Analysis device, analysis method and medium for impedance data of lung perfusion

Abstract

The present disclosure describes an analysis device for impedance data of pulmonary perfusion, including a memory storing a program and a processor coupled to the memory; when the program is executed by the processor, impedance data of a time period from the perfusion moment to the ventilation moment is obtained from the target position of the object to be measured; multiple cardiac cycle moments corresponding to multiple cardiac cycles are obtained based on the heart rate; pulmonary blood perfusion maps and pulmonary blood perfusion values ​​corresponding to each cardiac cycle moment are obtained; the beat-to-beat output map and beat-to-beat output value of the cardiac part are obtained based on the decreasing slope of the impedance corresponding to the pixels of the cardiac part within the target time range; and the pulmonary blood perfusion values ​​and beat-to-beat output values ​​corresponding to each cardiac cycle moment are compared to obtain the pulmonary blood perfusion map corresponding to the cardiac cycle moment with the pulmonary blood perfusion value closest to the beat-to-beat output value. Thus, the termination time of the perfusate reaching each area of ​​the lung tissue can be accurately identified, and an accurate pulmonary blood perfusion map of the lungs can be constructed.

Description

Technical Field

[0001] The present disclosure generally relates to the field of electrical impedance tomography technology, and more particularly to an analysis device, analysis method and medium for impedance data of lung perfusion. Background Art

[0002] Electrical impedance tomography (EIT) is a new type of medical imaging technology that applies a safe current to the human body through surface electrodes, measures the response voltage through the surface electrodes, and then calculates the impedance change inside the human body based on the image reconstruction algorithm. Electrical impedance tomography has the advantages of being non-invasive, radiation-free, and portable. It has good application potential in bedside real-time monitoring and has been applied to bedside pulmonary ventilation monitoring.

[0003] Therefore, more and more researchers have begun to use the impedance data generated by electrical impedance tomography to analyze the physiological state of the lungs. For example, a pulmonary blood perfusion map can be generated based on impedance data to assist in the assessment of the physiological state of the lungs. Patent document (CN111449657A) discloses a bedside saline contrast-based pulmonary ventilation-blood perfusion electrical impedance tomography method, in which the overall chest resistance curve during breath holding is analyzed to determine the starting point (T1) and end point (T2) of saline reaching the pulmonary blood vessels, and then the resistance-time change curve (slope fitting) of each lung region in the T1-T2 time period is used to construct a pulmonary blood perfusion map.

[0004] However, the injected saline reaches the pulmonary blood vessels at different times and at different times in different areas of the lung tissue. In this case, the scheme of using the chest overall resistance curve to determine the starting and ending points of the saline reaching the pulmonary blood vessels is bound to cause a certain time error, resulting in a significant deviation in the pulmonary blood perfusion map. Summary of the invention

[0005] The present disclosure is proposed in view of the above-mentioned situation, and its purpose is to provide an analysis device, analysis method and medium for impedance data of lung perfusion that can accurately identify the end time of the perfusion reaching each area of ​​the lung tissue and can construct an accurate pulmonary blood flow perfusion map of the lungs.

[0006] To this end, a first aspect of the present disclosure provides an analysis device for impedance data of lung perfusion, comprising a memory storing a program and a processor coupled to the memory; the processor is configured to, when the program is executed by the processor: obtain impedance data of a time period from a perfusion moment to a ventilation moment from a target position of a subject to be measured, wherein the target position includes a heart and a lung, the impedance data includes impedances of individual pixels of the target position that vary with time, the perfusion moment indicates the moment when perfusion of a perfusate is started in a breath-holding state of the subject to be measured, and the ventilation moment indicates the moment when the subject to be measured is ventilated again; obtain multiple heart cycle moments corresponding to multiple heart cycle moments based on the heart rate, The heart rate is determined based on a target impedance waveform in which the impedance corresponding to at least one pixel of the heart part changes with time; a pulmonary blood perfusion map and a pulmonary blood perfusion value corresponding to each heart cycle moment among the multiple heart cycle moments are obtained; a beat-to-beat output map and a beat-to-beat output value of the heart part are obtained based on a decreasing slope of the impedance corresponding to the pixels of the heart part within a target time range, wherein the target time range is determined by the perfusion moment; and the pulmonary blood perfusion value corresponding to each heart cycle moment among the multiple heart cycle moments and the beat-to-beat output value are compared to obtain a pulmonary blood perfusion map corresponding to a heart cycle moment in which the pulmonary blood perfusion value is closest to the beat-to-beat output value as a target pulmonary blood perfusion map.

[0007] In the present disclosure, multiple cardiac cycle moments after lung perfusion are obtained, and then the pulmonary blood perfusion map and pulmonary blood perfusion value corresponding to each cardiac cycle moment are calculated respectively according to the local impedance that changes with time, and the pulmonary blood perfusion value corresponding to each cardiac cycle moment is compared with the beat output value of the heart part, and then the pulmonary blood perfusion map corresponding to the pulmonary blood perfusion value closest to the beat output value of the heart part is determined as the target pulmonary blood perfusion map (that is, the pulmonary blood perfusion map of the lungs). In this case, the termination time of each area of ​​the lung tissue can be accurately identified according to the local impedance change, and an accurate and reliable pulmonary blood perfusion map of the lungs can be provided.

[0008] In addition, in the analysis device involved in the first aspect of the present disclosure, optionally, the processor is further configured to obtain a pulmonary ventilation-perfusion ratio map based on the target pulmonary blood perfusion map, wherein the pulmonary ventilation-perfusion ratio map VP satisfies the formula: VP=Ventilation / Perfusion, wherein Ventilation represents a minute ventilation map of the target lung area, Perfusion represents a minute pulmonary blood perfusion map of the target lung area, and the target lung area is the sum of the pulmonary ventilation area and the pulmonary blood perfusion area; the pixel value Ventilation of the i-th pixel of the minute ventilation map i Satisfy the formula: Ventilation i=(RR×V T ×(1-DS%))×V i / V lung , where RR represents the respiratory rate, V T represents tidal volume, DS% represents the proportion of dead space to total ventilation, V i represents the pixel value of the i-th pixel in the target lung area in the average tidal image, V lung represents the tidal value; the pixel value of the ith pixel of the pulmonary blood perfusion map per minute is Perfusion i Satisfy the formula: Wherein, SV represents the beat-per-beat value, HR represents the heart rate, and PerfusionMap lung represents the pulmonary blood perfusion value corresponding to the target lung area in the target pulmonary blood perfusion map, The pixel value of the i-th pixel of the target lung region in the target lung blood perfusion map is represented. Thus, a pulmonary ventilation-perfusion ratio map can be obtained.

[0009] In addition, in the analysis device involved in the first aspect of the present disclosure, optionally, the heart rate is determined based on the target impedance waveform of the impedance corresponding to at least one pixel of the heart part that changes with time, including: obtaining multiple time differences between multiple adjacent peaks in the target impedance waveform corresponding to each pixel in the at least one pixel and averaging the multiple time differences to obtain the average time difference corresponding to each pixel, and obtaining the target time difference based on the average time difference, wherein if the number of the at least one pixel is 1, the target time difference is the average time difference of the at least one pixel, and if the number of the at least one pixel is greater than 1, the target time difference is the average of the average time differences of the at least one pixel; and 60 is divided by the target time difference as the heart rate, wherein the impedance data of a preset time length is processed by a bandpass filter to obtain the impedance data of the heart part, and the target impedance waveform corresponding to the at least one pixel of the heart part is determined based on the impedance data of the heart part. In this way, the heart rate can be obtained based on the impedance of the heart part that changes with time.

[0010] In addition, in the analysis device involved in the first aspect of the present disclosure, optionally, the kth heartbeat cycle moment T among the multiple heartbeat cycle moments k Satisfy the formula: T k =T b +60 / HR×(k+1), where T k <T e , HR represents the heart rate, T b represents the injection time, T e Indicates the ventilation time. Thus, the heartbeat cycle time can be obtained based on the heart rate.

[0011] In addition, in the analysis device involved in the first aspect of the present disclosure, optionally, obtaining the pulmonary blood perfusion map and pulmonary blood perfusion value corresponding to each of the multiple cardiac cycle moments includes: obtaining the impedance of the pixels of the lungs that changes with time within a preset time range as the impedance sequence corresponding to the pixels of the lungs, wherein the preset time range is from each of the multiple cardiac cycle moments to the ventilation moment minus the preset window length; obtaining multiple descending slopes corresponding to the impedance in multiple time segments of the impedance sequence based on the time window of the sliding window method and taking the maximum descending slope as the pixel value of the pixel of the pulmonary blood perfusion map, wherein the window length of the time window is the preset window length; and taking the sum of the pixel values ​​of the pixels of the pulmonary blood perfusion map as the pulmonary blood perfusion value. In this way, the pulmonary blood perfusion map and pulmonary blood perfusion value corresponding to each cardiac cycle moment can be obtained based on the impedance of the lungs that changes with time.

[0012] In addition, in the analysis device involved in the first aspect of the present disclosure, optionally, based on the decreasing slope of the impedance corresponding to the pixel of the heart part within the target time range, obtaining the beat-to-beat output diagram and the beat-to-beat output value of the heart part includes: taking the decreasing slope within the target time range as the pixel value of the pixel of the beat-to-beat output diagram; and taking the sum of the pixel values ​​of the pixels of the beat-to-beat output diagram as the beat-to-beat output value, wherein the target time range is from the perfusion moment to the perfusion moment plus 1 second. In this way, the beat-to-beat output diagram and the beat-to-beat output value of the heart part can be obtained.

[0013] In addition, in the analysis device involved in the first aspect of the present disclosure, optionally, the perfusion material is saline.

[0014] In addition, in the analysis device involved in the first aspect of the present disclosure, optionally, each of the multiple heart cycle moments is greater than the perfusion moment and not greater than the ventilation moment. In this case, interference from other heart cycle moments can be reduced.

[0015] A second aspect of the present disclosure provides a method for analyzing impedance data of lung perfusion, comprising acquiring impedance data of a time period from a perfusion moment to a ventilation moment from a target position of a subject to be tested, wherein the target position includes a heart part and a lung, and the impedance data includes impedances of respective pixels of the target position that change with time, wherein the perfusion moment indicates the moment when perfusion of a perfusate begins in a breath-holding state of the subject to be tested, and the ventilation moment indicates the moment when the subject to be tested is ventilated again; acquiring a plurality of heart cycle moments corresponding to a plurality of heart cycle moments based on the heart rate, wherein impedances corresponding to at least one pixel of the heart part change with time based on the heart rate; The heart rate is determined by a time-varying target impedance waveform; a pulmonary blood perfusion map and a pulmonary blood perfusion value corresponding to each of the multiple cardiac cycle moments are obtained; a beat-to-beat output map and a beat-to-beat output value of the heart portion are obtained based on a decreasing slope of impedance corresponding to pixels of the heart portion within a target time range, wherein the target time range is determined by the perfusion moment; and a pulmonary blood perfusion value corresponding to each of the multiple cardiac cycle moments and the beat-to-beat output value are compared to obtain a pulmonary blood perfusion map corresponding to a cardiac cycle moment having a pulmonary blood perfusion value closest to the beat-to-beat output value as a target pulmonary blood perfusion map.

[0016] In the present disclosure, multiple cardiac cycle moments after lung perfusion are obtained, and then the pulmonary blood perfusion map and pulmonary blood perfusion value corresponding to each cardiac cycle moment are calculated respectively according to the local impedance that changes with time, and the pulmonary blood perfusion value corresponding to each cardiac cycle moment is compared with the beat output value of the heart part, and then the pulmonary blood perfusion map corresponding to the pulmonary blood perfusion value closest to the beat output value of the heart part is determined as the target pulmonary blood perfusion map (that is, the pulmonary blood perfusion map of the lungs). In this case, the termination time of each area of ​​the lung tissue can be accurately identified according to the local impedance change, and an accurate and reliable pulmonary blood perfusion map of the lungs can be provided.

[0017] A third aspect of the present disclosure provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by a processor, the steps of the above-mentioned analysis method are implemented.

[0018] According to the present disclosure, an analysis device, analysis method and medium for analyzing impedance data of lung perfusion that can accurately identify the end time of the perfusion reaching each area of ​​the lung tissue and construct an accurate pulmonary blood flow perfusion map can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present disclosure will now be explained in further detail by way of example only with reference to the accompanying drawings, in which:

[0020] Figure 1is a schematic diagram showing the change of the overall chest impedance over time involved in the example of the present disclosure.

[0021] Figure 2 is a schematic scenario showing a method for analyzing impedance data of lung perfusion involved in an example of the present disclosure.

[0022] Figure 3 is a flow chart showing a method for analyzing impedance data of lung perfusion according to an example of the present disclosure.

[0023] FIG. 4( a ) is a schematic diagram showing a target impedance waveform involved in an example of the present disclosure.

[0024] FIG. 4( b ) is a flow chart showing the determination of heart rate involved in the examples of the present disclosure.

[0025] FIG. 5( a ) is a schematic diagram showing a pulmonary blood perfusion diagram corresponding to a first moment involved in an example of the present disclosure.

[0026] FIG5( b ) is a schematic diagram showing a pulmonary blood perfusion diagram corresponding to a second moment involved in an example of the present disclosure.

[0027] FIG5(c) is a schematic diagram showing a pulmonary blood perfusion diagram corresponding to a third moment involved in the example of the present disclosure.

[0028] FIG5(d) is a schematic diagram showing a pulmonary blood perfusion diagram corresponding to a fourth moment involved in the example of the present disclosure.

[0029] FIG5(e) is a flowchart showing the method of obtaining the pulmonary blood perfusion diagram and the pulmonary blood perfusion value corresponding to each heart cycle moment involved in the example of the present disclosure.

[0030] FIG. 6( a ) is a schematic diagram showing a beat-to-beat output diagram of a heart region according to an example of the present disclosure.

[0031] FIG6( b ) is a flow chart showing the process of obtaining a beat-to-beat output diagram and a beat-to-beat output value of a heart region according to an example of the present disclosure.

[0032] Figure 7 It is a schematic diagram showing the pulmonary blood perfusion value and the beat-per-beat output value of the heart corresponding to each heart cycle moment involved in the example of the present disclosure.

[0033] Figure 8 is a schematic diagram showing a pulmonary ventilation-perfusion ratio diagram involved in an example of the present disclosure. DETAILED DESCRIPTION

[0034] Hereinafter, with reference to the accompanying drawings, the preferred embodiments of the present disclosure are described in detail. In the following description, the same symbols are given to the same parts, and repeated descriptions are omitted. In addition, the accompanying drawings are only schematic diagrams, and the ratio of the sizes of the parts to each other or the shapes of the parts, etc. may be different from the actual ones. It should be noted that the terms "including" and "having" in the present disclosure and any variations thereof, such as the processes, methods, systems, products or devices of a series of steps or units included or possessed are not necessarily limited to those steps or units clearly listed, but may include or have other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. All methods described in the present disclosure may be performed in any suitable order, unless otherwise indicated herein or clearly contradictory to the context.

[0035] The analysis device, analysis method and medium of impedance data of pulmonary perfusion involved in the present disclosure can accurately identify the end time of the perfusion reaching each area of ​​the lung tissue, and can construct an accurate pulmonary blood flow perfusion map of the lung. The analysis method of impedance data of pulmonary perfusion involved in the present disclosure can sometimes be referred to as an analysis method, an imaging method, or a pulmonary blood flow analysis method.

[0036] Figure 1 is a schematic diagram showing the change of the overall chest impedance over time involved in the example of the present disclosure.

[0037] The impedance data involved in the present disclosure can be obtained by electrical impedance tomography (EIT). In some examples, an electrode group can be arranged on the chest of the subject to be tested to obtain an image reflecting the electrical impedance distribution information of the heart and lungs of the subject to be tested within a certain period of time as impedance data. In addition, the impedance data may include the impedance of each pixel of the heart and lungs (that is, each pixel in the electrical impedance tomography image) that changes over time. In addition, each pixel of the heart and lungs can represent the pixel-level position of the heart or lungs (also referred to as a local point). As an example, Figure 1 A schematic diagram showing the change of the overall chest impedance over time is shown, wherein Tb may represent the perfusion time, T1 may represent the first time, T2 may represent the second time, T3 may represent the third time, T4 may represent the fourth time, and Te may represent the ventilation time. Each time will be described in detail later. In addition, the unit of impedance may be a relative value (arbitrary unit, au).

[0038] The analysis method involved in the present disclosure is described in detail below in conjunction with the accompanying drawings. In addition, the scenarios described in the examples of the present disclosure are intended to more clearly illustrate the technical solutions of the present disclosure and do not constitute a limitation on the technical solutions provided by the present disclosure. Figure 2is a schematic scenario showing a method for analyzing impedance data of lung perfusion involved in an example of the present disclosure.

[0039] In some examples, the analysis methods disclosed herein can be applied to Figure 2 In the scene shown. In the scene, the electrical impedance tomography device 20 may include an electrode device 21, a cable 22 and a working electronic device 23, and the analysis device 10 may include a memory 11, a processor 12 and a display device 13, and the memory 11 stores a program. The electrode device 21 is arranged on the chest of the object to be measured, and the working electronic device 23 feeds an alternating current or an alternating voltage to the electrode device 21 by means of the cable 22, and the working electronic device 23 can obtain the measurement signal of the electrode device 21 to generate impedance data using a reconstruction algorithm and transmit the impedance data to the analysis device 10. The analysis device 10 executes the program in the memory 11 through the processor 12 to implement the analysis method, which processes the impedance data into a pulmonary blood perfusion map and a pulmonary blood perfusion value corresponding to each heartbeat cycle, a target pulmonary blood perfusion map, and a pulmonary ventilation-perfusion ratio map and other data and transmits them to the display device 13. The display device 13 shows the data in the form of numbers, graphics or images. In this way, the physiological state of the lungs can be analyzed.

[0040] In some examples, the analysis method can be integrated into a ventilator or electrical impedance tomography device 20 in the form of computer program instructions. Thus, it is possible to conveniently assist in analyzing the physiological state of the lungs. In some examples, the analysis method can be stored on a server in the form of computer program instructions and executed by the server. In some examples, the server may include one or more processors and one or more memories. Among them, the processor may include a central processing unit, a graphics processing unit, and any other electronic component capable of processing data, and capable of executing computer program instructions. The memory can be used to store computer program instructions. In some examples, the server can implement the analysis method by executing the computer program instructions on the memory. In some examples, the server may also be a cloud server.

[0041] The analysis method involved in the present disclosure obtains multiple cardiac cycle moments after lung perfusion, and then calculates the pulmonary blood perfusion map and pulmonary blood perfusion value corresponding to each cardiac cycle moment according to the local impedance that changes with time, and compares the pulmonary blood perfusion value corresponding to each cardiac cycle moment with the beat-per-beat output value of the heart, and then determines the pulmonary blood perfusion map corresponding to the pulmonary blood perfusion value closest to the beat-per-beat output value of the heart as the target pulmonary blood perfusion map (that is, the pulmonary blood perfusion map of the lungs). In this case, the termination time of each area of ​​the lung tissue can be accurately identified according to the local impedance change, and an accurate and reliable pulmonary blood perfusion map of the lungs can be provided. In addition, the analysis method involved in the present disclosure also obtains a pulmonary ventilation-perfusion ratio map based on the target pulmonary blood perfusion map. In this way, the physiological state of the lungs can be analyzed more intuitively.

[0042] The analysis method involved in the present disclosure is described in detail below with reference to the accompanying drawings. Figure 3 is a flow chart showing a method for analyzing impedance data of lung perfusion according to an example of the present disclosure.

[0043] like Figure 3 As shown, in some examples, the analysis method may include acquiring impedance data (step S102), acquiring multiple cardiac cycle moments (step S104), acquiring a pulmonary blood perfusion map and a pulmonary blood perfusion value corresponding to each of the multiple cardiac cycle moments (step S106), acquiring a beat-to-beat output map and a beat-to-beat output value of a heart region (step S108), and acquiring a target pulmonary blood perfusion map based on the pulmonary blood perfusion map and the pulmonary blood perfusion value, and the beat-to-beat output value of a heart region (step S110).

[0044] As described above, the analysis method may include step S102. In some examples, in step S102, impedance data (also referred to as impedance data to be analyzed) may be obtained. In some examples, the impedance data may come from a target position of the object to be measured. In addition, the impedance data may include impedances of individual pixels of the target position that change over time. In some examples, the target position may be a body part (e.g., chest) of the object to be measured for analyzing pulmonary blood perfusion (i.e., constructing a pulmonary blood perfusion map of the lungs). In some examples, the target position may include the heart and the lungs. In this case, impedance data of the heart and the lungs can be subsequently obtained from the impedance data.

[0045] For example, the 16 electrodes of the electrical impedance tomography device 20 can be placed between the 4th and 5th intercostal spaces of the object to be measured (that is, the electrical impedance tomography device 20 can be connected to the object to be measured), and impedance data (also referred to as EIT data) can be collected at an acquisition frame rate of 20 frames / second. The impedance data can be composed of multiple EIT images, a single EIT image can be composed of 32×32 pixels, and the impedance of pixels at the same position in the multiple EIT images can form an impedance sequence, and the impedance sequence can include impedance that changes over time.

[0046] In some examples, the time period corresponding to the impedance data may include the time period from the perfusion moment to the ventilation moment. In this case, multiple heart cycle moments can be obtained based on the impedance data from the perfusion moment to the ventilation moment, and then the corresponding pulmonary blood perfusion map and pulmonary blood perfusion value can be obtained. In some examples, the perfusion moment may represent the moment when the perfusion material is started in the breath-holding state of the subject to be tested. In some examples, the ventilation moment may represent the moment when the subject to be tested is reventilated (that is, the moment when ventilation is restored). Thus, the perfusion moment to the ventilation moment can be determined. In some examples, the perfusion material can be used for angiography. In some examples, the perfusion material can be saline. In addition, the concentration of the saline can be 3%-10%. For example, the concentration of the saline can be 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc.

[0047] For example, after the electrical impedance tomography device 20 is connected to the subject to be tested, the subject to be tested holds its breath for a certain time (for example, more than 6 seconds), or presses the breath-hold key for a certain time (for example, more than 6 seconds) at the end of inspiration or expiration during mechanical ventilation of the subject to be tested, and during the breath-holding process, a perfusion substance (for example, a sodium chloride (NaCL) solution with a concentration of 3%-10% and a volume of 5ml (milliliter)-10ml) is injected into the body of the subject to be tested through the central venous catheter, and ventilation is resumed after the breath-holding ends, and the impedance data of the chest is recorded throughout the process. In addition, the impedance data of the chest may include the impedance data of the time period from the perfusion moment to the ventilation moment.

[0048] As described above, the analysis method may include step S104. In some examples, in step S104, multiple heartbeat cycle moments may be obtained. In some examples, multiple heartbeat cycle moments may correspond to multiple heartbeat cycles respectively (may also be referred to as multiple heartbeat cycle moments corresponding to multiple heartbeat cycles respectively). Specifically, the heartbeat cycle moments may have a one-to-one correspondence with the heartbeat cycle.

[0049] In some examples, each of the plurality of heart cycle moments may be greater than the perfusion moment and not greater than the ventilation moment. In this case, interference from other heart cycle moments can be reduced.

[0050] In some examples, the plurality of cardiac cycle moments may include a first moment, a second moment, a third moment, and a fourth moment corresponding to two, three, four, and five cardiac cycles from the perfusion moment. In some examples, if the fourth moment is greater than the ventilation moment, the plurality of cardiac cycle moments may not include the fourth moment.

[0051] Fig. 4(a) is a schematic diagram showing a target impedance waveform involved in an example of the present disclosure. Fig. 4(b) is a flow chart showing a heart rate determination involved in an example of the present disclosure.

[0052] In some examples, multiple heartbeat cycle moments can be obtained based on the heart rate. Thus, accurate heartbeat cycle moments can be obtained. In some examples, the kth heartbeat cycle moment T among the multiple heartbeat cycle moments k Can satisfy the formula:

[0053] T k =T b +60 / HR×(k+1),

[0054] Among them, T k <T e , HR can represent heart rate, T b Can represent the injection time, T e Thus, the heartbeat cycle time can be obtained based on the heart rate.

[0055] For example, the first moment T1 may satisfy T1=T b +60 / HR×2, the second moment T2 can satisfy T2=T b +60 / HR×3, the third moment T3 can satisfy T3=T b +60 / HR×4, the fourth moment T4 can satisfy T4=T b +60 / HR×5. Generally speaking, starting from the first moment T1, more perfusate will enter the lung tissue.

[0056] In some examples, the heart rate can be determined based on a target impedance waveform corresponding to at least one pixel of the heart region that changes with time. As an example, FIG4(a) shows a schematic diagram of the target impedance waveform. However, the examples of the present disclosure are not limited thereto, and in other examples, the heart rate can also be an empirical value.

[0057] In some examples, the impedance data of the heart can be obtained from the impedance data to be analyzed (that is, the impedance data recorded during the whole process). In some examples, the impedance data to be analyzed for a preset time can be processed by a bandpass filter to obtain the impedance data of the heart (that is, the impedance of the heart over time), and then the target impedance waveform corresponding to at least one pixel of the heart is determined based on the impedance data of the heart. In addition, the lower cutoff frequency and the upper cutoff frequency of the bandpass filter can be adjusted according to actual conditions.

[0058] For example, data of a preset time length (e.g., more than 10 seconds) can be arbitrarily selected from the impedance data recorded by the electrical impedance tomography device 20 during the whole process, and the lower cutoff frequency (e.g., 0.8 Hz (hertz)) and the upper cutoff frequency (e.g., 2.5 Hz) of the bandpass filter can be set. The impedance data of the preset time length can be processed by the bandpass filter to obtain the impedance data of the heart part, and then at least one pixel of the heart part can be selected (e.g., the pixel of the 6th row and the 17th column can be selected), and the target impedance waveform of the impedance change over time corresponding to the at least one pixel can be obtained based on the impedance data of the heart part. In some examples, at least one pixel of the heart part can be selected based on experience.

[0059] As described above, the heart rate can be determined based on a target impedance waveform corresponding to at least one pixel of the heart region that varies with time. In some examples, as shown in FIG4( b), determining the heart rate may include obtaining a target time difference based on the target impedance waveform (step S202) and obtaining the heart rate based on the target time difference (step S204). Thus, the heart rate can be obtained based on the impedance of the heart region that varies with time.

[0060] In some examples, in step S202, multiple time differences between multiple adjacent peaks in the target impedance waveform corresponding to each pixel in at least one pixel may be obtained, and the multiple time differences may be averaged to obtain an average time difference corresponding to each pixel. In some examples, if the number of at least one pixel is 1, the target time difference may be the average time difference of the at least one pixel, and if the number of at least one pixel is greater than 1, the target time difference may be the average of the average time differences of the at least one pixel. In some examples, in step S204, 60 may be divided by the target time difference as the heart rate.

[0061] For example, continuing the above example, after obtaining the target impedance waveform of the impedance change over time corresponding to at least one pixel based on the impedance data of the heart, multiple time differences between multiple adjacent peaks in the target impedance waveform are obtained. Let the time difference between the jth adjacent peaks be The average time difference corresponding to each pixel Can satisfy the formula: Among them, mean is the function of finding the average value. If the number of at least one pixel is 1, the heart rate can satisfy the formula: For example, the heart rate corresponding to the average time difference of 0.983 seconds may be 61.03 beats / minute.

[0062] Figure 5(a) is a schematic diagram showing a pulmonary blood perfusion diagram corresponding to the first moment involved in the example of the present disclosure. Figure 5(b) is a schematic diagram showing a pulmonary blood perfusion diagram corresponding to the second moment involved in the example of the present disclosure. Figure 5(c) is a schematic diagram showing a pulmonary blood perfusion diagram corresponding to the third moment involved in the example of the present disclosure. Figure 5(d) is a schematic diagram showing a pulmonary blood perfusion diagram corresponding to the fourth moment involved in the example of the present disclosure. Figure 5(e) is a flowchart showing the acquisition of pulmonary blood perfusion diagrams and pulmonary blood perfusion values ​​corresponding to each heart cycle moment involved in the example of the present disclosure.

[0063] As described above, the analysis method may include step S106. In some examples, in step S106, a pulmonary blood perfusion map and a pulmonary blood perfusion value corresponding to each of the multiple cardiac cycle moments may be obtained. As an example, FIG. 5(a), FIG. 5(b), FIG. 5(c), and FIG. 5(d) respectively show pulmonary blood perfusion maps corresponding to the first moment to the fourth moment.

[0064] In some examples, in step S106, pixel values ​​(also referred to as perfusion values) of the pixels of the lungs can be obtained based on the impedance of the pixels of the lungs that changes with time within a preset time range and the time window of the sliding window method, and then a pulmonary blood perfusion map can be obtained based on the pixel values ​​of the pixels of the lungs, and then a pulmonary blood perfusion value can be obtained based on the pulmonary blood perfusion map.

[0065] In some examples, the preset time range may be from each heart cycle moment to the ventilation moment in a plurality of heart cycle moments minus the preset window length. In addition, the preset window length may be the window length of the time window in the sliding window method (i.e., the time window length). For example, for the first moment, the preset time range may be T1 to T e -W, for the second moment, the preset time range can be T2 to T e -W, and so on, the preset time ranges corresponding to other heartbeat cycle moments, where T1 can represent the first moment, T2 can represent the second moment, and T e can represent the ventilation moment, and W can represent the preset window length.

[0066] In some examples, as shown in FIG5(e), obtaining the pulmonary blood perfusion map and pulmonary blood perfusion value corresponding to each cardiac cycle moment may include obtaining an impedance sequence (step S302), obtaining a pulmonary blood perfusion map based on a sliding window method (step S304), and obtaining a pulmonary blood perfusion value based on the pulmonary blood perfusion map (step S306). Thus, the pulmonary blood perfusion map and pulmonary blood perfusion value corresponding to each cardiac cycle moment can be obtained based on the impedance of the lungs that changes over time.

[0067] In some examples, in step S302, the impedance of the lung pixels that changes with time within a preset time range corresponding to each heartbeat cycle moment can be obtained as an impedance sequence corresponding to the lung pixels. Thus, multiple impedance sequences corresponding to multiple lung pixels can be obtained.

[0068] In some examples, in step S304, multiple time segments of the impedance sequence of each pixel can be obtained based on the time window of the sliding window method, and then multiple descending slopes corresponding to the impedance in the multiple time segments are obtained and the maximum descending slope is used as the pixel value of the pixel of the pulmonary blood perfusion map. The window length of the time window can be the above-mentioned preset window length.

[0069] Specifically, the window length and moving step of the time window can be set (for example, the window length can be set to 2 seconds and the moving step can be set to 0.1 seconds), the time window is moved along the impedance sequence with the moving step to generate multiple time segments, the impedance drop slope in each time segment is calculated, and the maximum drop slope is selected from the multiple drop slopes corresponding to the multiple time segments as the pixel value of the pixel of the pulmonary blood perfusion map. In this case, the pixel value of each pixel of the pulmonary blood perfusion map can be obtained, and then the pulmonary blood perfusion map can be obtained.

[0070] In addition, the largest descending slope among the multiple descending slopes corresponding to the multiple time segments may also be referred to as the perfusion value of the pixel of the lung. In some examples, the window length and the moving step length of the time window may be adjusted according to actual conditions.

[0071] In some examples, in step S304, the sum of the pixel values ​​of the pixels in the pulmonary blood perfusion map may be used as the pulmonary blood perfusion value. k Corresponding pulmonary blood perfusion value PerfusionMap Tk Can satisfy the formula:

[0072]

[0073] in, It can represent the kth heartbeat cycle time T k The pixel value of the mth pixel of the corresponding pulmonary blood perfusion map, M can represent the kth heart cycle time T kThe number of pixels of the corresponding pulmonary blood perfusion map. For example, calculated by the above formula, the pulmonary blood perfusion value corresponding to the first moment T1 may be 0.0763, the pulmonary blood perfusion value corresponding to the second moment T2 may be 0.0654, the pulmonary blood perfusion value corresponding to the third moment T3 may be 0.0537, and the pulmonary blood perfusion value corresponding to the fourth moment T4 may be 0.0517.

[0074] Fig. 6(a) is a schematic diagram showing a beat-to-beat output diagram of a heart region according to an example of the present disclosure. Fig. 6(b) is a flow chart showing a method of obtaining a beat-to-beat output diagram and a beat-to-beat output value of a heart region according to an example of the present disclosure.

[0075] As described above, the analysis method may include step S108. In some examples, in step S108, a beat-to-beat output diagram and a beat-to-beat output value of a heart region may be obtained. As an example, FIG6(a) shows a beat-to-beat output diagram of a heart region.

[0076] In some examples, in step S108, the beat-to-beat output diagram and beat-to-beat output value of the heart region can be obtained based on the decreasing slope of the impedance corresponding to the pixels of the heart region within the target time range. In addition, the target time range can be determined by the perfusion time. Generally speaking, the impedance of the heart region decreases fastest in the first second after the perfusate enters the heart. In some examples, the target time range can be from the perfusion time to the perfusion time plus 1 second. That is, T b To T b +1, where T b The perfusion time can be indicated. In this case, an accurate target time range can be obtained, and then an accurate beat-to-beat output diagram and a beat-to-beat output value can be obtained.

[0077] In some examples, as shown in FIG6( b), obtaining the beat-to-beat output graph and beat-to-beat output value of the heart portion may include taking the descending slope within the target time range as the pixel value of the pixel of the beat-to-beat output graph of the heart portion (step S402) and taking the sum of the pixel values ​​of the pixels of the beat-to-beat output graph of the heart portion as the beat-to-beat output value of the heart portion (step S404). In addition, the descending slope within the target time range may be the descending slope of the impedance corresponding to the pixel of the heart portion within the target time range. Thus, the beat-to-beat output graph and beat-to-beat output value of the heart portion can be obtained.

[0078] In some examples, the beat-per-beat output value SV of the heart region may satisfy the formula:

[0079]

[0080] Among them, SVMap nSV may represent the pixel value of the nth pixel of the beat-to-beat output map of the heart portion, and N may represent the number of pixels of the beat-to-beat output map of the heart portion. For example, calculated via the above formula, SV may be 0.0785.

[0081] As described above, the analysis method may include step S110. In some examples, in step S110, a target pulmonary blood perfusion map may be obtained based on the pulmonary blood perfusion map and the pulmonary blood perfusion value, as well as the stroke output value of the heart. In some examples, in S110, the pulmonary blood perfusion value corresponding to each heart cycle moment in a plurality of heart cycle moments and the stroke output value of the heart may be compared to obtain a pulmonary blood perfusion map corresponding to a heart cycle moment in which the pulmonary blood perfusion value is closest to the stroke output value of the heart as the target pulmonary blood perfusion map (i.e., a pulmonary blood perfusion map of the lungs). In addition, the heart cycle moment corresponding to the target pulmonary blood perfusion map may be the termination moment of the perfusion reaching each area of ​​the lung tissue. Thus, the termination moment can be accurately determined.

[0082] Figure 7 It is a schematic diagram showing the pulmonary blood perfusion value and the beat-per-beat output value of the heart corresponding to each heart cycle moment involved in the example of the present disclosure.

[0083] In some examples, the difference between the pulmonary blood perfusion value corresponding to each cardiac cycle and the heart beat output value can be obtained, and the pulmonary blood perfusion map corresponding to the cardiac cycle moment with the smallest absolute value of the difference is used as the target pulmonary blood perfusion map. Figure 7 As shown, the pulmonary blood perfusion value corresponding to the first moment T1 can be 0.0763, the pulmonary blood perfusion value corresponding to the second moment T2 can be 0.0654, the pulmonary blood perfusion value corresponding to the third moment T3 can be 0.0537, the pulmonary blood perfusion value corresponding to the fourth moment T4 can be 0.0517, and the beat output value SV can be 0.0785. The difference corresponding to the first moment T1 is the smallest, and the pulmonary blood perfusion map corresponding to the first moment T1 can be used as the target pulmonary blood perfusion map, and the first moment T1 can be used as the termination moment.

[0084] Figure 8 is a schematic diagram showing a pulmonary ventilation-perfusion ratio diagram involved in an example of the present disclosure.

[0085] In some examples, the analysis method may further include obtaining a pulmonary ventilation-perfusion ratio map (not shown) based on the target pulmonary blood perfusion map. Thus, the physiological state of the lungs can be intuitively analyzed based on the pulmonary ventilation-perfusion ratio map. In addition, the pulmonary ventilation-perfusion ratio map may represent the ratio of the pixel value (also referred to as impedance value) of the pixel of the minute ventilation map to the pixel value of the pixel of the minute pulmonary blood perfusion map.

[0086] In some examples, the pulmonary ventilation-perfusion ratio map may represent the ratio of the pixel value (also referred to as impedance value) of the pixel corresponding to the minute ventilation map of the target lung area to the pixel value of the pixel corresponding to the minute pulmonary blood perfusion map of the target lung area. As an example, Figure 8 The ventilation-perfusion ratio diagram is shown.

[0087] In some examples, the target lung area may be the sum of the pulmonary ventilation area and the pulmonary blood perfusion area. In some examples, the pulmonary ventilation area may be composed of pixels having a first percentage or more of the maximum pixel value in the average tidal map. In some examples, the pulmonary blood perfusion area may be composed of pixels having a second percentage or more of the maximum pixel value in the target pulmonary blood perfusion map. In some examples, the first percentage may be 10% to 30%. In some examples, the second percentage may be 10% to 30%. In addition, the first percentage and the second percentage may be adjusted according to actual conditions.

[0088] In some examples, the ventilation-perfusion ratio graph VP may satisfy the formula:

[0089] VP=Ventilation / Perfusion,

[0090] Wherein, Ventilation can represent the minute ventilation graph of the target lung area, and Perfusion can represent the minute pulmonary blood perfusion graph of the target lung area. Thus, a pulmonary ventilation-perfusion ratio graph can be obtained.

[0091] In some examples, the pixel value of the i-th pixel of the minute ventilation map of the target lung region is Ventilation i Can satisfy the formula:

[0092] Ventilation i =(RR×V T ×(1-DS%))×V i / V lung ,

[0093] Among them, RR can represent the respiratory rate, V T It can represent tidal volume, DS% can represent the proportion of dead space to total ventilation, V i It can represent the pixel value (also called impedance value) of the i-th pixel in the target lung area in the average tidal image, V lung It can represent the moisture value. In some examples, DS% can be set based on experience. For example, DS% can be set to 30%.

[0094] In some examples, the impedance data within a certain time period (e.g., 1 minute) before breath holding can be used to calculate the average of the time differences between adjacent peaks within the certain time period, and then 60 is divided by the average to obtain the respiratory rate. For example, assuming the average is 4.255 seconds, the respiratory rate can be 60 / 4.255=14.1 times / minute.

[0095] In some examples, the average tidal map can be obtained by averaging multiple respiratory cycle tidal maps corresponding to multiple respiratory cycles within a certain time (e.g., 1 minute) before breath holding. Can satisfy the formula: Among them, C can represent the number of respiratory cycle tidal graphs, The tidal graph of the cth respiratory cycle can be represented.

[0096] In some examples, the sum of the pixel values ​​of the pixels in the target lung area of ​​the average tidal image can be used as the tidal value (ie, V lung ).

[0097] In some examples, the pixel value of the i-th pixel of the pulmonary blood perfusion map of the target lung region per minute is Perfusion i Can satisfy the formula:

[0098]

[0099] Among them, SV can represent the beat output value of the heart, HR can represent the heart rate, and PerfusionMap lung It can represent the pulmonary blood perfusion value corresponding to the target lung area in the target pulmonary blood perfusion map (that is, the sum of the pixel values ​​of the pixels corresponding to the target lung area in the target pulmonary blood perfusion map), It can represent the pixel value of the i-th pixel of the target lung area in the target lung blood perfusion map.

[0100] The present disclosure also relates to an analysis device 10 for impedance data of lung perfusion, comprising a memory 11 storing a program and a processor 12 coupled to the memory, wherein the processor 12 is configured to implement the above analysis method when the program is executed by the processor 12.

[0101] The present disclosure also relates to a non-transitory computer-readable storage medium, which may store at least one instruction, and the at least one instruction may be executed by a processor to implement the above-mentioned analysis method. A person of ordinary skill in the art may understand that all or part of the steps in the analysis method in the above-mentioned example may be completed by instructing related hardware through a program (instruction), and the program (instruction) may be stored in a computer-readable memory (storage medium), and the memory may include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, etc.

[0102] Although the present invention is specifically described above in conjunction with the accompanying drawings and embodiments, it is to be understood that the above description does not limit the present invention in any form. Those skilled in the art can deform and change the present invention as needed without departing from the essential spirit and scope of the present invention, and these deformations and changes all fall within the scope of the present invention.

Claims

1. A device for analyzing impedance data of lung perfusion, characterized in that: A method of manufacturing a computer system comprising a memory storing a program and a processor coupled to the memory; the processor is configured to: Acquiring impedance data of a time period from a perfusion moment to a ventilation moment from a target position of the subject to be tested, wherein the target position includes a heart and a lung, and the impedance data includes impedance of each pixel of the target position that changes with time, the perfusion moment indicates the moment when perfusion of the perfusate begins in a breath-holding state of the subject to be tested, and the ventilation moment indicates the moment when the subject to be tested is ventilated again; Acquire a plurality of heartbeat cycle moments corresponding to the plurality of heartbeat cycles respectively based on the heart rate, wherein the heart rate is determined based on a target impedance waveform corresponding to at least one pixel of the heart region where the impedance changes with time; Obtaining a pulmonary blood perfusion map and a pulmonary blood perfusion value corresponding to each of the multiple cardiac cycle moments, wherein the impedance of the pixels of the lung that changes with time within a preset time range corresponding to each cardiac cycle moment is obtained as an impedance sequence corresponding to the pixels of the lung, a plurality of time segments of the impedance sequence are obtained based on a time window of a sliding window method, a plurality of descending slopes corresponding to the impedances in the plurality of time segments are obtained, and the maximum descending slope is used as the pixel value of the pixel of the pulmonary blood perfusion map, and the sum of the pixel values ​​of the pixels of the pulmonary blood perfusion map is used as the pulmonary blood perfusion value; Acquiring a beat-to-beat output diagram and a beat-to-beat output value of the heart portion based on a decreasing slope of impedance corresponding to pixels of the heart portion within a target time range, wherein the target time range is determined by the perfusion time, wherein the decreasing slope within the target time range is used as a pixel value of a pixel of the beat-to-beat output diagram, and the sum of the pixel values ​​of the pixels of the beat-to-beat output diagram is used as the beat-to-beat output value; and By comparing the pulmonary blood perfusion value corresponding to each heart cycle moment in the multiple heart cycle moments and the beat output value, a pulmonary blood perfusion map corresponding to the heart cycle moment where the pulmonary blood perfusion value is closest to the beat output value is obtained as a target pulmonary blood perfusion map.

2. The analysis device according to claim 1, characterized in that: The processor is further configured to obtain a pulmonary ventilation-perfusion ratio map based on the target pulmonary blood perfusion map, wherein the pulmonary ventilation-perfusion ratio map VP satisfies the formula: VP=Ventilation / Perfusion, Wherein, Ventilation represents the minute ventilation graph of the target lung area, Perfusion represents the minute pulmonary blood perfusion graph of the target lung area, and the target lung area is the sum of the pulmonary ventilation area and the pulmonary blood perfusion area; The pixel value of the ith pixel of the minute ventilation graph is Ventilation i Satisfy the formula: Ventilation i =(RR×V T ×(1-DS%))×V i / V lung , Where RR represents the respiratory rate, V T represents tidal volume, DS% represents the proportion of dead space to total ventilation, V i represents the pixel value of the i-th pixel in the target lung area in the average tidal image, V lung Indicates the tidal value; The pixel value of the ith pixel of the pulmonary blood perfusion map per minute i Satisfy the formula: Wherein, SV represents the beat-per-beat value, HR represents the heart rate, and PerfusionMap lung represents the pulmonary blood perfusion value corresponding to the target lung area in the target pulmonary blood perfusion map, Represents the pixel value of the i-th pixel in the target lung area in the target lung blood perfusion map.

3. The analysis device according to claim 1, characterized in that Determining the heart rate based on a target impedance waveform of impedance corresponding to at least one pixel of the heart region changing over time, comprising: Acquire multiple time differences between multiple adjacent peaks in the target impedance waveform corresponding to each pixel in the at least one pixel and average the multiple time differences to obtain an average time difference corresponding to each pixel, and acquire a target time difference based on the average time difference, wherein if the number of the at least one pixel is 1, the target time difference is the average time difference of the at least one pixel, and if the number of the at least one pixel is greater than 1, the target time difference is the average of the average time differences of the at least one pixel; and 60 is divided by the target time difference as the heart rate, wherein the impedance data of a preset time length is processed by a bandpass filter to obtain impedance data of the heart part, and a target impedance waveform corresponding to at least one pixel of the heart part is determined based on the impedance data of the heart part.

4. The analysis device according to claim 1, characterized in that: The kth heartbeat cycle time T among the multiple heartbeat cycle times k Satisfy the formula: T k =T b +60 / HR×(k+1), Among them, T k <T e , HR represents the heart rate, T b represents the injection time, T e Indicates the ventilation moment.

5. The analysis device according to claim 1, characterized in that The preset time range is from each heart cycle moment in the multiple heart cycle moments to the ventilation moment minus a preset window length; the window length of the time window is the preset window length.

6. The analysis device according to claim 1, characterized in that The target time range is from the injection time to the injection time plus 1 second.

7. The analysis device according to claim 1, characterized in that: The perfusate is saline.

8. The analysis device according to claim 1, characterized in that: Each of the plurality of heart cycle moments is greater than the perfusion moment and not greater than the ventilation moment.

9. A method for analyzing impedance data of lung perfusion, characterized in that: include: Acquiring impedance data of a time period from a perfusion moment to a ventilation moment from a target position of the subject to be tested, wherein the target position includes a heart and a lung, and the impedance data includes impedance of each pixel of the target position that changes with time, the perfusion moment indicates the moment when perfusion of the perfusate begins in a breath-holding state of the subject to be tested, and the ventilation moment indicates the moment when the subject to be tested is ventilated again; Acquire a plurality of heartbeat cycle moments corresponding to the plurality of heartbeat cycles respectively based on the heart rate, wherein the heart rate is determined based on a target impedance waveform corresponding to at least one pixel of the heart region where the impedance changes with time; Obtaining a pulmonary blood perfusion map and a pulmonary blood perfusion value corresponding to each of the multiple cardiac cycle moments, wherein the impedance of the pixels of the lung that changes with time within a preset time range corresponding to each cardiac cycle moment is obtained as an impedance sequence corresponding to the pixels of the lung, a plurality of time segments of the impedance sequence are obtained based on a time window of a sliding window method, a plurality of descending slopes corresponding to the impedances in the plurality of time segments are obtained, and the maximum descending slope is used as the pixel value of the pixel of the pulmonary blood perfusion map, and the sum of the pixel values ​​of the pixels of the pulmonary blood perfusion map is used as the pulmonary blood perfusion value; Acquiring a beat-to-beat output diagram and a beat-to-beat output value of the heart portion based on a decreasing slope of impedance corresponding to pixels of the heart portion within a target time range, wherein the target time range is determined by the perfusion time, wherein the decreasing slope within the target time range is used as a pixel value of a pixel of the beat-to-beat output diagram, and the sum of the pixel values ​​of the pixels of the beat-to-beat output diagram is used as the beat-to-beat output value; and By comparing the pulmonary blood perfusion value corresponding to each heart cycle moment in the multiple heart cycle moments and the beat output value, a pulmonary blood perfusion map corresponding to the heart cycle moment where the pulmonary blood perfusion value is closest to the beat output value is obtained as a target pulmonary blood perfusion map.

10. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by a processor, the analysis method according to claim 9 is implemented.

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