding to the uniform medium is difficult to obtain and is extremely susceptible to the accessories of the electrical impedance imaging equipment and the actual measurement error. Therefore, according to the invention, one signal amplitude vector in each group is used as a standard amplitude vector according to the electrode impedance value, so that the measured value of the measured object per se is used as the reference of dynamic imaging, and the interference of the imaging effect caused by different electrical impedance imaging equipment and accessories thereof or individual difference of the measured object and other factors can be avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a flowchart of an electrical impedance imaging method according to a first embodiment of the present invention.
Fig. 2 is a first sub-flowchart of an electrical impedance imaging method according to a first embodiment of the present invention.
Fig. 3 is a second sub-flowchart of the electrical impedance imaging method according to the first embodiment of the invention.
Fig. 4 is a third sub-flowchart of the electrical impedance imaging method according to the first embodiment of the invention.
FIG. 5 is a fourth sub-flowchart of an electrical impedance imaging method according to the first embodiment of the present invention
FIG. 6 is a sub-flowchart of an electrical impedance imaging method according to a second embodiment of the present invention
Fig. 7 is a schematic diagram of an electrical impedance imaging apparatus provided by an embodiment of the invention.
Fig. 8 is a schematic view of the electrode belt shown in fig. 1.
Fig. 9 is a schematic diagram of the iso-site image shown in fig. 1.
Fig. 10 is a schematic diagram of the coefficient matrix shown in fig. 4.
Fig. 11 is a schematic internal structure diagram of a terminal according to an embodiment of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The terms "first," "second," "third," "fourth," and the like in the description and claims of this application and in the above-described drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances, in other words that the embodiments described are to be practiced in sequences other than those illustrated or described herein. Moreover, the terms "comprises," "comprising," and any variations thereof, may also encompass other things, such as processes, methods, systems, articles, or apparatus that comprise a list of steps or elements, but not necessarily limited to only those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such processes, methods, articles, or apparatus.
It should be noted that the description relating to "first", "second", etc. in the present invention is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 1 and fig. 7 in combination, fig. 1 is a flowchart of an electrical impedance imaging method according to a first embodiment of the present invention, and fig. 7 is a schematic diagram of an electrical impedance imaging apparatus according to an embodiment of the present invention. The electrical impedance imaging apparatus 20 includes a body 21 and an electrode belt 22. When the object to be tested is tested, the object to be tested needs to surround the chest and fix the electrode belt 22, two electrodes 220 of all the electrodes 220 arranged on the electrode belt 22 apply high-frequency alternating signals emitted according to a certain rule, and the signals are measured between the other two electrodes 220. The electrical impedance imaging method is applied to an electrical impedance imaging device 20 for generating an electrical impedance image about the body of a measured object from signals measured by electrode strips 22. The electrical impedance imaging method provided by the embodiment reconstructs electrical impedance distribution of the measured object to form an electrical impedance image according to the measured signal based on the equipotential line back-projection algorithm. The electrical impedance imaging method specifically comprises the following steps.
Step S102, a plurality of continuous signal amplitude vectors are obtained. In this embodiment, each signal amplitude vector includes sub-signal amplitudes between two remaining electrodes of all the electrodes sequentially serving as pairs of excitation electrodes. Taking the electrode belt 22 shown in fig. 8 as an example, the electrode belt 22 includes 16 electrodes, and the 16 electrodes are numbered 1-16. When the electrode belt 22 forms a closed pattern around the chest of the measured object to measure the signal, two adjacent electrodes are sequentially selected as the excitation electrode pair, and the sub-signal amplitudes between the other two adjacent electrodes are sequentially measured. It will be appreciated that several signal magnitude vectors in succession are ordered according to time of measurement. For example, selecting electrode 1 and electrode 2 as an excitation electrode pair, and measuring the amplitude of the sub-signal between electrode 3 and electrode 4, electrode 4 and electrode 5, electrode 5 and electrode 6, and so on until electrode 15 and electrode 16 in sequence; and selecting the electrode 2 and the electrode 3 as an excitation electrode pair, and sequentially measuring the amplitude of the sub-signal between the two corresponding electrodes until all the two adjacent electrodes in the electrode band 22 are used as the excitation electrode pair, and measuring the amplitude of the sub-signal between the two corresponding electrodes. When all two adjacent electrodes in the electrode belt 22 are used as excitation electrode pairs, and the sub-signal amplitudes are measured between the other two adjacent electrodes, one measurement is completed, and all the sub-signal amplitudes obtained by one measurement form a signal amplitude vector. Wherein all sub-signal amplitudes in the signal amplitude vector are arranged according to the order of measurement. It will be appreciated that when the electrode strip 22 comprises n electrodes, a signal magnitude vector comprises n x (n-3) sub-signal magnitudes.
And step S104, respectively calculating the electrode impedance value corresponding to each signal amplitude vector according to the current value and the signal amplitude vector. In this embodiment, the sum of all the sub-signal amplitudes in each signal amplitude vector is calculated, and the quotient of the sub-signal amplitude sum and the current value is calculated as the electrode impedance value. It will be appreciated that the calculated electrode impedance value is a numerical value. Each electrode impedance value is used for representing the impedance of the whole chest of the measured object in one measurement. In the process of acquiring a plurality of continuous signal amplitude vectors, the amplitude and the frequency of the high-frequency alternating-current signal input from the excitation electrode pair each time are constant, but the amplitude and the frequency of the high-frequency alternating-current signal may be set according to an actual situation, which is not limited herein. Accordingly, the current value can be regarded as a constant value.
Step S106, dividing a plurality of signal amplitude vectors into a plurality of groups according to a preset rule. Wherein the plurality of sets of signal magnitude vectors are arranged in accordance with the acquired temporal order. In this embodiment, all the signal amplitude vectors in each set of signal amplitude vectors are continuous, and the plurality of sets of signal amplitude vectors are sorted according to the continuity of the signal amplitude vectors, i.e. time sequence. The specific process of dividing the plurality of signal amplitude vectors into a plurality of groups according to the preset rule will be described in detail below.
Step S108, the minimum electrode impedance value is selected from the electrode impedance values corresponding to each group of signal amplitude vectors as a standard impedance value. It will be appreciated that each set of signal magnitude vectors corresponds to a standard impedance value. When the chest of the measured object is detected, the electrode impedance value of the lung can be obtained. When a human body exhales, air in the lung is gradually reduced, and the corresponding electrode impedance value is also gradually reduced; when a human body inhales, air in the lung is gradually increased, and the corresponding electrode impedance value is also gradually increased. Therefore, the breathing cycle of the human body can be judged according to the change rule of the electrode impedance value. When the electrode impedance value is slowly reduced to the minimum, the corresponding moment can be considered as the end expiration; when the electrode impedance value slowly increases to a maximum, the corresponding time may be considered as the end of inspiration. Therefore, when the electrode impedance value is minimum, the corresponding signal amplitude vector can be judged to be the end-expiratory measurement, and the moment of the deepest expiration in the corresponding time period is the moment.
Step S110, using the signal amplitude vector corresponding to the standard impedance value as a standard amplitude vector. According to the functional characteristics of the lung of the human body, if the signal amplitude vector acquired by the human body at the end of expiration is taken as the standard amplitude vector, the measurement error caused by the difference of the electrical impedance imaging device 20 and the accessories thereof can be reduced to the maximum extent, and the individual difference between different tested objects can be kept and formed into the generated electrical impedance image as much as possible. Therefore, the signal amplitude vector corresponding to the minimum electrode impedance value is taken as the standard amplitude vector. It will be appreciated that each set of signal magnitude vectors corresponds to a standard magnitude vector.
Step S112, calculating corresponding equipotential impedance value vectors according to each signal amplitude vector in each set of signal amplitude vectors and the standard amplitude vector corresponding to the previous set of signal amplitude vectors. In this embodiment, the vector of equipotential impedance values includes the impedance value for each equipotential point in the image of the equipotential point. Wherein, the equal-position image is a pre-constructed image. Specifically, the iso-site image can be constructed using a Finite Element Method (FEM). An area of a measured object for measuring around the electrode belt 22 is used as a circle, a plurality of concentric circles are divided in the circle according to a certain rule, a plurality of nodes are arranged on each concentric circle to be used as equipotential points, and a plurality of units with triangular shapes are formed by connecting the equipotential points on the concentric circles to form an equipotential point image (as shown in fig. 9). The number of the concentric circles and the number of the equal-position points on each concentric circle may be set according to actual situations, and are not limited herein. How to calculate the corresponding equipotential impedance value vector according to each signal amplitude vector in each set of signal amplitude vectors and the standard amplitude vector corresponding to the previous set of signal amplitude vectors will be described in detail below.
And step S114, generating an electrical impedance image according to the allelic point impedance value vector. Rendering the equipotential point images according to the equipotential point impedance value vector, namely the impedance values of all the equipotential points to obtain the electrical impedance images. It will be appreciated that each measurement of a signal magnitude vector will produce an electrical impedance image. Wherein, the equipotential points in the equipotential point image are equivalent to the pixels in the electrical impedance image.
In the embodiment, the amplitude of the sub-signal obtained by each measurement forms a corresponding signal amplitude vector, and the electrode impedance value is calculated according to the signal amplitude vector calculation and the current value; and dividing a plurality of signal amplitude vectors into a plurality of groups, selecting a standard amplitude vector according to the electrode impedance value corresponding to each group, and calculating an equivalent point impedance value vector according to the signal amplitude vector and the standard amplitude vector so as to generate an electrical impedance image. When the electrical impedance image is generated according to the equipotential line back projection algorithm, a signal amplitude vector obtained by measuring a uniform medium is required to be used as a standard amplitude vector for calculating an equipotential point impedance value vector. However, in practice, the signal amplitude vector corresponding to the uniform medium is difficult to obtain and is extremely susceptible to the accessories of the electrical impedance imaging equipment and the actual measurement error. Therefore, according to the electrode impedance value, one signal amplitude vector in each group is used as a standard amplitude vector, different standard amplitude vectors are dynamically formed in the process of obtaining the signal amplitude vectors, so that the accuracy of the equipotential impedance value vectors is improved, and the interference of factors such as different electrical impedance imaging equipment and accessories thereof or the individual difference of the measured object and the like on the imaging effect can be avoided by using the measured value of the measured object as the reference of dynamic imaging. Meanwhile, the relevance between the signal amplitude vector and the electrode impedance value is fully utilized.
Please refer to fig. 2 in combination, which is a first sub-flowchart of an electrical impedance imaging method according to a first embodiment of the present invention. Step S106 specifically includes the following steps.
In step S202, a minimum value among the electrode impedance values is calculated. It will be appreciated that since the signal magnitude vector is continuous, the corresponding electrode impedance values are also continuous. In this embodiment, the first derivative of the electrode impedance value is calculated according to the calculated continuous electrode impedance values, and the minimum value of the electrode impedance value is obtained according to the first derivative of the electrode impedance value. Specifically, the first derivative of the present electrode impedance value is the difference between the present electrode impedance value and the previous electrode impedance value. And if the first derivative of the last electrode impedance value is less than 0 and the first derivative of the current electrode impedance value is greater than 0, the current electrode impedance value is a minimum value. It will be appreciated that as the electrode impedance value slowly decreases and the next electrode impedance value begins to increase, it is indicative that the current electrode impedance value corresponds to the end-expiration of the current breathing cycle; when the electrode impedance value slowly increases and the next electrode impedance value begins to decrease, it indicates that the current electrode impedance value corresponds to the end of inspiration of the current breathing cycle. That is, the electrode impedance values will exhibit a minimum and a maximum value during a breathing cycle. Accordingly, in a plurality of respiratory cycles, the minimum value of the electrode impedance value in each respiratory cycle is regarded as a minimum value, and the maximum value of the electrode impedance value in each respiratory cycle is regarded as a maximum value.
And step S204, sequentially dividing the minimum values of the preset number into the same group according to the time sequence. It will be appreciated that the predetermined number of minima are divided into the same group in chronological order of the calculated electrode impedance values. Wherein the preset number is 15-20. In some possible embodiments, the predetermined number may be 6-12.
Step S206, all signal amplitude vectors between the signal amplitude vectors corresponding to the last minimum value in the two adjacent sets of minimum values are divided into the same set to form a plurality of sets of signal amplitude vectors. In this embodiment, the signal amplitude vector corresponding to the last minimum value in the current set of minimum values and the signal amplitude vector corresponding to the next set of minimum values are the same set. It can be understood that the signal amplitude vectors corresponding to the preset number of expiratory cycles are divided into the same group according to the minimum value. The number of signal amplitude vectors in each set of signal amplitude vectors is not necessarily the same.
In the actual measurement process, a standard amplitude vector is preset before the acquisition of the signal amplitude vector is started. When a signal amplitude vector is obtained for the first time, calculating an electrode impedance value according to the signal amplitude vector, and calculating an equivalent point impedance value vector according to the signal amplitude vector and a preset standard amplitude vector; when the signal amplitude vector is obtained for the second time, calculating an electrode impedance value according to the signal amplitude vector, calculating a first derivative of the current electrode impedance value according to the current electrode impedance value and the last electrode impedance value, and calculating an equivalent point impedance value vector according to the signal amplitude vector and a preset standard amplitude vector; and by analogy, judging whether the electrode impedance value is a minimum value or not according to the first-order derivative of the electrode impedance value, storing the minimum value when the electrode impedance value is the minimum value, and marking the signal amplitude vector corresponding to the minimum value in the minimum values of the preset number as a standard amplitude vector until the stored minimum value reaches the preset number. And calculating an equivalent point impedance value vector of the signal amplitude vector obtained next time and the current standard amplitude vector, storing the obtained minimum value again, and marking the standard amplitude vector again according to the new minimum value. It is understood that the signal magnitude vectors acquired before the minimum reaches the preset number are of the same group.
In some possible embodiments, the signal magnitude vectors may be divided into multiple groups according to a preset time. And when the time for continuously acquiring the signal amplitude vectors reaches the preset time, dividing the corresponding signal amplitude vectors in the corresponding preset time into the same group. Wherein the preset time is 10-20 seconds.
In the embodiment, the electrode impedance value is subjected to the calculation of the first derivative to obtain the minimum value, so that the respiratory cycle of the tested object can be judged more intuitively and simply, and the judgment of the expiratory cycle of the tested object can be realized through a small amount of calculation. And dividing the signal amplitude vector according to the minimum value of the electrode impedance value, thereby realizing the adjustment of the standard amplitude vector and the dynamic range and greatly reducing the influence of measurement errors on the bit line back projection algorithm. Meanwhile, the standard amplitude vector and the dynamic range of the electrical impedance image are adaptively adjusted according to the respiratory cycle of the measured object, the dynamic range of the electrical impedance image at different moments can be adaptively controlled, and the method is suitable for electrical impedance imaging equipment with high requirements on real-time performance and dynamic performance.
Please refer to fig. 3 in combination, which is a second sub-flowchart of the electrical impedance imaging method according to the first embodiment of the present invention. Step S112 specifically includes the following steps.
Step S302, a coefficient matrix is constructed. Wherein the coefficient matrix is a constant matrix. The coefficient matrix is used for weighting the signal amplitude vector. The specific process of constructing the coefficient matrix will be described in detail below.
Step S304, calculating corresponding target amplitude vectors according to each signal amplitude vector in each set of signal amplitude vectors and the standard amplitude vector corresponding to the previous set of signal amplitude vectors. That is, each signal magnitude vector in each set of signal magnitude vectors is calculated with the standard magnitude vector corresponding to the previous set of signal magnitude vectors. In this embodiment, the target magnitude vector is calculated according to a first formula. Specifically, the first formula is: Δ V = logv m -logV Std . Where Δ V represents a target magnitude vector, V m Representing a signal magnitude vector, V, in a current set of signal magnitude vectors Std And representing the standard amplitude vector corresponding to the last group of signal amplitude vectors. It will be appreciated that each signal magnitude vector corresponds to a target magnitude vector. And calculating a corresponding target amplitude vector by using each signal amplitude vector in the first group of signal amplitude vectors and a preset standard amplitude vector. The target magnitude vector is used to represent the difference between the signal magnitude vector and the norm magnitude vector.
Step S306, calculating the product of the target amplitude vector and the coefficient matrix as an equipotential impedance value vector. And weighting the target amplitude vector by using the coefficient matrix so as to obtain an equipotential impedance value vector.
Please refer to fig. 4 in combination, which is a third sub-flowchart of the electrical impedance imaging method according to the first embodiment of the present invention. Step S302 specifically includes the following steps.
Step S402, constructing an equal-locus image. Wherein the allelic image includes a plurality of allelic points. In this embodiment, the iso-site image may be constructed using a Finite Element Method (FEM). An area of a measured object for measuring around the electrode belt 22 is used as a circle, a plurality of concentric circles are divided in the circle according to a certain rule, a plurality of nodes are arranged on each concentric circle to be used as equipotential points, and a plurality of units with triangular shapes are formed by connecting the equipotential points on the concentric circles to form an equipotential point image (as shown in fig. 9). And in the constructed equal-locus image, all the equal loci are numbered according to a certain rule. The number of the concentric circles and the number of the equal-position points on each concentric circle may be set according to actual situations, and are not limited herein.
Step S404, constructing an equipotential line image. The equipotential line image comprises a plurality of equipotential lines, and an equipotential area is formed between every two equipotential lines. And constructing an equipotential line image according to an equipotential line back projection algorithm, wherein the size and the shape of the equipotential line image are consistent with those of the equipotential line image. Specifically, two adjacent electrodes are sequentially selected as an excitation electrode pair, sub-signal amplitudes between the other two adjacent electrodes are sequentially measured, each sub-signal amplitude is back-projected to an equipotential line image to form a plurality of equipotential lines, and an area between the two adjacent equipotential lines is an equipotential area. It will be appreciated that the number of equipotential regions in the equipotential line image is the same as the number of sub-signal amplitudes in each signal amplitude vector. In the constructed equipotential line image, all the equipotential regions are numbered according to a certain rule. For example, when electrode 1 and electrode 2 are selected as an excitation electrode pair, the sub-signal amplitudes between electrode 3 and electrode 4, electrode 4 and electrode 5, electrode 5 and electrode 6, and so on are measured sequentially until electrode 15 and electrode 16, each sub-signal amplitude is back-projected into the equipotential line image to form a plurality of equipotential lines, and the region between two adjacent equipotential lines is an equipotential region (as shown in fig. 8).
Step S406, the elements in each column of the coefficient matrix are set in one-to-one correspondence with the equipotential points. Wherein, the sequence of each column element in the coefficient matrix is consistent with the sequence of the equipotential point numbers.
Step S408, the elements in each row in the coefficient matrix are set in one-to-one correspondence with the allelic regions. Wherein, the sequence of each row element in the coefficient matrix is consistent with the sequence of the number of the allelic region.
In step S410, elements in the coefficient matrix are generated from the equipotential point image and the equipotential line image. In the present embodiment, it is determined whether the equipotential points are located within the equipotential region based on the equipotential point image and the equipotential line image. When the equipotential points are located in the equipotential regions, the elements in the coefficient matrix corresponding to the equipotential points and the equipotential regions are 1; when the equipotential points are not located within the equipotential regions, the elements in the coefficient matrix corresponding to the equipotential points and the equipotential regions are 0. When the number of electrodes in the electrode belt 22 is constant, the elements in the coefficient matrix are fixed. Thus, the coefficient matrix is a constant matrix. For example, an allelic image includes three allelic sites: the equipotential line images comprise an equipotential point A, an equipotential point B and an equipotential point C, and the equipotential line images comprise two allelic regions: and the columns in the coefficient matrix correspond to the allelic points A, B and C one by one in sequence, and the rows in the coefficient matrix correspond to the allelic areas a and B one by one in sequence. If the iso-site a and the iso-site B are located within the iso-site region a and the iso-site C is located within the iso-site region B, the coefficient matrix is shown in fig. 10.
Please refer to fig. 5 in combination, which is a fourth sub-flowchart of the electrical impedance imaging method according to the first embodiment of the present invention. After step S112 is performed, the electrical impedance imaging method further includes the following steps.
Step S502, selecting a maximum sub-impedance value and a minimum sub-impedance value in the equal-locus impedance value vector as a first maximum sub-impedance value and a first minimum sub-impedance value, respectively. Wherein the vector of equipotential impedance values includes a number of sub-impedance values. It will be appreciated that the number of sub-impedance values in the vector of equipotential impedance values is the same as the number of sub-signal amplitudes in the vector of signal amplitudes. Each vector of equipotential impedance values corresponds to a first maximum sub-impedance value and a first minimum sub-impedance value.
Step S504, normalization processing is carried out on the corresponding equipotential point impedance value vector according to the first maximum sub-impedance value and the first minimum sub-impedance value. In this embodiment, the vector of the equivalent impedance value is normalized according to the second formula. Specifically, the second formula is:
wherein, d 1 Represents a vector of normalized allele impedance values, d 'represents a vector of allele impedance values, d' min1 Denotes a first minimum sub-impedance value, d' max1 Representing the first maximum sub-impedance value. It will be appreciated that each vector of equipotential impedance values is calculated with a corresponding first maximum sub-impedance value and a corresponding first minimum sub-impedance value.
In the above embodiment, the normalization processing is performed on the corresponding allele impedance value vector according to the first maximum sub-impedance value and the first minimum sub-impedance value in the allele impedance value vector, so that the sub-impedance values in the normalized allele impedance value vector are all distributed between 0 and 1, and the problem of difficult calibration of the equipotential line back-projection algorithm can be effectively solved.
Please refer to fig. 6 in combination, which is a sub-flowchart of an electrical impedance imaging method according to a second embodiment of the present invention. The electrical impedance imaging method provided by the second embodiment is different from the electrical impedance imaging method provided by the first embodiment in that, after step S112 is performed, the electrical impedance imaging method provided by the second embodiment further includes the following steps.
Step S602, selecting the minimum sub-impedance value in the equal-location-point impedance value vector as the first minimum sub-impedance value. Wherein the vector of equipotential impedance values includes a number of sub-impedance values. It will be appreciated that each vector of equipotential impedance values corresponds to a first minimum subampedance value.
In step S604, the maximum electrode impedance value is selected from the electrode impedance values corresponding to each set of signal amplitude vectors as a target impedance value. It will be appreciated that each set of signal magnitude vectors corresponds to a target impedance value. When the electrode impedance value is maximum, it can be determined that the corresponding signal amplitude vector is measured at the end of inspiration, and is the time of the deepest inspiration in the corresponding time period.
Step S606, using the vector of the impedance value of the equipotential point corresponding to the target impedance value as the vector of the impedance value of the target equipotential point. It will be appreciated that each set of signal magnitude vectors corresponds to a vector of target equipotential impedance values.
Step S608, selecting the maximum sub-impedance value and the minimum sub-impedance value in the target equipotential point impedance value vector as a second maximum sub-impedance value and a second minimum sub-impedance value, respectively. It will be appreciated that each vector of target equipotential impedance values corresponds to a second maximum sub-impedance value and a second minimum sub-impedance value.
Step S610, normalizing the corresponding allele impedance value vector according to the second maximum sub-impedance value, the second minimum sub-impedance value, and the first minimum sub-impedance value. In this embodiment, the vector of the equivalent point impedance value is normalized according to the third formula. Specifically, the third formula is:
wherein d is 2 Representing a normalized vector of the allelic point impedance values, d 'representing a vector of the allelic point impedance values, d' min1 Denotes a first minimum sub-impedance value, d' max2 Denotes the second maximum sub-impedance value, d' min2 Representing a second minimum sub-impedance value. Correspondingly, each equipotential impedance value vector is calculated with the corresponding first minimum sub-impedance value and the second maximum sub-impedance value and the second minimum sub-impedance value of the target equipotential impedance value vector corresponding to the previous set of signal amplitude vectors.
Other processes of the electrical impedance imaging method provided by the second embodiment are basically the same as those provided by the first embodiment, and are not repeated herein.
In the above embodiment, the normalization processing is performed on the corresponding allele impedance value vector according to the first minimum sub-impedance value in the allele impedance value vector and the second maximum sub-impedance value and the second minimum sub-impedance value of the allele impedance value vector corresponding to the maximum electrode impedance value in the previous group, so that the sub-impedance values in the normalized allele impedance value vector are all distributed between 0 and 1, and the problem of difficult calibration of the equipotential line back-projection algorithm can be effectively solved. Meanwhile, according to the fact that the difference between the second maximum sub-impedance value and the second minimum sub-impedance value is used as the denominator of the third formula, it can be guaranteed that the electrical impedance image generated by each group of signal amplitude vectors has a relatively stable standard range, and the electrical impedance image can truly reflect the measured signal amplitude vectors. The second maximum sub-impedance value and the second minimum sub-impedance value are also adaptively and dynamically adjusted, so that the electrical impedance image distortion can be avoided as much as possible.
Please refer to fig. 11, which is a schematic diagram of an internal structure of a terminal according to an embodiment of the present invention. The terminal 10 includes a computer-readable storage medium 11, a processor 12, and a bus 13. The computer-readable storage medium 11 includes at least one type of readable storage medium, which includes a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., SD or DX memory, etc.), a magnetic memory, a magnetic disk, an optical disk, and the like. The computer readable storage medium 11 may in some embodiments be an internal storage unit of the terminal 10, such as a hard disk of the terminal 10. The computer readable storage medium 11 may also be, in other embodiments, an external storage device of the terminal 10, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), etc. provided on the terminal 10. Further, the computer-readable storage medium 11 may also include both an internal storage unit and an external storage device of the terminal 10. The computer-readable storage medium 11 may be used not only to store application software installed in the terminal 10 and various types of data, but also to temporarily store data that has been output or will be output.
The bus 13 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 11, but this is not intended to represent only one bus or type of bus.
Further, the terminal 10 may also include a display assembly 14. The display component 14 may be a Light Emitting Diode (LED) display, a liquid crystal display, a touch-sensitive liquid crystal display, an Organic Light-Emitting Diode (OLED) touch panel, or the like. The display component 14 may also be referred to as a display device or display unit, as appropriate, for displaying information processed in the terminal 10 and for displaying a visual user interface, among other things.
Further, the terminal 10 may also include a communication component 15. The communication component 15 may optionally include a wired communication component and/or a wireless communication component, such as a WI-FI communication component, a bluetooth communication component, etc., typically used to establish a communication connection between the terminal 10 and other intelligent control devices.
The processor 12 may be, in some embodiments, a Central Processing Unit (CPU), controller, microcontroller, microprocessor or other data Processing chip for executing program codes stored in the computer-readable storage medium 11 or Processing data. In particular, the processor 12 executes a processing program to control the terminal 10 to implement an electrical impedance imaging method.
While fig. 11 shows only the terminal 10 with components 11-15 for implementing an electrical impedance imaging method, those skilled in the art will appreciate that the configuration shown in fig. 11 does not constitute a limitation of the terminal 10, and that the terminal 10 may include fewer or more components than shown, or some components may be combined, or a different arrangement of components.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, to the extent that such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, it is intended that the present invention encompass such modifications and variations as well.
The above-mentioned embodiments are only examples of the present invention, which should not be construed as limiting the scope of the present invention, and therefore, the present invention is not limited by the claims.
Claims (8)
1. An electrical impedance imaging method, characterized in that it comprises:
acquiring a plurality of continuous signal amplitude vectors, wherein each signal amplitude vector comprises sub-signal amplitudes between the rest two electrodes when two electrodes in all the electrodes are sequentially used as excitation electrode pairs;
respectively calculating an electrode impedance value corresponding to each signal amplitude vector according to the current value and the signal amplitude vector;
dividing the signal amplitude vectors into a plurality of groups according to a preset rule, wherein the signal amplitude vectors of the plurality of groups are arranged according to the acquired time sequence;
selecting the minimum electrode impedance value from the electrode impedance values corresponding to each group of signal amplitude vectors as a standard impedance value;
taking the signal amplitude vector corresponding to the standard impedance value as a standard amplitude vector;
respectively calculating corresponding equipotential point impedance value vectors according to each signal amplitude vector in each group of signal amplitude vectors and the standard amplitude vector corresponding to the previous group of signal amplitude vectors; and
generating an electrical impedance image according to the equipotential impedance value vector;
wherein, dividing the plurality of signal amplitude vectors into a plurality of groups according to a preset rule specifically comprises:
calculating a minimum value of the electrode impedance values;
dividing the minimum values of the preset number into the same group in sequence according to the time sequence; and
and dividing all signal amplitude vectors between the signal amplitude vectors corresponding to the last minimum value in the two adjacent groups of minimum values into the same group to form a plurality of groups of signal amplitude vectors.
2. An electrical impedance imaging method according to claim 1, wherein after calculating the corresponding equipotential impedance value vectors according to each signal magnitude vector in each set of signal magnitude vectors and the corresponding standard magnitude vector of the previous set of signal magnitude vectors, the electrical impedance imaging method further comprises:
selecting the maximum sub-impedance value and the minimum sub-impedance value in the equivalent point impedance value vector as a first maximum sub-impedance value and a first minimum sub-impedance value respectively, wherein the equivalent point impedance value vector comprises a plurality of sub-impedance values; and
and carrying out normalization processing on corresponding allele impedance value vectors according to the first maximum sub-impedance value and the first minimum sub-impedance value.
3. An electrical impedance imaging method according to claim 1, wherein after calculating the corresponding equipotential impedance value vectors according to each signal magnitude vector in each set of signal magnitude vectors and the corresponding standard magnitude vector of the previous set of signal magnitude vectors, the electrical impedance imaging method further comprises:
selecting the minimum sub-impedance value in the equipotential point impedance value vector as a first minimum sub-impedance value, wherein the equipotential point impedance value vector comprises a plurality of sub-impedance values;
selecting the maximum electrode impedance value from the electrode impedance values corresponding to each group of signal amplitude vectors as a target impedance value;
using the allelic point impedance value vector corresponding to the target impedance value as a target allelic point impedance value vector;
selecting the maximum sub-impedance value and the minimum sub-impedance value in the target equal-locus impedance value vector as a second maximum sub-impedance value and a second minimum sub-impedance value respectively; and
and carrying out normalization processing on corresponding allele impedance value vectors according to the second maximum sub-impedance value, the second minimum sub-impedance value and the first minimum sub-impedance value.
4. The electrical impedance imaging method of claim 1, wherein calculating the minima in the electrode impedance values comprises in particular:
calculating a first derivative of the electrode impedance value; and
and acquiring a minimum value of the electrode impedance value according to the first derivative of the electrode impedance value.
5. An electrical impedance imaging method according to claim 1, wherein calculating respective vectors of allelic impedance values based on each signal magnitude vector in each set of signal magnitude vectors and a corresponding norm magnitude vector of a previous set of signal magnitude vectors comprises:
constructing a coefficient matrix;
calculating corresponding target amplitude vectors according to each signal amplitude vector in each group of signal amplitude vectors and a standard amplitude vector corresponding to the previous group of signal amplitude vectors; and
and calculating the product of the target amplitude vector and the coefficient matrix as the equipotential impedance value vector.
6. An electrical impedance imaging method according to claim 5, wherein constructing the coefficient matrix specifically comprises:
constructing an isosite image, wherein the isosite image comprises a plurality of isosites;
constructing an equipotential line image, wherein the equipotential line image comprises a plurality of equipotential lines, and an equipotential area is formed between every two equipotential lines;
setting elements of each column in the coefficient matrix in one-to-one correspondence with the equipotential points;
setting elements of each row in the coefficient matrix in one-to-one correspondence with the allelic regions; and
and generating elements in the coefficient matrix according to the equipotential point image and the equipotential line image.
7. An electrical impedance imaging method according to claim 1, wherein calculating the electrode impedance value corresponding to each signal magnitude vector based on the current value and the signal magnitude vector comprises:
calculating the sum of all sub-signal amplitudes in each signal amplitude vector; and
and calculating the quotient of the sum of the sub-signal amplitudes and the current value as the electrode impedance value.
8. A computer readable storage medium for storing program instructions executable by a processor to implement an electrical impedance imaging method as claimed in any one of claims 1 to 7.
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| CN201341881Y (en) * | 2009-01-14 | 2009-11-11 | 河北工业大学 | Bio-electrical impedance imaging device for 128 passage |
| CN101794453B (en) * | 2010-03-25 | 2011-11-09 | 河北工业大学 | Reconstruction method of node mapping image based on regression analysis |
| CN102008303B (en) * | 2010-10-29 | 2012-05-23 | 重庆大学 | Frequency difference fast Newton's one-step error reconstructor (FNOSER) imaging method for electrical impedance tomography |
| DE102011106405B4 (en) * | 2011-07-02 | 2021-08-12 | Drägerwerk AG & Co. KGaA | Electro-impedance tomography device |
| CN102379697B (en) * | 2011-10-12 | 2012-10-24 | 中国人民解放军第四军医大学 | Detection device and calibration method for scanning and imaging pre-signal conditioning module by electrical impedance |
| CN102908141B (en) * | 2012-10-29 | 2014-08-13 | 中国人民解放军第四军医大学 | Inverse tangent method for reconstructing isopotential line back projection electrical impedance tomography image |
| DE102013213534A1 (en) * | 2013-02-05 | 2014-08-07 | Dräger Medical GmbH | Electroimpedance tomography apparatus and method |
| US20140221864A1 (en) * | 2013-02-05 | 2014-08-07 | Drager Medical Gmbh | Electric impedance tomography device and method |
| CN104146709B (en) * | 2014-07-29 | 2016-05-11 | 中国科学院合肥物质科学研究院 | A kind of multifrequency point bio-electrical impedance fast acquiring method |
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| CN113196072A (en) * | 2018-09-26 | 2021-07-30 | 亚琛工业大学 | Method and apparatus for battery diagnostics |
| CN109674471A (en) * | 2018-12-18 | 2019-04-26 | 中国科学技术大学 | A kind of electrical impedance imaging method and system based on generation confrontation network |
| CN109646000B (en) * | 2018-12-21 | 2022-05-20 | 南京邮电大学 | Node electrical impedance imaging method based on local subdivision |
| DE102021000312A1 (en) * | 2020-02-07 | 2021-08-12 | Löwenstein Medical Technology S.A. | Method and device for determining a regional compliance of a lung during spontaneous breathing |
| CN112798654B (en) * | 2021-01-26 | 2023-06-20 | 河南师范大学 | Rapid gradient method and adaptive jacobian matrix reconstruction method for electrical impedance tomography |
| CN113040741A (en) * | 2021-03-01 | 2021-06-29 | 中国农业大学 | Multi-frequency electrical impedance imaging method and system for crop root zone |
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